Timing question. VG33E swap

[Nefarious]

Okay am I missing something here? I finished my vg33e swap, set timing to 15 btdc initially. fired it up and it idled good but low, and also it would bog when i gave it gas. it was running okay, but when i set it to around 22 btdc the idle picked up to 700 where it should be and the bogging went away. there was also a lean pop when it was set to 15 but none at all at 22 and it sounds good. is this normal ? i thought stock timing is 15 degrees?? it seems to run well at 22 and not so well at 15... any opinions on this. want to make sure I get it right before i start driving on it! thanks

Edited December 19, 2011 by Nefarious

[sewebster]

Should be 15. is your crank pulley on right? Could be some other issue that is changed by going to 22 I guess.

[Kingman]

Are you 100% sure your distributor is in correctly?

[sewebster]

Are you 100% sure your distributor is in correctly?

 

Shouldn't really matter if he's using a timing light to measure it, right? Putting the distributor in wrong will just prevent you from getting to the timing you need. If you can get it to 15 deg BTDC then it should be in the correct position.

[Nefarious]

if my distributor was off a tooth would it change the timing reading i thought that was a constant.. does that sound like about 1 tooth, 7 so if it was off a tooth my timing reading might be off and even tho its running with the proper timing now, it displays wrong on the crank? the cap was pointed right at #1 but it could have been off slightly maybe.. sorry im still learning!! lol

[Nefarious]

this is a motor from another truck i dont know the history , i know it was running perfect in the truck i pulled it out of... it doesnt look like the crank had been touched at all. seems like nothing really had been touched too much on the engine haha. yeah i thought if the distributor was out a tooth then i just wouldnt be able to get the right amount of timing, i have full range of adjustment from tdc to 25 btdc. so i figured it was in right?? hmm.. curious... ill try again tommorrow setting it back down to 15 degrees since it seems to be running really well now. idle is right at 750. maybe the old ecu had to learn the new engine size? hmm..

[sewebster]

I bet you have done it correctly. I think there are 13 teeth on the distributor gear, so if you are off a tooth you move it by like 28 degrees or something. It sounds like you have it on the right tooth because you can get it to 15 BTDC. Personally I would put it there and find the problem. I think the crank pulley has only a few positions it will go on, so if you were off there it would be way more wrong.

 

Make sure you have the pickup on the #1 plug though

[Nefarious]

lol yeah it was on the number one plug. they were kind of clustered together maybe ill try and seperate it more, i dont think it could have gotten interference could it? hmm... strange. the injectors are the same between the two right ? i used the vg30 injectors.. they were the same pink tops as the vg33 injectors. the old vg33e fuel rail had one old style injector in it as well among the newer ones, spliced in. just trying to eliminate any possible issues... hmmm

[adamzan]

When you set the timing are you sure you're reading the crank pulley properly? If its at 15 the pointer thing should be in the middle of the 4 marks or if its the 5 mark pulley its on the middle mark. Just throwing that out there.

[sewebster]

When you set the timing are you sure you're reading the crank pulley properly? If its at 15 the pointer thing should be in the middle of the 4 marks or if its the 5 mark pulley its on the middle mark. Just throwing that out there.

 

This is a good point. My crank pulley has 7 marks and 15 is the middle mark as well.

[Nefarious]

I went based off the crank pulley furthest left marking being TDC. It didn't run properly until it advanced it to the very last timing mark. There were 5 if i remember correctly. 0 - 5 - 10 - 15 - 20. It's JUST past the 20 where it seems to run right... Lol this is so weird. I'm gunna finish my e-fan controller today and fire it up and let it just run for a while and then slowly turn the timing back to 15 and see what happens.

[Nefarious]

my dads buddy just had a possible suggestion... maybe whoever did the timing last has the crank pulley off 1 tooth, that would account for about 7 degrees retard would it not??

[adamzan]

It might be that. My dad had his r50 timing belt done at a shop, and they installed the belt a tooth off, I couldn't get it to run right no matter where I set the distributor. Eventually I tore it down and found the timing belt to be 1 tooth off. It ran OK but at idle it would start to run rough, it really bogged when the shop gave it back and they claimed something else was wrong, yet I dropped off a perfectly running truck

 

I would pull that and check, and throw a new timing belt on there while you're at it.

