1990 Trooper Missing and Knock on Accel

[chiz414]

My 90 trooper suddenly started knocking on acceleration. I thought the timing belt had slipped. When I checked it, it was OK. The engine will start and run but misses (seems like one cylinder) and pings on acceleration. I checked the timing, and the timing seems to be way off. I have adjusted the distributor, checked the rotor against TDC. When it is lined up the engine will not run. the only way I can get the engine to run is adjust the timing so the mark is actually 20 degrees After TDC. I was able to improve the idle by pulling a hose that runs from the air duct to a valve on the fender well and back to the intake manifold. I just bypassed the valve. It idles better but still misses and pings.

[89trooper]

Ahh!!, I have run into this problem twice! Once on my brothers(88) and then mine(89). Do not trust the mark on the crank/dampner. Get a new belt, check the tensioner and then set it up like chilton/haynes says. When you have the crank gear lined up, put the timing cover back on. No need to bolt it yet, just hold it in place. Slide the crank pulley on, and I bet your timing marks don't line up. Don't worry, mark where 0 meets all the way across.

I use whiteout, then cut into the pulley with a hacksaw. Just enough to mark it like an origninal timing mark would look. Then use the whiteout again on the cut so it stands out with the timing light.

This is very important! The first groove is for the Alt if I remember right. Mark on the front and back side of the pulley. The next belt position(the once closest to you now) you also mark. Just mark every spot you can see with the belts on so you can be sure everything is lining up.

What I think you will find is the piece of the dampener that is closest to the engine is 20-30 degrees off of what the part of it that is closest to you is reading. That is causing your timing issues.

You see, that dampener is actually 2 pieces and there is a rubber section that gets old and slips causing your timing marks to be off(old ford problem back in the day, thats how I found it). As long as you mark the closest pulley to you at TDC and use that mark, you won't have any problems. That piece is solid metal and won't slip.

Now you 'should' replace this bad part, but my trooper runs just fine with this setup. GL