BUCKING PART 2! IF I CAN'T FIGURE THIS OUT, I CAN'T KEEP THE CAR!

[TheresGabe]

I'm done. I've NEVER in 5 festivas and 2 aspires EVER been so stumped.

My car bucks. 1/2-2/3 of the way through 1, 2, and 3rd gear (and now acting up in 4th/5th) it bucks. Like it falls flat, comes back, then flat, then back....

I've replaced:
-Distributor cap/rotor
-coil
-plugs/wires
-TPS
-MAF
-Fuel filter
-Fuel pump

I have NEVER had to take my festivas to a shop, but I am completely at a loss. Anybody have any other ideas? It's bad enough now, that sometimes when I'm coasting in 4th, I can put my foot clear down, and it doesn't change revs at all. HELP ME PLEASE!

[getnpsi]

Windex with engine running lean on things, squeeze wiggle test. Finds vacuum and bad electricals for me. Make sure tps was clocked and putback in right.

[getnpsi]

Ive never had a clogged cat but ive read they show ugly heads under load like a fuel problem. Its an airflow problem which the computer tries to do what it can, so no power.

[RhodeStiva]

could your clutch be slipping then caught in gear again?

[drddan]

He said he floors it and no rev change. If clutch was slipping, I would think it would rev high when floored.
I am with getnpsi on the TPS install. It sounds like a sensor of some sort.

And dont you have a VAF, not a MAF? 1990 Festy should have a VAF, and if its not working right will cause issues.
Check VAF conections and make sure the vane in the VAF is moving freely

[bobbyspider]

enCrack in the intake after the vaf somewhere? When you hit the gas the engine rocks under load and opens the crack and don't allow air to come through the vaf and move the flap and cuts the fuel maybe

[shadetree]

Does this happin when cold / warm / hot ? Had an issue on my last car , wiring harness was rubbing the rad .
Just below the battery , when the engine heated up and fan came on the car would buck very bad .
Just an idea to check . The tci wire was grounding out through the coolant supplied ground the the ran case .
Good luck .

[koRnhead]

I would suspect a leak in the intake as well, just has gotten bigger now. Loose connection at the ecu, or a short someplace in line could do that i suppose.

[1990new]

Don't know if this may relate to your problem but I was just reading about distributors and read that when the optical sensor gets oil/dirt on it, strange things relating to ignition firing can happen.
Do you have the optical distributor or the hall effect distributor? If optical, you might try removing the metal cap and clean the wheel and sensor.

Or if you have a spare distributor, you might just try changing it out.

[gergorian]

Check for a loose ground at the front of the head near the thermostat housing. When I started my car for the first time I couldnt get any fuel pressure. hooked that ground up and the pump started running and car started fine.

[getnpsi]

Air hose is one thing gets me too. Agsin soapy water makes a flaky ground better so you can find it, and changes idle when it gets sucked into the engine when it shouldn't. A combustible fuel masks your lean condition so dont like using those plus it eats rubber that probably isnt new.

[FestYboy]

the TPS would have to be WAY out for there to be any kind of issue with power production, also it would't cause a lack of throttle response, all the TPS does is look at weather or not the throttle is in one of 3 positions (idle, run, WOT). there is a MAP and VAF sensor combo that takes care of load compensation in relation to throttle position. i'm wondering if there is a signal drop off within the harness (wiggle test at 2000 rpm). hmmmm. have no fear, I'm on the job (lol).

[1990new]

I do hope your problem is not the same as the problem I had with Bessie back in 2003.
She started acting as you describle and finally would not start at all.
The crankshaft nose keyway slot and the key were worn away. It was either get a new crank or get a new engine.
I went with the new engine.