Edited December 19, 2011 by adamzan

[devonianwalk]

 

I would pull that and check, and throw a new timing belt on there while you're at it.

 

 

And a new tensioner pulley. I had to go into my TB twice within a month.

[Tungsten]

Just a quick FYI: On MFI trucks, turning the distributor does NOTHING to the spark plug timing. The timing curve is actually controlled by the ECU and not the distributor. You only set the base timing to 15 BTDC so that the fuel injectors will fire at the right time.

[sewebster]

Just a quick FYI: On MFI trucks, turning the distributor does NOTHING to the spark plug timing. The timing curve is actually controlled by the ECU and not the distributor. You only set the base timing to 15 BTDC so that the fuel injectors will fire at the right time.

 

This is wrong. Rotating the distributor rotates the crank angle sensor. It's the only way the ECU knows what position the engine is at. It then decides when to fire the spark plugs. The distributor position isn't critical for that (spark firing) since the contacts are so wide, but it is critical for the position sensor.

 

I think there are only like 4 positions to install the crank pulley in, so it would be off by more than 7 degrees? Maybe 6 positions, nevertheless, a lot more. The crank sprocket can't be installed incorrectly, it is keyed.

 

However, if your timing belt was installed improperly then all bets are off. I would check that I guess.

[Tungsten]

Nope, on ECCS vehicles the distributor's CAS only controls the fuel injectors directly. There are more sensors than you think. The timing belt is way off if it doesn't work like it should.

Edited December 20, 2011 by Tungsten

[Kingman]

Adjusting the distributor sets the base timing on an MPFI truck, the ECU controls the actual curve. On a TBI truck adjusting the distributor changes both the base timing and the curve. This can be verified with a timing light..

[JamesRich]

I haven’t messed with a MPFI pathy yet but tungsten may be right. I was screwing my 01 quest van with a VG33. I wanted to give it a little more timing to see if it would give it a little more getup. On the OBDII system you have to disconnect the TPS sensor for the ECU to let go of the timing. I set the timing to 20 then plugged the TPS back in. Timing was back to 15. I set it to 25 and plugged it back in. Timing was back to 15. The 95 and under pathys are not OBDII but might work the same.

James

[sewebster]

I agree that the ECU controls the ignition timing... but I am saying that it uses the crank angle sensor (or camshaft position sensor) to know the position of the engine. This is what it says in the FSM (EC & EC 11 in the 94 FSM).

 

"The camshaft position sensor is a basic component of the entire ECCS. It monitors the engine speed and piston position, and sends signals to the ECM to control fuel injection, ignition timing and other functions."

 

I don't think there are any other sensors that do the same thing...

 

Anyway, I don't think this is particularly relevant to the problem at hand.

Edited December 20, 2011 by sewebster

[Tungsten]

I didn't mean to get off-topic, I'm just saying don't bother playing with the distributor.

 

It's actually very complicated but I reverse engineered the entire thing. In theory it is like a distributor-less system with a distributor. The distributor is there to only use 1 ignition coil. It's true that the crank angle sensor sends a signal to the ECU telling the ECU where the engine is but the crank angle sensor will only directly impact when the fuel injectors will fire. If you remove the distributor and spin the sensor by hand, you can hear the injectors click if you listen very close. Turning the sensor angle by adjusting the distributor will change the injector timing relative to the spark timing because of how the ECU works. The base timing does not matter for the actual ignition, the ECU will set it exactly to 15 BTDC no matter what. How does it know you ask? It has the ability to delay or advance the spark based on where the crank angle position is set or if the knock sensor mode gets activated.

[sewebster]

I didn't mean to get off-topic, I'm just saying don't bother playing with the distributor.

