TeeriggerAK49

My daughter and I put a 2009 5.3L GM LS and 4L60E in a 1988 Chevrolet truck. It runs perfect....most of the time. When I first start it up, it accelerates off the line fine, and shifts up a couple gears, then the throttle pedal gets weird. If you push it past 1/4 throttle, nothing happens and the engine RPM drops off and it almost seems like it disengages. If you keep the throttle below 1/4, it runs fine, you can slowly limp it up to 55 MPH. The oddest things is that almost exact 15 minutes into running it in this mode, it goes away and runs great. I have a scanner plugged in and it doesn't throw any engine codes at all.


Any ideas?

G Atsma

Sounds the "warm-up" stage is in limp-home mode. Once warmed up, all is normal, as you say. Did you have it tuned any time? Check the MAF sensor, TPS, and temp sensor.

TeeriggerAK49

This is only my 2nd LS swap, so I am newish to this. I had the ECM reprogrammed. The scanner I have saves freeze frames only. Would a scan tool that reads the ECM in real time tell me what sensor is sending it into limp mode?


I think you have it though. It only does the "limp mode" when it is a "cold" start after sitting extended periods.

G Atsma

It might, but I don't know too much about them. When you had the ECM reprogrammed, possible the "cold mode" somehow got mis-calibrated. Who reprogrammed it? You might contact them and tell them what is happening, and they either will re-do it, or give you a solution to the problem. I have a feeling whatever it is, is not complicated. Hope you get it sorted out!

TrickFlowTech

Are you using the matching pedal from the 2009 truck?

TeeriggerAK49

I am using the pedal from the engine/ transmission donor vehicle. I have a tuner guy scheduled to look at the programming next week. It looks to be a "cold code" Deal.


Thanks