Okay, so it has been unseasonably warm here lately. When it gets over 80 degrees or so, my '96 GS-R doesn't want to stay idling. It's fine in the mornings when it is cooler, and it is fine when I first start it in the afternoon to go home. But when I get off the highway (after about 10 minutes through town and 15-20 minutes on the interstate), it dies at stoplights / stop signs unless I keep my foot on the gas. I tested the ICV last night and it tested good. Has a CEL for "insufficient purge valve flow," but I wouldn't think that would cause it to die. It's had that problem since I got it last year, and it ran fine last summer in 90+ weather.

Any ideas?

 

ECT sensor, if you pull your spark plugs, [when car will not idle] you will most likely find it is running rich.

Check for trouble codes, even if CEL is not on, codes may be stored.

The ECT sensor supplies the ECU/ECM with engine temperature, when cold the ECU/ECM will run the engine rich as the engine warms up the ECU/ECM, [with info from ECT sensor] will lean out the A/F ratio.

 

fcm,

Thank you; I'll check the ECT sensor and pull any add'l codes tonight. It was throwing a code 14 this morning too (ICV valve circuit trouble), but I suspect that might be from pulling the ICV plug out last night while it was running.

Thanks again,

 

I realize this thread is a bit old, but I wanted to post my resolution so that it might help anyone else with this problem.

I discovered I had a small crack in the valve cover breather hose leading from the valve cover to the intake. I replaced this hose (the parts store guy gave it to me for free since it's only a couple inches long!) and I haven't had any trouble since then. Now that there have been a few more nice warm days, I am convinced the problem is solved.

After reading up on the operation of the breather / PCV system, I believe that the cracked vacuum line was allowing unmetered and unaccounted-for air into the intake. The warm-up mixture was rich enough to compensate, but once the engine was warm and the mixture leaned out, it was too lean with the extra air coming in and the engine stalled.

What I haven't figured out is why it only happened in warm weather. Does the ECU adjust fuelling for intake or ambient air temperature? Colder, denser air = more oxygen = more fuel = no stalling? Warmer less dense air = less oxygen = less fuel = stalling? Any ideas?