87 cabrio Electrical Issue???

Any help appreciated. 87 Cabrio, I don't use often in the summer (AC shot). Recently I got in and started it. It backfired once and quit. Re-started no problem. Drove about 4 miles and when I went to slow down, pushed in the clutch, it stalled.

Re-starts OK, but symptoms persist... Rev engine to about 2000-2500 rpm, take foot off gas, revs drop to about 200 before Idle stabilizes. Sometimes it stalls, sometimes it doesn't. I increased the idle speed to about 900. I know this isn't a permanent fix but it does help prevent the stalling.

The other symptom is when driving, in any gear except 5th, at a "cruising speed', neither accelerating nor decelerating, the oil pressure light and the battery light come on dimly. When I accelerate, decelerate or shift, the lights go out. This has not happened before, and the gauges tell a different story, oil pressure and volts show fine.

Any ideas?

jimDOTmullerATearthlinkDOTnet

Reply to
JM
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What type of fuel injection system does the '87 Cabrio have (I'm pretty sure it is CIS-e)? CIS-e and Digifant has throttle position switches for idle and wide open throttle (WOT). If the idle switch is broken, the idle stabilization circuit does not work. I recently had to replace the idle switch on my '87 GTi, and hunting for a replacement at the local junk yard I found that this switch was broken on a large number of the potential donor cars, so probably a common problem.

You can easily spot the WOT switch, it is siting on top of the throttle body (At least it is on my GTi, and I seem to remember the Cabrios at the junk yard having it in the same location). The idle switch is at the bottom side of the throttle body, and it is easier to "see" it with your fingers than your eyes. It is smaller than the WOT switch, and it does not have the long lever that the WOT switch has.

If you operate the throttle by hand (at the throttle body), you should hear the idle switch clicking as you move the throttle between all the way closed and barely open.

It is easy to test if the idle switch is the problem, but you may need to put the idle screw back where it was before you turned the idle up to

900 RPM. The connector that goes to the switches has three pins (for CIS-e, which I believe you have). Unplug the connector and get out a paper clip. You'll be playing with the connector at the end of the wires at the engine harness, not the one on the switch harness. With the engine running, try shorting the middle pin to the left pin. Then short the middle pin to the right pin. In one of the two cases the idle should stabilize. If you can get a stable idle with the paper clip, but not with the connector plugged in, chances are there is a problem with the switch. Most likely it is broken, but it could also be that it is simply out of alignment and does not close when the throttle is closed.

Working at the bottom of the throttle body of an A2 is a pain, not sure how the A1s are. I took the throttle body out for easy access when I did the job. If you do the same, remember to get a new gasket for the flange between the TB and the manifold. Removing the TB also gave me an opportunity to give it a thorough cleaning.

If it is not the switch, it could be the idle bypass valve (or whatever they called it that year). It is the long round thing with two hoses and a set of wires connected to it. It lets air pass around the throttle, on A2's it is mounted to the top of the valve cover.

JM wrote:

Reply to
Randolph

Did you try moving the big boots around when the engine is idling to note any engine speed changes? Might be a bad boot. Let us hope that the clamps are good and tight. You should inspect the boots. Maybe that backfire repositioned the fuel distributor plate. You need to check that.

Hmmm I was thinking upshift light causing this problem, but am not sure now.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Reply to
dave

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