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LT1-LT4 Modifications
1993-97 Gen II Small Block V8

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Old 03-26-2012, 10:25 AM   #1
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Default What are some symptoms of bad injectors?

Hey guys I got some injector questions.

A little history on the car....
My uncle bought it wrecked in '97 with 20K on it. Fixed it up and daily drove it till around 2001ish. Well after that, the car sat in his garage until august of every year for our local cruise night and that is the ONLY time it got driven. Once, MAYBE twice a year it got driven and no more than 200 miles were put on it.
Well my buddy bought it from him in 2009 after I found him the only car he would sell the car for. (2002 35th SE SS Camaro) The car has 53K on it now and has had nothing but problems after he bought it. First the fuel pump, then the starter, then the Opti, then the MAF.

The car runs "OK" but it starts extremely hard and just seems down on power and I suspect sticky or dirty injectors.

FWIW, He and I have identical mods. LT's, 3:73s, LM1, except I have a 6-speed. I always beat him no matter what. We dyno'd on the same dyno one day and he put down 243/287 and I put down 293/323.....


Sorry for the long story but I just need some input on the situation, do you think since the car barely gets driven that the injectors are the culprit??
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Old 03-26-2012, 10:31 AM   #2
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Could be a number of things really. If you suspect them, take them out and have them cleaned by a shop (professionally). I personally don't think its the injectors (mechanically) simply because they are a simple part that rarely fails. But they could be clogged or gummed up, sure.
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Old 03-26-2012, 10:31 AM   #3
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Whats the fuel pressure at? Put a guage on it at start up. Is the car running on all 8, is it missing?
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Old 03-26-2012, 10:34 AM   #4
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Quote:
Originally Posted by RamAir95TA View Post
Could be a number of things really. If you suspect them, take them out and have them cleaned by a shop (professionally). I personally don't think its the injectors (mechanically) simply because they are a simple part that rarely fails. But they could be clogged or gummed up, sure.
We are gonna pull them today and have out local diesel shop flow and test them.
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Old 03-26-2012, 10:36 AM   #5
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Quote:
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Whats the fuel pressure at? Put a guage on it at start up. Is the car running on all 8, is it missing?
We checked it last summer out of curiosity and it was at about 40 PSI or so at idle IIRC. It's on it's second fuel pump so I don't think it's that.
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Old 03-26-2012, 04:09 PM   #6
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Any more input??
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Old 03-26-2012, 06:06 PM   #7
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My 96 sounds similar to what you described. Mine had 138k on it and sat for about 4 years. It seems to start hard like you mentioned. It seems to roll kinda slow and make a loud bang every now and then. Not a backfire, kinda like the engine fires but not enough to go ahead and start and then the starter pulls down on the flywheel, then it finally starts. (I know that probably didn't make any sense, it's really hard to describe, it's a symptom I've never really seen before) It doesn't take long to start, just a rough/hard start.

I suspect injectors too. The car seems to run great but down on gas mileage that I seem to remember. The idle just doesn't seem quite right to me but nothing to set a code. I have replaced the opti, the wiring harness going to it, ICM, wires, plugs, coil, IAC, TPS, fuel lines, fuel filter, and cleaned the MAF. Still has the original fuel pump, pressure runs around 42/43 at idle and during cranking from what I remember.

Wish I could offer more advice but I can tell you that none of the things I replaced changed what I feel is the injectors. The opti was bad for sure but none of the other parts were "bad" as far as I can tell.

I'm interested in hearing the results from the injector testing.
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Old 04-30-2012, 12:06 PM   #8
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Any updates on this?
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Old 04-30-2012, 12:11 PM   #9
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Put some seafoam in the gas and see if it helps.
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Old 04-30-2012, 01:02 PM   #10
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People talk alot about seafoam but as a fuel system cleaner it works excellent. Throw a can in the tank. Menards always has the best price on it.
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Old 04-30-2012, 03:32 PM   #11
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We had the injectors cleaned and flowed but it still didn't help the problem. We are going to try the coolant sensor on the water pump to see if that helps the hard starting.
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Old 04-30-2012, 03:35 PM   #12
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Quote:
Originally Posted by 93M6Formula View Post
We had the injectors cleaned and flowed but it still didn't help the problem. We are going to try the coolant sensor on the water pump to see if that helps the hard starting.
Educate me... What effect would that have on the hard starts?
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Old 04-30-2012, 03:43 PM   #13
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Quote:
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Educate me... What effect would that have on the hard starts?
If asking about the coolant sensor, the one in the water pump is what the computer uses to measure the engines temp. If bad, the computer won't know how much fuel to deliver while cranking over.
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Old 04-30-2012, 03:47 PM   #14
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My car took alittle more cranking than normal. While changing the cam this winter I found about half the intake bolts very loose. After reassembly the car starts much better now, I don't lay all the blame on the loose bolts but I suspect they were part of it.
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Old 04-30-2012, 03:47 PM
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