bucking Buick

[mrvids]

Have a 93 Park Avenue Ultra with s/c 3800 and 100K. Under hard acceleration (like tonight while trying to merge onto the freeway with a semi closing in fast) the car started to buck and pop. It does the same from a standing start but doesn't seem quite as bad. If I accelerate smoothly & slowly it's not an issue.
When bucking at freeway speeds it took the engine a split second or two to compose itself and return to normal.

I revved the engine tonight in the dark hoping to see if a spark was jumping from any of the plugs or coil, from what I could see there was none. The MIL did not come on. Fuel pump is new, can't remember if the plugs and wires are new or not.
Could it be;
bad coil pack
bad plug wire (if they are the original ones)
something else??

[wake]

check your plugs and wires first

other possible culprits:
Crank position sensor (if going to replace ONLY replace with AC Delco)
Ignition Control Module
or a bad coil back

your symptoms sure sound ignition related

have you checked for any codes yet?
http://www.pontiacbonnevilleclub.com/fo ... =51&t=8689

[mrvids]

Will check tomorrow evening when I get the car back from Junior. I just drove it to fill it with gas for him before prices went up for the weekend.

[RJolly87]

I would be inclined to check fuel pressure myself in all honesty.

EDIT: Dumb question, I know, but how old is the fuel filter?

[PLAGUE PHANTOM]

what jolly said. if your fuel filter is old then it needs replaced. my car had similar symptoms earlier this year. After i replaced the fuel filter it went away

[wake]

i knew i was forgetting something

[00Beast]

Replace fuel filter, plugs, wires (NAPA Beldin) and Oxygen sensor (AC Delco ONLY). Then report back.

[mrvids]

I know the fuel filter, fuel pump, and sending unit were replaced recently. Have to check the paperwork to see about the plugs & wires.

[mrvids]

Got a code 23, which may be caused by;

1) Defective MAT sensor
2) Open sensor ground circuit
3) Dirty or corroded connection(s) at MAT and/or ECM
4) Open circuit between the ECM and the MAT sensor
5) Defective ECM

[willwren]

mrvids, find your airbox. On the rear of it (the side facing the driver) you'll find your IAT (Intake Air Temperature sensor, not MAT, or manifold absolute temp, your car has IAT instead of MAT) and then find the connector and hook it back up.

It's disconnected. And it cannot cause the problem you describe, so it's best to start looking at your ignition components. The O2 sensor is highly unlikely, but should be replaced if it's not an AC Delco, is over 50k old, or you don't know how old it is. The O2 (AC Delco only) for your car is a single-wire non-heated, and is very affordable compared to most.

[mrvids]

Is the Delphi o2 sensor the same as AC Delco? Locally they sell the Delphi sensor, but only the AC Delco connector wire. AC used to be under the Delphi umbrella but don't know anymore.

[00Beast]

Delphi will work fine too. You just don't want Bosch, BWD, etc.

[mrvids]

O2 sensor is gold-ish, and looks to be original. Cleaned the IAT, and the same problem occured. The plug wires say "Packard" on them, does that mean they are original wires or aftermarket?

[RJolly87]

Mine said Packard on them as well when I got them. I suspect either original or dealer serviced based on the spark plugs I pulled out of mine. You might be up for a full tuneup, and then see where you stand.

[mrvids]

New plugs & O2 sensor going in today, plug wire installation takes place early next week.

[willwren]

You cleaned the IAT? The one in the airbox? Was it disconnected? If it's hooked up and still throwing a 23 after clearing the codes, replace it. A wrecker unit will do fine.

[mrvids]

Disconnected, removed from the car, and used computer parts cleaner and then a very light shot of air to blow off residue. Replaced 4 sparkplugs as the that's all the TR55s they had in stock.
I need to visit the junkyard to get a computer core for my other car anyway, for the $5 or $10
for the IAT it'll eliminate one more possible cause for the problem.
Is there a way to clear the code without disconnecting the battery or using a tech 1?

[willwren]

Battery, Tech1, or any other OBD1 Scantool.

[Bugsi]

For what it's worth, the bucking under acceleration is exactly the symptom we had on the wife's `01 GPGT when the catalytic converter was plugged. Something to possibly look at, possibly common to 3800 cars.

[mrvids]

Waiting on plug wires & O2 sensor that should be arriving soon, changed all the plugs and now you can floor the gas pedal without the car bucking, but now if you floor the gas pedal, when you take your foot off the gas it stalls completely.