My last little problem to fix

[JamesRich]

I am very anal about how my vehicles run so if it ain't just right I am going to screw with it. My fuel mileage isn't what I think it should be and I had a little stumble when I would give it gas after shifting gears, which was worse when the engine was cold. I tore into it and started testing with my scanner.

I get the all clear code so no obvious places to look. I back probed the TPS and checked it for shorts to ground, it all checked ok.

Next I tested the injectors. On the throttle body there is only one plug so I had to release the wires for each injector from the plug. I'm not going to say what a pain in the @&%# that was but both injectors test ok.

Next I found a tip about loose grounds on the intake. I checked the grounds and they were tight and not corroded so they seemed ok. With the resistance problems these truck have I decided to run a new ground wire to them too. I ran a wire from the two grounds on the intake to the passenger side and grounded the other end where the ground cable from the battery bolts to the fender. Bingo! this has taken care of my stumbling problem! The truck runs smooth now through all rpms, but still seems to be lacking power.

At a 2000 rpm rev the O2 sensor switches rich to lean constantly like it should do so I decided to take it for a drive and watch the O2.

I put the computer on the dash and took off, I could still see around it so it seemed safe enough

I took this picture on the way to work, thats why there is a convenience store in the background.

The O2 switches good under light acceleration and steady cruising, but moderate and heavy acceleration it stays lean. I know most people will think running lean should burn less gas but the engine has to work harder under this condition and ends up burning more fuel. I need to gather some fitting to check fuel pressure and the pressure regulator but that's all I can think of.

Anyone else got any ideas?

James

[nunya]

Snap-on red brick! Haven't seen one of those in years!

[Precise1]

TPS??

 

B

[sewebster]

Throttle position sensor?

[krmiller07]

I am very anal about how my vehicles run so if it ain't just right I am going to screw with it. My fuel mileage isn't what I think it should be and I had a little stumble when I would give it gas after shifting gears, which was worse when the engine was cold. I tore into it and started testing with my scanner.

I get the all clear code so no obvious places to look. I back probed the TPS and checked it for shorts to ground, it all checked ok.

Next I tested the injectors. On the throttle body there is only one plug so I had to release the wires for each injector from the plug. I'm not going to say what a pain in the @&%# that was but both injectors test ok.

Next I found a tip about loose grounds on the intake. I checked the grounds and they were tight and not corroded so they seemed ok. With the resistance problems these truck have I decided to run a new ground wire to them too. I ran a wire from the two grounds on the intake to the passenger side and grounded the other end where the ground cable from the battery bolts to the fender. Bingo! this has taken care of my stumbling problem! The truck runs smooth now through all rpms, but still seems to be lacking power.

At a 2000 rpm rev the O2 sensor switches rich to lean constantly like it should do so I decided to take it for a drive and watch the O2.

I put the computer on the dash and took off, I could still see around it so it seemed safe enough

I took this picture on the way to work, thats why there is a convenience store in the background.

The O2 switches good under light acceleration and steady cruising, but moderate and heavy acceleration it stays lean. I know most people will think running lean should burn less gas but the engine has to work harder under this condition and ends up burning more fuel. I need to gather some fitting to check fuel pressure and the pressure regulator but that's all I can think of.

Anyone else got any ideas?

James

I'm curious. What kind of milage have you been getting. I recently discovered my rough running at cold start and erratic -idle problems were carbon build up in the intake, injectors and valves. I ran 2 bottles of Chevron Tech-ron through the tank, with about a 1/4 tank of fuel. Helped the start up problem and smoothed out the idle, however my milage is still really poor. I'm averaging around 10-12 mpg on the hiway! I was told everything from intake leaks to broken valve springs and all the obvious tune up related possibilites. It runs so smooth now, sometimes it's hard to tell if it's running. Now if I could get the milage up to a reasonable level I'd be a very happy camper! : ).BTW, where did you find the thread on the intake ground leads? And where on the intake are they located?

Edited November 1, 2010 by krmiller07

[JamesRich]

Snap-on red brick! Haven't seen one of those in years!

I hadn't needed it in years! Ever since OBDII systems came out I use my lap top with one of those cables. You guys with the 96 on up have this option. makes it alot easier to trouble shoot when you can see what all the sensors are doing. These cables are only around $100 if you have a laptop.

