finished transmission swap, now have lumpy idle and backfire
 

ok, i finally had the auto pulled and the 5spd installed. first let me say that its the best upgrade i could have done. everyone that has ridden in my car with the auto tranny are very impressed with the 5spd. but now (since i got the car back), ive been having idlingl troubles, lumpy erratic idle (at about 1k to 1.5k) and backfiring (soft popping from exhaust). i checked the repair manual and saw that it could be any number of things. so i figured id ask here for help. any thoughts would be appreciated.

cmon, i need some input here. im sure someone out there knows what the problem could be.

odd, idle effected from changing the tranny?

only thing that comes to my mind is the idle switch is always engaged and your acc warm up system is always on, i know that when i started up my 7, it would idle at like 1.5-2k for a few unless i put it in gear

-Jacob

Let me guess, you have a series 5 (89-91) car right?

A check of the profile behind door number one reveals that you have a 90 GTU, we have a winner!

You need to locate the EC-AT box in the passenger kick panel above the engine ecu. UNplug it, and your problems will for the most part go away. THis computer controls the tranny shift patterns and is a go-between for the stock engine ecu, and since you just removed all its inputs it is still in a state of shock and is screwing with your engine ecu. I have performed the swap several times and this is usually all the adjustment it needs. You might need to go back and adjust your idle once more though.

Let us know if it is the problem...

I heard that the fuel maps on the ecu are diffrent because of the diffrent loads. Could this be true?

Also, check that the main ground strap was put back on. Its left on a lot of times after a tranny pull. On a 5 speed its bolted on the drivers side.. Look down below the oil filter and near the slave cylinder. Its a big thick wire with a spade on the end.

This will affect your spark/power/idle, etc..

A poor ground will only affect the 3800 rpm hesitation not what the poor chap is describing hypntyz7 hit it on the dot of course cause he has done the swap more times than he can count....good ol' tennessee eh????

thanks much. as soon as my car gets back to me in va i'll check the EC-AT. i thought the ppl that did the swap for me had unplugged it, but i seems they didnt.