ROUGH and I mean rough run/idle

Ok, here is the situation:

1995 Sport - 190K on the motor. Ran like a champ ( faithful oil change etc...) untill lunch time today. Started runing REAL rough today, like it was missing.

Changed the cap/rotor/wires/plugs...no change.

Fuel filter changed, no change.

Checked codes and was thowing 13 (Map Sensor) changed that, no change.

Sprayed carb cleaner 'round all vacuum lines, TB and intake manifold, no change.

Checked fuel pressureand reads 39-42 psi.

Checked/tested injectors, all dump to 15 psi and all fire.

Going to run compression test tomorrow, but looking for maybe some other options suggestions or opinions.

Thanx in advance.

timing tooth jump?

Bump

Does it run fine at WOT? Similar to what mine would do after startup, turned out to be upstream O2 sensor. But mine would go away after running for 5-10 mins and wheneer I put it to WOT.

Thanx for the reply.

Nope, runs like s*** at start up and at WOT. O2 changed less then 3K along with cat.

Anything else?

It's a simple thing, but check the MAP sensor tube for cracks and your other sensor connections. Also check all grounds, especially the main strap by the MAP. Also thinking CPS, but that would throw a specific code. Good luck tracking it down.

Thanx for the reply otto.

Checked all vacuum lines, and no apparent leaks. Also was thinking cps, and one question; If it was marginal, would it still throw a code?

Will check grounds also.

Anything else?

Well, mystery solved. Failed compression. One cylinder TOAST. No reading at all.

95 Sport, soon to be parted. :smsoap: