Okay guys, here is my problem. My car (88 IROC) has what I can best describe as a surge (very small but noticeable) that shows up between 60-80 kph. It is not evident above or below that range. I have tested fuel pressure and it is fine. I have also done a tune up with new plugs (AC Delco), wires (Taylor), cap and rotor, and a new fuel filter. Nothing seems to be able to get rid of this annoying little problem. In my owner's manual it says "on occasion, you may feel certain incidental engine pulsations in the 40-80 kph range...these conditions are normal" but I have never felt them before now (has anyone?). I have a couple of ideas as to what the problem could be 1) O2 sensor relocated too far away from the stock location (header install) 2) TCC problem 3) TPS out of adjustment. Any help with diagnosis would be greatly appreciated.

 

Come on guys...I really need some help with this one...the car has plenty of power, but the "surge" is there. Any suggestions?

 

Had a similar surge (between 50-60 mph) after replacing my MAF and O2 sensor....I reset the ECM, and the sure went away, may be worth a shot if this just started after mod's.

 

Steve,

That's right about the point where the TCC goes to lockup. Depending on engine RPM, TPS, and road speed, the TCC will lock and unlock at about 67 KPH (41 MPH) at a minimum. Make sure the TPS is dead-nuts at 0.54VDC at hot idle and the minimum air position is correct. A higher TPS can cause slightly earlier lockup.

If you are curious about monitoring the TCC, you can connect a test light to the 'F' terminal on the ALDL. Supply 12VDC to the lamp and allow the ECM to ground the lamp throught the 'F' terminal. The light will be on whenever the TCC is in lockup. If you see a correlation, you may have found the "problem".



Later,
Vader

------------------
"Some Body...Someone"

 

Thanks for the replies guys...I'll check that stuff right away.

 

turn your a/c off.