View Full Version : ST185: What Just Happened?

10-07-2016, 01:49 AM
Going through a major refurbishment of a 1990 ST185 All-Trac. All original. Completed all mechanicals. Engine & drive train working as if the car just left the dealer's lot for the first time.

This week, spent 2 days removing the entire interior (less the dash & center console up to the shifter - everything else inside stripped) - prepping for body work & fresh paint. Will to detailing the interior at the same time - will install new interior when body refurbishment is complete (next spring).

Drove the car from highway into my garage - ran great. Removed the interior. Started the car to take it to a classic car body shop (temporary seat put in, of course), and the engine barely ran. Could tell it was running rich, and way to slow (would snub out if I didn't keep my foot on the gas, which in the early stages, was a lot. Finally warmed up and ran just a little better, but wouldn't slow idle. Turned the idle adjusting screw open about 3 full turns just to get up to 800 RPM idle. Still running rich with intermittent misses. Took it on the road - could not get the engine above 3500 RPM without it starting to buck a lot. Not running anywhere close to correct. Did not touch the engine compartment (that was already completely redone and verified all was operating great). Just removed the entire interior, disconnected stereo, speakers, inside lighting, etc., but no engine control wiring or anything.

Has anyone removed an interior of an ST185 and ran into the same thing? Is something on the inside affecting how the ECU controls the engine? If there is some kind of unique issue with interior power removal that affects engine operation, I would like to know that, so that I don't worry about it come next spring when the body work is done.


10-07-2016, 07:46 PM
Check your codes as a first step. Then check the circuit opening relay connector, and the connectors going into the ECU and from the engine harness into the chassis to make sure nothing got inadvertently disconnected. That's where I'd start :)

10-08-2016, 02:29 AM
I believe the Circuit Opening Relay simply turns the fuel pump on or off. If the engine runs at all, the fuel pump must be running, so I don't think the COR wiring is at fault (unless it is switching on/off rapidly, but I don't think by how the engine sounds that this is happening).

Would the ECU be storing codes if the check engine light is not on? I thought there were very few codes that could be set without the check engine light going on. But none-the-less, should run a scan of the ECU to check for codes just to make sure.

10-15-2016, 02:56 AM
20+ year old wiring can be... fickle. Like Chris said, double check all the wiring going to the ECU. If there are no visual breaks, start the car and GENTLY wiggle the wires and see if it has an effect.

10-16-2016, 08:25 PM
When I get back to Wisconsin, I will try to do that. It is in the body shop for the rest of the fall/winter for restoration, but I don't think they've made too much progress yet that I can do some inspections/diagnostics. Yes, 20+ year old cars, especially ST185's, can be fickle.

10-26-2016, 12:49 AM
I have an update to the discovery of causes for this issue, after seeing the car for the first time since posting this evening.

First, no codes were present - nice steady flashing check engine light. Noticed the distributor position was about as far retarded in the slots as it could go. Bolts were tight. I had a shop do the engine work, including timing belt & related parts, distributor overhaul and retime, etc. Checked timing, was about 0 deg to 2 deg BTDC. Before the symptoms in this post, this car was slightly more sluggish than a 2nd one we have. Then I thought "I wonder if the shop did not use jumpers on the engine diagnostic port when doing the timing?" So I remove the jumper, and sure enough, the timing was at 10 deg BTDC. This explains the slight sluggishness, but not the sudden rough operation.

Checked wiring, checked air lines and the piping between the MAF and throttle body, all looked good. Checked a lot, was almost time for the body shop to close, then the shop guy says "Why is that air hose clamp loose like that at the discharge of the turbo?". Sure enough, the clamp was actually broken. But the hose seemed good and snug. The body shop guy said he had a large clamp like that, just the screw wasn't great in that it would slip. Anyway, while the engine is running, I remove the old air hose clamp at the turbo discharge, put the temporary one on, start to tighten it, and the engine starts smoothing out and running well. The clamp couldn't be tightened, but it was a lot better than the broken one. So that is why I had engine problems, the darn air hose clamp at the turbo discharge just snapped open and was loose, and it must leak enough air even if it felt tightly mounted to the turbo, as a slightly tightened temporary hose clamp demonstrated.

So, I will likely get a replacement hose piece and two new clamps, and properly reset the timing, and I believe all will be better than ever on this engine.