i have a 95 formula with 111k miles.....when i bought it, i tuned it up (minus dist cap and rotor) and had the fluids drained and filled.

About 7 weeks ago i chaged the starter and ever since then, ive had a problem with surging idle...

the car usually sits at about 8-900 rpms, but lately its dyin down to just a hair under 500 rpms, then catches itself and goes back up to 900, then down again, then up.


my check eng light is on and the comp reads MAF and Knock sensors are bad....

is the surging idle due to the MAF or Knock sensors being bad or is there something else going on?

Sorry to hear about your engine problems.

There could be several things going on. First, a question. Did you use anti-seize on the spark plug threads? If you did, might as well change the O2 sensors--they might cause this problem. The silicones in the anti-seize compound contaminates the O2 sensors--they will not tolerate any silicones coming from anywhere.

Surging is generally caused by varying mixture...like too rich now, then too lean. It might not be the MAF, it could be a huge vacuum leak. Did you pull the rubber elbow? If so, the underside usually sticks and doubles up into the throttlebody causing a massive vacuum leak. You must remove it and check for tears. If not torn, carefully re-install it and make sure by getting your fingers under there that it slid on properly. Make sure that you do not overtighten the clamp--just snug it up a bit. If the rubber flange starts to distort, it is too tight. The rubber intlet elbow takes the "right" technique to install properly. A new elbow is snugged up so gently, that it mostly relies on the sticky in the rubber to stay on--maybe 1 ft lb of clamping force. It could also be any vacuum leak, anywhere on the engine--I have a paper that shows all the vacuum leaks possible on the car. PM me with your email address (to keep it private) and I will send you the paper.

The engine idle speed with a 6 spd trans is exactly 1000 rpm. The idle speed is regulated by the computer (PCM) and the idle air valve, it is not set with the adjustment screw on the throttlebody--just in case, needed to mention that there is no idle adjustment to this engine--the screw on the throttlebody regulates the overall fuel mixture and it is a super critical adjustment.

Now, on to the DTC codes...... There could be a problem with the anti-knock sensor, it's in the same area as the starter. Check the wire and the connection, was it broken when the starter was pulled? If the connection and wire are OK, it's possible that the anti-knock sensor has gone south. The MAF could conceivbly cause the problem, but not sure if it fails this way or not. Generally, a failed MAF causes a lean mixture (this results in high engine temps), but doesn't cause idle surges. However, every engine problem can have a variety of associated problems that can modify any failure. There is no way to check for a properly operating MAF short of an O-scope and checking the sine wave output--nobody has that equipment.

Good luck.