I have a 91 940 turbo....I have just replaced the plugs, wires, cap and rotor due to a misfire..

I have made sure theres no wires in close proximity to one another so theres no crossfiring happening there.

I do have the firing order correct and all wires are making good contact with both the cap and plugs...I have not replaced the coil but its my experience they are either good or they are not.

This has not corrected the issue...when I first start the car it runs perfectly but after15-20 seconds the misfire starts and get more pronounced as the car runs longer.

ANY help on this would be appreciated...this is my only means of transportation and I have to make sure its running properly.

Thanks in advance

 

Bad or real dirty injectors can cause a car to misfire. Poor fuel pressure could also be a cause.

 

Mass Air Flow meter?

 

Ok injectors are good....where on the car is the mass air flow meter?

Grasping at straws here now...gotta get this fixed

 

The MAF is usually just behind the air box/filter. Round with a larger connector on it. I have read that you can unplug it and your idle will smooth out. You can NOT drive with it unpluged. Search it to get more & better info.

 

Here are some fault codes that might help. I have found that an apparent misfire at idle which disappears when you rev the engine can be an injector which will work at higher fuel delivery levels but not lower ones. The old 'dumb' ones you could sonicate in a high fre bath, but the electronic ones you need to get cleaned. One way is to try an injector cleaner in the fuel, which can work, but the ones that do work are usually used by main dealers, rather than the ones you and I can buy, which are often not very impressive. With a catted car, you have to be very careful about what you add to fuel, for fear of damaging the cat or the oxygen sensor. That old thing of putting some ATF in the fuel I think are not recommended now. Check all connections (such as the MAF, sensor wires etc). Maybe the codes might give you a clue

Engine and OBD Diagnostic Codes