fast86z28

Ok heres the deal...90Iroc 305tpi/auto...new plugs/wires/cap/rotor/fuel filter/air filters/02sensor/coil etc. All this stuff I have done in my garage within the last week or two...I just got done doing the fuel filter and it is still running rough..I have the timing set at 6*...Im not sure if its a fuel pressure problem or what because like when you drive it, at 3/4 throttle it seems to run pretty good, then if you go full throttle it just acts all weird, its hard to describe, but it like hesitates really bad and the rpms dont climb like they should... I have checked the injectors and they all checked out good and pretty even across the board. I reset the tv cable etc...I really really do not wanna have to drop the fuel tank to replace the pump...If anyone can give me some suggestions that would be great...remember I am new to tpi I have built and worked on nothing but carbed cars so I could be missing something.

Brian Felts

Do you have a scan tool or are you getting any SES lights? Sure the plug wires are on the correct plugs? I really doubt the fuel pump is the problem. Maybe go back and check your TPS voltage and check to see if maybe you left a sensor unplugged.


Brian Felts

IROCthis88

definately check the wire connections on the cap and see what happens, i had that today with my 88 on the original 305 and thats what was wrong also adjust the idle screw on the throttle body if ya have a high idle

fast86z28

the connections on the cap are all fine. It idles fine, right around 850 or so, it just has a miss.

rezinn

Did you change all of that stuff to fix this problem, or it happened after?

It idles fine in gear? Got access to a scanner? Can you isolate the cylinder(s) that is/are missing?

fast86z28

It was running rough when I bought the car, I replaced all this stuff just on general principles. Thats what I always do when I get a new car, just so I know its done. It def. runs better than when I got it, but still not good enough...I'm not sure which cylinder it is, I guess I could find out, and no I dont have access to a scanner.

fisherbody86

You might want to check for a ruptured fuel pressure regulator diaphram. Pull off the vacuum line, if it's wet, it's ruptured. Not likely the problem here but check it anyway. I would also look into a faulty ignition control module. If it sputters at WOT, it sounds more like an ignition problem, not a fuel problem. Some NAPA stores will test your module for you, and it doen't cost much if anything at all.

fast86z28

How would I go about checking the ICM? Like I said I am new to FI...thanks everyone for your help.

fisherbody86

Unfortunatly, there is no way to test it with, say, a multimeter or something. There is always the "substitute a known good part" method, toss on a known good ICM and go for a test drive. Or you could have NAPA test one out for you. If your distributor is the small cap variety, I have a "known good part" that you could borrow as long as you mail it back to me. It's just sitting in my toolbox doing nothing right now.