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Intro: 93 SE V6 lacking power


PhreakdOut
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Hey there all:

I just discovered this forum last night when looking for some answers to repair questions. I wish I had done this a year or so ago when I bought the truck used. :blink:

 

My Pathy has all the typical questions in the FAQ and the Search function actually works (lol) so I won't bother anyone with the "What the heck is that terrible noise when I back off the driveway or why is it so noisy when it's running cold?" I will be torquing those bolts down as soon as the sun rises. As for the manifold, well time to look at headers of learn to love the "Model A Ford sound." Good grief I've hated that noise.

 

My Pathy was originally a South Carolina truck owned by a friend of mine at work. (He bought it new.) Just a few little spots of flaked off paint and very little rust. She has 195K on the odo but the speedo assembly was replaced at 55K so I'm kidding myself ... she's got a quarter million on her. The driver's side needs some body work after the wife spun it into a ditch on an icy day. (Don't get me started on that topic.) I've replaced the shattered chrome mirror assembly with a pair of black ones off EBay and it looks 100% better. (Chrome is so dated) :rolleyes: LOL.

 

The big problem I'm facing now is a recent lack of power. I know it's not a fast vehicle, but in the past 4 months it's become much worse. Time to get my lazy butt out there.

 

I checked compression and changed the plugs. Compression averages 120psi. Is this normal for this age of truck? It's very even all the way around so no worries about leaking headgasket. The plugs were greyish with no blistering. (Just on the edge of looking lean.) I suspect they were changed 25K ago. Wires are all in good shape as well.

 

I pulled the pass seat to check the codes (then realized the code lights are visible from the rear. DOH! Damn Nissan service manual. I ran diagnostics I through V and no codes came up. I'd hoped it would be something simple like a MAF. I hate timing belts. I've changed a bunch on Z31s. This is pretty much the same except with more room in the engine bay. I can't remember when my friend changed his belt but it's probably due.

 

I've also pulled the trans dipstick and fluid levels are OK. Shifting sucks. It'll run up to 5K and shift. But then again, we have no power so we have to floor it to get out of the way of traffic behind us. There was some crap on the stick but after wiping it off, running the truck for 15 minutes and checking it again, nothing. No burnt smell, that I can tell ... afterall I don't go running around smelling other peep's dipsticks. :shrug: That could land me in jail. I suspect the tranny needs a flush and filter but is acting accordingly to the throttle position.

 

Is this consistant with what you guys have seem? ( Embarrasing power levels were caused by the belt skipping a tooth on the gear. ) I'd hate to tear it all apart and not fix the problem. :furious:

 

Any suggestions?

- Gracias!

Brian

Edited by PhreakdOut
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you may look into adding external ATF cooler if the truck doesn't have that mod yet.. pronto!

 

shifting: shift selenoid, vac issues.. maybe

 

lack of power: cap&rotor, clean air and fuel filters, clean the maf.. there could be so many things.. you just have to start eliminating some of these..

 

if the t-belt has never been done.. better do it fast!

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you may look into adding external ATF cooler if the truck doesn't have that mod yet.. pronto!

 

shifting: shift selenoid, vac issues.. maybe

 

lack of power: cap&rotor, clean air and fuel filters, clean the maf.. there could be so many things.. you just have to start eliminating some of these..

 

if the t-belt has never been done.. better do it fast!

Great advice! Thanks. I saw quite a few postings stressing the cooler. I may delay that till spring since Mich weather is so cool right now and the Pathy's commute is just 8-9 miles per day.

 

ATF cooler, It doesn't have an external one (to my knowledge.) I will check for sure. I'll look into the solinoid. It wouldn't surprise me, the OE Vac lines are all hard and brittle. I'm looking to just buy vac line in a bulk roll. (My project Z will have all new lines when I get to it.)

 

Fuel filter, cap and rotor: Filter is definately on the hit list. Cap and rotor look new. I'll pull it off tonight and check the contact points to see if they look worn. The old plugs, the current wires and cap all looked like they were replaced just before I bought the truck.

