Engine Dies while Driving

[DMCVegas]

Does your idle hold 775 RPM at normal idle?

Sounds like you have a problem with the idle circuit since it started wide open.

I had that same problem. Driving home one night, pull up to a stop light and the engine dies. Fires right back up, but as soon as I took my foot off the gas it died again. Had to hold the gas pedal down to keep the engine from dying on the way home. Hit the wires between the ISM and the ECU with a multi meter to check resistance and found a bad one. Spliced in a new wire and never any any more trouble.

[Jimmycxc]

I had that same problem. Driving home one night, pull up to a stop light and the engine dies. Fires right back up, but as soon as I took my foot off the gas it died again. Had to hold the gas pedal down to keep the engine from dying on the way home. Hit the wires between the ISM and the ECU with a multi meter to check resistance and found a bad one. Spliced in a new wire and never any any more trouble.

Thanks. I would definitely need some pics to fully understand what you did. I can splice in new wires, but not sure where everything is located.

Also, with my issue, it doesn't always start right back up. I need to do more investigating to get more information.

[DMCVegas]

Thanks. I would definitely need some pics to fully understand what you did. I can splice in new wires, but not sure where everything is located.

Also, with my issue, it doesn't always start right back up. I need to do more investigating to get more information.

When cranking, hold the gas pedal down ¼ of the way. RPMs will shoot up, but don't be scared. Just make sure it runs. THEN take your foot off the pedal and see if it dies.

I don't have any pictures right now since I am no where near my car. However, for you anyone else coming into this thread, here is a quick video to give you an idea about how to check continuity to first watch:



Now not all meters will have the ability to beep. So you'll just have to keep an eye on your meter's gauge or display. But I have a feeling that most of us probably have something close to the Cen-Tech Harbor Freight special, so I'll reference one of those.

Set the Meter to ohms, 200 Ω to be exact. Touch the leads and you should pretty much have zero resistance. Now whenever you touch the opposite ends of a single wire, you should pretty much get the same result on the meter. This will tell you two things:

1. The wire is in good shape and shows connectivity.
2. If you're trying to sort out & locate an individual wire, you've not just located the correct one.

Now to check the wires between the Idle Speed Motor and the Idle Speed ECU, it's pretty easy.

Disconnect your car battery! Yeah can probably just leave the key out, but it's a good safety habit to get into. Hit the wrong wire that's powered, and you can risk electrical damage. Or even blown fuses, and that's just irritating.

Unplug the 3-wire connector from on top of the ISM. Then unplug both connectors from the back of the ECU. You should see one plug that contains Four wires, and another that contains Five. The plug that has has Five wires is the one you want to focus on. Wire 1 is 12V power, 2 is Ground (or Earth), and 3, 4, & 5 are the ones that connect to the ISM. Those are the ones you want to check. In this picture, look at the plug on the left with the five prongs. See the two on the bottom, and then that 3rd on the top, off by itself, all the way to the right? Those are the leads that power the ISM. Simply mirror that image to see which of the sockets on the wiring harness they plug into.

106896.JPG
Refer to Item 108 on your Master Wiring Schematic for further clarification and wiring color codes.

Now, you're gonna need some extended leads here because of the different locations inside of the Engine Compartment and the Passenger Compartment. But it can be done. Just connect your lead extensions first and verify the absence of resistance on your test wires to make sure they're all good. Then just plug the probes into the sockets to check for continuity.

No resistance on your wires means that they're good. Any resistance or failed continuity means that they're bad. Resistance may just mean some corrosion that needs to be cleaned off. So check your connections, clean them, and then retest. But it can also mean a bad wire with a potential break. In my case, I isolated the single bad wire, and then cut it an inch away from the ISM plug. I verified continuity through the plug itself was good, so then I just pulled a fresh wire in along side the harness, severed the bad wire behind the ECU plug too, and then just spliced it in. Everything worked just fine after that.

Is this the same problem you're having? I don't know. But before you cut anything, follow these instructions to test your wiring. And make sure you always disconnect and isolate the wire to fully test it for proper continuity.

[Jimmycxc]

A little update. The car starts up great on a cold start. It idles, although it does hunt a little bit (always done this). I can rev up the engine and it goes back to idling.

