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Old 08-19-2008   #21
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: I NEED A ECM... Where to BUY?

my car went from having no spark to no fuel day in and day out, turned out to be a bad prom chip in my computer.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 08-19-2008   #22
88GTAEd
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GTA Year: 1987
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

im having problems with my car also. im suspecting the ECM. i have done a speed density swap on my 88 and it runs like hell... i bought it in a junkyard so i wouldnt be surprised if its junk. one thing that may be making me suspect this is when i try and do a idle ajustment. when you put the key to on but not running and jump A and B on the ALDL, it makes the IAC goto fully closed. when I do this the IAC makes funky sounds. and i do have a brand new IAC in it. also the memcal is brand new. any ideas??
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Old 08-19-2008   #23
george88gta
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Re: I NEED A ECM... Where to BUY?

Quote:
Originally Posted by MunsonGTA
my car went from having no spark to no fuel day in and day out, turned out to be a bad prom chip in my computer.
Where do you obtain a new chip?
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Old 08-19-2008   #24
GTAGUY65
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Re: I NEED A ECM... Where to BUY?

I just put in a new dist. and Module too'
The Prom Chip I guess is my next step! I found one for 150.00 does that sound like a lot of money for a chip?
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Old 08-19-2008   #25
88GTAEd
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GTA Year: 1987
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

i paid 200 somethin for mine..
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Old 08-20-2008   #26
GTAGUY65
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Re: I NEED A ECM... Where to BUY?

I hear that the ECM rarely goes out.. and that a lot of people change the ECM and that is not the problem, I think that may be the case with me. but I was told by a mechanic that did some diognosis on mine that it was either the ECM or the chip. now a couple of days later I don't have spark either so it is totally out of commission . I hate to spend the money on the chip and that not be it either
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Old 08-21-2008   #27
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

Have you ck'd out the basic stuff,first?
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-21-2008   #28
gta wizard
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Re: I NEED A ECM... Where to BUY?

GTAGUY65, i have a prom chip out of my 89 350 tpi gta, there is absolutley nothing wrong with it, let me know if you want it and we will work out a price!
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Old 08-22-2008   #29
GTAGUY65
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Re: I NEED A ECM... Where to BUY?

Well I got the car running again!!! Remember I changed out the Distributor to rule that out.... well after a day I got no spark! well the Distributor that I changed out was causing that problem.... But now I am back to the original Problem with the Fuel Injectors getting an irratic pulse, and then not getting enough fuel to start when warm
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Old 08-28-2008   #30
GTAGUY65
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Re: I NEED A ECM... Where to BUY?

well I have the GTA at another shop, they say that the resistance varies from 4 ohms tp 16 ohms on my Fuel injectors and my fuel pressure was at 35lbs I think the fuel presure is supposed to be above 40lbs and the resistance of the injectors ahould be around 15ohms they said if the resistance is at 18ohms it can damage the drivers in the ECM.... 1 and 7 cyl are not firing
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Old 08-29-2008   #31
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

Hmmm, sounds like they are on the right track. Good luck.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-29-2008   #32
george88gta
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Re: I NEED A ECM... Where to BUY?

Quote:
Originally Posted by GTAGUY65
well I have the GTA at another shop, they say that the resistance varies from 4 ohms tp 16 ohms on my Fuel injectors and my fuel pressure was at 35lbs I think the fuel presure is supposed to be above 40lbs and the resistance of the injectors ahould be around 15ohms they said if the resistance is at 18ohms it can damage the drivers in the ECM.... 1 and 7 cyl are not firing
I believe that the stock GM injectors are spec'd at 16 ohms. From what I can find on the web, the range for our cars is 14-16 ohms. However, 4 ohms isnt right. Someone has either installed a low impedance injector or you have one that is slowly devloping an internal short. Either way, I would verify that you have one at 4 ohms and if that is correct, I would replace it. May be a good idea to replace them all. Check out the FORD 22 lb injectors. They are reasonably priced and work just fine.
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Old 08-29-2008   #33
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: I NEED A ECM... Where to BUY?

your fuel pressure needs to be set at 43 psi
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 08-29-2008   #34
MunsonGTA
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Location: Ravenna, OH
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GTA Year: 1987
GTA Engine: Custom
Re: I NEED A ECM... Where to BUY?

