dying problem

[kspharris]

Hi my car is on a fresh rebuild and it starts OK. It idles fine and drives fine until you run it hard for a pass or two and it then when you press in the clutch and let the car idle down it will die. Then it will take awhile for it to start again and you have to keep it idling yourself or it will die but after you keep it idling for about 2-4 minutes it will idle on its own. My data logger is not showing anything but temp sensor check engine light. My o2 is also showing low, like 0.2-0.4 at idle and rev. Bad o2 maybe? My ISC is as high as 92 steps, not sure how low it goes. Could this be a bad ISC? Any help would be appreciated thanks in advance.

 

[ddavisaf]

Well, if your logger is showing you that you've got "this wrong and this wrong and this wrong..." then you need to get those fixed first. It's hard to troubleshoot exactly what's wrong with one thing when you've got two or three other issues going on with the car.

Are you running rich at all?
Read Todd Day's Idle Reply to see if that fixes your problem.

If this process doesn't work, you are in the minority. Try looking for something basic, such as a loose throttle cable, first. Other sources of idle problems include fouled spark plugs, a defective or gunked-up idle speed control (ISC) motor, leaking injectors, a cracked vacuum hose, or a damaged intake manifold gasket. High idle can also be caused by a throttle cable or cruise control cables that are too tight.

Some troubleshooting tips: if your idle adjusts when your A/C compressor is on, or when all of the electrical accessories are on, the ISC is at least partially working. If your idle appears to fluctuate with temperature, suspect an air leak in a vacuum hose or at the air intake first.

If you need to check the ISC, do it when it is hot. The ISC resistance can sometimes change when it has cooled down. Thus, the ISC looks ok when checked, but misbehaves when actually operating. The same holds true for cables since they can tighten up during operation.

per VFAQ

 

[kspharris]

Hi my car is on a fresh rebuild and it starts OK. It idles fine and drives fine until you run it hard for a pass or two and it then when you press in the clutch and let the car idle down it will die. Then it will take awhile for it to start again and you have to keep it idling yourself or it will die but after you keep it idling for about 2-4 minutes it will idle on its own. My data logger is not showing anything but temp sensor check engine light. My o2 is also showing low, like 0.2-0.4 at idle and rev. Bad o2 maybe? My ISC is as high as 92 steps, not sure how low it goes. Could this be a bad ISC? Any help would be appreciated thanks in advance.

Right I understand that and that is what I am going to do but I can not do it until the weekend because the car is in another city and I can only go down on the weekends. I was just wondering if anyone had any suggestions because there are no CPU's out there in tha sticks. Yes I have read Todd Day's Idle Reply Thank you for your post. Thanks alot I will fix all the other stuff and see if that helps then do Todd's thing and if that dosen't help I Think that i might kill my car. Thanks again Keith.

 

[ddavisaf]

One more thing you might want to check is the caps in your ECU.

 

[kspharris]

One more thing you might want to check is the caps in your ECU.[/QUOTE
Thanks man i checked that allready with another cpu but the one i have and checked with was both new. Thanks anyway. Keith

 

[steve]

HMy data logger is not showing anything but temp sensor check engine light. My o2 is also showing low, like 0.2-0.4 at idle and rev. Bad o2 maybe? My ISC is as high as 92 steps, not sure how low it goes. Could this be a bad ISC? Any help would be appreciated thanks in advance.

There isn't a temp sensor check engine light. There is a check engine light and a warning light for the coolant level in the radiator overflow bottle.

Your O2 readings would suggest it's time for new O2 sensor but you should check all the wiring before replacing it just to make sure.

The ISC is acting up. Those counts indicate the ECU is trying to move the pintle out to raise the RPMs and nothing is happening so it keeps trying. That means that the ISC could be bad, the wiring has problems, or the drivers on the ECU are bad. Start by measuring the ISC coil resistances to go from there.

Steve