So I decided to try and move it to the other garage again. I got a little farther this time before it stalled the first time. I got into 2nd gear by keeping on the gas a little while I shifted and as long as I kept on the pedal, the car would drive. As soon as I let off, the engine would die. When it died, I would coast for as long as I could. I found out if, I tried to start it by pushing in the clutch and turning the key while I was still coasting, it would start right up. If I came to a stop, I would have to give it full throttle for it to start.

I still have to check for continuity between the ISM and Idle Speed ECU. I will hopefully have an update for everyone by the end of the day.

[Jonathan]

Sounds to me like your idle speed microswitch isn't engaging. Loosen the lock nut on the upper post and dial it in one full rotation (360 deg) towards the microswitch tab. Tighten the nut and go take it for a test drive. Double check the electrical connections on the switch are ok too while you're there. There are only two, the black ground goes to the top and the black/green one goes to the lower tab. Make sure neither of those has fallen off or is loose.

[Jimmycxc]

Still troubleshooting and discovered this...Took the air filter box off and with the car running at idle, I push down on the plate and it immediately stalls.

[Bitsyncmaster]

Still troubleshooting and discovered this...Took the air filter box off and with the car running at idle, I push down on the plate and it immediately stalls.

Does what it should. That air plate is not the throttle plate. It adjusts the mixture so your basically shooting to much fuel with very little air.

[Jimmycxc]

Does what it should. That air plate is not the throttle plate. It adjusts the mixture so your basically shooting to much fuel with very little air.

Gotcha. Thanks Dave

[Jimmycxc]

When cranking, hold the gas pedal down ¼ of the way. RPMs will shoot up, but don't be scared. Just make sure it runs. THEN take your foot off the pedal and see if it dies.

I don't have any pictures right now since I am no where near my car. However, for you anyone else coming into this thread, here is a quick video to give you an idea about how to check continuity to first watch:



Now not all meters will have the ability to beep. So you'll just have to keep an eye on your meter's gauge or display. But I have a feeling that most of us probably have something close to the Cen-Tech Harbor Freight special, so I'll reference one of those.

Set the Meter to ohms, 200 Ω to be exact. Touch the leads and you should pretty much have zero resistance. Now whenever you touch the opposite ends of a single wire, you should pretty much get the same result on the meter. This will tell you two things:

1. The wire is in good shape and shows connectivity.
2. If you're trying to sort out & locate an individual wire, you've not just located the correct one.

Now to check the wires between the Idle Speed Motor and the Idle Speed ECU, it's pretty easy.

Disconnect your car battery! Yeah can probably just leave the key out, but it's a good safety habit to get into. Hit the wrong wire that's powered, and you can risk electrical damage. Or even blown fuses, and that's just irritating.

Unplug the 3-wire connector from on top of the ISM. Then unplug both connectors from the back of the ECU. You should see one plug that contains Four wires, and another that contains Five. The plug that has has Five wires is the one you want to focus on. Wire 1 is 12V power, 2 is Ground (or Earth), and 3, 4, & 5 are the ones that connect to the ISM. Those are the ones you want to check. In this picture, look at the plug on the left with the five prongs. See the two on the bottom, and then that 3rd on the top, off by itself, all the way to the right? Those are the leads that power the ISM. Simply mirror that image to see which of the sockets on the wiring harness they plug into.

106896.JPG
Refer to Item 108 on your Master Wiring Schematic for further clarification and wiring color codes.

Now, you're gonna need some extended leads here because of the different locations inside of the Engine Compartment and the Passenger Compartment. But it can be done. Just connect your lead extensions first and verify the absence of resistance on your test wires to make sure they're all good. Then just plug the probes into the sockets to check for continuity.

No resistance on your wires means that they're good. Any resistance or failed continuity means that they're bad. Resistance may just mean some corrosion that needs to be cleaned off. So check your connections, clean them, and then retest. But it can also mean a bad wire with a potential break. In my case, I isolated the single bad wire, and then cut it an inch away from the ISM plug. I verified continuity through the plug itself was good, so then I just pulled a fresh wire in along side the harness, severed the bad wire behind the ECU plug too, and then just spliced it in. Everything worked just fine after that.

Is this the same problem you're having? I don't know. But before you cut anything, follow these instructions to test your wiring. And make sure you always disconnect and isolate the wire to fully test it for proper continuity.

Got 4 ohms resistance one the first wire. 0.3 Olmsted second wire, and no continuity for the third. Looks like I need to run a new wire.

[Jimmycxc]

Not sure what happened, but when I tested everything again before I spliced in a new wire and now each wire is either zero or 0.4 ohms.