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ST185: What Just Happened

Fri Oct 07, 2016 12:48 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.

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Re: ST185: What Just Happened

Fri Oct 07, 2016 1:58 am

check fuse box connectors, grounds, frayed wires, etc..

Re: ST185: What Just Happened

Fri Oct 07, 2016 3:16 pm

Make sure that when you were pulling the interior up around the dash the some of the harness wires to the ECU didn't get pulled a little loose.

The ECU is under the dash dead in the middle of the car. When you took out the carpet, a wire might have snagged and pulled one of the pulls out a little.

Re: ST185: What Just Happened

Fri Oct 07, 2016 3:59 pm

Not sure why one wire would pull out of the ECU terminal strip by pulling the carpeting out, but will check that. The wiring comes through as a set (harness), and it looked like it was secured to the body, so the carpeting removal shouldn't have been able to pull just one (or a few) wires out - but I don't want to rule this thought out, so will check it when I next see the car again. Thanks for that input.

Re: ST185: What Just Happened

Fri Oct 07, 2016 5:40 pm

If you have a bad connection sometimes all it takes is jolting the harness. if you don't find anything take a look at the crimps on the connector pins.
It's also possible a sensor just happened to go bad right then. O2, ECT, AFM.
If it was a 92/93 I'd suggest you jump TE2 and E1 and drive it, looking for codes.

Re: ST185: What Just Happened

Fri Oct 07, 2016 5:49 pm

It's a 1990. Is there a difference from 90/91 to 92/93 that would affect jumping the same connectors and find out what codes are thrown after taking it for a drive? I think the ECU's are of the same vintage (pre-OBD-II).

Re: ST185: What Just Happened

Fri Oct 07, 2016 9:08 pm

After you set the spark timing for the new build, did you tighten the distributor back down?

I haven't run into that problem on a 3S, but have on a small block Chevy where it runs great. Go on a test drive and it still runs great. Shut it off and it won't restart. It ended up being the distributor had turned a little on shutdown.

So, recheck your spark timing.

Re: ST185: What Just Happened

Sat Oct 08, 2016 1:22 am

That is a great observation - a distributor not tightened after timing completed, moves a bit. I know I was in the engine compartment only to remove the intercooler (to straighten out the fins to prep it for painting) then put the cover back on, I could have touched one of the spark plug wires that could have caused a distributor movement. This piece makes sense. I won't be around to see the car again for a couple weeks, but will check this very item when I see it again in 2 weeks.

Thanks for this input, Scott.

Re: ST185: What Just Happened

Tue Oct 25, 2016 11:24 pm

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.

Re: ST185: What Just Happened

Wed Oct 26, 2016 10:00 pm

Glad to hear that you found the problem.
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