 

I'm curious. What kind of mileage have you been getting. I recently discovered my rough running at cold start and erratic -idle problems were carbon build up in the intake, injectors and valves. I ran 2 bottles of Chevron Tech-ron through the tank, with about a 1/4 tank of fuel. Helped the start up problem and smoothed out the idle, however my milage is still really poor. I'm averaging around 10-12 mpg on the hiway! I was told everything from intake leaks to broken valve springs and all the obvious tune up related possibilites. It runs so smooth now, sometimes it's hard to tell if it's running. Now if I could get the milage up to a reasonable level I'd be a very happy camper! : ).BTW, where did you find the thread on the intake ground leads? And where on the intake are they located?

My mileage varies which is what bothers me. If I get on the interstate doing 70mph at 3000 rpms I can see the gas gage dropping like it was poring gas out the back.

My last hunting trip I averaged 17mpg for the whole trip. On the highway for the 70 miles to get to my camp the gas gage hardly moved. Riding around on trails in the woods maybe 15 miles I burned almost a half tank. Then the highway back the gage hardly moved again.

Now I can see with my scanner, on the highway at 60mph the fuel mixture is staying where its supposed to. while accelerating on the trails it's running lean and straining.

I already checked the TPS with info that came with my scanner. That is the same place I found the tip on the ground wires. The tip just said to clean the connection, I decided to add the extra wire.

I will try and scan a few of the pages and post them here. There wasn't much on Nissan's in there though. Now if I could just find the connections for my fuel pressure gage so I could check the pressure. I hate moving! I moved 3 years ago and still don't know where all my stuff is at!

James

[Kingman]

TPS shouldn't affect much at all, but it will screw with the idle sometimes. I've driven my TBI with it unplugged, ran perfect, and my Z31 doesn't have it hooked up either and makes no difference drivability-wise. Doesn't make a difference if it's plugged in either past tip-in (makes the throttle a little touchier). The TBIs seem to be a lot less sensitive to TPS inputs than the MPFIs.

 

You can manually adjust the AFM by a set screw on the rear most driver's side of the throttle body right by the mounting nut. It's a small flat head, turning it clockwise will lean the mixture and counter clockwise will richen it out.

Edited November 1, 2010 by Kingman

[krmiller07]

I hadn't needed it in years! Ever since OBDII systems came out I use my lap top with one of those cables. You guys with the 96 on up have this option. makes it alot easier to trouble shoot when you can see what all the sensors are doing. These cables are only around $100 if you have a laptop.

 

 

My mileage varies which is what bothers me. If I get on the interstate doing 70mph at 3000 rpms I can see the gas gage dropping like it was poring gas out the back.

My last hunting trip I averaged 17mpg for the whole trip. On the highway for the 70 miles to get to my camp the gas gage hardly moved. Riding around on trails in the woods maybe 15 miles I burned almost a half tank. Then the highway back the gage hardly moved again.

Now I can see with my scanner, on the highway at 60mph the fuel mixture is staying where its supposed to. while accelerating on the trails it's running lean and straining.

I already checked the TPS with info that came with my scanner. That is the same place I found the tip on the ground wires. The tip just said to clean the connection, I decided to add the extra wire.

I will try and scan a few of the pages and post them here. There wasn't much on Nissan's in there though. Now if I could just find the connections for my fuel pressure gage so I could check the pressure. I hate moving! I moved 3 years ago and still don't know where all my stuff is at!

James

If your truck is an 87 through 89 with TBI, all you need to do is disconnect the fuel line feed coming out of the regulator into the TBI and put your regulator in there and turn the key on to the last position before the starter engages. You should get a reading of at least 36 psi. I think the factory spec is 36.5 psi. Leave the gauge hooked up and see if it bleeds down. Mine read 36.2 and stayed around 32-34 psi after about 20 mins. As far as I know, the only reading you can take is a "static" reading, unless your trying to find out the fuel preassure while it's running?

