I am really in a bind, I cleaned my 2003 C5 Corvette with carb/choke cleaner, and after the cleaning its performance has been terrible, Im not sure where to begin, or what to correct.

The car backfires, and the engine performance is incredibly rough.

I get a check engine light, but when I do the code check procedure all I see are the historical codes.

Im kind of stumped and not sure what to do.

 

Post all your codes......so we can decide if they are related or not.

 

I will post all the codes when I get home to my vehicle though all end in H, which makes me believe they are all old codes. Im using the hold down options button and press fuel four times method of getting the codes. Is there a better method?

Also when I look at the throttle plate at rest, it is slightly open/ not completely vertical/closed. Should the resting position be completely closed on the throttle plate?

 

I see that you are new to the forum, so I'll exercise patience here. Just because a code is historical, does not mean it is not relavant, and can also help corroborate and existing problem. So I always ask guys to post ALL codes.

http://www.c5forum.com/ayc/dtcdic.php

 

[QUOTE=That1guy;1577449405]I am really in a bind, I cleaned my 2003 C5 Corvette with carb/choke cleaner

WHY!!!!!

 

I agree with both and think I know where Lucky is going with this. If you used carb and choke cleaner and cleaned more then just the throttle body (did you clean the MAF with it also)? that could be causing your problems. By telling us all codes it will help point to what is wrong.

You did hook up the MAF and the 2 plugs that go into your throttle body when you were done cleaning correct?

Regardless of what it is....please next time....no carb or choke cleaner...those cleaners are designed for just that...carbureted cars. You don't have either a carb or choke on your corvette's fuel injection system. Use the proper safe MAF or Fuel Injector/Intake cleaner made for these cars, it will be listed on the label of the can.

 

I have checked the can, and it was throttle body cleaner, not carb / choke cleaner. Previously I had been having some issues with slight a gas smell, that seemed to come from a number of sources, first was from the gas cap, which wasnt quite sealing perfectly, I replaced it. In two days the smell came back it was worst when I would first start the car, and seemed to come from both behind me driving it, and from the engine compartment.

I did a smell test, followed my nose, and saw it coming from a spark plug area, I pulled off the plug cover, and I went to undo the plug to inspect it, and it was really loose, so I tightened it and the smell really seemed to go away.

A few days later the smell came back, it seemed to come from both behind me as the driver, with windows down, and the top open, and from the engine compartment, I did a smell test again, and it seemed almost barely inperciptibly to come from a fuel injector, it also seemed to come from behind me when seated in the car top down.

The idle was getting a little rough, and I noticed the gas pedal produced some inconsistant results, so I figured I'd just tighten all the spark plugs, I'd clean the throttle body, then I'd replace the fuel filter.

I cleaned the throttle body, and immediately I got some really bad almost failing when I turn the ignition (but thats standard for right after a clean) after a bout 2minutes that went a way so I went for a drive, I noticed it drove really rough and tended to kick, I figured I'd test it at various throttle positions and it was worst at full throttle.


Here are the codes a new one just came up,
P0300C Just came up

Had some previous issues, with mirror not working with its night settings, and a door window not coming up hence the historical codes.
2282H
2283H
2860H

I'm presently having a shop change the fuel filter for me. I guess Im working a number of issues.

 

@xtremeVette
My MAF seems to be inside my black wing, which I disconnected prior to the cleaning the throttle body.

 

Ok P0300C...missfire...that will help narrow stuff down....well maybe... Did you check and get this new code before or after your were playing with that loose spark plug? If it was after (and I believe it was) you are still getting a missfire somewhere. Check all your plugs and wires very carefully. The fact you had one loose has me questioning this first. This is where I think your problem is.

This sounds almost identical to your problem...check it out! Good thread!
http://forums.corvetteforum.com/c5-t...fuel-odor.html

How many miles are on the car?

Not saying it is this (I doubt it), but a lot of guys get this code from an over-revved engine that has thrown a valve spring as well.

