code P0372,P1371 ???

[95 GA/TA]

I am trying to help my dad out with his car.It is a 1996 Trans Am,all stock except for flowmaster and CAI.It has 40,000 miles on it and only basic service is all that has been done so far.He was coming home today and the engine fluttered and quit on him.After sitting on the side of the road for a few minutes it would start up for a couple seconds and then die again.We finally made it home with it after a bit of pushing.The SES lighht came on so i scanned the car and these are the codes i got,PO372,P1371,one is high resolution,one is low resolution problems.I ve done some research and this apperars to be the opti spark going bad.I had forgotten but we did have to change the waterpump about 5-6 months ago.If anyone has any advice or input please let me know.Id just like some reassurance before he buys an opti.One last thing,after the car sat for a couple hours this evening it started right up and gave no codes,i drove it about a mile with no problems but after all that pushing this evening i was too afraid to try any further.Thanks for all you guys help, this site is awesome!!

[fastTa]

Those two DTC's are fairly synonomous with either the opti itself or the opti harness getting wet. Disconnect both ends of the opti harness (opti side and intake manifold side) and make sure they are not wet. If they are, spray them with contact cleaner to displace any moisture.

If you have an active P1371 (Low-Res signal not found), your car would not run because the PCM would not allow the fuel system to be energized. The fact that your car is still running now means that the P1371 is likely now stored and not currently active. The harness pigtails could have dried out, but you still need to check them for moisture. Another possibility could be the actual optical sensor module (receptor).

Clear the codes and run the car. Now what DTC's do you have if any?

[95 GA/TA]

The car has ran well since i reset the codes back in February.I checked all connectors and wires and everything looks good.The car doesnt get driven alot but im guessing it has had around 600-800 miles(no more than 25 miles at a time) on it since the first problem with the codes.It quit again tonight with no light, i scanned and got the lo resolution code in history.The car was hard to start and wouldnt most times but finally i got it started for a couple minutes and it set the hi resolution code which turned on the ses light.I also noticed the tachometer was not working at times either while i was trying to keep the car running,all the other gauges seemed to work ok.Im guessing its the opti going but just wanted to get you guys opinion,i was also curious if the tach has anything to do with the opti or maybe i have 2 seperate problems??Any help is appreciated.The odd thing is about 20 minutes later the car finally started and idled,reved up normal and the tach worked normal again with no problems.

[Injuneer]

The PCM reads the RPM from the Opti, and sends the RPM signal to the tach. Logically, a problem with the Opti pulse patterns would screw up the tach signal.

[95 GA/TA]

Thanks,thats what i thought but i wasnt for sure.That makes me feel pretty sure i have an opti problem.IF anyone has any more advice or info let me know.I just want to be sure before i spend the money for the opti.

[vipergtx500]

I am having the same exact problem and i just wanted to know if you replaced the opti or checked if the screws backed out and re tightened them, my opti is almost brand new so im guessing my screws backed out

[Injuneer]

I am having the same exact problem and i just wanted to know if you replaced the opti or checked if the screws backed out and re tightened them, my opti is almost brand new so im guessing my screws backed out

95 GA/TA has not posted here in about 2 years (at least not by reviewing "show all posts by...."), so not likely he will respond.

Do you have the EXACT same problems - same codes included? Have you cleared the codes, and how quickly did they come back? Have you checked the two wiring harness connectors for the Opti? They will corrode, or possibly have damaged pins?

What brand is your "almost brand new" Opti? Where did you buy it? There is some real junk for sale out there.

[vipergtx500]

the opti was replaced by the previous owner so i have no idea what brand it was. The symptoms are the same, the stalling/misfiring after few minutes, and trouble starting in the first place, and the tachometer periodically not working. The codes it throws are as followed:
P1371 -Too few ignition reference pulses
P0372 -Timing Reference High Resolution Signal 'A' Too Few Pulses
P1641 - EVAP fuel tank pressure sensor circuit voltage high, or fan 1 relay control circuit, or MIL light circuit, or A/C compressor clutch relay circuit
P1642 - EVAP fuel tank pressure sensor circuit voltage high, or fan 1 relay control circuit, or MIL light circuit, or A/C compressor clutch relay circuit
I'm going to check the coil, but based on what you said to 95/TA about the tach, im assuming its the opti, either the previous owner didn't install the waterpump correctly and its leaking on the opti, or the screws holding on the rotor in the opti have backed out. Anymore input would be greatly appreciated as I would not want to go through the annoyance of replacing the opti if it was something much more simple.
Also, do you think it could be the coil? if it could be id rather spend 50 to replace that and rule it out before taking on the opti swap.

[vipergtx500]

i just replaced the coil, i tried starting the car but it sputtered and then a little smoke came out of the intake, i tried again, it started but died immediately, so i tried again and gave it a little gas when it did start, and white smoke came out of the intake, this time i had the K&N off so it came out of the MAF, i don't think i blew anything, the car was barely started when the white smoke came out the first time, and it never did this before, could it be the fuel built up in the cylinders from trying to start it and it ignited all at once? i need some kinda of answer, im going to drain the oil tomorrow and check for coolant in the oil to make sure i didn't blow a head gasket, but i seriously doubt it, it wasnt on enough to blow anything but why did this happen only after i installed the new coil?
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[Jeff_in_Atl]

A corroded connector where the OPTI plugs into the harness will give the same problems. I had a new OPTI put on my 95 and 6 months later it died again. When they pulled it apart they found the connector they had just replaced was corroded. They put another new one on it. I told them to put silicone dielectric grease on the connector this time and as far as I know it has been OK. (I sold the car)

[Injuneer]

You might also want to provide some basic info about your car like the year, the model, engine, tranny and any major mods. You appear to be using a generic code list. With the correct info about the car, its possible to access the GM online code listings.

[vipergtx500]

its a 1996 Firebird Formula, 6spd, K&N intake, Flowmaster exhaust. The car just had the fuel filter, ICM, crank position sensor, and coil replaced. I removed everything and got to the opti, took the cap off and the screws were fine, it was dry as well no moisture at all. The wiring harness that connected to the opti was RTV'd into the opti, because the previous owner must have broken the clip off when he replaced the opti a few months ago. The bottom of the connect had a piece broken off but the leads were still there. I thought this might be the reason so i went to the junkyard and took one off an old caprice with the LT1. (Dealer wanted 140!). I put everything back together and now it wont even start. I just checked the connections with a multimeter: 1.53 V from the battery,The wiring to the ICM is little different on the 96-97 models, so the colors don't match up right, but i figured it out. aroud 12V from pink wire (to ignition) on the harness going into the coil, and about 12V from the outer wires (to coil, i think) on the harness going into the ICM. I cranked it and check the other lead, It was jumping alot, but it was from 0 to 1.4, not 1-4 like shbox's website said it should be. And there is definitely a bad ground or short somewhere. When i open the door the interior lights and a few lights on the dash flicker and there is a clicking sound from somewhere. I tried jumping it and it still didn't start so i don't thing the battery is causing it to not start. It has gotten progressively worse, I couldn't even turn the key today it just kept doing it and eventually it stopped so i could crank it. For this reason i think im gonna take it to the dealer, if it were just the opti (i prob need this too), it would def not being doing all that nonsense.
Here's other threads that I posted on, incase it helps to understand all the stuff i went through:
LS1tech
NJFBOA