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car runs rich and floods out
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jasontyms
Novice
Apr 27, 2009, 3:01 PM
Post #1 of 10
(1938 views)
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car runs rich and floods out
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I'm working on a 1990 cadilac deville with a 4.5L, it was sitting up for almost 5 years and I have changed the plugs,wires,dist. cap, rotor button, coil, and it still runs rich, pulled the gas tank, cleaned out the fuel tank and replaced the fuel filter, replaced the distrib.,the wiring harness for the dist.,.Talked with a cadilac expert and was told to movr the ground wire by the starter to another location on the engine and it still floods and backfires, replaced the ECM and still runs bad took the exhaust loose th check for stopped up convertor and still runs bad, have done a compression test and it was not perfect it was 120psi, checked the fuel pressure and it was within specs, I ran a new ground wire from the engine to the frame, Ihave pulled the injector rail off and replaced 2 injectors tha were stuck open, after all of this, I started pullin yhe plug wires off while it was running and i was able to pull four plug wires off before it made a difference in the idle, none of the plug wires are crossed and all of the plugwires have fire going through them. If anyone can figure this out then I give them kudos and will bow down to their expertise.
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Loren Champlain Sr
Veteran
/ Moderator
Apr 27, 2009, 3:59 PM
Post #2 of 10
(1934 views)
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Re: car runs rich and floods out
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Jason; The over-fueling could explain the low compression as the fuel will wash the oil off of the cylinder walls. It will also contaminate the engine oil. The fuel contaminated oil vapors will get sucked into the intake and make it run even richer. Domino effect. Now, to the over-fueling condition. Are you getting any trouble codes? Are you able to scan the ECM and get live data? Would be great to see what the CTS and injector pulse readings are.
When you said the fuel pressure was within specs, what are the readings? Does it hold pressure after you've turned the engine off?
Loren
SW Washington
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jasontyms
Novice
Apr 28, 2009, 2:28 AM
Post #3 of 10
(1928 views)
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Re: car runs rich and floods out
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the fuel pressure was right between 40-45 psi and the pressure does stay up when the vehicle is shut down, as far as trouble codes it did have a cam reference code for no signal but replaced the distrib. with a new one and it has not thrown a new code since I have been using a modis on the car and the cts was a problem that I thought it could have but it is reading normal too I have also thought about the tps but that reads correct also, now one other thing I have noticed is that the speedometer shoots up to 85mph and the fuel gauge will read empty at times, I want to think that there is a loose or bad ground but I have checked them all and all are good, I will go ahead and change the oil and mabe that will help. Thanks
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Loren Champlain Sr
Veteran
/ Moderator
Apr 28, 2009, 3:19 PM
Post #4 of 10
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Re: car runs rich and floods out
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Jason; Is the fuel pressure reading regulated or unregulated? Check for vacuum at regulator. Are you getting a MAP reading? Should have manifold vacuum to both the regulator and MAP sensor at idle. Have you checked manifold vacuum at idle? Should be in the 17-19hg range.
Is this an analog or digital speedometer? Does it 'bounce up' to 85 while the vehicle is sitting still? Or, when you drive it? If it's analog, could be a VSS problem. If digital, could be in the instrument cluster which wouldn't take much of a stab of thinking it could be connected to the fuel guage issue as well?
Loren
SW Washington
(This post was edited by Loren Champlain Sr on Apr 28, 2009, 3:21 PM)
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jasontyms
Novice
Apr 28, 2009, 6:11 PM
Post #5 of 10
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Re: car runs rich and floods out
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fuel pressure is regulated, I have vac. at map sensor and it appears to work I have swapped out the map sensor on it with a known good one, the vac. reads about 18hg, and the cluster is an analog cluster but the gas gauge is digital. This has been one vehicle that I have been ready to stick a rag in the gas tank and push it outside, On one note the guy that owns it told me he had taken it to the Cadilac dealership to get it repaired and they could not figure out the problem either. What do you think about the prom being bad in it I can't see much else, I did change the oil in it, it did have a strong gas smell to it, it did not help the way it ran though, I pulled the plugs and cleaned them and also ran another compression test on it and it averaged 178psi, which shows to be good.
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Loren Champlain Sr
Veteran
/ Moderator
Apr 29, 2009, 3:44 PM
Post #6 of 10
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Re: car runs rich and floods out
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Jason; Have you checked for TSBs on this? It's been years since I have run into a faulty prom. If you don't have the ability to pull up TSBs, let me know and I can check.
Loren
SW Washington
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jasontyms
Novice
Apr 29, 2009, 5:13 PM
Post #7 of 10
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Re: car runs rich and floods out
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I have checked for tsbs' on this but I have found none that fit it, did have another cadilac in today same year and same 4.5, and I did thy the prom out of that one and it did not make a difference I read all the data stream info from the good car and read the data streams from the sick one and the only difference was that on the sick one the map sensor was was staying at or around 5 volts and the other one was reading between 2.5-3.5, and the 02 sensor was almst always staying between 800-900mv but I did see it drop down lower a few times I have disconnected the 02 sensor and it did not make a difference in the way it runs, but I know the PCM picked up on it because I could see no reading on it in the data stream. Now If you want to look over TSBs on it feel free and maybe you can find something that I might have missed, I use Mitchell on Demand and I could have overlooked something. Thanks.
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Loren Champlain Sr
Veteran
/ Moderator
Apr 29, 2009, 6:09 PM
Post #8 of 10
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Re: car runs rich and floods out
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Jason; Both the MAP and O2 readings are telling us what we already know, that it's running rich. I'm really questioning the MAP, though. What is the BARO reading? Of course, I don't know what altitude you are. If the O2 is shorted to voltage, could be the problem?
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 30, 2009, 9:01 AM
Post #9 of 10
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Re: car runs rich and floods out
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I just cheated Loren: Altitude from sending location is dang close to sea level!
T
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Loren Champlain Sr
Veteran
/ Moderator
Apr 30, 2009, 4:10 PM
Post #10 of 10
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Re: car runs rich and floods out
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Ahhhhh. But did you account for Global Warming? And rising sea levels?
Loren
SW Washington
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