 

It's actually very complicated but I reverse engineered the entire thing. In theory it is like a distributor-less system with a distributor. The distributor is there to only use 1 ignition coil. It's true that the crank angle sensor sends a signal to the ECU telling the ECU where the engine is but the crank angle sensor will only directly impact when the fuel injectors will fire. If you remove the distributor and spin the sensor by hand, you can hear the injectors click if you listen very close. Turning the sensor angle by adjusting the distributor will change the injector timing relative to the spark timing because of how the ECU works. The base timing does not matter for the actual ignition, the ECU will set it exactly to 15 BTDC no matter what. How does it know you ask? It has the ability to delay or advance the spark based on where the crank angle position is set or if the knock sensor mode gets activated.

 

Right, I get that the ECU can adjust the timing advancing or retarding as required. However, doesn't it use the crank angle sensor position to know how to do this? My understanding is that the ECU assumes that where you set the distributor at idle = 15 BTDC and then adjusts based on that assumption. The sensor plate with the holes in it is attached to the distributor shaft and rotates, and the sensor itself that "sees" the holes is fixed to the distributor body.

 

I guess I'll think about it some more, but I think the ECU needs to know the engine position to do it's job, and the only way it knows that is by the distributor (and therefore crank angle sensor) position.

 

Further evidence is that when I set my distributor 180 degrees off the ignition timing was so far off that I blew up my muffler

[Nefarious]

hey i had another thought... i broke the original vg30e knock sensor when i was pulling the motor down and replaced it with the vg33e one. they looked identical and the part number i could see (some was worn off) looked the same. did i assume to much in using the vg33e knock sensor... its just a microphone basically isnt it ?

Edited December 20, 2011 by Nefarious

[Tungsten]

hey i had another thought... i broke the original vg30e knock sensor when i was pulling the motor down and replaced it with the vg33e one. they looked identical and the part number i could see (some was worn off) looked the same. did i assume to much in using the vg33e knock sensor... its just a microphone basically isnt it ?

From what I saw, VG30E and VG33E knock sensors are exactly the same so you can use either one. It should be good as long as it's not broken.

 

Right, I get that the ECU can adjust the timing advancing or retarding as required. However, doesn't it use the crank angle sensor position to know how to do this? My understanding is that the ECU assumes that where you set the distributor at idle = 15 BTDC and then adjusts based on that assumption. The sensor plate with the holes in it is attached to the distributor shaft and rotates, and the sensor itself that "sees" the holes is fixed to the distributor body.

 

I guess I'll think about it some more, but I think the ECU needs to know the engine position to do it's job, and the only way it knows that is by the distributor (and therefore crank angle sensor) position.

 

Further evidence is that when I set my distributor 180 degrees off the ignition timing was so far off that I blew up my muffler

You're right, it does use the CAS to determine the position. The base timing doesn't matter for spark because the ECU has an algorithm to determine where 15 BTDC is no matter where you adjust the distributor to. If you put the distributor on backwards you will not only cause the ECU to get confused but you will screw up the injection pattern too. Your muffler probably filled up with just enough gasoline to blow up. Essentially the distributor will do its job as long as it's installed in the correct orientation. You want to keep the base timing at 15 BTDC because the injectors will fire at the right time then and give you the best fuel economy. The only thing that has a direct effect on spark retardation is the knock sensor.

Edited December 21, 2011 by Tungsten

[Nefarious]

okay so i got the timing set back to 15 degree now that its been running for a while. it seems to be fine now, no more lean pop and no more bogging per say. there is still a hesitation RIGHT when u open the throttle. not so much with no load, moreso when i move the truck. i push down on the gas and just a split second it hesitates and might rev down just a hair and then once it starts going off it takes off like a rocket ship. i mean no joke it has POWER and lots of it.

 

i didn't really expect it my first time taking it down my driveway and it lit up both tires and launched the truck lol. I can't believe the power increase!!! It feels faster off the line now than my 5 speed 240sx and my pathy is an auto.... kind of surprising really.

 

So I just have this annoying little hesitation left to figure out otherwise it's running great. I think i'm going to go over the engine again and check all the grounds.... I think one for the driver side exhaust manifold is not there anymore and i am suspect of grounds that come off the harness by the coolant temp sensor.