1989 intermittent stalling problem

[Gilbert]

I have a 1989 SHO, which I bought new 15 years ago from Glengarry Ford in Ontario and now has 71K miles on it. It has been running fine until very recently.

A month ago, after having parked it in real cold weather for an hour at -30F, the engine started but revved up fairly high for 3-4 seconds and shut down. It did this about five consecutive times but came back to normal. It also occasionally stalls when slowing down like when
getting to turn a corner or slowing to a red light.

In the past couple of days, when driving, on a urban highway, 5-10 minutes after starting, in 5th gear at 2300-2400 RPM, the motor has
been stalling for a couple of seconds intermittently. It has not happened on uphill yet, but on flat or downhill conditions. Outside
temperature was around 10F. I may drive for 5 miles without occurring.

I have tried reading on the subject of fuel pumps but it seems they usually cause hard starting problems. The fuel filter has not been
changed yet nor the top 60K maintenance been done as I have yet to decide who will do it. The timing belt was changed last year. Any idea
what could be causing this?

I live in Montreal and used to have a mechanic privately take care of my car but he is not available anymore. I was dealing with another mechanic before but he died a month ago. Should I consider going to a Ford dealer?

--
Gilbert

 

[projectSHO89]

Welcome to the Forun, Gilbert!

Sounds like you have a very well cared for car. Hope it stays that way.

As far as taking your car to a dealer, I would do that only after interviewing them and determining if they have someone experienced with the SHO on staff. The level of ignorance at dealserships about this car is relatively high as it was a low production vehicle and most of the wrench-turners have never spent much time working with them. Sometimes you get lucky and find one of the mechanics who owns or has owned a SHO. Perhaps you will find another SHO owner/enthusiast in your area who can privately support your car.

From your symptoms, I think you have two problems. The first is easy. Your Idle Air Control (IAC) valve is sticking. That is causing the problems with erratic idle speed and loss of dashpot control on coast-down.
It is possible to clean some of these valves using the instructions at www.shotimes.com under "Maintenance". If cleaning it does not help, it can be replaced for around US$60 with a new IAC from AutoZone. One of your fellow Canadians can probably chime in with price and availability from sources north of the border.

It is somewhat possible that the IAC is also causing the stumbling while at cruising speed, however, there are more likely candidates.

Your first step will be to run the codes to see if the computer self-diagnosed anything. Run both the KOEO and the KOER sets. Let us know the results and we can help isolate the source of the problem.

Also, observe the CEL and the TACH when the engine stalls and you are trying to restart it. If the TACH is reistering and the CEL is on while cranking, then you probably have a fuel delivery problem. If either is missing, you have an ignition problem and are likely looking at either a cam sensor or a crank sensor (most common causes).

There is a wealth of information here in the Forums and also in the FAQs at Shotimes. Make your self at home and poke around.

Steve

 

[sideSHO]

Welcome Gilbert.
Steve pretty much hit it on the head.Check and clean the IAC.Run your codes.
The shotimes link he gave you is very informative.I got alot of info there when I was in my SHO diapers(outgrown the SHO diapers but I still wet the bed sometimes)

See ya around thumb

 

[Gilbert]

Originally posted by projectSHO89:
[QB] Welcome to the Forun, Gilbert!

Sounds like you have a very well cared for car. Hope it stays that way.

Since this is the best car I've had in the past 40 years, I'd like to keep it forever!

"As far as taking your car to a dealer, I would do that only after interviewing them and determining if they have someone experienced with the SHO on staff. The level of ignorance at dealserships about this car is relatively high as it was a low production vehicle and most of the wrench-turners have never spent much time working with them. Sometimes you get lucky and find one of the mechanics who owns or has owned a SHO. Perhaps you will find another SHO owner/enthusiast in your area who can privately support your car."

Since this problem is somewhat preventing me from using the car with ease, I've ended up bringing it to Gagnon Batteries Électrique, a place specialized in carburation and electricity for a long time. I have an appointment for tomorrow afternoon.


"Also, observe the CEL and the TACH when the engine stalls and you are trying to restart it. If the TACH is reistering and the CEL is on while cranking, then you probably have a fuel delivery problem. If either is missing, you have an ignition problem and are likely looking at either a cam sensor or a crank sensor (most common causes)."

No problem with the tach indicating the revs. No problem either to restart. It does so within a second. It just feels like the idle goes down too much and the computer is not fast enough to catch it before it stalls. The highway stalls are rather unnerving as they are rather abrupt and feel more like braking than lifting the foot from the accelerator.

I think I'll have a look to see if I can still get the shop manual as I did not get one when I got the car as I should have done.

I'm really fond of this car because while it can be considered high performance, it is not a car where your bottom is just a few inches from the ground or rough riding. To the unacostomed eye of some police officers, you are not spotted as already speeding like if you drive a Corvette or Mustang. Those bucket seats have proved to be the best I've experienced. Last year I drove nearly non-stop from Montreal to Jacksonville, FL and was quite comfortable. While having a powerful motor, it can be quite economical on the highway. Only my A/C and cruise control are not functional presently. My A/C stopped working 10 years ago. When I inquired about getting it fixed, last Spring, I was told it would be at least 1500$CDN to get it fixed... My wife bought a used 1999 Taurus SE with Duratec engine two years ago and use it instead when the weather is too hot. I have not investigated the possible causes of the cruise control malfunction.

Thanks again for the help! It is appreciated.

--

Gilbert

 

[Gilbert]

Finally got those codes:

14-24-29-59-66

After clearing the codes and rechecking 59 comes immediately again.

The mechanic where I brought it, mentioned lower codes are the most important.

I need to call them tomorrow as the could not get a price on the crank position sensor. They mentioned about 5 hours to do the job including changing the water pump which I think would be good preventive maintenance.

--
Gilbert