I took my LB9 (305) 1992 Z28 5 speed to the carwash. I was spraying down the motor with the engine running and it died. I figured I got something wet and the problem would go away, but it is not! I disconnected the TPS and reconnected it and it ran good for about 5 minutes. Any thoughts?


I don't have an OBD1, and it seems like nobody in town has one either. The check engine light comes and goes, the car bucks at low rpms. It's running rich.

Here is a link to a video of the problem
http://www.youtube.com/watch?v=dMW4fEWpxCE

 

You can check codes yourself with a paperclip: https://www.thirdgen.org/service-eng...ht-error-codes

If it ran fine before, you got something wet. Tried drying out the dist cap and rotor? Start it after dark and see if any plug wires are arcing anywhere. Maybe the pressure from the sprayer knocked off a connector for a sensor.

 

You probably got the IAC or TPS wet. I would not hose these motors down. Use some gunk and a get a small plastic pepsi bottle and fill it with water. Also, i would cover all the sensors i could with plasic grocery bags and tape them tight.LOL

 

Update

Finally some good weather. Pulled the cap off the distributor that was a first for me) and I took some pictures. Everything seemed pretty dry except the white part on the top either had grease or moisture. I'll let it dry out a bit. I'm thinking of plugging the hair dryer in on an extension cord..

Anyone have any thoughts from the pics?

 

You might have got the O2 sensor wet. There is a vent in the top. If you sprayed high pressure water in there, it will read incorrectly. If the engine is running, exhaust heat will dry it out. Or you can remove it and dry it out with a torch.

The problem is more likely ignition though. Usually the wires, but possibly the cap.

 

Thanks, I'll be back in a bit. Never again will I go crazy with the power washer at the car wash.

 

About right. Looks like I got my wires mixed up on the dizzy cap. I hope this is entertaining

 

Still going. Putting in some hours today. Back at square one.

It suppose it's one of three things.
TPS
MAFS
02 Sensor

Symptoms:
Won't hold idle, running extremely rich, runs pretty smooth if I hold it a 3K RPM. Have to keep foot on gas to keep it running.

Just went and played around with it a bit again. I left the ignition on for a minute and then started it. It ran way better (still not right), then eventually died. It was whining why it was dying. An old noise I heard when I first bought the car.

So frustrating....
Anyone, Bueller, Anyone??

 

Finally did the pin test. Last time I did it I screwed something up and had to send it to a shop. Knock on wood.

Reading code 45:
Oxygen sensor rich

Heading to Autozone. Could it be this easy?

Yeah I've been typing to myself a whole lot today. I think it helps me from losing it. BTW, 8PM tonight makes 27 hours awake after pulling a 12 hour shift. In the end, if I can cruise it tonight and do homework tomorrow, I don't give a damn.

 

How do you know that it is running rich? If i recall, a bad CTS may make it run rich. If your 02 says rich, I would think the ecm would compensate and make the car run lean.

 

Why don't you just unplug your MAF sensor and see if it runs any better. If it does , then the MAF sensor or one of its related components may be bad.

 

I second the MAF getting destroyed. Those are notoriously sensitive and most often won't throw a code.

 

Not sure if you got the problem fixed yet- I had a similar problem after spraying down my engine in the car wash. Ended up making a hairline crack in my distributor cap that I couldn't see. Tried replacing the cap during my troubleshooting and problem went away.

 

I can't be sure, it seems like I've been wrong a lot lately. However, the car is spitting out black junk and the tailpipes are blacker than usual. (I clean the tips regularly)
Shoot, I may be running lean. However, I couldn't get to the 02 sensor that night so I drove it to a cool dude I know in Hudson Oaks TX.

Didn't know I could do that. If the 02 sensor doesn't fix it that will be next up on the list. Thanks for the help thus far.

 

And that will be next up on the list if the MAF idea doesn't fix it. Thanks guys

 

Well the 02 sensor did not help at all. I was wondering though, does it have one or two. I had the one on the left side upstream replaced.

On to his shop, pull MAFS, followed by new cap, followed by running great or back to square one with the expensive shop.

 

Well, disconnecting the MAFS seemed to help a bit. It ran a little better. The original mechanic said it was running rich too. Hmmm, dropped of at another local shop. Need some odds and ends done anyway.

I will be posting the outcome and correct diagnosis of the problem when complete.

 

Update:
Alright. It's running good again. It was the TPS.


Thanks for the help guys!

 

good for you dude.

 

Great post!!! I've had similar problems in the past. Cool to find out the cause. So it was really just the TPS? How much do they cost?

 

I went through two TPSs on my 82 by washing the motor. I learned to wrap the TBs in plastic bags before cleaning the motor. Funny though, I wash and polish the motor in the IROC beasty regularly(show car) and have never replaced a sensor(sensors are supposed to be weather resistant). Go figure.

 

$81 Locally from Oriely. However, since I paid the repair shop to find the problem, I paid them for diagnostics and "installation" (two screws) to the tune of $200.