Jeep loses throttle

I swapped a lq4 from a 05 chevy truck into a '81 jeep scrambler and it seems to start and run fine but the problem is that if I start it and just let it idle without touching the pedal for 10-15 seconds it will only give me 20% throttle. If I start it and immediately gas it to keep the rpm up in the 2000-2500 rpm range for those same 10-15 seconds then it will give me full throttle from then on out. The throttle response (or not) will stay till the key is cycled. It throws a code for maf frequency low, which I'm guessing is related to the issue but I'm not sure how to fix it. Truck drives just fine when you have throttle but it's a pain to do every time you start it up.

The engine is stock with a credit card style MAF and shorty headers, running the stock electric gas pedal and all I've done so far is to adjust maf frequency vs airflow to compensate for the new maf. Any help is appreciated.

Okay, I have a little update. It looks like it's transmission related. Or lack of an automatic transmission at least. It seems to be going into limp mode but it doesn't throw any codes and I can't figure out why. I got all the codes taken care of except the "no MIL" code which I'm pretty sure isn't causing any issues. I've set all the switches I can find to manual trans mode and maxed out any torque management but it still does it. My buddy wants to give the jeep to his son so it really needs to be running right and I'm at a loss.

Attachment 40132

Any update on the problem???

Curious as to what it might have been or still is.

I couldn't get it going and couldn't figure anything out so I downloaded a tune for a '04 4.8L truck that came with a manual trans and changed all the fuel/airflow tables to match the 6.0. It fired right up, throttle works great, snaps to 100% no problem but I created a new problem. Now if you ease into the gas it loses communication with the throttle and throws code U0107. It goes to idle and stays there till you clear the code. It will do it with the engine on or off. I'm wondering if the trucks use a different throttle control module and this is causing an issue. I changed all the electronic throttle settings to match the 6.0 but I'm wondering if I should try them with the 4.8 settings as they were different.

I swapped all the throttle settings to the ones from the 4.8 tune and no difference. I can reflash with the original 6.0 tune and throttle works fine till it goes into limp mode like it did before. With the engine off the throttle works normally with the 6.0 tune so I know all the wiring/connections are good and it has to be in the tune somewhere.

Instead of trying to swap all the numbers yourself and possible make another issue, I would contact support and have them see if they can make you a segment swapped file, that way it will be a 6.0 truck file with a manual trans.

I think by you trying to swap the stuff around, the computer and getting all mixed up and making another problem.

That was the conclusion I came to as well. I sent them an email this morning. :)

After several emails with support I'm no better off. They have no idea, told me to try a TAC module as that's what usually goes bad. A new TAC module and a new pedal later and the symptoms haven't changed. I was told they have no idea and it is "virtually impossible to diagnose." I can't believe nobody else has had this issue and I refuse to believe that I'm just screwed. Another car had a similar issue and was solved by a custom tune where they "tuned out" the auto trans. I think this needs to be done here but without help from support I'm not sure how to go about it. Since the 4.8L tune changes the problem completely I'm thinking about getting a pedal/TAC/throttle body from a 4.8 but this is another couple hundred bucks on a guess.

Any ideas? Anyone?

Not that this will help any...but I had no end of problems trying to make a 2006 6.0L swapped into an S10 run properly off the electronic throttle. Most of my problem was with making cruise control work with the manual trans, but I also ran into some of the same issues you did... U0107 code was one of them. I tried a few combinations of different tunes, tac modules, pedals etc. None of them would work. Every change would solve one issue and create another. In the end I swapped to a 0411 PCM and cable throttle and haven't had any issues since.

Did you swap harnesses or just do some rewiring for the cable throttle?

Just needed to rewire for tps, iac, and o2's if I remember right. I also needed the red pcm plug instead of the green. It wasn't hard at all though.

Got it all sorted out, turns out we had the throttle pedal from the wrong year. The engine and TAC were from '06 and while we ordered a '06 pedal the part numbers didn't match up. I already had that tune set up for a '04 manual trans truck and had a spare TAC from an '04 so I put in the older TAC, did a write entire to the '04 tune and she runs like a champ. It turns out that the '03-05 stuff can all be swapped around but the '06 has to all match.