91 Integra, 155k

Mods:8lb Lightened Flywheel, AEM FPR, BLOX IM, MSD Wires/Cap/External Coil, JG Bored 62mm TB

Problem: Car occasionally stalls when disengaging the clutch (coming to a stop) OR the idle goes very low, 400-500rpm. Sometimes when I put in the clutch the idle goes straight down to zero, just dives all the way. Other times it dives, bounces, then stalls. The car restarts fine after stalls, has no other problems, no power loss, no stuttering, nothing. Accelerates fine.

I had the flywheel installed for a year before this problem started happening so its not the flywheel being too light for the ECU to compensate.

Otherwise, idle is 800rpm but car runs a tiny bit rough, runs very smooth at 1000rpm.

No codes are being generated by the ECU. Grounds are solid, battery terminals new. No vacuum leaks detected. Recently cleaned IACV. Injectors, cap, rotor, plugs are all new.

Because the car accelerates fine and drives fine I do not believe this is a spark or fuel delivery problem. The only problem I have is the stalling or low idle when I put the clutch in and its not all the time.

Any ideas appreciated




Modified by themilman at 1:36 PM 9/6/2006

 

Not to slpit hairs, but I think the correct term when you push the clutch pedal down is 'disengaging the clutch'. Anyway...

Did you set your base idle speed? You disconnect the IACV with the engine running and adjust the air bypass screw on the throttle body to hold 650-700RPMS. Shut her down, reconnect the IACV and reset the ECU to clear the code. Then, see what happens.

 

Thanks, both for the nomenclature correction and the base idle adjustment. I don't think that's causing the stalling, but it can't hurt.

 

Just to follow up, I failed to mention the base idle should be set when the engine is warmed up to normal oprating temperature.

FWIW, I had a '90 Civic Si with similar symptoms. I was at around 200K miles. The RPM would drop to near stalling when I would coast towards a red light, but only between the times the temp guage was coming off the cold point and normal operating temp. Also, when thoroughly warmed up, I could notice a surge or minor bucking when trying to hold a steady speed of 25mph in third gear. Another symptom was with the car standing still, I tried to hold a steady 2500 rpm on the throttle. It would fluctuate about 100rpm. Probing the O2 sensor I determined it was slow and lazy. It was just a single wire sensor, BTW. I tried a generic Bosch sensor for about $50 and it eliminated most of my symptoms for about 2 weeks. I exchanged it for another one with same results. I ended up buying a Honda OEM sensor for $170. Everything was still OK when I sold the car about 100K miles later. Just my eperience. Yours may vary.

 

I did have a stuttering problem awhile back. Replaced the O2 sensor with a Bosch and it solved the problem. The ECU uses the O2 reading to determine injector duration so this made sense. I'm thinking about getting a Denso O2 sensor just for piece of mind to eliminate it as a possibility. Thanks for input.

 

Just ordered an OEM Denso O2 sensor, $40 shipped from sparkplugs.com, can't be that. Cheapest on Ebay is $42 shipped.

 

bump

 

bump for knowledge

 

I put a new ECU in and it immediately threw code 7, BAD TPS!!!

My OEM ECU didn't throw this code so there was no way for me to know.

Now I just have to find a new TPS