I posted this up in my build thread but thought I might get a little more insight if I ask the question to a bigger audience.

Let me start with a little background info on my swap.

1968 f100
6.0 lq4 from a 2003 hummer with drive by wire still used
Local guy did the work on my harness getting rid of the unused stuff and adding in power, setting it up for speed density.
ls1 intake
80 lb siemens deka injectors
98 corvette fuel rail with an fittings
dual bosch 044 pumps supply and return at tank
borg warner s480 turbo
IAT is on intake tube between the intercooler and throttle body ( I was doing some reading on the EFI live forum and wonder if my location might be problematic as it is between the radiator and fairly close to the engine.
4L80E controlled by the factory computer
Blue Green computer

Let me know what else would help with the background information.

So truck has had a few issues with tuning, throttle pedal is similar to an on off switch and very choppy. I did pay a shop for the tune that is in the truck....

But the big problem is that the truck is going into limp mode or some other issue after a little bit of run time. I am getting no codes and have gone over the wiring trying to make sure all connections are good.

It happened several time over the past weekend and left me stranded.

Truck will run and drive for a little while and then for no apparent reason it will begin to run really rich and poorly, then all of a sudden the accelerator pedal will stop working and it will continue to run worse and worse.

If I plug in my cheapo code reader, I get no codes.

If I turn the ignition off, and back on and try to restart it, still runs terrible and no throttle pedal.

If I kill the power via the battery disconnect switch and turn it back on, the truck runs "right" again for a little while.

Its does not appear to be heat related, as it has happened after the truck has sat overnight....and been fired up the next day without the battery shut off overnight.

Looking for some insight as to what the hell to do now.

Go to a different tuner? New harness?

Buy EFI live and work on it myself?

Thanks in advance for any help.

Sean in Portland

 

Likely you are going into Reduced Engine Power mode because the turbo is supplying more air to the map sensor than what is predicted under NA conditions with the stock settings. You need to max out the p0106 error MAP Calculated Max table. Also you need to delete/disable the P0106 error code in the DTC table. That should make the throttle work correctly all the time. The rich condition could be caused by a multitude of tuning errors.

Based upon how you described the 2/3 bar map issue they may not have the map min/max settings correct in the diagnostics section correct either. You do not need a 3 bar map sensor to run 9psi.

You are getting messed over on tuning price. Man, I have even done tunes for free.

I would find another competent tuner.

 

Funny thing is that I bought a factory GM style two bar map sensor and they refused to install it. They said that it would only be good to 8 or 9 psi......I explained to the guy on the phone that no, that is not how it works. It would be good to about 15 psi. He said that they wont tune it on the two bar. I had to buy a generic three bar sensor from them (Add another $100 to the bill)

I agree about the MAP and the tuner. The big question is who do I go to?

Thanks for the info though.

Sean

 

You are located where?
Portland, Maine or Oregon?

One bar is approx 14.7 psi. Thus a factory 1 bar map goes from absolute vacuum to atmospheric pressure of 14.7 psia. Think of it as the air around you is pressing 14.7 psi against you. That's why in space where there is not atmosphere, you would explode. A 2 bar map sensor goes from absolute vacuum to 28 psia or 14.7 psig. Psig is gage pressure. Like what you read on a pressure gage. So if you want to build 14 psi of boost above the already 14.7 psi of atmospheric press you need a 2 bar sensor.

 

Check your pm from me.

 

You know lots more than I with tune and boost but I wonder why no codes? I'm having a problem about the same but it throws code U0107. Your code reader may not read anything but "P" codes but if you lift the battery cable it will clear the code. Try to beg a better code reader and take it for a trip. You should be able to read all codes and clear them. Gives a better idea where to look for a solution.

 

Hey Sean,

Did they tune it at the shop on the dyno?
Did everything work when you took it home?
How long before the issues started?
What cam is in it?

Ron

 

I have never seen a code u on my crappy code reader, but don't know if it will read u codes either.

Lucas said that he was not seeing any codes on EFI Live eiher.


They did tune it at the shop on the dyno.

No, when I first went to start it up in their parking lot, it was in limp mode and I had to kill power to get it back on the trailer. it has never been right, but it ran and drove much better on the stock tune obviously without being able to get into it much. Idled good, better throttle control and although it would eventually go into limp mode, it never died and would not restart like it is doing now.

The issue has been there since I first got the truck started up. I originally thought it might have been from the stock map sensor and the turbo but it was not apparently. Maybe could be something with deleting the MAF or running speed density?

Still running the stock cam in it. Motor is all stock right now.

I need to order some valve springs and a cam from martin soon.

Thanks for the help Ron.

Sean

 

Hey Sean

Have you by chance tried a different throttle body?
It sounds like a DBW issue, which will put it into limp mode.

I'm thinking the tuning just made your orig problem worse.

I'll do some more research and see if I can at least scan with HPT. I do know that I can't tune due to the custom EFI live OS.

Ron

 

Ron, you can tune it. Just do a write entire over what is in his PCM. Guess I should have give you the heads up that he would contact you about tuning.

His custom OS and tune are crap anyways. Read my post above on how to fix the reduced engine power issue. Shoot me a PM or email or call if you want to discuss options (either of you).