 

I got the code after I tightened the spark plugs. Would a thrown valve spring cause it so that the throttle body isnt resting in its closed position?

or could a throttle body that isnt resting in its closed position cause a P0300.

 

You probably cracked a plug or plugs. Pull them and check.

If you can find someone with a code reader it should isolate the problem. Autozone should be able to help.

The stock system will only show a generic misfire which you have (P0300).

 

If your referring to the throttlebody being like 5% open, it is suppose to be that way. I asked the same question when I was porting mine. I was told, it is done that way on purpose. It will never fully close like a carb or the old corvette tuned port injection throttle bodies. So yeh we can rule that out.

Iam really leaning toward narrowing it down to what exactly is causing the missfire and what cylinder is doing it. You can always take it to autozone or a car part store and have them plug their scanner in to see if that last code digit pops up (P030X) narrowing it down to what cylinder (like the post I linked above described). This way you know if your having a single cylinder missfire or a multiple missfire?

Hopefully Lucky will chime in soon, he is good with narrowing this type of stuff down. I just try to approach it with a common sense type of trouble shooting attitude. As JW has mentioned...things are highly pointing toward your plugs or wires right now. Check also your injector harnasses/wires as well. You need to determine if your miss-firing due to spark or because of fuel. Don't let the smell push you one way or the other it can be very mis-leading.

Did you read the post that I linked you to? might also have a blown gasket or one on it's way out....many possibilities here...got to narrow it down more.

 

Tomorrow morning, I'll pull out my code reader, see what it shows. Cracked plug is certainly a possibility as I tightened some of them probably more than I should.

Im hoping the gas smell is a red herring, and changing the fuel filter should correct it. Im at 93K miles, I last had the fuel filter changed at 44K miles. Though my gas cap wasnt forming a perfect seal, and I suspect maybe that's contributing to the filter.

The sound isnt really so much a backfire as it sounds more like pop from my cats in the back, (Im guessing gas exploding in the back) which leads me back to the cracked plug theory.

The other gentlemen that had the fuel smell and the P0300 had a cracked header gasket, I think checking plugs, and changing the fuel filter are some good first steps.

I really appreciate the help this forum has given me, I've been reading it for a number of years, and today was the first day I registered.

 

No problem....we all on here are glad to help out.
When you have a second....fill out your profile so we know a name and location to where you are.

 

I had to get back to the office, I just picked my car from having the fuel filter changed to try and work on the gas smell.

The verdict, it's a 2003.5 hence no fuel filter. great... now Im wondering if 2003.5 are subject to the gas leak issues the 2004's are?

I realized that I tighented the plugs after I did the throttle body clean but before I started it up to test it the first time.

That made me realize that my hands were probably dirty, and I could have fouled up the ends of the plugs, sure enough I took a rag and wiped them down, and 4 of them had a bit of dirt and grease on them.

So now Im left with a slight gas smell, and slight exhaust smell/burnt carbon type smell (new), I still get an occasional pop from the rear exhaust but it's once every 3 minutes or so.

This leads me to believe I am still sending some gas out the rear exhaust pipes. Im not sure where the exhaust/burnt smell came from, it start on the way to the mechanic, and is till there even after I cleaned off the plugs?

Im scratching my head.

 

What is the condition of the plugs, color, etc? Did you inspect for cracks? Since you went to a shop, did you have them put a scanner on it, to isolate the misfire (which can also be isolated by the plug condition)? How old are the wires? Where is the fuel smell coming from..i.e. engine, rear of car, etc?

 

Anybody else know the mid year '03 didn't have a fuel filter? This dealer doesn't offer a blinker fluid changeout or anything does he?

Charlie

 

It does have a fuel filter........it's just in the tank.

 

EXACTLY! Someone is working on the dude's car that doesn't know the car has an in-tank filter. I really advise never taking your car back to this mechanic.

Charlie