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So my wife and I headed over to our Monthly Corvette Club meeting and parked the Corvette out side. We were there for 2 hours ...came outside ready to leave. Normally I turn the key to the start position and the engine immediately starts. Tonight...as I turned the switch to start, the engine seemed to fire up...then quit. I tried 2~3 more times with the same result. I waited about a minute and tried again giving it throttle. It almost started so I repeated...this time it started...sputtered a bit and then ran. I revved it up a few times and it seemed to be fine. So we drove the 15 mile trip home with no issues except it seemed to have a stumble off idle like a bad accelerator pump in a carburetor. I drove it 100 for a short stretch on the highway and it ran great so no worries about it. I got home, pulled into the garage and shut it down....waited a few seconds and started right back up. I went inside ...waited about 20 minutes...came back out and it started the same crap that happened earlier in the parking lot. I ran the battery down trying to start it so I have the battery on charge now.
I have a check engine light on now when it does run so I know it's throwing a code. I have and OBD II plug under the dash but I know these cars use an OBD I system. How do I check the codes...what kind of reader do I need?
It starts to run when I engage the starter but it will not hit and continue running like it usually does. The Opti was changed 2 years ago by the previous owner so I don't think that's the problem.
With a freshly charged battery it cranked right up but idles very rough. I snapped the throttle...engine smoothed out and "Check engine soon" light came on. I manually operated the throttle under the hood and got that off idle stumble again. Car smells like it's running rich just a bit.
I'm going to leave the battery on trickle charge overnight and check again in the AM
I'm thinking CTS on the water pump but I don't want to just start chasing parts. Could a weak battery be causing this? Car has 71K miles on it and normally runs like a top.
Possibly a fuel injector stuck open, flooding the engine? You said it's fine when you rev it; could be way too rich at idle and causing the engine to stall. Any black smoke when it's idling?
Fuel pressure gauge could show the leaking injector (won't hold pressure after turning key off). If it's really stuck open, you might hear it with a mechanic's stethoscope (injector won't sound like the others).
Not sure if an OBDII code reader would work for a 94, even if it plugs in. I have one from Harbor Freight which works well on my 96. Other more experienced forum members can point you in the right direction.
OK....charged the battery overnight and it fired right up this morning...no problem. I let it warm up...no warning lights or codes. Drove it a bit and it still has that flat spot stumble off idle...it smoothed out a bit then gave me the "Service engine soon" light....so it's throwing a code from somewhere. I'm definitely getting a new battery though. I'll check with Auto Zone on renting a code reader.
As Dmaxx said, read the codes and stop trying to make the car heal itself. You might be causing harm to the motor each time you attempt to clear up the problem by driving the car.
OK...read the codes the "Old Fashioned" way with the paper clip reading the dash trick. Whole list of stuff in history. So I cleared everything and started it up and drove it around. Ran like crap for about 30 seconds....got the service engine light..then smoothed out and ran well. Drove about 10 miles ...came home and read the codes. Got home...turned it off and read codes. I got #36= Distributor Ignition High Pulse...#42 Ignition Control System Shorted and #62 Oil Temp Sensor Low Circuit Voltage.
But here's the mystery to me...the car runs great while it's up and running...no miss...no hesitation...with the ASR turned off it will light 'em up and bark the tires 1-2 shift....IOW...runs great. It's just this starting thing. I'm seriously thinking battery...Florida is hell on batteries and I have already replaced one in my 2016 Yukon that was 14 months old...this one is 2 years old.
OK...new battery. Still have hard start issue when warm but not as bad. Took it over for a quick look at from GM mechanic (N/C). He suspected Fuel Pressure Regulator but no leaking. Once this thing settles out after 30 seconds or so..."Service Engine" light comes on and it smooths out. If were carbed I would think I needed to adjust the primary float or change a Power Valve. Now everything in run by sensors and ECM. GM guy told me if it was the Opti it would miss fire all the time or maybe not even run. This thing will fly...hot as it has ever been. It's just this GD starting deal. I'm stumped. Oh Still throwing #36, 42, #44, #68 and 77.
Anybody have a clue what that opening connects too? I put a cap on it in the meanwhile.
That is a special hose. I had to get it from GM many years ago.
It has a special formed bend in it and the opening diameter at each of the ends are different.
You might find it in after market today, GM may or may not have it.
If you need a part number I may be able to dig one up if I still have the old bag.
That is a special hose. I had to get it from GM many years ago.
It has a special formed bend in it and the opening diameter at each of the ends are different.
You might find it in after market today, GM may or may not have it.
If you need a part number I may be able to dig one up if I still have the old bag.
That would be great if you can...thanks. Any Idea what it connects to? I can make one up temporarily if I know what it connects to.
So in fooling around with my issue I looked at the Opti very closely and took these pics.
I think this is what I have:https://documents.holley.com/83811.pdf
There is a vacuum line that exits the bottom of the distributor at about 6 o clock...snakes up thru and behind the alternator bracket. It continues beneath the driver's side Injector cover and has what appears to be a check valve inline on it's way to a connection on the rear of the intake manifold.
I'm thinking the screw at the top allows for timing adjustment.
Understanding this, does anyone on this forum have experience with this Opti? The vacuum line looks "Factory" to me. I have had one "Old School" Mechanic tell me that on the 1994 LT1 Corvettes the factory made a mid year change to use the vented Opti. He is going to take a look at my car Thursday.. My car left the factory in January 1994 so it may have had this revision.
UPDATE..2 days ago I put several ounces of Stabil along with 10 Gallons of 93 Octane gasoline. I drove the car a bit yesterday with no issues. Drove it again today...20 miles. Normal driving and ran out 1st and second WOT up to about 80...NO ISSUES !! No Codes !! I am still having it checked out tomorrow by a local knowledgeable performance tech.
OK...took the car to a very reputable and reliable performance tech here in Ocala, Fl. He read all the codes with engine running and this is where I am: After checking harness voltages to and from the Opti, Temp sensors, etc.....I need a good replacement PCM/ECM. He explained that Code 42 is usually always the PCM and when you eliminate Harness and Sensor Voltage and resistance issues....it all comes back to the ECM/PCM. So...I'm looking for this Service Number and Broadcast Number.
If you know of a source for this with any warranty...please let me know.
12-05-2018, 11:29 PM
Sudden Hard Start/ Won't Start issue '94 LT1