 

Air fliter is a K&N and I cleaned and oiled it just recently.

 

Soo many possible causes! I agree, I'm planning to go down the list.

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well don't delay on the external tranny cooler man.. i know MI winters can actually be pretty brutal but the problem with the stock one is that it get's plugged up thus rendering the thing completely useless and thus ATs tend to burn up.. if you have already noticed all this heat from the shifters, you should really get on it.. you'll be working in the area anyway when you do the t-belt.. there are great writeups on all of this in the garage how to.. if you need more then either bump one of those or just start another thread with your specifics.

 

good luck.. where in MI?.. i'm in indy.

 

 

one more thing: open up the hood at night with the engine running.. if you see a light show those wires only look good.

Edited by mzxtreme
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Air fliter is a K&N and I cleaned and oiled it just recently.

 

Yep...like MZ said, clean the MAF.

You said you recently noticed a loss of power, as well as recently having oiled the filter. You may have over-oiled it and gunked up the MAF.

I'd def. try that one...

 

Oh yeah, welcome!

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Welcome to the forums, I am sure you will find much useful information here (as you already seem to know :aok:

 

And congrats on being one of the few who not only use, but also figured out the search function ;)

 

 

I checked compression and changed the plugs. Compression averages 120psi. Is this normal for this age of truck? It's very even all the way around so no worries about leaking headgasket.

 

According the a 1989 FSM and a 1994 FSM the standard compression value is 173psi, while the minimum is 128psi (largest difference between the lowest and highest cylinder is 14psi)... all numbers are rated at 300rpm

 

So if you came up with typical pressure of 120psi @ 300rpm through all six cylinders, then your engine is showing it's age.

 

I don't recall exactly what the numbers were with my old engine (around 280K when tested) but it was much higher than that. I want to say that it was in the 150-165 range, but I cannot be sure of that :shrug:

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...

 

lack of power: cap&rotor, clean air and fuel filters, clean the maf.. there could be so many things.. you just have to start eliminating some of these..

 

Yep...like MZ said, clean the MAF.

You said you recently noticed a loss of power, as well as recently having oiled the filter.  You may have over-oiled it and gunked up the MAF. 

I'd def. try that one...

 

Oh yeah, welcome!

I felt stupid for not thinking about that. -thnkboutit- As soon as I read it I immediately ran over to Murray's Auto and picked up a new filter and cleaner. I sprayed the MAF wire a few times and let it dry. Swapped out the filter and the K&N was still a little oiley. This makes a lot of sense. Duh!

 

I took it out for a short test drive and my "seat-of-the-pants dyno" didn't notice much improvement. I will try hitting it again with the cleaner and disconnecting the battery. (Perhaps that will force the MAF to "relearn" if there is such sophistication in this ECU.)

 

I'll post up if it works. Hopefully this is just a case of Rectal-Cranial Inversion on my part.

 

att1.gif

Edited by PhreakdOut
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That will fit in your pathy... dont think the "T"urbo will.... Should only have to swap the Oil Pick up and the Pan, Use the ones off the Pathy motor -bounce- Then use the Pathy Intake up.... P...

 

4wd Water pump you will have to slip the t-belt back off and on.. or use a 2wd Water Pump (I did on my 91)

 

 

So other than the obvious Turbo what are the differences.... 3.0 head/block...

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That will fit in your pathy... dont think the "T"urbo will....  Should only have to swap the Oil Pick up and the Pan, Use the ones off the Pathy motor -bounce- Then use the Pathy Intake up.... P...

 

4wd Water pump you will have to slip the t-belt back off and on.. or use a 2wd Water Pump (I did on my 91)

 

 

So other than the obvious Turbo what are the differences.... 3.0 head/block...

Trust me, I "like" my Pathfinder but I love my Z. I wouldn't do it. If I can get to spring with a few temp fixes, then I'll yank the engine out of the Pathy and rebuild her during the summer. My bad for not giving her attention this summer. I think this is her protest. (Acts just like my wife)

Edited by PhreakdOut
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I cleaned the MAF a couple times now. I also cleaned around the throttle body and found some holes that we covered in carbon. I'm not entirely sure what it is. Perhaps some bypass for idle quality? The truck idled just fine before.

