Car started running on 4 cylinders

[silverQ]

Went to the grocery the other day and it had this problem. The whole car just moving violently from side to side reved it up for a few secs and it went away.
Yesterday moved the car in the driveway and the problem has returned and won't go away tried restarting three times.Thanks for the help guys,

[silverQ]

It is a 1991
Now thinking it is the power transistor gone bad on the passenger side bank. The 1994 FSM .pdf I have shows a different pin out / connector on this part can anyone lookup how to test the 1991 part thanks a ton.

[goody90q45]

Where's the test procedure in the 94 FSM so I can get close in the 92 FSM?

[silverQ]

Where's the test procedure in the 94 FSM so I can get close in the 92 FSM?

sure, they are calling it a power transistor in the index
in my 94 fsm the test procedure is located at EF & EC-218

[goody90q45]

Chart/test procedure in the 92 FSM is the same, pinouts on the power transistors are different.

92 Power Transistor is:

X A C
E B D on one end,

3 1
4 2 on the other end.

I have spare Power Transistors if you find yours is bad. PM me if you need one.

[silverQ]

Chart/test procedure in the 92 FSM is the same, pinouts on the power transistors are different.

92 Power Transistor is:

X A C
E B D on one end,

3 1
4 2 on the other end.

I have spare Power Transistors if you find yours is bad. PM me if you need one.

Not sure what to think of my results. First test I am getting continuity when I should not be and am not getting continuity when I should be; same for the third test. Did test both power transistor units and got the same results.

[Q451990]

Not sure what to think of my results. First test I am getting continuity when I should not be and am not getting continuity when I should be; same for the third test. Did test both power transistor units and got the same results.

Every time I've tested one I get the same bass ackard results. My dad was an electronics guy, and he was able to give me a very detailed explanation about why this happened, how the multimeter was probably designed differently than the one they used to do the test in the FSM, etc. That discussion was about 13 years ago, so I don't remember the details - but I know we determined that everything reading backwards wasn't an issue, and that the part was working fine.

Heath

[silverQ]

Put it back together not sure what to do next, still starting it seems. Will reading the codes do any good? I have no check engine light coming on. Thanks

[Skibane]

Will reading the codes do any good? I have no check engine light coming on.

I would think that if it was running on just 4 cylinders for a while, it fer damned sure should have thrown at least few codes!

[silverQ]

Okay checked the codes at the ecu and it kept repeating 54-54-54- ... never gave me a 55.I started it and it was real lumpy but I reved it up some and it smoothed out alot. I do have one iffy injector so it is not running perfectly smooth anyway. I did experience something interesting after I let it warm up most the way. When I reved it up to around 3000 it got real lumpy again like it was running on 4 cylinders but after about 15 seconds it smoothed out some again. I have actually experienced this on the road when I give it more throttle then necessary .. sometimes it is like my wheels become square for about 10 seconds I think this is related. Think it might be an injector sticking open causing a major pressure drop in the rail? Thanks

[goody90q45]

With no codes relating to engine performance it sounds like it could be your fuel pump control unit (FPCU) having intermittent failure. Try taking it out of the circuit by unplugging the connector and running a jumper from the pin shown in the pic to ground. This will make the fuel pump run on high speed only but is a quick check. The FPCU is under the rear deck and you get to the connector by removing just a couple of upper plastic fasteners from the rear trunk trim.

[silverQ]

add'l symptoms
was also running very rich would flood while cranking and not fire or start and soon flood out while running

got a code 21--ignition signal in the primary circuit is not entered during engine cranking or running

solution
replaced crank angle sensor CAS aka distributor will start reliably now no longer rich

new problems
after sitting 6mo. maf failure and passenger side valve cover seal failure terrible smoke
a cyl. was missing out possible coil issue still code 21 present
many other pre-existing problems

let it go, drove the car to pick-a-part indianapolis, indiana

[Q451990]

let it go, drove the car to pick-a-part indianapolis, indiana