SHO died today, again!

[drdave]

Gen II, 1993 MTX, 225,00 miles. Seems to have a heat related problem. It did this a couple of times last year, did it last week when it was 95 outside, and today when it was 84.

After about a 60 mile highway drive, I come to a stop and the the idle drops to around 200rpm and just sputters, then dies. If I try to restart, it will go to around 200rpm and sputter and die again. If I let it sit for five minutes, it will start and run smoothly for about thirty seconds, then do the same thing. If I let it cool down, it will drive like nothing ever happened.

I haven't run codes yet, but I'm sure it will throw a CPS, like they always do after a stall.

I figure it's a heat problem related to the CPS or the DIS, but it's really hard to track down. After it died this afternoon, I cooled down the DIS with some spray, and the car seemed to run fine. But I'm not convinced it' wasn't just a coincident.

Any ideas?

 

[dstig1]

Well the telltale for the CPS is the tach not moving when you are cranking under a no-start. The signal from the CPS drives the tach.

There's too many things it could be. Fuel. Spark. Air. When it's not working you need to have the tools handy to find the issue (fuel pressure gauge would be handyto see if you have a vapor lock problem, for example). Air might be the IAC causing trouble. Spark could be a number of sensors or other electronics. No way to tell other than searching when it happens and checking off the possibilities.

 

[drdave]

I guess I should have been more clear. By CPS I meant crank position sensor. I think you'll get tach with that, but not if it's the cam position sensor. I do get tach. After it dies, I don't have long cranks, it will start readily, just won't get above 200-300 rpm, and then it will die.

Unfortunately, it always happens during rush hour traffic, never when I'm close to home. I always have my tools with me, just more concerned getting it out of traffic. Hasn't happened yet at a place that I can do any meaningful troubleshooting.

I do seem to get a pressure buildup in my gas tank when this happens, but not more than I'd expect in hot weather. But relieving the pressure has no effect on the problem.

 

[Minnesho]

if the cps is bad, you won't get tach at all. not even 200-300

 

[SolidState]

I'd like to suggest that it is fuel pump related. In the early days of the SHO, pump failures were common due to overheating fuel pumps.

 

[SHO_Driver]

I agree with SolidState. I had the exact symptoms when my pump was dying. It also threw a fuel code.

 

[drdave]

I ran the codes. The only code I got was a 542, I've pretty much had this code since I've owned the car, which is about 8 or 9 years. Was expecting to see a 211 but didn't.

I have to admit, I haven't changed the fuel filter in a long while, but I can't see that being heat related. My fuel pump always whines, but always has. Sounds no different than it ever did. But it is the OEM pump. It wouldn't hurt to replace it, but I don't want to do that to troubleshoot this problem, only to find out it wasn't the problem.

I cleaned the contacts on the DIS and put a fresh film of heat sink compound on it. We'll see if it makes a difference.

 

[SHO_Driver]

The only way to know for sure is to check the fuel pressure while its acting up. If its too low then you confirmed it.