Motor blew up today.....need some tuning experts in here.

[Fast355]

I am not sure what mechanicman is getting at with the MAF and MAP signals. I have never tuned an engine with a stock throttle body or an air cleaner that did not drop below baro as the rpm climbed nor have I tuned any engine that had steady maf/map signals. They ALL bounce. Dodge 4.7/5.7/5.9, GM TBI, TPI, LT1, Vortec, LS1, 3100, 3400, and even my 2012 Titan thats been tuned since 2,000 miles. Gotta remember the engine runs in big pulses as the various valve open and close and the sensor reading multiple times a second record thes pulses.

I would be more inclined to believe he has an issue in the VE table thats causing the PCM to run lean after AE times out. It also helps to bring PE in sooner than the OE 90% and bypass the delay by lowering the delay rpm.

[mecanicman]

My responce seemed more justified at the time, I had a rough day at work. I find it very frustrating when someone asks for help, then discounts everything you say. My patience was thin and for that I appologize.

I have not been on as my primary computer, the one I do all my tuning with, died. I have lost huge amounts of data and am still stuggling to piece it back together.

[mecanicman]

I am not sure what mechanicman is getting at with the MAF and MAP signals. I have never tuned an engine with a stock throttle body or an air cleaner that did not drop below baro as the rpm climbed nor have I tuned any engine that had steady maf/map signals. They ALL bounce. Dodge 4.7/5.7/5.9, GM TBI, TPI, LT1, Vortec, LS1, 3100, 3400, and even my 2012 Titan thats been tuned since 2,000 miles. Gotta remember the engine runs in big pulses as the various valve open and close and the sensor reading multiple times a second record thes pulses.

I would be more inclined to believe he has an issue in the VE table thats causing the PCM to run lean after AE times out. It also helps to bring PE in sooner than the OE 90% and bypass the delay by lowering the delay rpm.

Every engine is a little different, some dance more then others. But I believe I do a lot more tuning then most of you as I run it as a buisness locally and do it remotely as well. I see more logs then the average person and have a trained eye for it. I am not trying to brag, but you didnt find it strange I predicted valve train problems and then shortly after it was posted a failed valve spring was the cause? Because I have seen it before, its subtle but its there.


My collection of logs was lost recently, so this is the best example I could find. This is a stock l76 with a mild cam, so not drasticly different from what the s10 is running. You can see there is a 1 kpa variation but overal pretty smooth.


The same example I posted before, you can see its more jagged and has a lot more variance to it.


This was what stood out to me at first, I can see now with the logs there is another problem present, but this is what killed the engine, not the lean spike.

[mecanicman]

From the log you posted I can see its not the injector data causings your lean issue, may be the cause of your "shark fin". I dont agree with the negative portion of the short pulse adder table, but thats another story I dont feel like getting into right now. Your lean spike happens above any pulse width the short pulse adder will effect.

Perhaps try a different file when the engine is up and running? I can modify an express van file for you, have used it before on the same swap without issue.

[lwrs10]

Finally some time to reply...

Finished up swapping the engine out. Bone stock motor with the same intake and injectors. Still had the lean spike and still had the big KPA fluctuations. Looking through my tune I noticed I forgot to change my injector timing back to stock, as it was changed to match my cam values. Changed it back to stock and BLAMMO! No more lean spike. I tested it at least 20 times, and I am 100% sure injector timing was the issue. I can change it and make the lean spike happen, change it back no spike. So glad I got that ironed out.

But the KPA dance was still there. On a bone stock motor. Not a single part in the valvetrain was common between motors. So on a longshot i tried something.

Here is my stock V6 air intake on that V8 motor, with a stock intake. It does have the V8 MAF and tube, but that is the V6 hat. I started looking at this because my WOT KPA indicated a restriction somewhere.




So on a drunken escapade I grafted an 03 Cobra JLT intake I had laying around as a spare to fit this truck. This is a 4" cold air. And I had the BIG 5 wire MAF laying around from my LS swapped S10 blazer that blew up due to a lifter failure.

Here is what I came up with:



And holy hell.....what a difference it made. I now hover around 100kpa WOT. Truck feels a lot more powerful, gas mileage went up damn near 8mpg, and everything ironed itself out I was having problems with.

I swapped my cam and fixed heads back on it yesterday and truck runs great. Absolutely a totally different engine now. I rented an hour of dyno time today and it put down some damn good numbers too. 389hp/422tq, and those are corrected numbers on a dynojet.

So moral of the story is dont screw with the injector timing on these motors, and do not run cheap valve springs. Causes weeks worth of headaches.

