1990 Deville Lacks power...PLEASE HELP!

BrandonDrouillard

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I bought a 1990 Deville that I thought needed a simple tune-up. It seemed to have a pretty bad miss, but other wise seemed to be clean and in good shape. It had one owner which was an older lady. Clean oil, no leaks of any kind and no check engine light is on; yadda, yadda.

I took it home and changed the plugs, wires, rotar, cap and air filter. All of the plugs looked as if theyed not been changed in a while and I noticed that #2 plug looked real bad. I started it up and it didn't run any better. Its still got the miss, it accellorates like it's pulling a 4 ton truck behind it and the trip meter says it's gettin about 6 miles to the gallon.

I checked the #2 plug again and was black on one side but it didn't seem like a "sure fire" oil fowl. None the less, I replaced the plug and used a non-fowler with it and just for the heck of it I swapped out the injector on that cylinder. No difference, so I took the non-fowler off. Still no difference.
I had my friend hook up his code reader to it and the code reader said that the computer is not responding.

I thought maybe the exhaust or cat converter might be the culprit so I cut the cat off and nothing changed, so I'll be welding the cat back on saturday.
When I first start the car it runs the best. After I go up and down the street one time it seems to load up and run worse.

I consisered replacing the computer, but am not entirely certain that there is any thing wrong with it. It sort of feels like I'm chasing a ghost. I don't really no what to try next. I've always wanted a Cadillac and if I could get this one runnin' good that would be sweet.

Any advise will be much appreciated.


Brandon
 
Deville was the FWD model w/ 4.5 L? changed to 4.9 L in '91? Those FWD engines were aluminum blocks with steel liners & "O" ring seals. I would suggest doing a compression check on cylinders and a "radiator bubble test" to check for blown gaskets, leaks, etc. This engine was replaced by NorthStar 4.6 L in ~ '92-93 ..... probably for good reason.
Cad Broughham was the RWD model, and as I recall, 1990 RWD had the 5 L carborated engine as well as the 5.7 L throttle body injection version adapted from Chev & Corvettes, a much (in my opinion) better engine.
Good luck !!!
 

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