Problem while driving... had this posted in the wrong section before...

[87lxstang]

I have a 92 MTX that has been the best car i've ever owned. I've daily driven it problem free... until the other day. When you begin moving the rpms will drop drastically and it sort of bucks... you clutch, and they either shoot back up or the engine dies. This happens intermittently but does occur frequently... several times per minute at any speed, any gear.

If the vehicle is sitting, running, with the car out of gear and the parking brake on (clutch in or out, doesnt matter) it will not flinch at any point in the RPM band. I assume the problem is due to vibration or engine load.

I scanned it and got codes 212, 219, and 543. From what I understand, 219 is "limp mode"? Please help, I cant daily drive an 87 mustang on slicks!

 

[projectSHO89]

I'd suspect an intermittent crank sensor signal or an intermittent fault in the DIS module.

Perhaps the crank bolt has loosened and allowed the dampener and timing gear to walk outward, causing an intermittent crank signal.

Perhaps the DIS module has developed an intermittent fault.

Possible, but less likely, is that you have an intermitent DIS ground fault.

Also, check the rear DIS electrical connector to see if it is touching (or almost) the roll restrictor. This happens when the subframe bushing or mount fails and the whole engine drops a bit.

A few things to check...

Steve

 

[93rev2sev]

How does it run if you unplug the MAF?

 

[87lxstang]

Actually havent tried yet with the MAF unplugged, but I did clean it with MAF cleaner. I think the key here is that it only does it "while moving." If i leave it out of gear, i can simulate driving (through the rpm range, hold it at any RPM, push the clutch in/out) and it runs like a top... as soon as it has a real load on it, it acts up...

I've been told from a couple Ford mechanics that if it were a CPS it'd do it parked. I also have a little bit of the "oil in the socket" problem... but not bad at all, so I was told to go ahead and do that ... if it fixes it, good... if not, it needs to be done anyway...

 

[dpsutphin]

This is just a guess, but I had a similar problem. I found a couple of bare spots in the injector wiring. Taped them up, and no more problem. Both were where the wiring crosses the intake. but anywhere those wires touch metal, they could cause a short, which will keep the injector from firing, causing the bucking. It probably wouldn't do it sitting still because there would be no engine movement to cause the wire to short out.

In any event, it won't take long to check the wires out.

Good luck.

 

[87lxstang]

Well, I pulled my plug wires and had oil completely covering the plug on 4 cylinders. Did the infamous gasket change... came out very good. Did new plugs and wires too, as well as examined all sensors and wiring for frays/loose connections, ect... The original problem still persisted. I swapped the cam sensor because it was cheap and easy, still didn't fix it. I am leaning towards crank sensor now, but a Ford mechanic said it would act up parked if it was a CPS... any thoughts/experience?