[Fast355]

Finally some time to reply...

Finished up swapping the engine out. Bone stock motor with the same intake and injectors. Still had the lean spike and still had the big KPA fluctuations. Looking through my tune I noticed I forgot to change my injector timing back to stock, as it was changed to match my cam values. Changed it back to stock and BLAMMO! No more lean spike. I tested it at least 20 times, and I am 100% sure injector timing was the issue. I can change it and make the lean spike happen, change it back no spike. So glad I got that ironed out.

But the KPA dance was still there. On a bone stock motor. Not a single part in the valvetrain was common between motors. So on a longshot i tried something.

Here is my stock V6 air intake on that V8 motor, with a stock intake. It does have the V8 MAF and tube, but that is the V6 hat. I started looking at this because my WOT KPA indicated a restriction somewhere.




So on a drunken escapade I grafted an 03 Cobra JLT intake I had laying around as a spare to fit this truck. This is a 4" cold air. And I had the BIG 5 wire MAF laying around from my LS swapped S10 blazer that blew up due to a lifter failure.

Here is what I came up with:



And holy hell.....what a difference it made. I now hover around 100kpa WOT. Truck feels a lot more powerful, gas mileage went up damn near 8mpg, and everything ironed itself out I was having problems with.

I swapped my cam and fixed heads back on it yesterday and truck runs great. Absolutely a totally different engine now. I rented an hour of dyno time today and it put down some damn good numbers too. 389hp/422tq, and those are corrected numbers on a dynojet.

So moral of the story is dont screw with the injector timing on these motors, and do not run cheap valve springs. Causes weeks worth of headaches.

My injector timing has been changed and it runs GREAT. Just do not run more than 6.5 as that coincides near to BDC. My issue with the lean spike was the PE RPM delay being set at 2,000 rpm, which was overlapping the stall speed.

[lwrs10]

My injector timing has been changed and it runs GREAT. Just do not run more than 6.5 as that coincides near to BDC. My issue with the lean spike was the PE RPM delay being set at 2,000 rpm, which was overlapping the stall speed.

mine was at 6.86.

[Fast355]

Every engine is a little different, some dance more then others. But I believe I do a lot more tuning then most of you as I run it as a buisness locally and do it remotely as well. I see more logs then the average person and have a trained eye for it. I am not trying to brag, but you didnt find it strange I predicted valve train problems and then shortly after it was posted a failed valve spring was the cause? Because I have seen it before, its subtle but its there.

My collection of logs was lost recently, so this is the best example I could find. This is a stock l76 with a mild cam, so not drasticly different from what the s10 is running. You can see there is a 1 kpa variation but overal pretty smooth.

The same example I posted before, you can see its more jagged and has a lot more variance to iThis was what stood out to me at first, I can see now with the logs there is another problem present, but this is what killed the engine, not the lean spike.

You are comparing a WOT and a part-throttle log. Two different beasts

Attached are 3 different vehicles. My Express, my 2012 Titan, and a 4.8. Every last one has a rough MAF signal at WOT and yet all run well.

[mecanicman]

You are comparing a WOT and a part-throttle log. Two different beasts.

TPS is 100% in both, and you can see it other places.

[mecanicman]

Finally some time to reply...

Finished up swapping the engine out. Bone stock motor with the same intake and injectors. Still had the lean spike and still had the big KPA fluctuations. Looking through my tune I noticed I forgot to change my injector timing back to stock, as it was changed to match my cam values. Changed it back to stock and BLAMMO! No more lean spike. I tested it at least 20 times, and I am 100% sure injector timing was the issue. I can change it and make the lean spike happen, change it back no spike. So glad I got that ironed out.

But the KPA dance was still there. On a bone stock motor. Not a single part in the valvetrain was common between motors. So on a longshot i tried something.

Here is my stock V6 air intake on that V8 motor, with a stock intake. It does have the V8 MAF and tube, but that is the V6 hat. I started looking at this because my WOT KPA indicated a restriction somewhere.




So on a drunken escapade I grafted an 03 Cobra JLT intake I had laying around as a spare to fit this truck. This is a 4" cold air. And I had the BIG 5 wire MAF laying around from my LS swapped S10 blazer that blew up due to a lifter failure.

Here is what I came up with:



And holy hell.....what a difference it made. I now hover around 100kpa WOT. Truck feels a lot more powerful, gas mileage went up damn near 8mpg, and everything ironed itself out I was having problems with.

