Hello,

I had a problem with hesitation at idle and while accelerating. Shop said it was likely the compressor - so my nephew replaced compressor, idler and tensioner pulleys. Probably wasn't the problem but was probably about time to replace. We found some codes to indicate a misfire on cylinder 3 - so we replaced that coil.

Then I read the suggestions to replace the plugs and wires - which I think were original on this 1998 Aurora with 163k miles! The plugs were in pretty bad shape.

Now, the car no longer hesitates or jerks while accelerating as it once did. However, it now has a rough idle that sputters and sometimes even gently backfires.

There are codes for random misfires.

This wasn't happening before the new plugs/wires and was the immediate result after replacing them.

Any ideas as to what might cause the problem? Is there anything we might have jarred or damaged while replacing plugs&wires?

Any suggestions would be greatly appreciated.

Did you use AC delco parts?
Is it possible that the gap was closed when you installed one the plugs?

The rough idle is solved and was pretty obvious - My nephew had routed the #5 and #7 wires wrong. He was doing the work because he knows more about cars than I do. ;)

I did use AC Delco parts - as I'd seen recommended in forums.

Now, I think that I dropped a screw into the transmission. Ugh. Is that possible if one would fall exactly the wrong way from near the coil pack?

It's making a grinding noise if I put it in gear.

Thanks all for your suggestions.

Actually, It's making a clank/rattle noise from the engine even when not in gear. The engine isn't shaking or sputtering anymore since the wires are routed correctly.

The clank/rattle/grind isnt rhythmicly repetitive but is consistently present. It _really_ sounds like there's something in there. I don't know how I could have dropped a washer or screw in there from near the coils -- can anyone think of how I might have caused such damage?

Crossed wires. Always best to look for the most obvious in that situation. I've done the same thing. It's suprising how well this engine runs with two cylinders crossed.

It's definetly from the engine not possibly the a.c. pump or something else on that end?

I suppose it really isn't likely that anything could have gotten into the engine or transmission. How about somewhere between the engine and something else and would knock around?

The sound _could_ be from AC Compressor or elsewhere on the belt.

There is a scraping sound on the belt -which I attribute to not being aligned correctly. When the idler pulley was replaced, perhaps the plate that holds it on wasn't tightened properly - or something with the tensioner pulley.

The rattle/grind/clank sounds like something loose that is getting knocked around on something that is moving. It isn't regular like the scrape-scrape-scrape on the belt. It's more like rattle..clank.grindgrind..clank..rattle.rattle

Thanks for your thoughts.

In the past when I have changed plug wires, and resulting in the car running rough. My problem was always a wire or two in the wrong location.

Unless your really used to changing and routing V8 wires, it's better to change-out one plug and wire at a time to avoid mixing.

Attention Attention: Do Not Use AC-Delco parts, it's just a myth started by GM and it's dealers/parts sellers. Truth is: With AC Delco plugs and wires you get 17mpg gas mileage and soon they need replacement under high-heat Aurora system. Instead, if you use NGK Irridium plugs and Borg-Warner wires you get 22-25 MPG, smooth running, cooler temperature engine and longer life. Took me $1000 and many visits to mechanics and 3 plugs/coils purchases to find this out. I did that and for the past 10,000 miles my engine has been fine with great gas mileage (22mpg average) for a 4900 pound car (including 2 passengers and 500 pounds extra weight from the back load.
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I had a problem with hesitation at idle and while accelerating. Shop said it was likely the compressor - so my nephew replaced compressor, idler and tensioner pulleys. Probably wasn't the problem but was probably about time to replace. We found some codes to indicate a misfire on cylinder 3 - so we replaced that coil.

Then I read the suggestions to replace the plugs and wires - which I think were original on this 1998 Aurora with 163k miles! The plugs were in pretty bad shape.

Now, the car no longer hesitates or jerks while accelerating as it once did. However, it now has a rough idle that sputters and sometimes even gently backfires.

There are codes for random misfires.

This wasn't happening before the new plugs/wires and was the immediate result after replacing them.

Any ideas as to what might cause the problem? Is there anything we might have jarred or damaged while replacing plugs&wires?

Any suggestions would be greatly appreciated.[/QUOTE]

I have two 1995s and both get around 25mpg. Both run AC-Delco plugs and wires.

Changing from one good condition plug-wire combo to another will not change mileage 5-8mpg. That is a fact not some wild statement.