Quits , no pattern

[93SHO_2]

My 93 5 speed SHO quits running. No pattern, at idle, while accelerating, and while cruising. It is hard to restrart, 5 minutes to one hour later.
Starter cranks fine, all accessories work, and fuel pressure is 38 lbs (I carry a gauge with me now after replacing the filter and fuel pump a week ago to no avail). No sputter or hesitation before it shuts down. When it runs, it runs great.

This also happened 18 months ago (winter) and was "cured" by replacing the starter solenoid. I have again replaced the solenoid yesterday and it did not correct the problem.

I have also swapped the Ignition Control Module, the coil pack, and the fuses in the power distribution box. All with no improvement.

My $29 tester says #551 (KOEO), Idle Air Control Circuit, and I have replaced the IAC valve (twice). Once I have it running the tester does not identify any useful codes (just a power steering switch).

It runs N to O temp with the A/C on. I replaced the radiator and the thermostat. (A catless pipe is on order.)

The plugs and wires have less than 20K, and when it runs it does not miss nor sputter.

Any thoughts would be appreciated

 

[JC]

Belive it or not the same thing happens to me. Its happend a few times monthes back and i ended up replacing the o2 sensor, ignition module, and throttle position sensor. Car ran fine up unti tonight when im going 20mph, and without a sputter or anything just died on me. Cranks just fine, ahd to sit there for 15 minutes then finnaly it started up again. I dont get it?

 

[Chrisssssssss]

Do you get a tach reading when you crank? If there is no crank reading, then you can possibly say it may be your CPS (Crank Position Sensor). This is located underneath your timing belt routing. Just a thought.

 

[SHOemup]

Here's my theory. I think it's the CPS. What i think happens is this: You have a waterpump leak. The coolant leaks from the waterpump on to the CPS and then hits your cats and burns away leaving no sign of a leak. When the CPS gets too hot from the coolant, your car will shut down for no apparent reason. The waterpump and CPS are both tough to get to but easy enough to change when you get there. Just my .02

 

[93SHO_2]

Both O2 sensors are new.

There are no visible leaks in the water pump. I'll try to listen for hissing when it gets hot.
(I replaced the water pump about 50k ago, I just got out of therapy, and I'm not looking forward to that ordeal again.) The previous bout occured about 30K ago, I doubt the water pump was leaking at that time, stopped leaking, then started leaking again recently (but, I'll continue to consider the CPS theory, anyone know the CPS error code?).

The tach does jump between 0 and 300 rpm while cranking, but failing to start.

No error codes on the throttle position sensor. I disconnected the throttle sensor and got the appropriate error codes so my tester appears to be accurate.

 

[Chrisssssssss]

If the tach jumps like that between 0-300 RPM, I think that is a symptom of a failing CPS. It is a pain to change, but not impossible. I think that it is the problem, like SHOemup says, usually due to waterpump leakage. Remember the CPS is nothing but a magnetically activated switch, and it is electrical. We all know what happens when electronics get wet, don't we...

 

[BeatDaSHO]

it's probably the cps. i just had the same exact problem. the tach would move between 0 and 300 while cranking. i decided to replace it. While i was in there, i decided to just replace the water pump just because i was in there. turns out, the damn thing was leaking right onto the cps. i'm glad i replaced it because if i never looked, then i would have had to gone back in within a couple miles. And a failing cps will throw a code 14 on the generation I SHO's but not always.

Greg

 

[pete c]

A slow leak from the wp is damn near impossible to detect. Are you loosing coolant?

Also, when I had this problem, the ce light would flash intermittently as I cranked it. I think that means that the computer is seeing the cps intermittently.