I know what you mean about wtching the gauge drop rather "quickly" mine does that from the full mark until it gets down to around 1/4- 1/2 mark. I'd be extremely happy to get 17 mpg on the hi-way! I posted in "my garage" about a month ago with my symptoms. After digging further and on othe Pathy sites, I came across the threa and TSB about the premature carbon bvuild up problem. The factory engineer who was on the design team for the TBI system wrote the fix on "walnut" blasting the intake and valves to get rid of the fuel saturation problem from carbon build up, as well as poor milage and erratic fuel mixtures and rough idle issues.

Have you checked your 'cat' if your still running one? Maybe it's plugged or plugging up?

 

krmiller07

[krmiller07]

I hadn't needed it in years! Ever since OBDII systems came out I use my lap top with one of those cables. You guys with the 96 on up have this option. makes it alot easier to trouble shoot when you can see what all the sensors are doing. These cables are only around $100 if you have a laptop.

 

 

My mileage varies which is what bothers me. If I get on the interstate doing 70mph at 3000 rpms I can see the gas gage dropping like it was poring gas out the back.

My last hunting trip I averaged 17mpg for the whole trip. On the highway for the 70 miles to get to my camp the gas gage hardly moved. Riding around on trails in the woods maybe 15 miles I burned almost a half tank. Then the highway back the gage hardly moved again.

Now I can see with my scanner, on the highway at 60mph the fuel mixture is staying where its supposed to. while accelerating on the trails it's running lean and straining.

I already checked the TPS with info that came with my scanner. That is the same place I found the tip on the ground wires. The tip just said to clean the connection, I decided to add the extra wire.

I will try and scan a few of the pages and post them here. There wasn't much on Nissan's in there though. Now if I could just find the connections for my fuel pressure gage so I could check the pressure. I hate moving! I moved 3 years ago and still don't know where all my stuff is at!

James

If your truck is an 87 through 89 with TBI, all you need to do is disconnect the fuel line feed coming out of the regulator into the TBI and put your regulator in there and turn the key on to the last position before the starter engages. You should get a reading of at least 36 psi. I think the factory spec is 36.5 psi. Leave the gauge hooked up and see if it bleeds down. Mine read 36.2 and stayed around 32-34 psi after about 20 mins. As far as I know, the only reading you can take is a "static" reading, unless your trying to find out the fuel preassure while it's running?

I know what you mean about wtching the gauge drop rather "quickly" mine does that from the full mark until it gets down to around 1/4- 1/2 mark. I'd be extremely happy to get 17 mpg on the hi-way! I posted in "my garage" about a month ago with my symptoms. After digging further and on othe Pathy sites, I came across the threa and TSB about the premature carbon bvuild up problem. The factory engineer who was on the design team for the TBI system wrote the fix on "walnut" blasting the intake and valves to get rid of the fuel saturation problem from carbon build up, as well as poor milage and erratic fuel mixtures and rough idle issues.

Have you checked your 'cat' if your still running one? Maybe it's plugged or plugging up?

 

krmiller07

[krmiller07]

TPS shouldn't affect much at all, but it will screw with the idle sometimes. I've driven my TBI with it unplugged, ran perfect, and my Z31 doesn't have it hooked up either and makes no difference drivability-wise. Doesn't make a difference if it's plugged in either past tip-in (makes the throttle a little touchier). The TBIs seem to be a lot less sensitive to TPS inputs than the MPFIs.

 

You can manually adjust the AFR by a set screw on the rear most driver's side of the throttle body right by the mounting nut. It's a small flat head, turning it clockwise will lean the mixture and counter clockwise will richen it out.

Kingman, I think I read a post a few moths ago about this "mystry" screw. Is your truck a V-6? and are you sure the direction you turn it (as you wrote) leans and richens the mixture? What is "AFR"? Do you mean Air Flow Richness or Air Flow Regulator?

 

Thanks,

 

krmiller07

[Kingman]

Kingman, I think I read a post a few moths ago about this "mystry" screw. Is your truck a V-6? and are you sure the direction you turn it (as you wrote) leans and richens the mixture? What is "AFR"? Do you mean Air Flow Richness or Air Flow Regulator?

 

Thanks,

 

krmiller07

 

Air/Fuel Mixture (you replied before I edited AFR to AFM, although AFR could mean Air/Fuel Ratio). It's a V6, but it makes no difference as the throttle body system is identical between the Z24I and the VG30I and mines not even TBI anymore.