I swapped my cam and fixed heads back on it yesterday and truck runs great. Absolutely a totally different engine now. I rented an hour of dyno time today and it put down some damn good numbers too. 389hp/422tq, and those are corrected numbers on a dynojet.

So moral of the story is dont screw with the injector timing on these motors, and do not run cheap valve springs. Causes weeks worth of headaches.

Glad you got it sorted. Nice numbers our of mostly stock vortec 5.7.

[Fast355]

TPS is 100% in both, and you can see it other places.

What I was getting at is the first log was at WOT the whole log and the 2nd for only a brief period. That being said I would expect a 6.2 with variable cam timing to have a smoother MAP/MAF signal than the older engine. It has a larger throttle body, larger intake ducting, higher flowing intake, etc.

I am wondering if I could even get a 3" elbow like that above my throttle body, much less a 4".

[mecanicman]

What I was getting at is the first log was at WOT the whole log and the 2nd for only a brief period. That being said I would expect a 6.2 with variable cam timing to have a smoother MAP/MAF signal than the older engine. It has a larger throttle body, larger intake ducting, higher flowing intake, etc.

I am wondering if I could even get a 3" elbow like that above my throttle body, much less a 4".

L76 is 6.0, that one is variable cam timing and dod delete running a lingenfelter converter box and 0411 pcm. Has a stock car intake with an ebay adapter plate for a stock 85mm truck throttle body, a marginally larger version that is the same as whats on the vortec 5.7.(i have actually put the 85mm on 4.3 buy changing the shaft so pulls the right way and some very slight grinding). Cam is 230/238 .600”/.604. Engine currently resides in a 1990 silvia running 11.30's with traction issues.

I may not have been as right as I thought I was about the valve spring, but I bet if he posted a log of the same situation you are calling part throttle now it would be a lot smoother. It was likely the valve spring causing the steady state cruise tick and the intake setup causing the wot dance. Either way I wouldnt consider it normal.

[Fast355]

L76 is 6.0, that one is variable cam timing and dod delete running a lingenfelter converter box and 0411 pcm. Has a stock car intake with an ebay adapter plate for a stock 85mm truck throttle body, a marginally larger version that is the same as whats on the vortec 5.7.(i have actually put the 85mm on 4.3 buy changing the shaft so pulls the right way and some very slight grinding)..

I am fairly certain the WOT dance you are seeing in all of my logs is the restrictive intake designs on the engines I am tuning. My Titan only has a 74mm TB or close. The Express has the restrictive elbow in place. The 4.8 has a stock throttle body as well. I wish it would end up closer to the 99-100 KPA baro pressure, but it falls where it falls at the moment.

I am actually running the L31 marine intake now and could probably step up to an 85mm LS TB with a little rework and could possibly get a 3" short radius elbow on top, but there is not much room there.

The Titan has a 4" CAI on it at the moment, but it necks down to smaller than 3" at the intake coupler.

I am waiting to see the results of a project being performed by a Titantalk member. Basically he had a big LS intake porting shop graft a LS2/LS3 intake flange and LS2/LS7 throttle body to a 2007+ Titan intake manifold and built a true sleeveless 4" CAI.

[lwrs10]

L76 is 6.0, that one is variable cam timing and dod delete running a lingenfelter converter box and 0411 pcm. Has a stock car intake with an ebay adapter plate for a stock 85mm truck throttle body, a marginally larger version that is the same as whats on the vortec 5.7.(i have actually put the 85mm on 4.3 buy changing the shaft so pulls the right way and some very slight grinding). Cam is 230/238 .600”/.604. Engine currently resides in a 1990 silvia running 11.30's with traction issues.

I may not have been as right as I thought I was about the valve spring, but I bet if he posted a log of the same situation you are calling part throttle now it would be a lot smoother. It was likely the valve spring causing the steady state cruise tick and the intake setup causing the wot dance. Either way I wouldnt consider it normal.

The 5.7 and 4.3 throttle bodys are the exact same, except for the throttle shaft and blade, and are both 70mm. The one on my truck is a 76mm from a marine engine. I would be very interested in this 85mm one you are talking about. What did it come off of?

[mecanicman]

The ls engines use the same throttle body. There are some differances, but if you have one of each type you can swap the pieces to make it work. The 6.0 is supposed to be 85mm, I think I measured it less then that but was bigger then what I had. Mostly is swapping the shaft cause they pull different ways. Some have vacume tubes that stick out and interfere. I had a collection of both and was able to make one that worked. I think I used a cutoff wheel to extend shaft opening for blade just slightly. I had to grind the stock plastic intake to make it work.