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91 trans am wont start

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Old Oct 17, 2011 | 05:05 PM
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91 trans am wont start

Has fuel...has spark plug wires are correct... But spark looked a little weak, how do I test the ICM and is that where I should start... Pulled #1 plug after trying to start and it was wet.... Also has new fuel pump, wires and plugs....#7 injector was only reading 9.2 ohms so I know I need to replace it as well but where should I look next
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Old Oct 19, 2011 | 05:35 AM
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Car: 1990 T/A w/WS6
Engine: 5.7L V8 TPI
Transmission: 700r4
Axle/Gears: 3.23 w/ posi
Re: 91 trans am wont start

Originally Posted by onebad400
Has fuel...has spark plug wires are correct... But spark looked a little weak, how do I test the ICM and is that where I should start... Pulled #1 plug after trying to start and it was wet.... Also has new fuel pump, wires and plugs....#7 injector was only reading 9.2 ohms so I know I need to replace it as well but where should I look next
does it start if you spray starter fluid into the plenum?
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Old Oct 19, 2011 | 05:58 AM
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Re: 91 trans am wont start

Sprayed starter fluid in it and now it starts on its own but acts like it has a miss scanned the computer and no bad sensors
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Old Oct 19, 2011 | 06:34 AM
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Car: 1990 T/A w/WS6
Engine: 5.7L V8 TPI
Transmission: 700r4
Axle/Gears: 3.23 w/ posi
Re: 91 trans am wont start

Originally Posted by onebad400
Sprayed starter fluid in it and now it starts on its own but acts like it has a miss scanned the computer and no bad sensors
the miss is probly causing it, had the exact same problem with my 90 trans am.
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Old Oct 19, 2011 | 06:37 AM
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Re: 91 trans am wont start

What was causing the miss? It has to be mechanical I am doing a compression test this weekend
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Old Oct 19, 2011 | 06:41 AM
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Car: 1990 T/A w/WS6
Engine: 5.7L V8 TPI
Transmission: 700r4
Axle/Gears: 3.23 w/ posi
Re: 91 trans am wont start

Originally Posted by onebad400
What was causing the miss? It has to be mechanical I am doing a compression test this weekend
you said injector seven was reading 9.2? thats probaly whats causing the miss, the injector isn't working.
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Old Oct 19, 2011 | 07:42 PM
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Re: 91 trans am wont start

I replaced it already and it is stil missing. could a injector read the correct ohlms and still not fire... and would that throw a code hooked up a live data reader and all the sensors were working and the injector pulse was ok.
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Old Oct 20, 2011 | 04:09 PM
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Car: 1990 T/A w/WS6
Engine: 5.7L V8 TPI
Transmission: 700r4
Axle/Gears: 3.23 w/ posi
Re: 91 trans am wont start

Originally Posted by onebad400
I replaced it already and it is stil missing. could a injector read the correct ohlms and still not fire... and would that throw a code hooked up a live data reader and all the sensors were working and the injector pulse was ok.
are they all reading 15 ?

as for the code only one way to find out.
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Old Oct 20, 2011 | 08:04 PM
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Re: 91 trans am wont start

There are no codes, and they all read 16.2 or with in a ten hundredth
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Old Oct 20, 2011 | 08:09 PM
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From: P.A.
Car: 1990 T/A w/WS6
Engine: 5.7L V8 TPI
Transmission: 700r4
Axle/Gears: 3.23 w/ posi
Re: 91 trans am wont start

Originally Posted by onebad400
There are no codes, and they all read 16.2 or with in a ten hundredth
interesting, i need to research a little,
but i'd say its, something with injectors considering that it won't start except with starter fluid.
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Old Oct 21, 2011 | 06:01 AM
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Re: 91 trans am wont start

After you.get it started once it starts its self
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Old Oct 21, 2011 | 06:23 AM
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From: Spring Hill, Fl.
Car: 87 iroc-z
Engine: 454
Transmission: th350
Axle/Gears: 3.73
Re: 91 trans am wont start

cold start system working?
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Old Oct 22, 2011 | 03:07 PM
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Re: 91 trans am wont start

What's the cold start system? Would one injector not firing cause a code
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Old Oct 22, 2011 | 03:18 PM
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From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 91 trans am wont start

Originally Posted by redneckjoe
cold start system working?
last year 4 cold start was 87. He has a 92.
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Old Oct 22, 2011 | 03:48 PM
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Re: 91 trans am wont start

91 but same difference
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Old Oct 25, 2011 | 11:31 AM
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Car: 87 IROC Z28
Engine: 355 cid TPI
Transmission: Custom Built 700R4 w/3,500 stall
Axle/Gears: QP fab 9" 3.70 Truetrac
Re: 91 trans am wont start

It's quite possible that your hard start and misfire are related. The misfire is certainly where I would go first, just because it's much easier to pinpoint. No, your 91 will not set a misfire code. Misfire codes(P0300-308) did not start until 1995 with OBDII. Many things can cause a misfire or a rough idle. Connect a vacuum gauge and watch for a jumpy needle for a clue to a bad intake valve. Use a KV tester to measure KV from the ignition coil, then at each plug wire to look for a leaky wire. Use a scan tool to monitor BLM and Integrator to look for a lean or rich condition. Use a smoke machine or carb cleaner to look for vacuum leaks.

To find a misfire, start with a power balance test. To do this you will need to disconnect the IAC with the car running. Yes this will set a code but we don't care about that right now. Then, using spark plug boot pliers with a ground lead attached so that the pliers become a ground, pull one plug wire at a time from the cap. As you remove the wire hold the pliers close to the contact of the cap to so that the pliers conduct the spark. Note the rpm drop as you remove each wire and look for one that drops less than the others. Once you find the cylinder that doesn't drop like the rest, you have found your missing cylinder. Now you can focus on that cylinder with a compression test and leakage test to determine the cause of the miss. The leakage test is vital because even if the cylinder passes the compression test, it may have a leaky valve that is causing a power loss. Once you verify mechanical health, you can swap injectors with another cylinder to see if the misfire moves with the injector. You can also swap plugs from one cylinder to another to find a bad plug.
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Old Nov 27, 2011 | 07:33 PM
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Re: 91 trans am wont start

do 91 trans am have/need a mass air flow sensor. also does anyone have a picture of one and the plug that hooks up to it?
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