KHE Posted April 18, 2005 Report Share Posted April 18, 2005 My '96 SLS is hard to start warm - it cranks excessively and if I depress the accelerator pedal slightly, it starts. This has been a minor nusiance for several months but since my wife is the princple driver of that car, it hasn't made the top of my to-do list....LOL... I checked the FPR and there was no fuel leaking from the nipple so I pulled the fuel rail and checked for a leaking injector. None of the injectors were leaking. I then decided to clean the throttle body as preventive maintanence. The throttle body was really crudded up and it tool a lot of elbow grease to clean it. Since I cleaned the throttle body and disconnected the negative battery cable, the car starts warm just fine. How would the filthy throttle body make the car hard starting when the engine is warm???? Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted April 18, 2005 Report Share Posted April 18, 2005 Good question. I would have bet on the FPR. Looking forward to Guru's answer. Link to comment Share on other sites More sharing options...
JasonA Posted April 18, 2005 Report Share Posted April 18, 2005 How would the filthy throttle body make the car hard starting when the engine is warm???? Maybe no air? When cold, a choke is a good thing. But when warm, it should start on a normal A/F mixture. Maybe if the throttle body was glued closed, it wasn't getting enough air to start when warm, and when you crack the butterfly open, you're now supplying it with the air it needs. Just a guess... Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
navion Posted April 18, 2005 Report Share Posted April 18, 2005 I second jadcock's anayalsis. It could have been a malfunctioning ISC motor also. Does the ISC operate? To check, with the engine idleing, switch on the A/C & watch the RPM. It should drop & then recover. Better would be to watch the ISC it's self while someone switches the A/C on. You should see the ISC plunger push against the throttle lever to maintain the engine's idle RPM. Question for Guru. Should the ISC compensate for an increasingly dirty throttle body? Britt Britt Link to comment Share on other sites More sharing options...
KHE Posted April 18, 2005 Author Report Share Posted April 18, 2005 The '96 does not have an idle speed motor - it has an idle air control valve. The ECM compensates for a dirty throttle body - after cleaning the TB, the negative battery terminal is disconnected to restore the default settings. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted April 18, 2005 Report Share Posted April 18, 2005 I am not real familiar with the idle control circuit but as I understand it the valve opens to a port behind the throttle plate. Isn't it possible that the port was carboned up and choked off? Link to comment Share on other sites More sharing options...
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