2002 Chevy Corvette Z06 DIY Fix Part 3: Puttin' Her Back Together

Just a thought could the pinging also be a timing problem?

Can you post a video of the engine noise? I'm curious to hear what detonation sounds like, and I don't really have an engine I can mess around with.

There's nothing I hate more than spending several hours on a repair that doesn't fix the problem.
Grrrr...

+1 on hybris

How many miles on the beast? Well, it was probably driven pretty hard, so maybe one of them long pushrods are outta whack!

Did you at least clean the throttle body?

^ LOL

How about doing a full tune up. You never know what the prev. owner did...put in the wrong plug, changed out coils, etc.

JP

I wish you would just take it to a shop that specializes in Vettes. I know there's one somewhere around you.

I hate to say it since it is a done deal now but you should have bought a Supra, NSX or an S2000. Just saying. Good Luck with fixing it. I do want to see how it runs when in good shape and your impressions of a car.

Don't take it to the shop - I really dig this kind of thing. Next time take way more pictures and really explain everything that happened - each part coming off, what it does, how it differs from other engine parts, etc.

The suspension walk arounds are great. This could even be better but it will take more effort.

How did this detonation run by you in the test drive before you bought the car?

Did you guys try some seafoam/techron etc etc? Have you ruled out carbon buildup in the cylinders from a 'gentle' previous owner?

time to get this thing to a Corvette-specialized shop...

Rat poop would seem to indicate that said vermin likely had a little snack on some wires on the way to the bathroom. This may prove extremely hard to locate, as you do not know which direction the rat took on the way to the bathroom at the intake manifold.

Crap. I hate it when that happens.

+1 on brooksbell. I really like the suspension walk-arounds, too. More of this hands-on sort of thing would be great.

Props to you guys for taking this on. As far as what to do next? I have to admit that if it was me, I'd be heading for a specialist shop. Of course, that would mean saving some dough up first, because if I'm going to the speed shop I might as well get some performance mods done too, right?

However, since it's not me; I say pull 'er back into the garage; because I love seeing the photos and reading the story.

That stinks all that work and it still does not run right. I think a full tear down may be in order. Vettes tend to be abused .

Still no word how this detonation was missed on the pre-buy inspection. I suppose one was not done...

You could do the old-timer's trick of SLOWLY pouring water into the intake while revving the motor. I've never been brave enough to do it, but many people claim it does an excellent job of removing carbon deposits from the combustion chamber.

that's too bad. i also have to give you guys props for doing it, very interesting, and at least it is checked off the list.

So, how many days were their backs sore after all that futile leaning over the fenders?

Since you found evidence of rodent activity in the engine compartment, I'm willing to bet you the knocking problem is rodent damage, probably a gnawed wire somewhere. Also, check that air cleaner and related plumbing. That throttle body definitely shows evidence of dust and dirt on it, and that shouldn't be unless there was a hole in the air filter, or somewhere downstream of the filter.

+2 brooksbell

Sorry the effort didn't fixed the problem... but a lot of people learned from your experience, write-up, and photos. Keep them coming.

I would also like to hear what the noise sounds like... please record and post if possible.

Thanks!

+3 brooksbell, I'd love to hear the nitty-gritty about the engine components that you're dealing with. Just don't take it to a shop, it would be really cool (and informative) if y'all would DIY this car as much as possible!

Sorry the fix didn't work.

Well, at least you guys narrowed it down... I would have probably had a big ol' meltdown myself, simply because this car is "new" to you guys. Didn't you guys test drive and notice the det. before you made the purchase?

I doubt if it is carbon or dirt of some kind....it has too few miles and several full throttle runs will usually clean out any combustion chamber carbon. It must be the ecu unit.....I also doubt it was a chewed wire....most of the time the car would just not run. Some how the timing is not being adjusted correctly....maybe a ecu flash or could be just a bad one....or maybe the previous owner put an after market chip in it and it needs 93 octane+. Good luck......oh and I will also ask the quetion....WHO TEST DROVE THE CAR BEFORE YOU GUYS BOUGHT IT?

to those asking how ping didn't get noticed before,

PO could have put 100 octane gasoline in before selling, that's why they didn't notice the ping.

I'm still not 100% certain what you guys are hearing/feeling is actually detonation.

When you get the tuner software hooked up to the ECU and scan, if it's detonation you will be able to tell for certain. The knock sensors will display it and you can get record a video clip and post the video up here for all to see. I'd be happy to take an all expenses paid trip out to Cali so I can hook my HPTuners up to your Vette to see what is going on. Ah, the things I'd do to help out complete strangers. ;-)

Who is to say that the ECU was actually stock when they bought it? Once a tuner or someone takes a look to see if the Timing curves are stock, (yes, there are two of them) or not, they may take a degree or 3 of timing off, the detonation issue may be solved.

This is a great place to go ask about any tuning issues....good 'ol LS1tech!
http://www.ls1tech.com/forums/pcm-diagnostics-tuning-7/

I could never attempt what you guys are doing, but I love reading about it.

Starting with the knock sensor seems the wrong way to go about fixing a knocking problem. Find and address the root cause. I'd do plugs and wires and inspect the timing belt.

