Let's say, hypothetically, you have a '91 N/A GXL with 118,000 miles. You're religious about scheduled maintanence including oil changes, spark plugs, fuel filter, etc. and it responds by being completely trouble-free. It's running smooth-as-silk when it suddenly starts showing symptoms like a rough idle at any temperature, a considerable fuel consumption increase, a higher rev (6000+) bog-down and an accumulation of a black, sooty substance on the bumber right above each exhaust pipe tip. You'd start resolving the problem by first doing cheap, easy things like changing the spark plugs and using fuel injector cleaner. While you're changing the plugs, you do a complete inspection of the engine compartment looking for loose vacuum hoses and the smell of fuel, but you find nothing wrong. A restart of the engine with new plugs doesn't make a difference...it's still idling rough. Now what would you do?

Just curious because that's my story too.

 

A compression check..?..?

what did I win, what did i win??

 

Well, if your advise enables me to resolve this problem, I'm prepared to offer you an entire case of my gratitude!

 

Definitely a compression test. I have the same story, almost to the tee. Mine ends with an engine swap!

 

Thanks for taking the time to offer some input. You can't imagine my distress at the possibility of needing a completely new engine. Can you elaborate on your experience with this?

 

Anyone else?

 

Compression check and check/replace the PD and O2 sensor. if the compression is fine then I would also clean the injectors (by taking them out and having it done right, not by some pour in the tank crap).

Your almost at your 120K major service anyway so things like the 02, PD, belts, plugs, plug wires, all filters and fluids should be replaced anyway with things like the gas tank pickup filter, injectors, etc should be cleaned.

and if compression is bad you will want all those things replaced before you put a rebuilt motor in anyway.

Rough idle when cold or just when warm???

*edit
and no matter what you should not smell gas under the hood!!!!!! if you do you must not drive the car until it is fixed.!!!!!

 

Sounds like you're running on the rich side hence the black soot.

 

Thanks so much for your input! The general consensus is a compression check so I'll do that first. Will poor compression automatically necessitate an engine replacement or do you all mean a rebuild is also an acceptable resolution? Can you tel me what "PD" is? Thanks.

 

A new engine is a rebuild.
Yes, it is FAR more preferable to rebuild PRIOR to blowing an apex seal.

saves the cost of a new rotor and housing!

$$$