Stumbling 84 under quick acceleration.

84 Indy 2.5 auto.

If you give it gas quickly the engine stumbles and never recovers even in park.
Give it gas slowly and it’s fine, with a lot of pressure on the break pedal and in drive it will creep the car forward.

No error codes.

These are the things that have been replaced in order with no change…

Throttle Position Sensor
Ignition Module
Coil
Fuel Pressure Regulator
Manifold Absolute Pressure sensor
Cap and Rotor
Fuel Filter
(checked fuel pressure and was pegged to 10, my gauge only goes to 10)
Computer

What in the hell is left???

Need to get this pace car back on the road.

Since no one else seems to have any ideas, I'll at least offer a stab... try removing the fuel filler cap, and see what happens.

Probably won't make any difference. Costs nothing to try ...and a bump to the top, so someone with an actual clue might post .

changed the IAC with no change...

???

I may sound like a stuck record, but even if my radio will not play I check the EGR valve. Yours (if OEM) is a negative back pressure valve. It can seem to function OK and still really screw things up. A small valve on the upper end of the stem regulates vacuum to the main diaphragm. It gets fouled with carbon and valve malfunctions. Unplug vacuum line from EGR, plug line and see what happens.

thanks, i aint got anything to lose.

and where in MO are you?
KC will be atending a show this weekend and the pontiac show in omaha next weekend.

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Buddy *there are two "G"s in my name*
Ling = 84SE 350 N2O Poly MrMike seats Sequentials
"unnamed"=85GT stock (mostly)
KCFOG

Buddy, I live in Southwest MO. Near Roaring River State Park and Table Rock Lake (hills and curves and fun to drive).

Disconnected the EGR with no change.

Ran a hot wire from the battery to the coil to rule out the possibility a problem with the harness keeping the coil from getting enough amps with no change.

While testing with the jumper wire a blue spark was noticed coming out of the side of the boot on the #2 spark plug. Two week old spark plug wires and they are bad.

The car runs fine on the old wires.

Now… why the hell did it only do it when the throttle was opened quickly?

this one almost beat me...

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Buddy *there are two "G"s in my name*
Ling = 84SE 350 N2O Poly MrMike seats Sequentials
"unnamed"=85GT stock (mostly)
KCFOG

Timing?

just for record and something to check, i suppose, in the future, i'll offer the problem i had with mine when it acted this way... get this and doesnt' it sound stupid. it's a duke and the distributor cap that i put on was el cheapo from autozone. gp sorensen i think. it had jumped off the top on one side, causing the rotor button to chew everything up in there. my car ran fine till i tried to go above something like 3000 rpms. that's just my little misfire experience.

Have you checked the throttle cable for stretch. If the TBI isn't opening fully as you depress the gas then your A/F ratio will be all out of whack.

David

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His Fiero: 1984 2M4 Coupe

Her Fiero: 1984 2M4 Convertible

the problem was the wires, and was found out last night.
i just dont understand why it did it only when the throttle was opened quickly

bump to keep it active for a little longer

[This message has been edited by buddycraigg (edited 01-19-2004).]