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PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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LonghornIii
New User
Dec 5, 2008, 9:32 AM
Post #1 of 8
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PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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Engine Performance problem
1995 Chevy Lumina 6 cyl Two Wheel Drive Automatic 123000 miles
Ran great until the fuel pump went out. No problems at all. Had to replaced the fuel pump, It ran fine for about a week and now at times It runs rough. It just does not want to go, Loss of power.
Almost wants to die but It doesn't.
Computer Is not detecting any problems. Check Engine has not came on and I can't find anything else to Indicate a problem but the way It runs. Any help locating the problem would be great.
Can anyone help me Please. After talking to a few people, I have now replace the fuel filter, The fuel pump for a second time, new strainer and cleaned the tank.
Little to no change but now after replacing the fuel pump again, It Is now running with a miss all the time and It Is hard to start. It was not before. Now It seems as If One of the cylinders Is not firing all the time. It Is putting even at Idle and I still am not getting anything from the computer to point me In the right direction or even Indicate that there Is a problem. Please help me locate the problem Please. I am not able to put It In the shop so I need some help locating the problem so I can fix before things get worse.
(This post was edited by LonghornIii on Dec 5, 2008, 9:35 AM)
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autojoe
User
Dec 5, 2008, 11:17 AM
Post #2 of 8
(5574 views)
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Re: PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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how did you clean tank?with water?maybe water in gas?spray some carb cleaner into intake and see if miss goes away.If it does then you have a lean missfire.do you have a fuel gauge to check fuel pressure?Does the miss get worse when you increase throttle?you can take a spark tester and disconnect a plug wire and hook to spark tester and start car and see if good spark.shut car off and repeat on all plugs.Should have crisp blue spark.If I had to guess I would say fuel related.try turning key to on position not start and then off for 2 seconds and then to on position do this 3 times and then try to start car.does car start better?Without a scan tool or fuel pressure gauge it is just guessing.I have ignition scope and scan tools labscopes ect and without proper testing equipment it is hard to diagnose.let me know answers to these questions.
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DanD
Veteran
/ Moderator
Dec 5, 2008, 2:00 PM
Post #4 of 8
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Re: PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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A 95’s on board diagnosis-tics do not have misfire detection, so the PCM (computer) will not be of much help; unless the problem/circuit is monitored by the PCM. With you saying that there are no codes; the PCM and its monitored circuits are likely ok?
I say that with a bit of conjecture because the PCM mostly monitors electrical and not mechanical; as in a plugged/dirty injector, will not set a fault code; saying, number whatever cylinder's injector isn't squertung fuel.
But that doesn’t mean that the PCM hasn’t lost its ability to control certain components.
There are inputs to a PCM from the sensors and output commands from the PCM; if the PCM sends out a command to open an injector and the PCM sees the “normal” voltage drop across the injector’s solenoid’ it doesn’t know that the fuel cannot pass through the injector because it is plugged.
You’ll have to determine which cylinder(s) is/are misfiring, manually and from there, determine the cause.
There is no SILVER BULLET fix for this; you will need to know the proper and safe (electrical & personal) way of finding out which cylinder(s) are the problem.
Sorry but finding the root cause of this issue, could be difficult and need the attention of an experienced technician.
Dan.
Canadian "EH"
(This post was edited by DanD on Dec 5, 2008, 2:33 PM)
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DanD
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Dec 9, 2008, 1:49 PM
Post #6 of 8
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Re: PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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There are a number of different ways to find out which cylinder(s) are not producing power.
I guess the safest way would be for you to get yourself a spark tester. Pick any cylinder you want to start with and disconnect the spark plug wire; then connect the tester to it. Start the engine, if the misfire feels the same, you’ve found the cylinder giving the problem. If the engine shake/mis is worse, go on to the next.
There are other faster ways but trying to explain it so that you don’t hurt yourself or the vehicle’s ignition system, would be like trying to explain in text, how to tie your shoes laces.
Take the car in and have it diagnosed; then if you still want to, take the car home and try and fix it
Dan.
Canadian "EH"
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LonghornIii
New User
Dec 12, 2008, 1:05 AM
Post #7 of 8
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Re: PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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I took a chance and replaced all 6 spark plugs just to count that out as the problem and I came across something Interesting. 5 of the old spark plugs were fine (still somewhat clean and looking good) but the 6th spark plug was black as charcoal.
As I said I replace all 6. After driving It for a day with no change I decided to check the spark plugs just to see there condition. 5 of the spark plugs were fine (still clean and looking new) but the 6th spark plug was black as charcoal after one day of driving. Can that be the cylinder that Is causing the misfire? If so what should I do next?
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DanD
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/ Moderator
Dec 12, 2008, 4:52 AM
Post #8 of 8
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Re: PLEASE HELP!!! 1995 Chevy Lumina Engine misses.
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Defiantly that’s the one to be looking at.
Check that that cylinder is getting spark from the coil pack? If you still have one of the old spark plugs; connect it to that cylinders spark plug wire and then ground the spark plug with a jumper wire. Crank or start the engine; there should be a blue, consistent spark jumping the air gap.
Next perform a compression test on the engine, comparing the pressures produced by all the cylinders. It should be around 125 -175psi with no more then a 25 or 30 psi difference.
You say that the plug is black; that usually means that it’s getting fuel but it maybe getting too much from a leaking or dirty injector?
You’re getting closer to finding the problem; let us know what you find after the above tests.
Dan.
Canadian "EH"
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