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ENGINE SURGING


myeldog

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CAN SOMEONE TELL ME WHAT COULD POSSIBLY BE GOING ON WITH MY 1994 ELDORADO ? IT SEEMS THAT NO ONE IN S. GA. CAN. OK HERE IS THE PROBLEM. ON THE HIGHWAY IT RUNS AND RIDES VERY WELL, BUT IN SLOW OR CITY TRAFFIC IT SURGES ANB BUCKS LIKE CRAZY. WHEN I AM STOPPED THE RPM RISES AND FALLS BETWEEN 1000 AND 2500,(NOT GOOD).A LOCAL DEALERSHIP AND SEVERAL ASE SHOPE WANT TO THROW PARTS AT IT .NO ONE HAS BEEN SUCCESSFUL. THE LIST STARTS WITH CRANKSENSORS COILS FUEL PRESS REG FUEL FILTER AND IDLE RELEARN. GUYS I NEED HELP, I HAVE KEPT HER IN THE GARAGE FOR A MONTH NOW BECAUSE OF THE PARTS TOSS. sad.gifsad.gif :

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CAPS MEANS YOU ARE YELLING FOR FUTURE REFERENCE

See these threads, the 94 has something called mouse holes,

This 94 had similar surging, do a search under mouse holes

http://caddyinfo.ipbhost.com/index.php?sho...&hl=mouse+holes

http://caddyinfo.ipbhost.com/index.php?sho...&hl=mouse+holes

http://caddyinfo.ipbhost.com/index.php?sho...&hl=mouse+holes

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CAN SOMEONE TELL ME WHAT COULD POSSIBLY BE GOING ON WITH MY 1994 ELDORADO ? IT SEEMS THAT NO ONE IN S. GA. CAN. OK HERE IS THE PROBLEM. ON THE HIGHWAY IT RUNS AND RIDES VERY WELL, BUT IN SLOW OR CITY TRAFFIC IT SURGES ANB BUCKS LIKE CRAZY. WHEN I AM STOPPED THE RPM RISES AND FALLS BETWEEN 1000 AND 2500,(NOT GOOD).A LOCAL DEALERSHIP AND SEVERAL ASE SHOPE WANT TO THROW PARTS AT IT .NO ONE HAS BEEN SUCCESSFUL. THE LIST STARTS WITH CRANKSENSORS COILS FUEL PRESS REG FUEL FILTER AND IDLE RELEARN. GUYS I NEED HELP, I HAVE KEPT HER IN THE GARAGE FOR A MONTH NOW BECAUSE OF THE PARTS TOSS. sad.gifsad.gif :

Sounds like you have a problem with the idle speed control (ISC) motor. There is tons of information in the archives on the ISC.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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My guess would be the phenolic spacer plates clogged with carbon (mouse holes included as Scotty mentioned). No amount of parts will fix it if that is the problem. Just plain old elbow grease so to speak. However I would try some aggressive Wide Open Throttles (WOTs) in 2nd gear, about 8-10 in a row first. How many miles on your Eldo? Do you ever experience a slight surging or bucking while the cruise control is engaged?

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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Hmmm....my bet is still on the idle speed control - while the EGR passages may need to be cleaned, they wouldn't have any affect at idle as there is 0% EGR commanded at idle and WOT.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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myeldog, emailed me this additional information:

Just talked to the mechanic who last worked on the caddy. and the only

other ifnfo that I got was that the idle speed control motor had been

tested. Also the vaccuum sys checked for leaks. I have 88,000 miles

onthe caddy the original wires are still on but not the OE plugs. code

044 right oxy,and 023&036 EGR ??? were noted last night on the on

board diag. Other parts or tests noted in orig post. What should PCM

inputs/output read ? is there a standard, the caddy reads HI/LO throughout

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According to your mechanic they tested the ISC, and checked for vacuum leaks.

What kind of spark plugs are you using? How bad do your ignition wires look? If you have an ohm meter check the resistence and record it and post it here.

code 044 right oxy,and 023 & 036 EGR

P044 (E044) ........................................ Right Oxygen Sensor Signal Lean

P023 (E023) ..................... Electronic Spark Timing (EST) Signal problem [EGR]

P036 (E036) ................................. EGR Valve Pintle Position Out of Range

A code P044 will set if:

1) There is an O2 sensor circuit fault giving a false lean indication (check wiring)

2) When the air fuel ratio is actually lean due to a vacuum leak or fuel control system fault (check injector wiring make sure injector wiring is not travelling side by side with the ignition wires and make sure the injector connections are good). Consider doing a power balance test....Check fuel pressure.

If you send me an email address I can send you the P044 diagnosis tree

P036, start by removing and cleaning your EGR valve, don't soak in solvent that can get into the diaphram. Use small wire brushes, try to get to the pindle with them. Don't breath the dust from the EGR

P023, see this thread

http://caddyinfo.ipbhost.com/index.php?sho...ic=7217&hl=e023

and this one:

http://caddyinfo.ipbhost.com/index.php?sho...ic=7217&hl=e023

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I just went thru this last week.

Same symptoms as you are describing.

It was my ISC.

However, if it is the ISC, then it will never act up unless you foot is OFF the gas.

In other words, the problem will only occur when you are not depressing the throttle.

In reading the description of your problem, I am not sure if you are having a problem while driving slow, with or without touching the throttle.?

It makes a considerable difference in diagnosis.

- Problem only when off the throttle?

or

- Problem also when driving slow WITH throttle applied?

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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  • 4 weeks later...

surge no more !!! Hey guys it took some time to get this reply out I could not stop riding wink.gif Here is what we did to get the Eldo back on the road . The predominant codes were 25,35 &44 the diagnostic tree was ran on each one and the end result was to replace the ECM. We bought a reman ECM , installed it and drove the car no less than 150 miles. went back for diagnosis no codes were found. biggrin.gif The eldo is running like new. the only problem is i cant stay out of it,could it be that i have really discovered why we (the eldo) fell in love in the first place. anyway thanks to all who gave me a reason not to give up on her??There is no love like caddy love cool.gif Thanks again guys!!!

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surge no more !!! Hey guys it took some time to get this reply out I could not stop riding wink.gif Here is what we did to get the Eldo back on the road . The predominant codes were 25,35 &44 the diagnostic tree was ran on each one and the end result was to replace the ECM. We bought a reman ECM , installed it and drove the car no less than 150 miles. went back for diagnosis no codes were found. biggrin.gif The eldo is running like new. the only problem is i cant stay out of it,could it be that i have really discovered why we (the eldo) fell in love in the first place. anyway thanks to all who gave me a reason not to give up on her??There is no love like caddy love cool.gif Thanks again guys!!!

First - congratulations! The computers (ECM, BCM) are very close to the heater core, which is hot all the time. That makes me nervous... unsure.gif

The saddest thing in life is wasted talent

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Hey that's great news myeldog. Glad to hear you got it running smooth again. Also thanks for reporting back to complete the thread and sharing the information.

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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