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1989 2.6 Trooper driveability problem

From: Doug
Product: Trooper 1984 - 1991
Date: 02 Apr 2002
Time: 01:46:08
Remote Name:


I just purchased an '89 trooper with #2 and 3 cylinders at 60psi. At idle and at all speeds on acceleration, the engine speed fluctuates randomly, between 50-100 rpm, with a loss of power on the lower part of the flucuation. Watching the tachometer you can see the needle rise not smoothly, but in small increments. Truck does not accelerate smoothly, as if the intake was being block on and off. I replaced head with a new aftermarket casting, and now have equal compression (120psi) across all four holes, but the truck still has this drivablity problem. There are no codes, just 12,12,12,12. The O2 sensor responds quickly when a vacuum leak is presented. Idle is +/- 950rpm. Cat is clear, no clogs. New plugs, wires, cap, rotor, injector seals. Can't find any vacuum leaks. Timing is correct. Throttle body is clean. All new intake manifold gaskets also. Does this sound like something you may have run into? thanks, doug

Last changed: April 02, 2002