Edited November 1, 2010 by Kingman

[krmiller07]

Air/Fuel Mixture (you replied before I edited AFR to AFM, although AFR could mean Air/Fuel Ratio). It's a V6, but it makes no difference as the throttle body system is identical between the Z24I and the VG30I and mines not even TBI anymore.

 

I'm gonna play devils advocate here. Wouldn't turning the idle mixture screw counter clockwise (or out) lean out the mixture? Allowing more air in (giving it more air per given unit of fuel)effectively leaning it out? Sorry about that! I'm quick on the keyboard this morning! This problem has been haunting me and making me nuts. it's been getting colder here in MN and my rig spend more time "warming up" in the morning! And costing me more $$$ doing so!

 

krmiller07

[Kingman]

I'm gonna play devils advocate here. Wouldn't turning the idle mixture screw counter clockwise (or out) lean out the mixture? Allowing more air in (giving it more air per given unit of fuel)effectively leaning it out? Sorry about that! I'm quick on the keyboard this morning! This problem has been haunting me and making me nuts. it's been getting colder here in MN and my rig spend more time "warming up" in the morning! And costing me more $ doing so!

 

krmiller07

 

I may have it backwards, but I turned mine counter clockwise to lean it out originally and it ended up richening the mixture an insane amount. I don't think it's ever used that much gas going only a few miles up the freeway! I got back on here and the guy had posted his findings with an exhaust gas analyzer and reported that it was the opposite.... I turned mine back in and it sucked less gas.

 

Warming up... don't let it sit and idle when it's cold. It's not good for your engine whatsoever as the fuel will not completely burn when cold at idle, and ends up as nasty carbon deposits everywhere. The faster you get that thing out of closed loop the better, all that's needed when first starting before driving is about 15 seconds for the oil to completely circulate.

 

Edited November 1, 2010 by Kingman

[krmiller07]

I may have it backwards, but I turned mine counter clockwise to lean it out originally and it ended up richening the mixture an insane amount. I don't think it's ever used that much gas going only a few miles up the freeway! I got back on here and the guy had posted his findings with an exhaust gas analyzer and reported that it was the opposite.... I turned mine back in and it sucked less gas.

 

Warming up... don't let it sit and idle when it's cold. It's not good for your engine whatsoever as the fuel will not completely burn when cold at idle, and ends up as nasty carbon deposits everywhere. The faster you get that thing out of closed loop the better, all that's needed when first starting before driving is about 15 seconds for the oil to completely circulate.

 

Thanks man,

 

Where did you find the posting with the guy and the analyzer? I'd be interested in reading it. I know these rigs never got great milage when they came out. i bought an 88 SE new in 89 as a carry over. And suck fuel pretty bad then, but mine seems worse than i can ever remember. the sad part is, I just replaced the engine a year ago, with a unit out of a 2wd P/U with 42k documented miles. So I know for the most part, that it in good shape. Compression was recently tested @ 190-196 lbs. The only thig we didn't do was pull the heads and freshen them up. Now that the earlier posted carbon issue was taken care of, it runs smoother that it ever has. I ran a BG Intake Systen Cleaning through the whole intake system just after the motor was installed, and you wouldn't believe the crap that came out of the 'cat' less exhaust! I left a black circle on the wall of the gararge 10" in dia.! I got about 450-500 miles to a tank of gas after that on the hi-way. have you ever tried that system? Seems to work pretty good. Theey spray the cleanr directly down the throat of the TBI, while it idles at around 1500 rpm, then you ad the "44k" fuel addative to your tank of fuel. I had my cat on then, butafter you drive the thing long enough to get the cat good and hot, it all burns through and won't srew up the O2 sensor(s).

 

krmiller07

[MY1PATH]

I'm gonna play devils advocate here. Wouldn't turning the idle mixture screw counter clockwise (or out) lean out the mixture? Allowing more air in (giving it more air per given unit of fuel)effectively leaning it out? Sorry about that! I'm quick on the keyboard this morning! This problem has been haunting me and making me nuts. it's been getting colder here in MN and my rig spend more time "warming up" in the morning! And costing me more $$$ doing so!

 

krmiller07

 

The screw is not letting more engine into the engine Like a carb. The screw is letting more air go past the Air sensor and more air past the sensor tells the ecu to add more fuel.