I'll second nuieve.

Higher octane gas removes the noise, so that eliminates many possibilities.

Newer plugs of the proper type and proper gap could be worth a try ... dirty / non-optimal plugs might fire better with the higher octane dinojuice.

Any signs of PO tempering with the ECU are also worth looking into.

I suggested that it may have been tuned from the day they first mentioned the problem. Taking it to a tuner or hooking up the software themselves is the way to go. BTW: there's no timing belt on a GenIII V8 and if there was something wrong with one you'd be looking at way bigger trouble than some pinging.

OK, not sure why Edmunds hasn't talked about the C5 forums take on knocking, but here goes:

"I just found out that little bucket that was holding my pcv valve was worn and was letting some vacuum leak issues occur at light part throttle. I redesigned the pcv system and eliminated the bucket..No more ping. First thing I suggest is replace the 6 dollar pcv valve from the dealer. (updated part thats not in part store) Try that first. IMO"

"Could be carbon build up in the cylinder heads. Do you do alot of stop and go driving rarely get on it leave it idle for long periods? I would try the decarbonization"

"Finally - no more ping......this is what fixed it. Besides replacing the rear knock sensor & connector, and a full decarb (twice), the technician at the dealer put the GM2 on the car and we drove. Everything looked perfectly normal. So he took the car in the shop, went into his GM site, (this is basically what he said) plugged in my VIN and searched for Spark Knock. Lo and behold, there was a fix for the computer. The fix covers spark knock, erratic fuel guage, and some other code. He said it wasn't a full "bulletin" but was listed anyway. The car runs perfect. No ping, no bogging down, no "stuck in 4th unless I really hit it". I'm done."

" bodyblue says:

07:51 AM, 02/17/10

"It must be the ecu unit..."

Damned good thing you're not a mechanic. The ECU is almost never the culprit in a pinging situation. In fact, ECU failure rates on a modern vehicle are next to nil. I never even heard of an ECU failing in a C5 Corvette. I'm sure it's happened, but it would be an extremely rare event, and I'm sure the symptom wasn't pinging. More like the engine quitting.

"..I also doubt it was a chewed wire....most of the time the car would just not run. "

Damned good thing you're not an electrician or an electronic repairman either. Damaged wires frequently cause intermittent problems, or problems that affect the running quality but not disabling the engine. Rodent damaged wires cause many engine problems, but the engine still runs.

"Some how the timing is not being adjusted correctly..."

Yes, like a sensor not providing the correct reading to the ECU would result in incorrect timing and pinging. An ECU receiving flawed data will behave the same as a faulty ECU. An ECU is only as good as the data it is receiving from the sensors it relies on.

"maybe a ecu flash or could be just a bad one....or maybe the previous owner put an after market chip in it and it needs 93 octane+."

Chip? You don't "chip" a C5 Corvette. The ECU has programmable flash memory in it, and it has to be programmed with a computer attached to it. The "chip" method went out with the C4 Corvette, and OBD-I systems.

Why are you posting about something you clearly know nothing about? If you don't have anything intelligent to say, don't say it at all. We need knowledge, experience, and facts. Not guesses.

""It must be the ecu unit..."

Damned good thing you're not a mechanic. The ECU is almost never the culprit in a pinging situation. In fact, ECU failure rates on a modern vehicle are next to nil. I never even heard of an ECU failing in a C5 Corvette. I'm sure it's happened, but it would be an extremely rare event, and I'm sure the symptom wasn't pinging. More like the engine quitting.

"..I also doubt it was a chewed wire....most of the time the car would just not run. "

Damned good thing you're not an electrician or an electronic repairman either. Damaged wires frequently cause intermittent problems, or problems that affect the running quality but not disabling the engine. Rodent damaged wires cause many engine problems, but the engine still runs.

"Some how the timing is not being adjusted correctly..."

Yes, like a sensor not providing the correct reading to the ECU would result in incorrect timing and pinging. An ECU receiving flawed data will behave the same as a faulty ECU. An ECU is only as good as the data it is receiving from the sensors it relies on.

"maybe a ecu flash or could be just a bad one....or maybe the previous owner put an after market chip in it and it needs 93 octane+."

Chip? You don't "chip" a C5 Corvette. The ECU has programmable flash memory in it, and it has to be programmed with a computer attached to it. The "chip" method went out with the C4 Corvette, and OBD-I systems.

Why are you posting about something you clearly know nothing about? If you don't have anything intelligent to say, don't say it at all. We need knowledge, experience, and facts. Not guesses."

Wow, here comes the hate from that world renowned auto expert..

Can you please post the failure rates of modern ecu, please? Since your are going to be a complete creep in this thread I will match you word for word there Stinkray.

Please post any study of rodent chewed wires as it relates to starting and running problems. I said if it was a chewed wire and I meant chewed through....god you are a vindictive moron..... AND if the wire is chewed through, that would usually cause a COMPLETE failure of that circuit, resulting in (most likely) a much larger problem than just a lite knocking at full throttle. (even if the knock sensor wiring failed it would cause more than just light knocking...and probably a check engine light as well since any short or failure in that circuit causes other voltage problems)...do you really want to talk about this or are you one of those guys that really dont get dirty and just have other people to do your bolt on work so you can have your track days and drink Martinis after word while trying to cover up your bald spot in the bar?

