05-07-2007, 11:53 AM
Join Date: Jun 2006
Total Cats: 0
Tech help - 4000rpm stumble on accel
I have an acceleration problem that I need some help trying to solve.
Problem: when accelerating at full throttle the car stumbles badly between 4000-5000rpm and then accelerates fine up to redline.
If I accelerate hard up to 4000rpm, then back off but still accelerate slightly (50% throttle) I can get past 5000rpm and nail it again.
I mostly tracked the car last year so I just kept the rpms above 5k and would be good, but I am daily driving it now and trying to get it fixed plus it's not healthy to leave this uncorrected.
This happened after I swapped my engine last year. I had the same setup, just swapped a new 1.6 and the problem started.
I played around with the LINK settings, not much change. Re-loaded FM defaults and re-tuned slightly, no change.
Relevant notes on car:
-1.6 Turbo with piggyback Link (not full LINK)
-single injector at throttle body
-O2 signal modifier (olderguy)
-new O2 sensor installed recently
-just installed a bunch of ground wires in case it was bad grounding
-changed over the TPS, temp sensor and rad switch from old to new engine
- any other sensors I should check?
- re-wire the piggy?
- was suggested I adjust the O2 clamp settings?
I assume it has something to do with the piggyback ECU taking over from the OEM computer since the transition is around 4000rpm where the OEM ECU would go into open loop (or is that full).
Any ideas more than welcome.
Thanks in advance,