: my engine on my 98....



Ordnanceman
05-12-05, 04:48 PM
sorry for posting so much i'm new to this website, my question is, when i bought my deville i noticed it needed a tune-up cause it was hesitating bad, so i changed the spark plugs and the wires, it did the job but when i hit like 1500-2000 rpm it shakes then at like 51-54 mph it shakes or hesitates, should i get a fuel injection cleaning or what please help. this car has 72000mi and its been kept in south florida. what else do you guys recomend i do to just keep up with its maintenance as far as how many miles it has and it being in extreme climate. thanks.

zonie77
05-12-05, 08:16 PM
I would recommend :
replacing the fuel filter,
check the fuel pressure regulator,
check/replace the air filter.

See what those do and let us know.

Change the coolant asap. There are a lot of threads about this. The anticorrosion additive wears out. Change it.

BeelzeBob
05-12-05, 09:39 PM
The first thing that I would recommend is to check the fuel pressure. It sounds like the fuel pressure may be weak and causing the missing due to a lean condition common with low fuel pressure.

If you can locate a fuel pressure gauge it is simple to check by screwing the guage connection to the schraeder valve fitting on the fuel rail. The fuel pressure should remain constant at about 50 PSI and rise 2-3 PSI as you open the throttle to WOT. If the pressure drops at any time it is not supposed to do that and would indicate a restriction in the fuel line and/or a bad pump. Tape the gauge to the hood or windshield so that you can drive with it where you can see it as the only way to tell if it is the fuel pressure is to drive and watch the fuel pressure when the problem occurs.


You might also refer to this post...

http://www.cadillacforums.com/forums/showthread.php?t=38913



You can make a cheap fuel pressure gauge if you can locate an old R12 refrigerant recharging kit. The schraeder valve fitting on the R12 adapter will fit the fuel pressure fitting on the fuel rail. Find a cheap gauge and plumb it to the R12 schraeder valve fitting with a piece of hose and you are in business.