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91 Eldorado loosing power


bschelle

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Someone with a '91 service manual should be able to confirm the minimum fuel pressure spec. Another possibility is a failing fuel injector. A Tech-2 scanner hooked up to the car will show what cylinder(s) if any are misfiring. Observe the misfire counts and see what cylinder(s) is misfiring. One possibility is there be a fuel injector that has a running short in it and once it heats up, it won't deliver fuel to the respective cylinder(s).

The injectors are expensive and you need to use the OEM injectors or there will be a fuel imbalance.

Edited by KHE

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

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The injectors are expensive and you need to use the OEM injectors or there will be a fuel imbalance.

I have replaced the original injectors with refurb. Ford injectors for Crown Vic, Mustang, etc. I paid $150 for a set and did not notice any difference in performance or fuel economy. Many 4.9 owners have done the same.

The saddest thing in life is wasted talent

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I ordered a set of reman injectors for $137. I should have them early next week and will post back how it goes. Will I mess up the engine if I drive it the way it is?

By the way, as far as I remember, to lift up the fuel rails you do not have to remove completely PS pump or anything else. Just loosen them up and you will see a way to lift the rails. The new injectors probably came with o-rings. Use them instead of old ones. Clean the are around the injectors with a brush, before lifting them up. My engine was a mess because of several oil leaks.

The saddest thing in life is wasted talent

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I ordered a set of reman injectors for $137. I should have them early next week and will post back how it goes. Will I mess up the engine if I drive it the way it is?

By the way, as far as I remember, to lift up the fuel rails you do not have to remove completely PS pump or anything else. Just loosen them up and you will see a way to lift the rails. The new injectors probably came with o-rings. Use them instead of old ones. Clean the are around the injectors with a brush, before lifting them up. My engine was a mess because of several oil leaks.

This is the second set of injectors since I have owned it. You are right about the PS pump, I didn't have to remove it the first time.

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Just throwing this out there as a thought...does the 91 OBD system have the same diagnostic capabilities as later OBD1 models? Specifically I mean could a power balance check be done on this car by disabling the injectors one by one?

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Just throwing this out there as a thought...does the 91 OBD system have the same diagnostic capabilities as later OBD1 models? Specifically I mean could a power balance check be done on this car by disabling the injectors one by one?

Yes, it does.

The saddest thing in life is wasted talent

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You will eventually find the problem by continuing to throw parts at it but it is going to get expensive... The injectors could be bad but they may well not be. A scan tool that is able to monitor the misfire counts could easily pinpoint the problem. I would find out what is actually done to remanufacture the injectors. If it is just new o-rings and cleaning, that may not solve the problem - particulary if the injector coil has a short in it.

I believe that model also has the ability to turn off individual injectors from the climate control panel - when the problem occurs, turn off the injectors one at a time. When you turn one off that DOES NOT make the engine run worse, that is the problem injector.

Edited by KHE

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

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You will eventually find the problem by continuing to throw parts at it but it is going to get expensive... The injectors could be bad but they may well not be. A scan tool that is able to monitor the misfire counts could easily pinpoint the problem. I would find out what is actually done to remanufacture the injectors. If it is just new o-rings and cleaning, that may not solve the problem - particulary if the injector coil has a short in it.

I believe that model also has the ability to turn off individual injectors from the climate control panel - when the problem occurs, turn off the injectors one at a time. When you turn one off that DOES NOT make the engine run worse, that is the problem injector.

That's exactly the test I was talking about.

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So what was your prognosis?

Do you have an ohm meter?, check each injector's resistance

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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