IIRC not all the TBI engines had this screw I think some of them had it ajusted and plugged at the factory...

Edited November 2, 2010 by MY1PATH

[JamesRich]

You can manually adjust the AFM by a set screw on the rear most driver's side of the throttle body right by the mounting nut. It's a small flat head, turning it clockwise will lean the mixture and counter clockwise will richen it out.

I remember that post, hopefully mine has the screw. Once I get a fuel pressure reading and know that is ok, I will try adjusting that screw and see what I get with fuel mixtures.

James

[krmiller07]

I may have it backwards, but I turned mine counter clockwise to lean it out originally and it ended up richening the mixture an insane amount. I don't think it's ever used that much gas going only a few miles up the freeway! I got back on here and the guy had posted his findings with an exhaust gas analyzer and reported that it was the opposite.... I turned mine back in and it sucked less gas.

 

Warming up... don't let it sit and idle when it's cold. It's not good for your engine whatsoever as the fuel will not completely burn when cold at idle, and ends up as nasty carbon deposits everywhere. The faster you get that thing out of closed loop the better, all that's needed when first starting before driving is about 15 seconds for the oil to completely circulate.

 

 

 

Kingman,

 

You mentioned earlier that your rig doesn't have TBI any more. Did you opt to go with the 2 barrel carb set up? I was reading bout that, and haven't heard from anyone who's actually tried it. Aside from having more options for jetting what are the benefits? And is it worth the trouble and expence? I heard you have to convert the distributor over to one with vacum advance to make this work. Or you can modify a dist out of an earlier model Z car at about $400.00 a pop!

[Kingman]

Kingman,

 

You mentioned earlier that your rig doesn't have TBI any more. Did you opt to go with the 2 barrel carb set up? I was reading bout that, and haven't heard from anyone who's actually tried it. Aside from having more options for jetting what are the benefits? And is it worth the trouble and expence? I heard you have to convert the distributor over to one with vacum advance to make this work. Or you can modify a dist out of an earlier model Z car at about $400.00 a pop!

 

I swapped in a Z31 MPFI intake, injection system, and computer. I have a thread about it on here, you can see a picture in my signature - far right.

 

Mr.510 is the one who takes TBI lower intake manifold cores and guts them, then welds the adapter plate on to install a Holley 2 barrel carb for Datsun VG510s.

 

James, what does your O2 sensor do above 2800 RPM? That's when it completely takes over the fuel mixture. Seems weird that it would lean out under acceleration...

Edited November 2, 2010 by Kingman

[JamesRich]

I swapped in a Z31 MPFI intake, injection system, and computer. I have a thread about it on here, you can see a picture in my signature - far right.

 

Mr.510 is the one who takes TBI lower intake manifold cores and guts them, then welds the adapter plate on to install a Holley 2 barrel carb for Datsun VG510s.

 

James, what does your O2 sensor do above 2800 RPM? That's when it completely takes over the fuel mixture. Seems weird that it would lean out under acceleration...

I never watched the O2 above 2800 at a steady cruse, under WOT it stays lean.

This gives me more to think about because on the interstate at 70mph it is running at 3000 rpms. At this speed you would think there was a hole in the tank with the way the fuel gage is dropping. With the resistance issues on these trucks I wonder if I need to ground the exhaust pipe? The O2 is new but to be burning that much fuel it cant be actually running lean.

I would love to go with the carb option right now if it were an easy swap. I'm getting really tired of screwing with this early limited feed back injection system.

My blood pressure just jumped a notch higher yesterday thanks to my local nissan. I decided to park the pathy and drive the Titan till I get time to work on it. My wife just brought my titan to nissan to replace the electric A/C condenser fan that nissan extended the warranty on to 80K because they are crap. Now the blower fan inside the truck stays on high no matter what the auto climate control is set on.

I'm so fed up with this dealer screwing thing up on my truck when they are doing warranty work that I am calling Nissanusa and ratting them out!

James

[krmiller07]

I never watched the O2 above 2800 at a steady cruse, under WOT it stays lean.

