Need help! lq4 turbo Yukon runs horrible with load.

[bruce80424]

Hello,

I have a yukon that wont run right when a load is placed on the motor. The installer/tuner has been stumped for many months now. We cant seem to figure out what is going on. When the car is park it revs fine to the limiter. But when you drive it, it runs horrible. I personally haven't driven it but the shop says that the tune seems fine. I had them send me a log and the config file to post here to ask for some help. Could someone please take a look at the tune and log and see if there is something wrong with the tune.

They say it revs fine in park, but when you drive it it acts like the computer is taking out timing or something at around 2500 rpms or as soon as boost comes on then it is very hesitant till around 4500 then it starts to take off again.

Tuner said that they have exhausted everything to try to get my truck running but it has been 6 months now and I have no truck. Said they checked it with wideband and cant find anything wrong with the tune.

Specs on the truck.
rebuilt lq4 block
799 heads
ls6 cam and springs
on 3 turbo kit fmic
Garret gt4094r turbo a/r .95 (I think)
FAST truck intake manifold
Fast fuel rails
Walbro pump
Aeromotive regulator
Injector dynamics ID 750
BBK dbw t body
MAD DOG level 3 4l60e

2000 yukon slt
2WD
Drive by wire
traction control

Truck ran and drove perfect when I dropped it off in October.
Now the fuel guage is at the 6 oclock position, and I noticed the tack wasnt working then it kicked on after about 30 seconds.

I would happily pay someone for their time if they can solve this issue.
Any other info needed please let me know.

Thanks

[mecanicman]

You need a new tuner. They are commanding 6.27:1 afr every time you go into PE because they don't understand the tables. Its pretty obvious in the log, if they cant see that take it somewhere else. I have attached a file with a fixed main cause of your issue although this is still not tuned. Use compare function to see differnace.

[bruce80424]

Thanks so much four response. Im sure its something simple they overlooked. I forwarded it to the shop..

I just ordered hp tuners for myself. I only have experience tuning DTA and Vems management systems. Which are very basic ecu's. I was hoping to get my truck back with a decent tune to start with, then I can learn the HP software on my dyno..

[smokestack]

I would have got my truck back and found a tuner... 6 months? Scary stuff there!

[bruce80424]

You need a new tuner. They are commanding 6.27:1 afr every time you go into PE because they don't understand the tables. Its pretty obvious in the log, if they cant see that take it somewhere else. I have attached a file with a fixed main cause of your issue although this is still not tuned. Use compare function to see differnace.

So I got the demo software running on my laptop. I am trying to see what you are talking about. I used the compare function. All I could see that you changed was the coolant temp PE table from 1.17 to 0. To me it looks like It was just adding fuel no matter what the temp in PE mode. from my interpretation it is adding 14.7/1.172 = 12.54 / 1.172 = 10.7. So PE mode was commanding 10.7 afr. If you don't mind could you elaborate how you came up with a 6.27 afr?

I do not dis agree with you at all. I have only a hours reading time with the software. I will be getting mine setup next week.

My tuner has promised me a new log with a wideband hooked up So we can see better what is going on,





To me it looks like when the engine is placed under load something is killing the spark advance and the fuel..

When TPS and MAP are going up, spark advance and injector duty cycle are going to zero. Isnt that what is killing the motor???



Any input is greatly appreciated

Thanks

[mecanicman]

Your "hours" of reading has not educated you sufficiently. The Ect temp is an adder to the current PE value. So 1.172+ 1.172 = 2.344 14.7/2.344=6.27 which is what your log shows. Pics to follow. I don't care if you don't agree with me at all, your wrong!

[mecanicman]

This is a screenshot of your log from the same area as the picture you posted. All I did was replace the wideband pid with the commanded afr pid so you can see whats happening. Your engine is falling on its face because of the insanely rich fuel being commanded, just look at the blue arrows.

Look in the title of the pics you posted, it says Power Enrichment Fuel Adder.

[bruce80424]

Listen man. I am not trying to be rude.

If you read the above post

I said I do "not" dis agree with you at all.. I appreciate your help. Second I have only an hour with the software so its basically nothing..

Can you please cut me a little slack

I am trying to learn from you guys

[mecanicman]

You edited your comments, not what it said the first time, but fair enough. You have the evidence in front of you to support what I said. Changing that table to 0's or back to stock should have you back on the right path. If your paying a shop to do this and they cant see the obvious over rich condition being commanded you should take it some where else.