 

Try to step on the gas from a dead stop and you'd think you were pulling a stump or dragging an anchor. (Just like the commercials)

 

Looking over the MAF wiring harness, I noticed some electrical tape. It was wrapped well so I had assumed it was from the factory. I pulled it off and saw the three wires going into the MAF harness. (Matches the EWD in the service manual.) But there was this bare wire (looked like an engine ground) that was wrapped inside the harness and not connected to anything. Just folded over up against the harness and taped up. What the heck is that? I didn't notice it on the EWD. Does anyone have an engine ground wire coming off their MAF wiring harness? The previous owner may have torn it loose when changing air filters and just taped it up in this cheesy manner. The wire is silver, flat and has no insulation. Hence must be a ground.

 

Any help, other than offering me a gun, is appreciated. I owe you guys enough already.

 

Mil Gracias.

Edited by PhreakdOut
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I would suggest changing the O2 sensor.

 

When they get dirty, they provide inaccurate readings. The inaccurate reading makes the ECU think the truck is running leaner or richer than it really is, so it squirts more or less fuel than optimal. I monitor fuel economy as an indicator of sensor decay.

 

It will not trip an error code until it is showing readings way out of whack.

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Don't want to start a K&N debate, but I'd switch to an OE paper filter.

Here is that ground wire I was talking about. You can see where it was folded back under the electrical tape and had melted into the MAF wireing harness insulator boot. (Wierd)

 

(Sorry about the photo size. I reduced it in Photobucket, but it seem to take their webpage some time to update linked photos.)

 

th_IMG_5610.jpg

 

I'm pretty sure it's a vacuum issue or fuel pump. The brake's performance has gotten worse with this issue. (Low vacuum in the brake booster?) I had a split in the line between the throttle body and the inlet valve to the purge tank on the driver's side. I replaced the hose and no improvement. I checked the other two, nada better. I tried unhooking the purge line, plug it and then do the cruise test. Nope. I noticed that after I shut down, the fuel pump is noisey for 30 seconds. Kind of a buzz or whirring noise. Not like other fuel pumps I've had in the past after you turn the key one position. I have a new fram fuel filter and will put in this afternoon or tomorrow am.

 

I have little to no time to chase down problems on it so the wife is pushing me to get rid of it. :angry: I love the truck but honestly, it's driving me batty. I'm sure one of you Pathy Gurus would have it up and going in two minutes. (My loss)

 

Here's the link to the FOR SALE THREAD: http://www.nissanpathfinders.net/forum/index.php?showtopic=11216

 

Here's a pic of the truck being stubborn in my driveway.

 

th_IMG_5590.jpg

Edited by PhreakdOut
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fuel injector cleaners?? transfer case?? i dunno.. so the rpms will rise like normal but the power doesnt go to your wheels?? tried 4x4??

It seems the RPMs rise just a little slower. Like the engine is restricted. Not making power because of the MAF, a plugged converter, the mixture, the ignition spark, the fuel delivery ... etc. I'm not sure what it is.

 

It appears to be a vacuum issue as the brake booster is not much help anymore. Recently I noticed braking was affected. I doubt it's the converter as it's not getting really hot from a restriction.

 

Considering how quick the change in performance happened, it seems like an electrical connection or a dryrot vacuum line has come loose. It all came about after servicing the K&N filter.

 

As suggested before, I got rid of the K&N and went paper, cleaned the MAF VERY well. It's possible that a connection in the MAF or a line close by has broken connection?

 

We just bought a replacement vehicle today, so I'm done trouble shooting. She still runs and drives ... it's just the off idle performance bites right now.

 

So if anyone is interested, please check out the Vehicle for Sale thread. The first $900 takes it. I need it gone soon. (No room in the driveway and impatient wife)

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