LuvF-bodies

Advice needed on 94' LT1 which runs perfectly when cold, then Tach needle jumps and stalls out when warm. It usually only re-starts when completely cooled down. I just replaced AC Delco Coil (new C/wire), and the AC Delco Ignition Control Module is also new. I replaced the Optispark about 35,000mi. ago along w/H2O pump (no leaking), the TPS has also been replaced recently. The dash is not showing any SES or Check Engine codes, but should I purchase a Scan Tool next, or get the Fuel Pressure Tested (maybe pump or relay is failing). I'm tempted to get another ICM , maybe I was sent a defective one? What next ?

Injuneer

What brand is the Opti?

Scan it. DTC 16 for loss of the Opti cam position sensor low resolution pulse shuts down the fuel system, and does NOT turn on the SES light. ICM codes (41/42) also do NOT turn on the SES light. You need a real OBD-1 scanner, not the cheapie ($30 Actron) that simply shorts the DLC pins. 1993 was the last year shorting the pins worked.

There are dual OBD-2/OBD-1 scanners, but some of them need an external 12V power supply, because there is no 12V pin on the OBD-1 DLC. And don't try the Innova brand. Their LT1 code database is corrupt, and the scanner spits out a list of seven bogus codes.

Consider free download of Scan9495. Link in a sticky post at the top of the "Computer Diagnostics....." forum.

LuvF-bodies

OK right, I'll get a Scanner. I've read about ACTRON Bosch Super Scanner CP9145 OBD I OBD II OBD 1.5, about $100. I may also need to get the 12 Pin adapter cable; JUST to tell me it'll be my (No name, just found invoice) Opti-Spark ($600 in 2003); OR the New AC Delco ICM (two hours use). Thanks that's Exactly what I was thinking, LOL.
The thing is the last time the Optispark "Failed" it really failed (2003), and the previous ICM was a "BadOne", and lasted only a few months, and I guess the fuel pump would be more obvious, as I hear it prime up for a few seconds everytime I start car. hmm. Thanks for the advice, and I'll re post, later

PS: You also say the OBD1 Scanners will show a "Universal" code number, and meaning easily found on internet (in case not included w/Scan Tool) like,"DTC 16" = loss of the Opti cam position sensor low resolution pulse shuts down the fuel system, etc ?

Injuneer

Shoebox has a list of codes specifically for the LT1:

http://shbox.com/1/Dtcs.htm

Or you can download a copy of the 1994 factory service manual here:

http://www.firebirdnation.com/forums...2-wiring-diag/

Shoebox shows how to use jumpers for 12-pin to 16-pin:

http://shbox.com/1/xraycable.jpg

It's normal for the fuel pump to prime for two seconds, then shut down. At that point it's waiting for the PCM to receive the fuel permit signal from the PASS-Key (security) system, and for the PCM to find the low resolution pulse signal from the Opti, so the PCM can restart the pump.

LuvF-bodies

Hi, so you think this Innova brand of GM Scan tool, "Will Not function properly" as you said ? https://www.amazon.com/dp/B000EVU8C0...=IA7GKQDC1V40R

Do you think this Scan Tool will work on my 1994 w/12 Pin connector;http://www.ebay.com/itm/ACTRON-SUPER-AUTO-SCANNER-CP9145/282113578619?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35389%26meid%3D8cc4b0496ae4495fb2d43a1323af7189%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D371672352755 I'm purchasing appropriate cable adapter for 12 Pin as well. It'd be great to know before I spend money, thanks

Injuneer

The Innova you linked is basically a paper clip in a box. It shorts the DLC pins to flash the codes on the SES light. That's all you get for $18. As I mentioned above this will not work after 1993.

The Innova was mentioned with respect to a combined OBD-2/OBD-1 scanner. Specifically the model 3120 produces a list of seven codes every time it hooks up to an LT1 PCM. Same scanner is available as an Equus 3120. Our resident scanning guru, GaryDoug determined that the code list stored in the scanner for he LT1 PCM is not the correct list, making it useless for the LT1.

I believe GaryDoug has tested the Actron CP9145 on his LT1. PCM and has found it to work correctly.

GaryDoug

I have never used the CP9145. I believe it is obsolete now. I did review the newer version, CP9185 (about $80), and it did perform well for 94 or 95 F-body cars. You would also need the CP9127 OBD1 adapter cable with power cable (about $30).
https://www.amazon.com/Actron-CP9185.../dp/B000T8UG52

Actron/GM OBD I ALDL cable kit CP9127- Read1Reviews onActron #CP9127

Check various sources for these often, because the prices fluctuate wildly. For example, last year Advance Auto Parts sold the CP9185 for $150. Right now, they sell it for $250.

shoebox

If you can find the old CP9145, it works as confirmed by many on several boards.

GaryDoug

My review: Actron CP9185 Elite AutoScanner - ECM/PCM Product Reviews - Firebird Nation

I just noticed that one of the "Other Sellers on Amazon" has this scanner for about $71 including shipping.

LuvF-bodies

That's great information on the Scanners, the newer CP9185 should do nicely, and the CP9127 should work w/OBD 1 interface, but why does it say "includes cigarette lighter adapter" ? Isn't the Scanner self powered ? I'll find out, thanks again on the information, damn I love these Forums. I do this w/my Quadcoptor Drones as well, LOL I'll post results

GaryDoug

The answer is in my review. But, it means that the scanner display backlight does not function without external power. So it is very hard to read the display using the internal battery only.

LuvF-bodies

Thanks, more useful info. The latest is Today I start and run car and before it even warms up to 180 F, like 3 minutes running , the Tach needle jumps all over and it stumbles and eventually would die (I shut off). The ambiant air here is about 80 deg. I wait only a couple of minutes, and it restarts and idles perfectly, hmmm ? A half hour later I go to move car, and it wouldn't hold idle for one minute! I can't wait for my Scanning tool, sad.

GaryDoug

Have you ordered one yet? I was thinking about grabbing one of those $71 ones myself, but didn't want to take that option away from you in case they just had one.

LuvF-bodies

Hey I've been wasting time trying to get the Download of this "Scan9495" Free Diagnostic tool to open properly after it's been downloaded, and I keep getting the Pepper Zip Red X Application Not Found, when I try to Open it ? I tried various files at that site, nothing ! All that after I made my own OBD1 Cable, lol "Consider free download of Scan9495. Link in a sticky post at the top of the Computer Diagnostics....." forum

GaryDoug

It appears you have downloaded a crappy app called Pepper Zip which set your association for all zip files to itself. Uninstall it immediately if it isn't already removed. It's probably either spyware or some kind of add-on for something. It's possible your antivirus program has removed it. When you download something on the web, watch out for other programs that come along for the ride by checking off "Decline" for every one. When you uninstall stuff like this, the pc should set the association back to the Windows zip utility.
Right-Click on the scan9495 zip file, click on "Open with..." and select File Explorer or Windows Explorer after checking on "Always use this app..." at the bottom of the window.