'90 5.0 runs rough only when in gear???

[White5.0]

Car starts and idles perfect. No surging. Revs fine in neutral no misfires or anything. But when car is put into drive it bucks badly and almost stalls similar to dropping the clutch too fast on a 5 speed. I was thinkin maybe fuel filter or timing but it revs perfect and we set timing?? What else should i check??

[PaceFever79]

Does it die as soon as you put it in gear?

If no codes, I'd be suspecting the torque converter.

[White5.0]

No it doesnt die... You can drive it but its reaaallllly bad. Torque convertor as in somehow installed wrong or as in need a new one?

[PaceFever79]

Now that you've elaborated it doesn't sound like the converter.

Take it to Auto Zone or Advanced and have them read the computer codes.

Or you can buy the diagnostic tool for about 50 bucks.

[White5.0]

Now that you've elaborated it doesn't sound like the converter.

Take it to Auto Zone or Advanced and have them read the computer codes.

Or you can buy the diagnostic tool for about 50 bucks.


its not even driveable at this point. its like you're in a 5 speed just idleing then you drop the clutch and it bucks and just before it stalls you press the clutch in to save it, then you drop it again, then repeat. its bad hahah

but like i said in neutral or park it revs perfect, idles perfect, no surgning, sounds like the timing is dead on. once its in gear its all screwed up


and its a bone stock 5.0...no bolt ons, no cam, no intake, nothing.

[PaceFever79]

It's probably one of the sensors.

You need to read the computer with one of these (http://www.sears.com/shc/s/p_10153_12605_00914783000P?mv=rr&i_cntr=1306164392887).

autozone, advanced, pep boys, even harbor freight sells them.

[PaceFever79]

You should also test the fuel pressure.

[White5.0]

Ill try pullin codes and checkin fuel pressure and see wat i find

[silvernotch]

might sound odd but is the spout connector plug in? had a buddy that forgot to plug it in,idled fine soon as he put a load on it stalled would run for s##t.

[349Stroker]

might sound odd but is the spout connector plug in? had a buddy that forgot to plug it in,idled fine soon as he put a load on it stalled would run for s##t.


good point and what u set timig at?

[White5.0]

might sound odd but is the spout connector plug in? had a buddy that forgot to plug it in,idled fine soon as he put a load on it stalled would run for s##t.

yeah its plugged in...definitely easy to forget though


good point and what u set timig at?


just at the factory 10*...maybe ill try advancing it a little

[92306gt]

what computer is in the car? if you have another to try, id try that.

[jaa55]

had the same problem with a MAF sensor before

[White5.0]

what computer is in the car? if you have another to try, id try that.

its the factory computer from a '90 auto...i didnt look at it but im guessing its an A9P. im gonna try a few smaller things first then maybe try throwin a new ECU in


had the same problem with a MAF sensor before

i was thinking this is a possibility. im gonna try the fuel filter first and start small before tossing in a new mass air.

[jaa55]

dont you have a spare off your car you can try?

[Black Vert]

Don't you have a Moates QH, can't you just datalog the sensors?

[White5.0]

dont you have a spare off your car you can try?

Ya ive been tryin parts off my car... We put a new fuel filter in and tried using the coil and mass air meter off of my car that i know work but had no luck


Don't you have a Moates QH, can't you just datalog the sensors?

I have a QH on my 87... The car having issues is my dads '90.. Its almost bone stock


After timinig it better it now is drivable. But when you hammer it it starts cutting either fuel or spark it seems like... Ill try pullin codes tomorrow. I think its an electrical issue

[mustang50lx]

How old are the tune up parts? Is there an air leak (Torn boot ?) between the MAF and the throttle body? Is the actual fuel pressure good? Distibutors have also been known to cause odd problems also.

[lib88stang]

Put a fuel pressure gauge on it that you can watch while you drive it

[Mark Aubele]

How old are the tune up parts? Is there an air leak (Torn boot ?) between the MAF and the throttle body? Is the actual fuel pressure good? Distibutors have also been known to cause odd problems also.


Put a fuel pressure gauge on it that you can watch while you drive it

These two. Sure sounds like something simple if it runs better with more timing. Pull you dizzy out of your car and try it (mostly for the TFI module).

[PaceFever79]

If it runs better with more initial advance that could still be a faulty sensor
not telling the computer to richen ... TPS, MAF, MAP, fuel pressure.

Personally, I think it is a lean bog. Need codes!

[Mark Aubele]

Find anything out yet?

[PaxtonShelby]

Check the vacuum hoses on the MAP tree. Revving in Park isn't torquing the motor over as much as when it is in gear and you're sitting there holding the brake pedal. You may have a badly cracked vacuum hose that opens when you put it in gear. A bad motor mount could make the problem even worse. Just a thought - but at least it would be a cheap fix. Good luck!

[White5.0]

Check the vacuum hoses on the MAP tree. You may have a badly cracked vacuum hose that opens when you put it in gear. A bad motor mount could make the problem even worse.

all vacuum lines are good, motor mounts are brand new.

also tried a mass air meter and distributor that are known to work properly (from my car) as well as new spark plugs. still does it.

I WILL get codes tomorrow...i've just been too busy lately. I got a job offer and had a bunch of stuff to take care of because of that. Ill get back at it tomorrow

right now my thoughts are that it is an electrical issue, sensor, or maybe something wrong with the tranny/torque convertor. but thats just my guess

[Mark Aubele]

Trans wouldn't make it do what you are describing.

[White5.0]

ended up being an electrical issue. forgot to hook up two grounds. got it fixed and it runs great now. Thanks for the help everyone!:thumbsup: