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Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 1808
Experience:  ASE Master Certification. GM World Class Certification
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I purchased a 1992 Buick Century and proceed to begin

Customer Question

I purchased a 1992 Buick Century and proceed to begin replacement of everything. I did the suspension front and rear including brakes. The engine ran rough with the O2 sensor light on. I replaced the O2 sensor and then went further. I replaced all of the fuel injectors, spark plug wires, the coils, MAF, IAP and fuel pressure module. It wasn't until everything was done that I then took it out for a drive. On acceleration it would hesitate, miss and even backfire. So I began undoing what I had done. I put back in the original MAF, IAP and Fuel Pressure Module. Same results. I don't have the originals for the others. I had also replaced the power steering pump (as it was bad) and the alternator. Under the alternator I see a single green with a white stripe wire with a two prong plug that is not plugged into anything. It's not very long - and I can't find anything near the alternator that it should go into. I didn't notice it until after all the issues propped up. So while I am good at replacing things, my trouble shooting skills are limited. Not ready to take it to a shop and pay them to trouble shoot - so I'm looking for advice on where to begin. I will do a compression test mid week. After that I am at a loss. What would be your plan of attack for something like this?I did purchase a Used throttle body but did not install it. I have a TPS but did not install it (looked like I needed to remove the throttle body and didn't want to go that far.Additional Info - I replaced the Alternator as I had an electrical short. While replacing the Power Steering Pump, I did not disconnect the battery. I had to pry the pump out of place and used a screw driver between the pump and the alternator. Smoke poured out of a couple of places - it burned the alternator fusible link. So to be on the safe side I replaced both the fan motor and the alternator. Don't know if this fried anything else.
JA: OK. To minimize me, please click the down arrow at the top right corner of this box. OK. To minimize me, please click the down arrow at the top right corner of this box. I hope not. How many miles are on the car? Have you had the fuel pressure tested recently?
Customer: 80K miles. Don't know how to do a pressure test. I didn't have these issues until I started putting in new parts.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: So far, tried to put in the original parts - but I don't have all of them - so I'm at a stopping point.
JA: Anything else you think the mechanic should know?
Customer: no
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Buick Mechanic about your situation and then connect you two.
Submitted: 4 months ago.
Category: Buick
Expert:  john aka eauto replied 4 months ago.

is the firing order correct?

Customer: replied 4 months ago.
I double checked the order. I have since pulled all plugs (which were new) and all look the same.
Customer: replied 4 months ago.
Two more pieces of information:
1). When I purchased the car two months ago, I stated it ran rough - it is more correct to say it idled rough. I ran fine off idle.
2). The last thing I did in trying to figure out what I might have done to make the car run so bad was to disconnect the MAF. It ran worse. I then filled the tank with premium and drove around and there was no change.
Expert:  john aka eauto replied 4 months ago.

is it skipping?

Customer: replied 4 months ago.
Not sure what you mean by skipping. Except when under load (increasing speed, going up hill), it runs fine. When under load, it is bucking, losing power and even backfiring. I am also posting to a Buick forum at:
and added the following information there:
When I first got the car, it idled drove fine.
I was able to get the code and replaced the O2 sensor. The two codes were:
13 - Oxygen sensor (O2S)/heated oxygen sensor ((HO2S) Wiring open circuit, O2S/HO2S, ECM
44 - Oxygen sensor (O2S)/heated oxygen sensor (HO2S)
I replaced the O2 sensor and the code went away.
The car idled rough. That is when I started replacing things. I replaced the Coils, plugs and spark plugs and it still idled rough. I don't know if I test drove it or not. I was working on the suspension and brakes at the same time.
I then replaced the fuel injectors, the fuel pressure regulator, MAF and IAC. That is when it would hesitate, miss and backfire on load.
I also got an error code 44
44 Oxygen sensor (02S) – mixture lean Wiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low, exhaust system leaking, 02S, ECM
I started reinstalling the old parts including the fuel pressure regulator, MAF and IAC. It got rid of the error code, but the car still has the same symptoms on load.
Before doing any of this work, I had replaced the fuel filter.
I don't have the original fuel injectors, coils, spark plug wires - so I can't reinstall them.
Expert:  john aka eauto replied 4 months ago.

it sounds like a bad plug wire or the firing order is incorrect can you exchange the plug wires and try a different set?

Customer: replied 4 months ago.
They are brand new - not to say that they can't be bad.
Expert:  john aka eauto replied 4 months ago.

i would exchange them and try a different set before guessing and throwing parts at it. do you want me to get you a firing order diagram so you know that that's correct?

Customer: replied 4 months ago.
I will get a different set and try them. I have a firing order - so I'm OK there.
Expert:  john aka eauto replied 4 months ago.

let me know what happens

Customer: replied 4 months ago.
I went out and purchased new plugs and plug wires (keep in mind that what I was replacing was new) and the behavior totally changed. Now from 0 to about 20 is extremely difficult - even on a flat road. Once I hit about 20 the car is totally different. Lots of power. There is still a small hesitation under load - but nothing like before. The attached picture shows how I wired the car.
Expert:  john aka eauto replied 4 months ago.

it still sounds like a bad firing order I'm going to pull up spec and compare give me a min

Customer: replied 3 months ago.
I had provided some mis-information before. I had not reinstalled the original IAC. Once I did the car ran like it did when I purchased it 3 months ago. It has an uneven idle but runs fine. I noticed a minor hesitation which I probably overlooked when I first purchased it. The next step is to replace the harmonic dampener and crank position sensor to see if that resolves the remaining issues. I have to wait two week ends to find out.
Expert:  john aka eauto replied 3 months ago.

I would check the ignition modular I would have that tested as it could be the issue and also have you cleaned the throttle body ? have you checked for vacuum leaks?

Customer: replied 3 months ago.
The ignition module is also on order. Still have to check for vacuum leaks and clean the throttle body.
Expert:  john aka eauto replied 3 months ago.

I would think the issue would be in the throttle body or vacuum leak before it would be a balancer or crank sensor issue

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