Help! First Corvette - 1994 Admiral Blue LT1 - Error Code Issue

[SnakeDr]

Failed Emissions at NJ DMV

Of course I didn't expect to pass. However I was approaching my 14 day window after registering my Vette. Tonight or tomorrow I will change out the injectors, filter and plugs.

I'm wondering if I should do cap and rotor and wires. Guess I will know when I fire her up again.

Emissions
Primary Emissions Test Performed: TSI - Fail
Mode:
Gas	Reading	Standard
HC ppm	347	220
CO%	4.5	1.2
CO2%	11.9
2%	0.6
Mode:	HIGH IDLE - FAIL
GAS	Reading	Standard
HC ppm	120	220
CO%	3.13	1.2
C02%	13.1
2%	0.1

 

[2VettesMike]

Ran a test on each injector

Driver side front to back (left to right)
(12.6 ohm/10.64v 12.5 ohm/10.62v) (12.4 ohm/10.83v 12.6 ohm/10.6v)

Passenger rear to back (left to right)
(10.7v/12.6 ohm 10.7v/12.6 ohm) (10.7v/12.6 ohm 10.7/12.8 ohm) Bold face is the one with worn electrode.

I would be more concerned with the lower voltage on the passenger side injectors. Two volts lower voltage is a lot. May be a loose ground on that side which would drop some of the voltage feeding the injectors. Lower voltage would make the injectors sluggish to operate, i.e. not as good a shot of fuel...

Thanks,

Mike

 

[John Robinson]

So the car has sat for a couple of years which means in the area it was in there would be moisture or condensation in the gas. You don't say how far you have driven it. If you have not put many miles on it since you bought it you still have bad gas even if you put fresh in with the old. That would partially explain the knock problem. And of course if this is the case you will not pass an emission test just because of the fuel. My suggestion is that after you put in the new injectors and filter go drive the car for at least 500 miles to work all the old gas out and start with fresh. I would think you might then be able to pass the emission test.

 

[SnakeDr]

So the car has sat for a couple of years which means in the area it was in there would be moisture or condensation in the gas. You don't say how far you have driven it. If you have not put many miles on it since you bought it you still have bad gas even if you put fresh in with the old. That would partially explain the knock problem. And of course if this is the case you will not pass an emission test just because of the fuel. My suggestion is that after you put in the new injectors and filter go drive the car for at least 500 miles to work all the old gas out and start with fresh. I would think you might then be able to pass the emission test.

Believe it or not....I put 800 plus miles on the car in the first two weeks full time back on the road. I've added sea foam two or three times to the tank.

 

[SnakeDr]

I would be more concerned with the lower voltage on the passenger side injectors. Two volts lower voltage is a lot. May be a loose ground on that side which would drop some of the voltage feeding the injectors. Lower voltage would make the injectors sluggish to operate, i.e. not as good a shot of fuel...

Thanks,

Mike

At the time of the test, my battery was putting out 11.5v. It's a brand new AC Delco battery. You guys reminded me about cleaning the grounds. This is something I remember from my dad that will make a car run bad on pre-EFI cars.

However I was trying to trace the ground wire from the battery and it is burried. When I get the car up in the air tonight I will search and clean grounds. Other than the main battery...just look all over the engine bay? Thanks...

 

[John Robinson]

Hope this helps

 

[SnakeDr]

View attachment 9855Hope this helps

John - Just bought the full service manual for a 1994 corvette. Should be here in a couple of days. Thanks for your help.

 

[LT4man]

Believe it or not....I put 800 plus miles on the car in the first two weeks full time back on the road. I've added sea foam two or three times to the tank.

I do believe you!

What you are discovering is a mechanical issue which does not have a simple "clean" solution.

On the subject of grounds, the ones at the left (driver's) side upper bellhousing bolt are subject to corrosion AND breaking. There are several grouped together at that junction. Good idea to dismantle, clean and reinstall.

 

[SnakeDr]

I do believe you!

What you are discovering is a mechanical issue which does not have a simple "clean" solution.

On the subject of grounds, the ones at the left (driver's) side upper bellhousing bolt are subject to corrosion AND breaking. There are several grouped together at that junction. Good idea to dismantle, clean and reinstall.

I'm about to jack her up. She is cooling down now.

 

[SnakeDr]

I'm about to jack her up. She is cooling down now.

I dismantled and cleaned the bell housing grounds. They were a little oily if anything. Slightly,...I say slightly loose was the nut ...the wiring looks okay but its in tight location. I'm not working with a lift. I cleaned them up best I can and tightened the nut.

Comparing the voltage out of the battery vs. the injectors and other access points, I don't see that big of an issue. Did see a slightly better voltage after cleaning that ground.

Do you need to drop the exhaust to get full access to the wiring?

I'll be back. Going to crawl around the car...Cleaned the two horn and bell housing ground (on the bell housing side) so far.

 

[Hib Halverson]

Sea Foam is unlikely to fix the problem.

First is to troubleshoot the KS system per the FSM. It might be the KS itself but it might also be wiring and connections.

As for lean exhaust on the right side, in addition to checking for an injector problem, have you check/tested to see if there is a vacuum leak somewhere?

If the fuel filter was restricted or plugged I would think you would have lean exhaust on both sides.

