help 91 cad deville

Kathy Attison

Asked by May 26, 2016 at 02:15 PM about the 1991 Cadillac DeVille

Question type: Maintenance & Repair

I just had  new egr valve. new cat converter. new
fuel assembly. new fuel filter. new fuel pressure
regulator. new throttle position sensor installed.
Ignition modual checked. The car doesn't start like
it used to. It  is sluggish during acceleration. As
soon as it hits 43 mph it starts to run rough. I am
getting the fuel injectors cleaned next week. Does
anyone know why it starts to run rough at exactly
43 mph.

1 Answer


Wow, shotgun parts change! '91 how many miles on it? 4.9 V8 OK I always scan the computer for codes. Just a Shot in the dark but loss of power after all the parts you have had changed.. leaves the CPS (Camshaft position sensor) suspect ..Timing issue low power, low top speed ,sluggish etc etc.. Regards INJECTORS rarely good bad. Find faculty that can truly scan the computer in real time '91 basic but still lots info from the computer. regards OH you're proably running on 4cylinders no power.. READ THIS: If you shift from park or neutral to drive or reverse with a throttle angle of 20 degrees or more the computer thinks the driver has caused an unsafe condition or damage to the vehicle and throws code E097. When this happens the computer will shut down fuel injectors 2,3,5 and 8. The fuel injectors will not be re enabled until one of the following conditions is met: Throttle switch is closed or throttle angle is less than 3 degrees and the vehicle speed is 8 MPH or less. Check TPS and throttle switch for proper operation.SCAN THE VEHICLE!

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