[bruce80424]

This is a screenshot of your log from the same area as the picture you posted. All I did was replace the wideband pid with the commanded afr pid so you can see whats happening. Your engine is falling on its face because of the insanely rich fuel being commanded, just look at the blue arrows.

Look in the title of the pics you posted, it says Power Enrichment Fuel Adder.

Ok great thanks for that info.. I see exactly what you mean now.



EDIT check the time stamp on my edit post, you would see that I edited it before you posted your reply. So I couldn't have changed the wording after you read it

[bruce80424]

Bruce 00 yukon log 8 (2).hpl

Above is a new log with the PE fuel dump taken out.

Still spits and sputters like multiple misfires..


The log looks ok to me. Still chasing our tail trying to figure out what is going on.. Had a wide band hooked up wile driving it, it never went below 11.something durring the log. The wideband pid in the log isn't correct. When you floor it it is very hesitant and craps out. I cant tell anything is wrong from the log.

Maybe someone here can see something wrong with the config.

Tuner said that he has a different ecu in there now reflashed which is why it says olds bravada 2001. However the truck is a 2000 yukon.

Any opinions are greatly appreciated.

[La RPM]

Bruce 00 yukon log 8 (2).hpl

Above is a new log with the PE fuel dump taken out.

Still spits and sputters like multiple misfires..


The log looks ok to me. Still chasing our tail trying to figure out what is going on.. Had a wide band hooked up wile driving it, it never went below 11.something durring the log. The wideband pid in the log isn't correct. When you floor it it is very hesitant and craps out. I cant tell anything is wrong from the log.

Maybe someone here can see something wrong with the config.

Tuner said that he has a different ecu in there now reflashed which is why it says olds bravada 2001. However the truck is a 2000 yukon.

Any opinions are greatly appreciated.

Tell your tuner to actually tune the VE/MAF curve using the error reported from a properly operating wideband reading. They are just guessing at fuel.

Also might want to try disabling LTFT

[bruce80424]

Thanks for the help. I have been trying to get him to send me a log with a correct wideband reading for over a week now. They cant seem to even do that for me.

If the engine is breaking up under boost, Wont misfires show up in the wideband log as lean spikes as the unused o2 is picked up by the wideband???

They keep telling me that the a/f is fine, but cant show me a log.
I would take it somewhere else but I have already paid for them work. Anyone have a LS tuner mechanic recommendations for the Denver area? I guess eventually Ill have too. 7 months later I still dont have a working truck..

I dont know wtf to do now...

[GHuggins]

The only things that typically causes a turbo engine to spit and sputter under boost are either it's too rich (below 10.3 air fuel) or it's too lean (typically 17 or higher air fuel) then there's plugs and ignition. What kind of plugs and what are they gapped to? Try colder plugs TR7's gapped to .030" - .032". Had an ecoboost on the dyno yesterday with 50,000 miles misfiring under boost because of this...

Further and final note... Cut your losses before your motor blows. If a tuning shop doesn't want to justify something as important as an air fuel sensor or know how to tune something like a VE table or most importantly know what a good air fuel ratio is, then you really really really don't want to go there. Turbo additions are hard enough to tune sometimes for experianced tuners. No way in hates would I trust a non caring shop like the impression I'm getting from the one your using, to tune anything boosted. Just that simple...

[bruce80424]

So I think we finally got it worked out. I ordered a new PCM with the latest updates from gm and it is working now. I was told that since my pcm is a 2000 gmc and has never been updated by the dealer it wasnt working properly with HP tuners. So we put a new pcm in with the latest updates from GM and now it seems to be fine..

Anyone else have this issue before???

Thanks guys for the input on this issue...

[KBK]

Thanks for posting the problem you we're having. I was having the some problem with my silverado! Tried everything possible under the sun. Changed the computer and loaded my tunes and the truck ran like a champ! Four months of changing parts and tuning finally came to a end. Thanks Bruce

[Montecarlodrag]

I was told that since my pcm is a 2000 gmc and has never been updated by the dealer it wasnt working properly with HP tuners.

That is one of the most ridiculous excuses I have heard.
You only need 20 min to set up a working base tune for a turbo LS, maybe a couple hours to fix issues like you describe, they took 6 months to make it run. Scary