Recently purchased my first vette '01 A4, after driving this car I hope to own a vette for the rest of my life.

Anyway I have noticed a slight miss during idle in park, not noticeable during acceleration...it is very slight. I checked the 3 clamps (tightened 2 of them on the air intake) thought maybe there was unmetered air. That did not fix it. So I turned on the AC just to see if that had any affect and it seemed to eliminate it for some reason. Has anyone experienced this problem?

Thinking about running a can of Seafoam through a tank of fuel maybe carbon buildup?

There are no codes and it has 19k miles on it. Any comments would be appreciated, this is a great site enjoy spending time here.

 

check plugs and ignition wires.

read codes.

 

Thx for the reply.....vettegirl!

There are no codes and the plug wires seem to all be tight, have not removed the plugs to check them. I figure if I do that I might as well change them, after 9 years they probably need it. Will do that soon, I am hoping the seafoam clears it up for now, used it on my '03 Silverado and it worked wonders on it.

 

Time for some Techron by Chevron. When the a/c is on it puts added load on the engine and will help stablize the idle. The less stable idle normally will improve after using Techron. There are other injector/fuel system cleaners, but Techron is the only one I know that is approved by GM. Techron will also help keep the Corvette's fuel gauge system to work properly.

 

Will get some Techron tomorrow then....THX!

Should I run 93 octane? There are no mods and I don't plan on any other than maybe an exhaust upgrade?

 

I run no less than 91 and will take 93 octane when I can get it. Not because I'm worried about knock, but because the higher grades normally include better fuel system cleaners. Lots of folks including myself have had fuel gauge problems. The higher grades keep it working properly.

 

I've always used Chevron Gas with Techron, have added the bottles of Techron, yet I was getting knock (can see on hptuners) to the point that my front knock sensor would kick in on high rpm/heavy load scenarios. The car would feel like it lost 40+hp until I cleared the knock sensor code.

I Seafoamed and got lots of smoke and also added an oil catch can... the knock went away mostly and the code never came back for about 5k miles... then it happened again.

I repeated the Seafoam treatment although much less smoke, and I would still get the code sometimes...


Then I decided to polish the entire engine so I took it apart and here's what I found inside a 68k mile LS6 that was Seafomed 100 miles before disassembly:




There was hard baked on carbon that only a wire brush could remove. The intake ports and valves were squeaky clean on the throats (due to the Seafoam and Techron), but the exhaust valves were just like the chambers and the throats needed very aggressive wire brushing to remove the carbon.

There is no way that Seafoam or anything else could have removed what I did physically. No way.

I don't have the engine back together yet, but I'm sure my carbon problem will be gone for quite some time.

 

For some of us older folks, it use to be GREAT fun cleaning up heads that used leaded fuels from the day. Even a wire brush wouldn't cut the stuff.

 

So you wire brushed the aluminum head? How does the mating surfaces look? Any scratches where the gasket is supposed to seal?

 

The wire wheel and drill were used only on the chambers with the valves still in the protect the valve seats. The valves were marked with a Sharpie for the cylinder number before removal.

The deck surface of the block, the gasket surface of the head, and the piston tops were all done with a razor blade and WD-40. Then I used a mild scrotchbrite pad and some WD-40 to clean any little discoloration the razor couldn't get. It took me almost a day to complete the block/piston work I took so much time. It's okay, I got to drink plenty of beer.

The exhaust valve throats were treated to a benchgrinder with a wire wheel, while carefully staying away from the valve seat area and the shank/stem. Everything cleaned, oiled, and bagged for future use.

Also, the coolant passages were stuffed with rags before scraping and the head bolt holes were cleaned/tapped.

The whole thing was approached as a "mini-operation" for a family member.


Beer bottle carefully placed for the photo-op. Heavy carbon buildup on piston tops.

Finished shortblock.


Both banks taped off afterwards to shield from dust of sanding/polishing the part of the block that shows. The valley cover and timing cover was later removed for sanding/polishing and cam swap


Bling! (timing cover not done in this pic, now has billit pulley)



With this going on top

 

Man, I found out what was in store after I took it apart. I've never had an old timer clue me in about carbon scraping until after it was done and I started chatting about it.

Turns out that "cleaning the carbon" was a common thing in the past. It seems that all the young'ns (like me) have been spoiled this whole time with electronic fuel injection and unleaded fuel.... but in the end, the carbon still grows... just at a slower rate.

Perhaps the fact that I have an '01 with it's low tension piston rings that has something to due with me getting this issue at only 55-65k miles.

 

I did a heads/cam swap this spring. While I was in there I switched to the LS6 style valley cover PCV and installed a catch can. I'm hoping to slow the rate of carbon build up on my new heads. I'm not sure if this is typical or not (after about 18k miles):

And of course, nice polish job Joshua- as usual.

 

9 year old plugs should be replaced.

besides reading codes in the DIC i recommend a gm code reader be used.

 

My cousin owns a GM Dealership and I do plan on taking it to there service dept. soon, definitely if I can't get it cured with the Techron and plug change. Will update as the trial and error process develops.

 

Why would you recommend this? What code reader are you speaking about?

 

ALWAYS run 93 octane if it is available. Or 91 if that is the highest octane you have,

Never run 87.

 

Looks reall nice!

 

Auto Zone currently has Techron buy one get one free.. Make sure you get Techron Plus

 

OK, I bought the Techron Plus ($7.99 @ Advanced Auto) Auto Zone 1 mi further my luck I guess. Anyway on the bottle it states to mix with 12 gallons of fuel, should I mix with say 6 or 10 gallons for a stronger solution?

 

You can mix it a little stronger. But I wouldn't expect results from one bottle. You should use a bottle in the next several tanks to truly clean the injectors. Techron won't cure combustion chamber carbon though. Just mild intake runner and intake valve cleaning.

Like I said earlier... I faithfully used Chevron, always added bottles of Techron at double strength, added a catch can, sucked Seafoam into the running engine through the pcv inlet on the manifold and had plumes of smoke. And look at the pictures of the carbon buildup.

True carbon issues are described below.

Does your car ping slightly (or heavily) under hard acceleration? If you can hear it audibly and you are using premium gas... that means the fuel is pre-igniting from a combination of higher compression from the carbon buildup taking up space in the chambers and potential temperature hotspots at the tip of a mini carbon spike. (I found some in mine) If so, then you should find a person with hptuners who can ride along with their laptop and see the spark knock occuring. If that's the case I would highly recommend physical removal of the carbon. It would be a good time to upgrade your cylinder heads and add a hotter camshaft.

The fact that you have a slight stumble at idle or very slow speed I wouldn't say that's from carbon. I'd say it's a weak ignition system from plugs or wires and/or fueling issues most notably a fuel injector (or more) being partially clogged. If you want the best for injector cleaning I would recommend Lucas injector cleaner. I've had great success using it for a motorcycle that had injector clogging from stale gas.

Just like Techron, the key is to cycle through several tanks to lessen the issue. And at that point you should still periodicly invest in a bottle or two for maintenance.

Hope this helps...