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bad ecu?

16K views 106 replies 9 participants last post by  arena314 
#1 ·
hey guys what are some signs that you might have a bad ecu? my car runs like absolute **** and I can't figure it out at all me and my friend whose a mechanic played around with it for hours with no conclusion. the only code I'm getting that won't clear at all is a p0602. the car runs horribly it's extremely rich and cuts out it seems like. also my bama tuner won't tune the car it won't allow it. I'm starting to think in need a new ecu what do you guys think? I'm at a complete loss here and if it's bad how do I go about getting a new one? thanks
 
#32 ·
unplugged it and my sct tuner then let me upload a new tune so I did. the car is running wayyyy better it pulling how it should and feels good. the only thing now is the idle is strange sometimes it will idle normally but sometimes it will drop down alot and stall out but it's not stalling a lot but it seems to be running great other then that. think the idle could be bc of the really bad exhaust leak it has due to the rotted out headers
 
#35 ·
Awesome! :)

Fixing the exhaust leak will undoubtedly make it run better. If you still have a problem with an erratic idle after the exhaust is repaired, it's possible that the IAC may be failing. If you have to replace it, Motorcraft or Hitachi are the recommended brands.
 
#36 ·
I'm thinking and hoping it's the exhaust leak throwing off tbe 02 sensors. it's a really really bad leak my longtubes are rotted right by where they meet up with the x pipe so that's right around where the first 02 sensors go and before the rear 02 sensors so it's not a good spot for a leak. I have a stock bbk o/r h pipe and bbk tuned length shorties once the longtubes are out is everything going to bolt up normally again since stock length headers are going back on?
 
#40 ·
besides the idle the car is running great it's fast and nor bogging or anything like it used to just the idle is a little screwed up

---------- Post added at 08:27 PM ---------- Previous post was at 08:26 PM ----------

and I called bama and talked to them about that and they said to just upload the tune to the new car once you unmarry it to the old one
 
#43 ·
at this point I've tried unplugging the tps sensor and it won't change much it will just make the car stall out after I rev it. I've tried 3 different iac valves 2 that I know 100% were in good working order (both pulled off of perfectly running 4.6's) I swapped my accufab throttle body over to my bbk throttle body and checked for leaks. the only other possible reason I can think of for my bad idle is the 02 sensors being thrown off by a big exhaust leak.. what do you guys think? anything else I should check? besides for the sometimes surging idle/stall it will idle ok every once in a while and tbe car doesn't stumble at all its actually very fast
 
#51 ·
after pulling the Diablo sport chip out of my ecu I loaded a preloaded tune up to it from bama that I had loaded on my last mustang. I called bama and they told me I didn't need to give them a new number or anything off the new ecu they said just unmarry it from your old car and reset it then load the same preloaded tune up to your new car. my last car was a pi swapped 96 gt
 
#54 ·
I'm not sure if you can make changes like that with the SCT. Perhaps someone who knows will chime in.
The PI swapped engines have a higher compression ratio than a normal PI engine, so I'm wondering if the tune might be significantly different enough to cause some idle problems.
 
#56 ·
I'd load the factory tune on for troubleshooting. That will eliminate any issues with the tune. If you have the cats removed, that should be the only code you'll get. Then you can work the codes from there. Much easier than fiddle-farting around with unknowns.
 
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