Hi, i have a 89 RS with a 350 TBI, i got a chip burned from TBIChips.com, and replaced all sensors, the problem is that when i start it up cold it idles at a constant 1500 RPM (so the factory tach says), then as the engine warms up a little it idles up and down, it will go up to 1000 RPM and then down to 400-500 and then jump back up again, and the when the engine warms up the whole way the idle smooths out to about 550 RPM and its fine, and no where in the description do i loose power or acceleration, could this be a bad O2, i just replaced it about 1500 miles ago, but it was a BOSCH, and i heard that they are just bad O2 sensors. Thanks alot!

 

ive got the same exact problem. i also have a 350 with a chip from tbichips. it would be awsome to solve this if anyone knows anything about it.

 

i think it just happens when the car is in open loop. because if you start it warm it wount idle properly either, for maby half a minitue then it starts idling better

 

You both need to get into chip burning. You cannot trust any mail order chip no matter what they know about your combo. It takes many many burns to get a tune right. The only way to do it is to read the datalogs in front of you and make changes as you go. A wide band 02 is a must to nail down any WOT tuning as well.

 

I dont have the time or $ right now to invest in chip burning hardware, is there anything else i can do, because there has to be, not everyone that has done this swap is cappable or willing to invest the time and money in researching and burning chips, and I know that they dont just junk the car because of it, also ,i didnt do any radical changes to the engine, and actually its completely stock 350 i put in and i had a chip already burned for it.

 

You are going to have to take it to someone or bite the bullit and do it yourself. Even though your combo is mild it still has different fuel and spark needs than your 305 did. This is the reality with these systems unfortunately. People who swap motors and or heads and cam on their 305 are leaving out a crutial part of the combo when they don't get into chip burning.

 

seems to be a function of the IAC doing its "thing". it detects the low idle and tries to prevent the engine from dying by adding air(purposeful vac leak) and some xtra gas. when it goes CL i assume the IAC is fully seated or nearly so and idle is stable. IAC is a love hate relationship. necessary evil. my engine died first time this season when engine was relatively cool. seems the cold air this morn(45F) leaned out the car too much. WB told me so! winaldl would have told me somethig too(iac counts) had i been logging. time to read up on iac function and consider at least dataw/ logging winaldl(step 1). their is some satisfaction to this tuning thing.