This gives me more to think about because on the interstate at 70mph it is running at 3000 rpms. At this speed you would think there was a hole in the tank with the way the fuel gage is dropping. With the resistance issues on these trucks I wonder if I need to ground the exhaust pipe? The O2 is new but to be burning that much fuel it cant be actually running lean.

I would love to go with the carb option right now if it were an easy swap. I'm getting really tired of screwing with this early limited feed back injection system.

My blood pressure just jumped a notch higher yesterday thanks to my local nissan. I decided to park the pathy and drive the Titan till I get time to work on it. My wife just brought my titan to nissan to replace the electric A/C condenser fan that nissan extended the warranty on to 80K because they are crap. Now the blower fan inside the truck stays on high no matter what the auto climate control is set on.

I'm so fed up with this dealer screwing thing up on my truck when they are doing warranty work that I am calling Nissanusa and ratting them out!

James

 

This is turning out to be a very interesting thread! I also replace my O2 sensor, and the coolant temp sensor (the one behind the AC bracket)with no notable changes. It still ran rich, and rough (like a carbed vehicle with a sticking choke) then I had the exhaust system ( from where the cat used to be),muffler and tail pipe replaced (because it was rusted out). Within 25 miles I noticed it started running better. Then the next day, after it sat overnight I went to start it cold. Much to my suprise, it started and ran normally until it was up to operating temp. No it runs like a champ, with the exeption of the fuel milage being really poor. No I cant say if it was the exhaust system made the difference (odd) or it was all the techron I dumped in the tank. I suppose it's possible the carbon started disolving in the injectors that may of been not closing all the way, or the carbon was so bad on the intake valves that it was saturated with fuel and dripping into the combustion chambers? Any way I think I should be getting better milage than I am. Like you stated, I should not be seeing the fuel gauge drop like a rock while cruising at 65-75 mph!

 

Feel free to call me when the Titan needs pads and rotors! I work for Frozenrotors. My link.I can set you up with a much better solution to brakes than what your dealing with (and not break your bank account) no pun intended!

Let me know what you find out with this fuel milage issue.

 

Keith

 

krmiller07

Edited November 3, 2010 by krmiller07

[JamesRich]

This is turning out to be a very interesting thread! I also replace my O2 sensor, and the coolant temp sensor (the one behind the AC bracket)with no notable changes. It still ran rich, and rough (like a carbed vehicle with a sticking choke) then I had the exhaust system ( from where the cat used to be),muffler and tail pipe replaced (because it was rusted out). Within 25 miles I noticed it started running better. Then the next day, after it sat overnight I went to start it cold. Much to my suprise, it started and ran normally until it was up to operating temp. No it runs like a champ, with the exeption of the fuel milage being really poor. No I cant say if it was the exhaust system made the difference (odd) or it was all the techron I dumped in the tank. I suppose it's possible the carbon started disolving in the injectors that may of been not closing all the way, or the carbon was so bad on the intake valves that it was saturated with fuel and dripping into the combustion chambers? Any way I think I should be getting better milage than I am. Like you stated, I should not be seeing the fuel gauge drop like a rock while cruising at 65-75 mph!

 

Feel free to call me when the Titan needs pads and rotors! I work for Frozenrotors. My link.I can set you up with a much better solution to brakes than what your dealing with (and not break your bank account) no pun intended!

Let me know what you find out with this fuel milage issue.

 

Keith

 

krmiller07

The Titan is already running a set of slotted frozen rotors and hawk pads! It fixed the shaking problem I've had since the truck was new. I don't think I could work with you guys. I would want to treat every gun and automotive part I have. Y'all would run me out of there!

On the Pathy I think I may be due for y'all all to line up and take turns giving me a good swift kick in the butt! When I bought the truck it had an exhaust leak right in front of the Y pipe. Every bolt on the exhaust system looks like it will break off if I screw with them so I figured I would ignore the leak because it's not very loud. Now that I think about it, the leak is in front of the O2 so if the exhaust has decent enough flow it will suck fresh air into the system and make the O2 get a lean reading and then richen up the mixture to try and compensate.

This is just my educated guess, I'm not screwing with the exhaust till after hunting season so I guess I'll just have to learn to ignore the fuel mileage for now.

This little truck will drive me drinking trying to get it running right!

