Gen IV throttle issue
Thread Starter
Teching In
Joined: Feb 2017
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Gen IV throttle issue 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?
Any ideas?
Thread Starter
Teching In
Joined: Feb 2017
Posts: 6
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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.
I think you have it though. It only does the "limp mode" when it is a "cold" start after sitting extended periods.
TECH Senior Member
Joined: Jun 2016
Posts: 22,308
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From: Central Cal.
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!
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Joined: Feb 2008
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Are you using the matching pedal from the 2009 truck?
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