 

[John Robinson]

I am in the process of cleaning all my grounds. Don't forget the two behind the battery. I removed the battery and the battery box. Then I was able to use a 1/4 drive socket with 3 long extensions and reach down from the top and removed the bolts on each one of these. Used an air grinder with a small wire wheel to clean the connectors on the wires and the frame.

The reason for doing all this is because I blew a radiator hose and sprayed the whole engine compartment down with anti freeze. I now have a tachometer that jumps around so I am cleaning all the grounds (they all so far have been corroded)to see if the tach will straighten itself out. I may also make the car run better.

 

[SnakeDr]

My biggest issue right now is the heat more than anything else. My house faces south east and is taking the heat head on. It's been a heat wave since I brought this car home. Tomorrow is going to be hot also. I'm beat tired.



I was trying to change that one bad plug and was cussin....Sweat running down my face but trying to patient trying to start the threads.

Talking to myself..."SnAkeDR...you should have just went out and bought a three or four year old C6"

 

[SnakeDr]

What I did Saturday:

• Installed a set of FIC injectors.
• Installed OEM Gas Filter
• Installed set of OEM AC Delco Plugs (this went pretty quick after a good night sleep)
• Installed OEM AC Delco plug wires on passenger side only.

Car does appear to drive much better. Engine is not as noisy.

However, there are some old vacuum lines that need to be replaced also. I noticed a rubber hose on the passenger side under the MAP sensor. It was connected to another electrical device.

I didn't have a chance to clear the check engine code today. My question is will it clear itself or do I have to manually have to clear it?

FSM manual is on the way.

P.S I did see one more ground. It was right above the water pump. That's my next ground to clean.

 

[LT4man]

You can clear the codes with a scan tool.

OR

50 ignition on/off cycles should clear any codes.

 

[SnakeDr]

You can clear the codes with a scan tool.

OR

50 ignition on/off cycles should clear any codes.

Looks like DTC 64 has cleared using the procedure below and I rechecked it after driving it for 30 miles. What hasn't cleared is DTC 43. When shorting out pins 4 and 12, and trying to clear it...I'm still getting error code 43. I will have to troubleshoot that one with a ohm meter using the procedure in the beginning of this thread.

Another issue with this car is the radiator cooling fan runs all the time.

I also corrected four vacuum lines.

• Two connected to exhaust manifold on the passenger side. One looks like its PVC and the other connects to a sensor.
• Another appears to belong to the cruise control.
• Another attached on top right behind the MAF and should be connected to a EGR line below the ASR unit??

I do feel a slight stumbling at low speed. Check engine light is still on of course.

• DTC 43 - Knock Sensor (KS) Circuit
• DTC 64 - Bank 2 (Right Front) Heated Oxygen Sensor (HO2S) #1 Circuit (Lean Exhaust Indicated)

Press the TRIP RESET button until “1.0″ is displayed in the module number area. Then press the TRIP/ODO button until “1.7″ is displayed in the module number area. Once there, press and hold the ENG/MET button until “—“is displayed. This will clear any CCM codes. After “—“ is displayed, turn the key off, wait ten seconds, turn the key back on and check for any CCM codes.

 

[SnakeDr]

No more check engine light

In most cases the sensors are good it's the wiring and grounds that have gone bad. Until you eliminated bad grounds and wires as the problem stop throwing parts at it. I am sending copies of the DTC code sheets from 93 FSM. Hope they help you to find the problem. Before you buy any more parts go to ebay and buy a 2 volume FSM set for your car.

View attachment 9813View attachment 9814View attachment 9815View attachment 9816View attachment 9817View attachment 9818View attachment 9819

Thanks Jon, LT4man and everyone else on this thread.

I found my last error code problem. Turns out I had about a inch of bare wire on the KS that was grounding out on the heat shield. Everything else appeared to be okay. Sensor itself checked out. I put some electrical tape on it and used a wire tie pull wires away from the passenger exhaust.

Cleared the code. Powered her up ... and no more check engine light.

Took her for a test ride, and the power appears to be back. Not to mention the new plugs and injectors helps a lot.

It's a BEAST again.

The final test will be passing NJ DMV inspection.,
Thanks again, Jon...followed your FSM notes.

Thanks FIC.

 

[LT4man]

You are very welcome!

Nice to hear about a happy ending to a C4 running issue.

Let us know when your Vette passes the emission test.

While driving your Vette with its new found power, please be sure to SAVE the WAVE!

 

[Hib Halverson]

Just wanted to follow up on the problems covered in this thread. If I read the final few posts correctly, the DTC64 was caused by vacuum leak(s) and the 43 was caused by a KS wire shorting to ground.

Is this correct?

If so, did the car pass the New Jersey "smog check"?

 

[SnakeDr]

Just wanted to follow up on the problems covered in this thread. If I read the final few posts correctly, the DTC64 was caused by vacuum leak(s) and the 43 was caused by a KS wire shorting to ground.

Is this correct?

If so, did the car pass the New Jersey "smog check"?

• DTC64 was cleared by injectors, plugs and/or wires. DTS64, means the engine was running lean on one side.
• HH43 was caused by the KS wire shorting out.

I fixed two vacuum leaks after clearing DTC64. In reality, you make one change and test and keep repeating until the issues are resolved. However, there were so many little issues I made two or changes at a same time.

I'm taking it to NJ DMV on the way to work. Let you all know in a few.