Quote:
Originally Posted by george88gta
Where do you obtain a new chip?
i had a custom tune by lsracingchips, had the same tune put on a new chip and the car started up. i'm not quite sure how i fried the chip...
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 08-29-2008   #35
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

Quote:
Originally Posted by MunsonGTA
i had a custom tune by lsracingchips, had the same tune put on a new chip and the car started up. i'm not quite sure how i fried the chip...

I bet Mr Murphy paid you a visit..........
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-29-2008   #36
GTAGUY65
PAUL
 
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Location: Southern Oregon
Posts: 116


Re: I NEED A ECM... Where to BUY?

OK I guess it is somewhat still a mystery why my car is missing... #1 and #7 are the misfireing cylinders. (but they seem to pull ok 2000 rpms and above)
The injectors in the GM book say the resistance is supposed to be 10ohms
here is the run down on my injectors as follows
#1) 16.0, #3) 7.6, #5) 16.0, #7) 10.5 OHMS
#2) 4.9, #4) 14.8 #6) 16.0 #8) 16.0 OHMS
obviously #2 and # 3 injectors are in question...
then why is #1 and #7 missing? when the injectors are within the parameter? it is getting spark, (plugs and wires are good! No vacuum leaks)
So the injectors on the "even" bank are bad, but the cyls. on the "odd" bank are having problems. Mechanic wants to see if Cam is bad, I have 135lb compr. on both #1 and #7 I have a hard time thinking that the cam is bad with only 89,000 miles on although I personally did not put most of those miles on it. Oh the fuel pressure at Idle is 38lbs. at start up I think it is supposed to be 43 Question do Different manuals have different values for resistance and pressure? it seems I read different things in different places when the the GM manual says 10 ohms for injectors

Thanks for all your input. I may have to park it for the winter and save up to start tearing it down
PS was wondering what are the original cam specs or grind? if I do change cam what would be a good upgrade or should I stay with a stock grind... PAUL

Last edited by GTAGUY65; 08-29-2008 at 10:26 PM.
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Old 08-30-2008   #37
FearThisGTA
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Posts: 4,742



GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: I NEED A ECM... Where to BUY?

I agree on the cam thing. I would find it hard to believe the cam is bad. The cams in these cars are not flat tappet, unless you have a 305 tb then it maybe a hyd flat tappet otherwise it should be a roller, a small one but non the least a roller. So, I dont think thats your problem. I think he was on the right track with the injectors. Imo, I would put all new ones in from Ford Mtr Sports as mentioned above, hth
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 08-30-2008   #38
GTAGUY65
PAUL
 
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Location: Southern Oregon
Posts: 116


Re: I NEED A ECM... Where to BUY?

OK my plan is to remove the intake and replace intake manifold gasket -due to slight water leak-an adj. fuel pressure reg. in it but WHICH ONE? and what else should I think about while I have it apart this far?
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Old 08-30-2008   #39
george88gta
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Re: I NEED A ECM... Where to BUY?

Quote:
Originally Posted by GTAGUY65
OK my plan is to remove the intake and replace intake manifold gasket -due to slight water leak-an adj. fuel pressure reg. in it but WHICH ONE? and what else should I think about while I have it apart this far?
I would use the Holley adjstable, Summit part number 512-501 http://store.summitracing.com/partde...5&autoview=sku
Just be sure to check clearance between the top of the adjusting knob and the bottom of the plenum. I had to grind away a few thousandths of an inch to get clearance. Others have had it fit fine without the need for grinding. I like the GM gaskets. You will need the plenum gaskets as well. Dont forget to put a thin film of RTV sealer around the water holes (block and intake) before assembling.
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Old 08-30-2008   #40
GTAGUY65
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Re: I NEED A ECM... Where to BUY?

Yeh I was reading an article in Pontiac Performace and they said they had to grind for clearance too, do you grind the knob itself.
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