James

[frozenrotors]

The Titan is already running a set of slotted frozen rotors and hawk pads! It fixed the shaking problem I've had since the truck was new. I don't think I could work with you guys. I would want to treat every gun and automotive part I have. Y'all would run me out of there!

On the Pathy I think I may be due for y'all all to line up and take turns giving me a good swift kick in the butt! When I bought the truck it had an exhaust leak right in front of the Y pipe. Every bolt on the exhaust system looks like it will break off if I screw with them so I figured I would ignore the leak because it's not very loud. Now that I think about it, the leak is in front of the O2 so if the exhaust has decent enough flow it will suck fresh air into the system and make the O2 get a lean reading and then richen up the mixture to try and compensate.

This is just my educated guess, I'm not screwing with the exhaust till after hunting season so I guess I'll just have to learn to ignore the fuel mileage for now.

This little truck will drive me drinking trying to get it running right!

James

Hi James,

 

I feel your pain! I had the same exhaust leak where the manifold connects to the down pipes, I seriously doubt that a leak in or around the 'Y' pipe is going to draw that much air back into the exhaust system to cause the 02 sensor to pick it up!? But then again I can't explain my sudden change of cold start idle issue either! It still want's to fall into the rough idle mode, for a few minutes when warming up. However I think it was Kingman who suggested not letting it sit while warming up. That kind of goes against my better judgment of letting the heat fully transfer into all the engine components before putting any load on them. But it does make sense if you want the 02 sensor to go into open loop mode! I haven't tried adjusting this idle (mystery)screw in the back of the throttle body yet. My TB has one, for some reason! I'd prefer to do it with an exhaust gas analyzer , but I don't have access to one unless I can get into a shop that will set me up and not bleed my wallet!

 

I have you PM in regards to your question. I am looking into it. If you want to call and talk to our head Cryo tech guy, call me at 1-888-323-8456 between 8:00am - 5:30 pm CST M-F. Or I can have him call you, If you want to PM me your work # that will work too.

 

Keith

km@frozenrotors.com

Edited November 4, 2010 by frozenrotors

[adamzan]

The Titan is already running a set of slotted frozen rotors and hawk pads! It fixed the shaking problem I've had since the truck was new. I don't think I could work with you guys. I would want to treat every gun and automotive part I have. Y'all would run me out of there!

On the Pathy I think I may be due for y'all all to line up and take turns giving me a good swift kick in the butt! When I bought the truck it had an exhaust leak right in front of the Y pipe. Every bolt on the exhaust system looks like it will break off if I screw with them so I figured I would ignore the leak because it's not very loud. Now that I think about it, the leak is in front of the O2 so if the exhaust has decent enough flow it will suck fresh air into the system and make the O2 get a lean reading and then richen up the mixture to try and compensate.

This is just my educated guess, I'm not screwing with the exhaust till after hunting season so I guess I'll just have to learn to ignore the fuel mileage for now.

This little truck will drive me drinking trying to get it running right!

James

An exhaust leak there will make your mileage worse. I have one right now and my mileage has gone down quite a bit. I can only get like 450km's to a tank if I'm easy on it. I used to be able to get 500 or even close to 600 driving like a grandma.

[JamesRich]

An exhaust leak there will make your mileage worse. I have one right now and my mileage has gone down quite a bit. I can only get like 450km's to a tank if I'm easy on it. I used to be able to get 500 or even close to 600 driving like a grandma.

We'll see, I did some Cajun engineering! I clamped a big pair of vise grip pliers on the flange to hold it together Lol! It slowed the leak down but didn't seem to make too much difference with the O2 running lean. Maybe it needs a little run time to register the difference. I'm going hunting this weekend so I will see if it makes a difference. I hope I don't loose my vise grips!

James

[krmiller07]

I swapped in a Z31 MPFI intake, injection system, and computer. I have a thread about it on here, you can see a picture in my signature - far right.

 

Mr.510 is the one who takes TBI lower intake manifold cores and guts them, then welds the adapter plate on to install a Holley 2 barrel carb for Datsun VG510s.

 

James, what does your O2 sensor do above 2800 RPM? That's when it completely takes over the fuel mixture. Seems weird that it would lean out under acceleration...

Kingman,

 

I've been looking fpr the thread on the Z31 intake and injection swap. Under what section did this get posted?

 

Thanks