| Author | Message | ||
| Carl Rose (Carl_rose)
Junior Member Username: Carl_rose Post Number: 58 Registered: 10-2002 |
Dr. Reese if you need the throttle body exploded diagram for disassembly drop me a line: [email protected]  Carl | ||
| Carmine Nicoletta (Ncarmine)
New member Username: Ncarmine Post Number: 48 Registered: 6-2002 |
Daniel, my idle speed became erratic while taking a trip one cold morning. In my case, it turned out to be a sticky throttle plate. The spring loaded butterfly was gummed up due to old grease. I was advised to take the throttle body apart from the intake and thoroughly clean it. If you spray cleaners, the solution may discolor the intake and valve covers if not careful. All you'd need is a new gasket. | ||
| Daniel B Reese MD (Dbr328gtb)
Junior Member Username: Dbr328gtb Post Number: 138 Registered: 5-2001 |
Thanks David. I'll look into it. Carl, thanks for book recommendation. Dan | ||
| david handa (Davehanda)
Member Username: Davehanda Post Number: 404 Registered: 5-2001 |
Dr. Reese, it is not uncommon to have a sticky throttle plate. From the outside, you can try lubricating the mechanism with some silicone spray. From the inside (remove the rubber intake) you can clean the plate and pivot points with carb cleaner spray...I know of a couple people who have done this on fuel injected 308's. | ||
| Daniel B Reese MD (Dbr328gtb)
Junior Member Username: Dbr328gtb Post Number: 137 Registered: 5-2001 |
Thanks very much David and Carl. It sounds like my system works ok. I really dont think my carpet is in the way, but I'll check. Other than carpet or stuck throttle is there any reason why a tap of the accel will revert to normal idle? It certainly wouldnt happen with a tap in the first few minutes but will after about 5-10 minutes when it is winter. | ||
| david handa (Davehanda)
Member Username: Davehanda Post Number: 401 Registered: 5-2001 |
Here's a cheaper on-line source to Bosch FI information: www.auto-solve.com/mech_inj.htm | ||
| Carl Rose (Carl_rose)
Junior Member Username: Carl_rose Post Number: 54 Registered: 10-2002 |
Hi Dr. Reese, Pulled copy of the book I referenced (ISBN 0856964824):  Carl | ||
| david handa (Davehanda)
Member Username: Davehanda Post Number: 394 Registered: 5-2001 |
No, "tapping" the throttle pedal should do nothing, to include dropping the idle, that is why I was asking Dr. Reese to check his floor mats again. If the mat IS pushing against the pedal, a couple light taps will often times push the offending mat back sufficiently to drop the idle down....At least it did in my case, until I secured the mat. | ||
| TomD (Tifosi)
Intermediate Member Username: Tifosi Post Number: 2108 Registered: 9-2001 |
make sure nothing is hanging up your throttle cable. sometimes these can stick ever so slightly especially in colder weather. Please correct me if I am wrong but does tapping the accelerator have any affect in getting a FI car to run more smoothly? I did not think so, this is more of a carb thing? | ||
| Carl Rose (Carl_rose)
New member Username: Carl_rose Post Number: 48 Registered: 10-2002 |
Hi Dr. Reese, Good book on this topic is the Haynes manual on Fuel Injection. Covers K-Jetronic, which is the factory 328 system. Highly reccomend - about $14 from most bookstores. "Cold" or "fast idle" is the modern equivalent of a choke system & typically runs "open loop" (no feedback from O2 sensor) until the coolant reaches a certain preset temperature. The auxiliary air valve & the cold start injector (passenger side of plenum) along with ECU program calibration are main components. If you let the car idle long enough (until warm) will spontaneously revert to "closed loop" (monitoring O2 sensor input) and drop to 1000 RPM. Or at least that's what mine does. Hope this helps, Carl | ||
| Daniel B Reese MD (Dbr328gtb)
Junior Member Username: Dbr328gtb Post Number: 136 Registered: 5-2001 |
David, Thank you very much for your response! Dan | ||
| david handa (Davehanda)
Member Username: Davehanda Post Number: 388 Registered: 5-2001 |
BTW, when the auxillary air valve failed on cars I've owned, it has always failed in the closed position, so the cold idle never came on. But I don't know if that is how they ALWAYS fail. | ||
| david handa (Davehanda)
Member Username: Davehanda Post Number: 387 Registered: 5-2001 |
Dr. Reese, Please do double check the floor mat, this has been the case with both my previous 308 and my current 328. Fast idle caused by the mat sliding up against the throttle. The cold idle circuit is operated by the auxillary air valve. It opens via cold temps, and when you start the car, current is applied to it and (I think) heats up a bi-metallic strip that slowly closes the valve. This valve allows extra air past the throttle plate and consequently more fuel is applied as well. Is sounds like yours is operating normally. I thought mine was stuck open all the time (Idle was always around 1900 rpm), until I checked the floor mats. A little judiciously applied Velcro fixed things right up. :-) | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 3070 Registered: 12-2000 |
I use to think I had cruise control, just turned out to be the carpet. | ||
| Daniel B Reese MD (Dbr328gtb)
Junior Member Username: Dbr328gtb Post Number: 135 Registered: 5-2001 |
Funny! My carpet is well away from the pedal though | ||
| John Delvac (Johndelvac)
Junior Member Username: Johndelvac Post Number: 196 Registered: 11-2001 |
I don't know how it works, but I have a funny story. I was asked this before and the result was that the guy's floor mat was riding up on the petal. Ha! The only reason I knew to look there was that I had the same problem with my floor mat! | ||
| Daniel B Reese MD (Dbr328gtb)
Junior Member Username: Dbr328gtb Post Number: 134 Registered: 5-2001 |
What is the reason for a fast idle? I know it comes on with a cold engine and it will revert to normal idle after a period of time. How is this regulated? I've noticed in winter (Virginia) it will fast idle for a long time. Usually when my water temp moves past 140 (5 to maybe 10 minutes) I will tap the accelarator and then it will normal idle. When does it decide to go to normal idle? If I were more patient, would it go to normal idle on its own? I believe it only fast idles for a few minutes in the summer. How do you know the fast idle isnt working properly (other than it wont idle fast). Thanks for helping this mechanical novice! |