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Engine Gear Down

Started by hudsont, June 20, 2008, 08:54:29 AM

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hudsont

Hey Guys.  Relatively new to owning a Cadillac.  Just a reminder I have a 4.5 litre V8
1988 Cadillac Eldorado.
Since I have had it I have flushed the Transmission and replaced the filter cleaned the pan.
Flushed the rad, Changed the oil.

My question is this.  When I start the car it does not appear to be gearing down after having run for
a minute, it really doesnt until I put it in Reverse.  Is this Normal?  Is there a sensor?  It sounds like it
is running rich.

Any suggestions before I take it back to the Dealer.

Thanks
Trevor Hudson
St catharines Ontario
Canada
Trevor

TJ Hopland

Most common reason for a high idle on an EFI car is some sort of a vacuum leak.   When 'extra' air is being sucked into the engine the computer sees the exhaust go lean and adds fuel to get things to balance things out which results in higher rpms.  Maybe the load from the transmission is enough to drag it back down to a more normal level.  Could be something as easy as a loose vacuum line.   You can do the same thing you did with carbs, that is spray carb cleaner around all possible places with engine running and listen for a change.  A bad fuel pressure regulator can also cause the problem but was not that common with the TBI's and is built into the injector pod so its hard to check.   I assume this is still a TBI, if its multiport then the regulator will  be between the fuel rails sort of near the distributor under the air intake hose plenum/ filter box. You can pull the vacuum line off and look for signs of fuel.  If there is any replace the regulator.  Its not expensive but to replace it the fuel rail has to come off and there is quite a bit in the way.

A scan tool would be the easy way because you could look at the readings the computer is seeing to get an idea whats happening.  It could be a bad sensor giving computer bad info. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Kevin M. Parkinson

#2
I own a 1990 with the 4.5 litre V8.  Being fuel injected, the car should operate in the normal RPM range upon starting.  There shouldn't be a "warm-up" time like the older carburated cars.  I turned down a free Cadillac a couple of weeks ago.  It was another 1990 that had, among its long list of issues, your same problem.  The Idle Speed Control Actuator may be a place to start if you are going to diagnose and repair the car yourself.  A search on Rock Auto . com will get you to a picture of the part.  

Also, as recommended a hundred times or more on this message board, I recommend you start with the purchase of a repair manual.
1925 V-63B Custom Suburban
1941 Series 6719
1956 Fleetwood 75 Imperial Sedan
1967 Sedan deVille
1968 Sedan deVille
1972 Fleetwood 75 Sedan
1972 S&S Cadillac Victoria Hearse Senior #779
1980 Fleetwood Limousine
1996 Sedan deVille
2006 DTS 1SD
2018 CT6 3.0TT Platinum
2018 Escalade ESV

hudsont

Thanks For the info I will start there and keep you posted....and I will get the repair Manual!! Immediately
Trevor