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95 cutlass cierra, 3.1L, injector problem!
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Paul G
New User
Oct 14, 2007, 6:30 AM
Post #1 of 6
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95 cutlass cierra, 3.1L, injector problem!
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Car was rough idling and missing. Replaced clogged fuel filter, pulled 6 injectors, had them benchtested and rebuilt, replaced, 2 failed dumping fuel, removed the 2 and replaced with new. after all that, #4 cylinder is still fouling causing rough idle and missing. compression is good(165 psi). Is it possible a brand new injector is bad as well or related to an electrical failure? Please help. Thank you.
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DanD
Veteran
/ Moderator
Oct 14, 2007, 10:30 AM
Post #2 of 6
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Re: 95 cutlass cierra, 3.1L, injector problem!
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Some of the injectors (I believe they’re called multech) that GM used in the mid 90’s were real fussy about being cleaned or “rebuilt”; if the proper procedure wasn’t used you may have inadvertently ruined them. Switch the injector with another cylinder and see if the problem follows the injector or not?
Dan.
Canadian "EH"
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Paul G
New User
Oct 14, 2007, 10:45 AM
Post #3 of 6
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Re: 95 cutlass cierra, 3.1L, injector problem!
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Rebuttal to Dan D's reply- Thanks Dan, I replaced the #4 cylinder with a brand new Napa parts injector to no avail, leading me to believe the ECM or some portion of the wiring is suspect. Anyone else have Similar problems?
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DanD
Veteran
/ Moderator
Oct 14, 2007, 1:44 PM
Post #4 of 6
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Re: 95 cutlass cierra, 3.1L, injector problem!
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Well ok you didn’t mention that one of the two new injectors went into #4 cylinder and yes a new component can be defective right out of the box but it’s not likely.
You could begin with testing the resistance value of all injectors, 12 to 16 ohms is acceptable. Next would be to perform an injector balance test which means the use of a stand alone tester or a scan tool that is capable of firing an injector for an exact amount of time via the vehicles PCM (computer). Plus a fuel pressure gauge to measure the pressure loss while the injector is on. ½ pound difference between cylinders is acceptable
If by chance you don’t have access to this equipment, do as I suggested in my last post and switch #4 injector with a cylinder that you know is running properly and see if the problem follows the injector.
I take it that you’ve checked that #4 injector has power being sent to it on the pink wire with the ignition on or engine running?
Or that the injector driver for #4 (Lt blue/black wire at the injector) from the PCM is capable of firing the injector? A quick easy way to check for both of these is with a noid light connected to the injectors wiring harness. The light should flash every time the PCM wants to fire the injector. Here’s a picture of a noid light kit but I think you can purchase them individually they don’t cost a lot.
Don’t use a test light connected across the harness; a regular test light draws to much current and it will likely burn out the driver. Burn out a driver and you replace the PCM.
Good luck and let me know if you need any of the above explained?
Dan.
Canadian "EH"
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Paul G
New User
Oct 14, 2007, 8:36 PM
Post #5 of 6
(3284 views)
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Re: 95 cutlass cierra, 3.1L, injector problem!
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Wow Dan, It sounds like you really know your P's & Q's!. I have to be honest becaause it sounds easy to pull these injectors, but its not. There is a pile of parts, I'm sure you know just to get to the rail,etc., a very time consuming endeavor. I know its grunt work to figure it out and this is the third time I am repeating this process. I was hoping for some type of diagnostic check which would not entail the disassembly of the plenum and all related parts. It doesn't sound like it. Plus the fact I am a Saturday afternoon mechanic and don't have access to all the sophisticated gear you have described. Is it possible you run a garage and are close by to Buffalo? I am so desperate what with the weather changing that I would make the trip! Thanks at any rate, you are a kind and knowledgeable person and I appreciate your help in the matter. Paul
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 15, 2007, 5:33 AM
Post #6 of 6
(3279 views)
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Re: 95 cutlass cierra, 3.1L, injector problem!
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Interesting thought of direct biz from the site! Best guess is you are about 150 miles from each other,
T
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