Stalls out at idle
Thread Starter
Registered User
Joined: Jul 2002
Posts: 1,277
From: Phoenix, AZ
Stalls out at idle
The car runs phenomenally well. I have the idle set at 750 rpm but just now 3 separate times in the span of 5 minutes at idle it will just die. Never has it done this before. 2nd time it took a bit of turning of the starter to fire up.
I listen for the whine of the fuel pump before I start the car and it is there.
Any ideas where to start? Maybe a fuel pump starting to go bad? It is original and is 12 years old and 72K miles.
I listen for the whine of the fuel pump before I start the car and it is there.
Any ideas where to start? Maybe a fuel pump starting to go bad? It is original and is 12 years old and 72K miles.
Registered User
Joined: Nov 2006
Posts: 334
From: Roanoke VA
Maybe the ICM. When it dies, can you get it to start back and keep it running? Generally when they go bad, they either just die completely or they wait until the engine (and the ICM) heats up, then they act up, and shut the juice off to the coil.
Thread Starter
Registered User
Joined: Jul 2002
Posts: 1,277
From: Phoenix, AZ
Yes car starts back up and runs fine. Thinking about it, it did hesitate 2X while at the track last weekend...you know just a quick 1/2 second of no power then back on it as if nothing had happened. I assumed that it is the opti because that is what a bad opti in the past has done. Anything has only been while it is warm so that is another indication now.
Last edited by 95Blackhawk; Dec 5, 2007 at 09:43 PM.
Registered User
Joined: Jun 2007
Posts: 187
Could be ICM or the IAC as well. I’m thinking the IAC is not opening when the engine is warm. Warm wires don’t conduct as well and that is probably causing an issue in the IAC if damaged. The engine could be having a hard hot start issue because the IAC is not opening far enough and the engine is not getting enough air that’s why you have to hit the peddle to open the TB blades.
I have read about some heat sink issues with the ICM.
This is from shoeboxes site. Good luck
ICM Cooling Mod
Some people have reported ignition problems that seem to be heat related. One item that can be relieved of some heat stress is the Ignition Control Module (ICM). Merely spacing the coil and ICM bracket away from the cylinder head has solved miss problems in some cases. Any time you can reduce the amount of heat in an electronic component, it will normally prolong it's life and allow for more stable operation.
Getting to the coil and coil replacement is covered elsewhere in my Tech Pages, so I am not going to step through that procedure.
On my 1995 Z, I used a very simple approach to creating some space between the coil bracket and the head. I used some common 3/8" flat washers that I already had laying around. After removing the coil and studs, I put 2 washers between the "stud nut" and the cylinder head on the inboard stud. There is also a bracket for the EVAP hose that goes on this stud to take up some room. I used 3 washers on the outboard stud. With the thickness of the washers I had, this made the distance on each stud approximately the same (approximately 3/16").
The washers are used, because without the coil bracket sandwiched on the stud, the threads would bottom out in the head. This just gives a little extra space, which is not a problem.
Once the washers are in place and the studs screwed back in, you can mount the coil on the outside of the stud nut, instead of the inside where it was before. Torque value for both the stud to head and the nut is 18 lb. ft.
The total gap came out to about 1/2". Note that one of the studs has more threads on the outside portion of the stud nut. This is the stud that goes in the outboard head hole and is longer to accomodate the ground straps attached to it.
Another note: 1993 owners may have a bolt instead of a stud on the inboard side and others may have identical studs on both sides. It really does not matter. The intent is to create an air space between the head and the coil bracket. A little ingenuity and a couple of additional fasteners may be needed.
Tighten up the fasteners and reconnect electrical harnesses and you are done. I don't have any dyno runs or temperature comparisons for before and after, but for next to nothing in cost, this mod can't hurt.
I am not the first one to do this and it could be done using other methods and materials (perhaps, even more effectively). This just happens to be the way I did mine.
Update: At least one person monitored the temperature of the ICM and the head after the mod. With the engine running, the ICM stayed cooler, but when the engine was turned off, the ICM did not dissipate heat as fast as the head did. I did not get any info on how long the ICM stayed hotter. I am just providing that for your information and you can draw your own conclusions.
I have read about some heat sink issues with the ICM.
This is from shoeboxes site. Good luck
ICM Cooling Mod
Some people have reported ignition problems that seem to be heat related. One item that can be relieved of some heat stress is the Ignition Control Module (ICM). Merely spacing the coil and ICM bracket away from the cylinder head has solved miss problems in some cases. Any time you can reduce the amount of heat in an electronic component, it will normally prolong it's life and allow for more stable operation.
Getting to the coil and coil replacement is covered elsewhere in my Tech Pages, so I am not going to step through that procedure.
On my 1995 Z, I used a very simple approach to creating some space between the coil bracket and the head. I used some common 3/8" flat washers that I already had laying around. After removing the coil and studs, I put 2 washers between the "stud nut" and the cylinder head on the inboard stud. There is also a bracket for the EVAP hose that goes on this stud to take up some room. I used 3 washers on the outboard stud. With the thickness of the washers I had, this made the distance on each stud approximately the same (approximately 3/16").
The washers are used, because without the coil bracket sandwiched on the stud, the threads would bottom out in the head. This just gives a little extra space, which is not a problem.
Once the washers are in place and the studs screwed back in, you can mount the coil on the outside of the stud nut, instead of the inside where it was before. Torque value for both the stud to head and the nut is 18 lb. ft.
The total gap came out to about 1/2". Note that one of the studs has more threads on the outside portion of the stud nut. This is the stud that goes in the outboard head hole and is longer to accomodate the ground straps attached to it.
Another note: 1993 owners may have a bolt instead of a stud on the inboard side and others may have identical studs on both sides. It really does not matter. The intent is to create an air space between the head and the coil bracket. A little ingenuity and a couple of additional fasteners may be needed.
Tighten up the fasteners and reconnect electrical harnesses and you are done. I don't have any dyno runs or temperature comparisons for before and after, but for next to nothing in cost, this mod can't hurt.
I am not the first one to do this and it could be done using other methods and materials (perhaps, even more effectively). This just happens to be the way I did mine.
Update: At least one person monitored the temperature of the ICM and the head after the mod. With the engine running, the ICM stayed cooler, but when the engine was turned off, the ICM did not dissipate heat as fast as the head did. I did not get any info on how long the ICM stayed hotter. I am just providing that for your information and you can draw your own conclusions.
Thread
Thread Starter
Forum
Replies
Last Post