Hello all thanks in advance for reading this.
I havent been able to find a Helms manual yet and didn't find anything my year in a search. Can someone tell me what this code is and what it means. A little background I havent had the time to diagnose it futher. I have a 94 and sometimes have a issue where it cranks for a bit(sometimes one to two seconds sometimes six seconds) before it starts. Other than that it seems to have a very slight miss that seems to go away under hard acceleration. So I got the chance to pull codes this is the first time I have pulled codes on this car and it didn't react as I have read it should. I put the pin in 4 and 12 turn the key on, but dont start and I get
C12
1
1 ---
4 H32
4 ---
9 ---
A. ---
1.0

Just as typed
nothing displayed more than once and once it got to 1.0 it stayed there I let it set as is for 30 seconds or more waiting for it to flash c12 and nothing. It did not flash. Any thoughts?

 

H32 is an EGR history code, not current. Are you running a stock exhaust system?

 

yes it is completely stock with the exception on iridium plugs

 

I have the same exact problem with my 95. I have the same codes too, I have a few more though. C12 is just telling you the test is being performed and module 1 is "okay." If your battery and starter seem to trying to crank the car really well I have to think you have the same problem. Couple questions, does the car sometime backfire a little or seem to stop cranking for a moment? Do the plugs and wires look to be in good shape? If so, I think it has to be the distributor and or the opti on my car. I think that the car is sending spark to the wrong cylinder at the wrong time during start. Usually, under normal operations it runs great. Sometimes when I bog the car down it backfires too. I'll be interested to see what other people comment.

 

hello John. The battery and starter are cranking away and do not slow down at all. it has never backfired. if yours is stoping for a moment during cranking and back firing then I would bet you are right about your cars issue being the opti. mine seems to run very well once it starts.

 

thanks for the replys!!

 

I am thinking this might be a fuel pressure problem I havent had a chance to check, but thinking the pump may not be kicking on or building pressure quick enough. I have tried turning the key on and giving the pump a few seconds to build pressure and it didn't seem to help

 

I'd guess a fuel pressure issue. Had a buddy with a similar issue. Have you changed the fuel filter lately? An old partially clogged filter will make the pump work harder and burn it out faster too. I have a fuel pressure gauge down in Jenks I'd be willing to loan you but I won't be back in town until Friday. If you're still hunting then let me know!

 

I'm thinking fuel but not a pressure problem, but a too rich problem. The reverse of what you're thinking. This would be caused by the FPR (fuel pressure regulator) leaking back directly in to the manifold. Pull off the vacuum line from the FPR and see if there is fuel in it. If it's wet that's your problem.

I once put the vacuum line in a cup and it filled in an hour.

Over night the fuel bleeds back into the engine and causes a long crank time in the morning. This is a common problem and easy to check before going any further. Of course if it all looks good problem is elsewhere.

 

dclafleur I doubt I will be able to sort this out by then so as long as you don’t mind I will take you up on your generous offer thank you! PM inbound.

I have a new filter in the garage going to wait till I burn some more gas out of the tank to install it. I changed the plugs out to iridium about 100 miles ago and the plugs looked pretty clean showed no signs of being too lean or rich. Also this issue has occurred after shutting the engine down for less than thirty minutes.
Pcolt94 I will check that hose this evening and post up what I find.
Thank you for your suggestions.

Another question though. Is the way I described, the way the computer is supposed to act? I was under the impression that it would flash each code 3 times and then flash C12 three times when it was done.

 

The earlier GM cars did work that way when it only used the SEL light to flash to get the codes.
The 94 uses the digital speedometer as the readout. It displays the codes by module number. 1 is the CCM, 4 is the PCM (the codes that most people refer to and relates mainly the engine), and 9 which is the EBTCM (the brake system and brake computer). I'm not exactly sure when the speedometer took the place of the light in the corvette but it might be that 92 was the first.

The on board diagnostics reads out all the codes. Scanners usually only read module 4, the PCM codes. There are more modules and code sets that deal with the SIR system but usually not spoken of almost ever. If you get the FSM Helms manual for the car it will explain all of this. The manual will not fix your car every time but it is a great asset and explains how a lot of the systems work and interface.

The SEL or check engine light will tell you if there is a code set in mod 4, the PCM. There is an SYS error that the speedometer will flash that indicates there is a code in module 1, the CCM. Best thing to do is to clear it and see if a valid code returns. A "H" is an historic code or old (past) code.

When you connect pins 4 and 12 it will automatically run once and check for all the codes. You have to recycle the key to see all the codes again. But there is a procedure to operate in a manual mode going module to module and looking at each test in that module or error. The on board stuff can do a lot more but it's all in the FSM book. There is piles of information.

 

thank you for the info!!

 

Pcolt94 the Vac line to the pressure regulator was dry and I saw no signs of gas leakage. the line was original so i replaced it and a few other old cracked lines off the manifold but non apeared to be very bad or leaking. I havent had a chance to take it out to see if that helped but Im not thinking it did.

 

Hmm, there seems to be an epidemic of this around here. I wonder if we all live in e10 gas areas?

My trouble began complete with spitting, coughing and backfire on occasion after sitting awhile. This also in colder temps.

My fuel pressure was good, and stayed good. I did replace the PCV and the leaking attatched hose. I replaced the leaking FPR. I replaced the 2 year old plugs. No more backfire, but it still wants to long crank.

Now, if I "bump" it for a second. Then start it, it fires right up. My brother, a veteran GM tech mentioned the possibility of a failing crank position sensor.

But check your fuel pressure first as you could have a bad fuel pump or clogged filter.

 

No crank sensor in the 94. The crank sensor is on the 96 with OBD2.

You might check that there is spark right away when the engine starts to crank.

 

pcolt94

I am hoping I will have time this weekend to check that. I have driven it a few times since my last post and it has not had an issue I killed and restarted three times while out and no issues.

 

Thanks for the responses guys!