"Chip? You don't "chip" a C5 Corvette. The ECU has programmable flash memory in it, and it has to be programmed with a computer attached to it. The "chip" method went out with the C4 Corvette, and OBD-I systems. "

You are almost as obtuse as your GM shill-mate 1487, I said it might be a ecu flash....and when I meant "chip" I should have meant flash memory update...when you have been around cars as long as I have I sometimes slip back into old speak. The first college class I took was in OBD1.....Fords EEC IV was the first system I really had fun with (My 84 Capri RS Turbo). So kiss my waste-gate and get over yourself.

And you notice that my suggestions are about the same as the others on here....so are you going to make yourself look stupid and attack them also or just come after me because I dont think your Vette or your CTS-V or any of the other cars you claim to own are that great? Oh and while we are on the subject of not that great cars, any Rat-motored Vettes are the worst Vettes of all. If you wanted a understeering, overheating pig that could only produce nice burn-outs then I guess that is the Vette for you Any real classic Vette lover that knows anything realizes that small block vettes are the way to go. Since my family had a 71, 73, and a 79 I think I can speak to this.

"We need knowledge, experience, and facts. Not guesses."

Who is "we", Mr Goodwrench? Cant be my brother the Master Chevrolet Tech...who I called and asked about this problem. (remember he is the one who drives Toyotas and Fords).....is "we" you and your fellow GM excuse maker friend on here? Now if you want to start some flaming you can see I am more than willing to make you happy. Or if you just want to post suggestions on an interesting thread that would be better......either way, it is up to you.

^bodyblue

I'm sorry dude, but stingray is dead on in his interpretation of your post, a little harsh perhaps, but correct none-the-less. I base this on owning 3 straight LSX vehicles (00 TA WS6, 05 Vette C6 and 09 CTS-V) which I have substantially taken apart and modified myself, tuning included.

Also, I can vouch for stingray's car collection, the dude and his cars are legit.

Also, the 71 Vette is nice car, but in 1973 the engines got choked big time (including a 454 making only 275 hp). The 79' was a complete turd power-wise as well.

Can we please stop the juvenile name calling and b.s.? I participate in these blogs to post and receive intellegent comments about the topics at hand. It's one thing to maybe question the validity of a post, but this is getting a little old. It's always bodyblue ripping on everyone and talking sh*t. Grow up a bit, ok?

Seafoam it . Give it a tune-up. See if you can find someone to do a bore-scope analysis, it may just need a de-carbon.

to bodyblue-

Get over yourself, you ain't that smart.

"Also, the 71 Vette is nice car, but in 1973 the engines got choked big time (including a 454 making only 275 hp). The 79' was a complete turd power-wise as well."

They were all nice cars.....untill they all fell apart one piece at a time. The '79 almost killed my uncle when the cruise control came on by itself and almost put him through the garage.....the speedo cable broke 4 times in two years. It was slow until the headers, 300hp cam and assorted other things made it quick.....it had the 3.56 gears and gymkana suspension so it handled nice and rode like a truck. And um, dude, (do you really say dude?) stingray is not dead on.......I was incorrect to say "chip" and it is probably not the ecu but then we wont know for sure what it is until it is fixed. I get to speculate as much as anybody else, and he has a chip on his shoulder for me because I said something mean about his Caddy once so he attacked and was attacked in turn. He is desperate to defend what he drives because evidently his cars are a huge part of his self image....so if you insult his ride you insult him. He probably is legit but has serious problems if a car can make him so defensive and angry.

Audi....I did get a little hot but since 454 was obviously being nasty first I did feel justified in ripping him. All I did is comment on an interesting thread and was told I was an idiot, which I am not.

Kingfish......evidently nobody is as smart as stingray....I surrender to the superior intellect.

" bodyblue says:

04:01 PM, 02/17/10

He is desperate to defend what he drives because evidently his cars are a huge part of his self image....so if you insult his ride you insult him. "

You are very, very wrong with that assessment. I'm actually the complete opposite. I could care less what other people think of my rides. Especially someone like you. I buy my cars to please ME and only me. Not to impress others. Those trying to compensate for something or with low self esteem buy cars to impress others. That's not me.

"Kingfish......evidently nobody is as smart as stingray....I surrender to the superior intellect. "

Good, you finally came to your senses. Now move along to some other thread, preferably one where you will fit in better with fellow idiots and smack talkers.

SO the jury is out, bodyblue is the loser.
More rounds to come.!
Thank you.

Sorry it didn`t work out guys, but at least u had good pizza and a good debate down there LOL
And besides, it ain`t that interesting if it is over that quickly, huh?
This gives people more knowledge at the end.

Also, you guys found the rat poop, which I think is a clue as to what the true problem is. You wouldn't have found the rat poop evidence if you hadn't done this project, so it definitely wasn't a waste of time.

Seafoam seems like an easy next step.