I have a 92 rs that i put a 350 TBI jasper motor in and it ran great for like a week but started surging at idle. i have tried to fix this problem with a custom chip and adding more fuel, thinking maby it was too lean at idle but nothing seems to be working. the surgings seems to come and go but only at idle. Any suggestions on what could be causing this problem?

 

ah jasper...

whats your fuel pressure like while it is surging?

have you checked for vacuum leaks? i would start buy spraying carb cleaner or starting fluid if you are brave around the intake below the throttle body...

haven't had much luck with jasper... bought a T56 from them a few months ago... grabbed the input shaft and went wow that has allot of play... indicated it at .10 wobble all the way around... called them up they said they would send a new one second one arrived no shaft play this time filled it with oil about 5 minutes later i have this puddle of ATF on the floor... WTF started looking around and come to find out jegs/summit sells a brand new tremec T56 for $1000 less than jaspers reman. with no core charge or skid charge i tell jasper i am sending the tranny back and want a refund they ok it but want to charge a restocking fee... because i should be able to just replace that seal without sending it back...

needless to say i would never buy anything from them again...
don't know about their engines though i would bet it would have been cheaper to buy the parts your self and pay someone to assemble it for you...

 

Thank you for your advice. I have checked for vacume leaks and have also repaced the MAP sensor and the map sensor vacume line to the tbi and it still surges. Oh and I am running about 13.5 psi.

 

Idk if u have fixed your issue by now or not but I have a surging idle problem with my 305 and it makes a howling noise took Otto a shop they told me the throttle bodyseal was bad and causing the engine to get a bad air/fuel mixture causing surging and whistling noise from the throttle body..the seal is o ly 5 bucks gunna replace it this week myself hopefully fixes it :/ I'm pretty sure it will thoeverything else vacuum lines,map sensor egr valve has all been replaced.hopin it fixes it