Mechanics

CAR HESITATES WHILE DRIVING, IDLES HIGH WHILE SITTING

1994 Buick Century • 100,000 miles

Buick Century 2.2 EFI with OBD 1.5. Car hesitates at speed (kind of bucks), and it sometimes idles high when sitting. I've replaced the plugs, wires, air filter, fuel filter, fuel pump, and throttle position sensor. The hesitation doesn't happen all the time, but does happen quite a bit.
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Formulaoneman
September 19, 2012.




Scan for codes and check fuel pressure it should be 41-47 if pfi or 9-11 if tbi. Check gasket under tbi for leaks, spray with choke cleaner if rpm changes you found the leak. The hesitation at speedmay be the torque converter clutch kicking in and out, depends on what speed it is

Hmac300
Sep 19, 2012.
OK thanks I'll check the items you listed. However, I did spray around the manifold, and didn't get any idle changes. Also, the TC clutch is disconnected because it was making the engine stall at stop signs, and I haven't had a chance to change it. The hesitation is at speed (anywhare between 30 and 65 mph or so).

Tiny
Formulaoneman
Sep 19, 2012.
Have you checked it for a sticking/bad egr valve?

Saturntech9
Sep 20, 2012.
No I haven't done that yet. What's the procedure to test it, or should I just go ahead and replace it and the solenoid? Last night driving home (around a 20 mile commute), it was doing its hesitation thing, then the check engine light came on, and the hesitation stopped. Problem with the check engine light, is that my code reader won't read an OBD 1.5, and the Buick dealer wants $60 each time. The OBD 1.5 is kind of an odd ball one, and you can’t jumper it either. Does anyone know a way to get the codes out? This is a "commuter" car that I bought back after I hit a deer with my good car last year, and I don’t want to spend a bunch of money fixing it.

Tiny
Formulaoneman
Sep 20, 2012.
Cross a&B on the aldl with a paper clip. Count the light flashes like 12 24 etc. Come back to the site and look unedr trouble codes obdI. It may also be the egr contol piece whichi is electric
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Hmac300
Sep 20, 2012.
This is an OBD 1.5, not OBD 1, you can’t jump it. It's kind of a high breed between 1 and 2. It has an OBD 1 block, but no B terminal wire. The GM OBD reader will read it (at $60 a shot), but an OBD 2 reader won't. I think it’s an interim step between 1 and 2 that GM did before they went to 2 in 1996(?).

By the way, thank all of you for your prompt and helpful replies! I’m going to donate as soon as I figure this out.

Tiny
Formulaoneman
Sep 20, 2012.
Oh that's t right they only used that on olds and buick it has the 14 hole aldl. They went to obdII in 95

Hmac300
Sep 20, 2012.
Its a 16 pin connector like the obd2 and gm went to obd2 in 1996 like everyone else because it was federal law. That is a pain when there obd1.5 to find a cheap scan tool to read them you could get a old tech 1 scan tool or a pro link scan tool on ebay. Let me see what I can find for you.

Saturntech9
Sep 20, 2012.
If you want to read the codes and read live data etc to figure this out
your going to have to get a more advanced one like a mac tools task master thats the one I have or a matco pro scan plus or otc nemisys cornwell tech plus.I bought mine used on craigs list you can look on ebay sometimes on ebay ones with the older software you can het ffor 200 or under.

Saturntech9
Sep 21, 2012.
Looks like the actron cp9185 and cp9190 will read that car also. But the other scan tools I mentioned are way better.

Saturntech9
Sep 21, 2012.

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