sharky55

I have an annoying hesitation problem with my '89 IROC that I cannot seem to figure out. The engine hesitates only upon throttling and ONLY after cold starts. After reaching normal operating temperature, the problem is completely gone and usually greatly diminished after the car temp gets above 100 degrees. Obviously, this problem is much worse during the winter months and sometimes in the summer it will hardly be a problem at all. I put in new plugs, wires, rotor, cap, fuel filter and cleaned the throttle body. None of these caused any change. I did notice a dramatic change for the better when I replaced the PCV value, but the problem still exists.

Because of this, I suspect that it could be emissions related, possibly involving the EGR valve. I haven't checked this yet because the valve is not easy to access freely. Most EGR problems would register a trouble code with the ECM in the car anyway and I have never had any codes so I am in doubt about this one. Is there a good chance that this problem is indeed related to the EGR valve? Anyone had a similar experience and found this to be the source?

I thought about carbon buildup on the intake valves, but I have tried several cleaners in the fuel tank without definitive evidence of improvement. I also thought about having the carbon manually scraped off, but I don't really want to bother with that unless I am sure it is the cause of the problem. The car does sit a lot between drives but most of my miles are on the highway. Shouldn't products like Chevron Techron take care of that anyway? Is there ever a situation where carbon buildup is so bad that no liquid cleaner can effectively remove it???

Does anyone have any other ideas or has anyone experienced a similar problem? I sure would appreciate any help I could get on this. Thanks!

alexrela

check your coolant temp sensor.

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'91 Camaro 3.1 t-tops 44k original.
'98 GMC Sonoma excab 4.3 auto 35k.

REDROC

I JUST HAD THE SAME PROBLEM MYSELF WITH MY '87 IROC 5.7 TPI. IT WAS THE IDLE AIR CONTROL VALVE. THEY ARE FAIRLY CHEAP. I GOT MINE AT ADVANCE FOR 31.34 AFTER TAX. AUTO ZONE HAS THE CHEAPEST PRICE, 5.00 CHEAPER THAN ADVANCE, THAT IS IF THEY HAVE ONE IN STOCK. GOOD LUCK!

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1987 CAMARO IROC-Z 350TPI
K&N AIR FILTERS
MSD COIL
3.27 BW REAREND W/POSI.
JET FAN SWITCH
MORE TO COME...
1981 CAMARO Z-28
ACCEL SUPERCOIL, CAP & ROTOR
ZOOM TIMING SET
SUMMIT CAM & LIFTER SET,
WORTH ABOUT 50 MORE HP
3.08 REAREND
350CI 4BBL QUADRAJET
TH-350 AUTOMATIC