Diagnostic man

[corvette66]

On Saturday morining I am taking the vette into see the Diagnostic man. I have finally given up on trial and error; getting sick of messing around with it. I have never actually taken any of my vehicles to get a diagnosis print out, what am I in store for? Im only having it checked, not actually fix'd. I'll fix it myself, but need to know whats wrong. Are they as good as I been told, or is it a waste of 70 bux?

thanx, dano

 

[Ken]

Seventy dollars is an relatively normal hourly rate for the technician, mechanic, or "wrench", whichever that person prefers to be called.

You're paying for his knowledge and expertise. You'll have to make that decision, as to his reputation and your trust in it.

Good luck, I've been there, done that. I'd like to say you get what you pay for, but cost is not always the determining factor. I've had the best of 'em screw things up.

 

[vetteboy86]

I did and search and read your posts about your car. My question is what do you want to get out of this service? The things happening to your car are unfortunate, and we all feel for you. What information did they say they could get from your car?


Craig

 

[corvette66]

Ken thanx for the good luck, my car needs a lot of it.

Haha well craig, if you did a search on my problems, you know what I have been going through with this C4. If it could happen on a vette, it has happened to mine. Most all the problems I have had in the past I have fix'd. But still have 2 of the problems. One being that my car still idles like a piece of sh*t. So if I could just figure out what is causing the rough idle, I would be all smiles. Second problem: my overdrive is still not working. I think I know what it is, just have not yet got around to fixing it.

So what I am looking to get from the diagnostic test; what sensors are bad, or what else could be causing my idle to be rough.

thanx

 

[corvette66]

Just got back from the Diagnostic man. Here is how it went down.

First he says that my car is to old for the machine. So he can't hook it up to the diagnostic hicky. So he just looks it over for a while and comes upon a problem. Your car has a vacuum leak he says. I thought it did, but I could not locate it, so he found it for me. He also said that it was a major leak and would cause the rough idle. So I fix'd that problem after I got home.

Well it still seems to be runn'n rough. So I guess I'm back to the drawing board

 

[vetteboy86]

Okay I think that the whole deal is crap. I had my car at a shop about 4 years ago. It wans't too old then, and I doubt it is to old now. The car should be equipped with OBD I. I think there are alot of cars running around that have this still. You can buy the ones from mid america, and ecklers. Do you have a corvette shop near you. I cant believe there isn't a place that can scan an
OBD I system.

I am sorry about your luck, hopefully the guy didn't charge you, and if he did he would be hearing from me. Let us know, because there has to be a place to have your car scanned.

Craig

 

[G Winter]

On the not being able to scan . Our local shop has a hand held scanner. He was telling me that the scanner can only hold so much data,much like a pda. He was telling me that when he updates, which is done over the phone many times, that the oldest data is deleted to make room for the new. My guess is that you would have to find someone with a scanner that has enough memory that not as much old data is deleted, or maybe a gm dealer is the place to go . I could go in with a car to scan tomorrow and a week from now he wouldn't be able to scan it. I also notice that for diff yr ranges he had to change cartriges.

 

[corvette66]

thats pretty interesting stuff. I'm not sure if there are any vette shops around, I will have to look into it. But no, the guy did not charge me at all. Real nice guy, but very busy. I will probably call around to the GM garages, most likely my best bet.

 

[582Boat]

Engine running rough

Have had a idleing problem with my 1985, I was told by a previous owner of a 1987 Vette to spray carburetor cleaner into the air intake throttle body this is to clean out years of junk. Myself, I am going to try this.

 

[Ken]

Don't use carburetor cleaner, at least that's what they say. You're supposed to use "throttle body cleaner", or something like that.

 

[vetteboy86]

I know they make the two, however I wonder what the difference is? I am a little worried to do that, because where does "years of junk" really go?


Craig

 

[582Boat]

Throttle Body Cleaner

Don't use carburetor cleaner, at least that's what they say. You're supposed to use "throttle body cleaner", or something like that.

My mistake, I really ment to state (Throttle Body Cleaner) I knew better as soon as I sent the thread. Doc

 

[vette-dude]

My mistake, I really ment to state (Throttle Body Cleaner) I knew better as soon as I sent the thread. Doc

The reason for the Throttle Body Cleaner use is that the product needs to be 02 sensor safe. If not you will ruin your 02 Sensor. Use the product and a toothbrush to scub the throttle body if you are doing it on the car. Open the butterflies and scrub back there too. then squirt some down the little hole you will find just in front of the butterflies to help clean the pintle on the IAC.

I don't see why the Diagnositc place couldn't put a scope on your engine. We just did my 91 L98 engine this weekend. An Allen Test Center or Sun Tune up Center should do the trick. Think it only took about a 4 or five wire hookup and found the cause of the rough idle was the sparkplug wires. Showed right up on the scope. Too many Mechanics these days are taught that if it doesn't code out on the DTC or the hand held scanner then they are lost as to what the problem is. Most don't have nay idea how to use a test center or how to evaluate the results. My neighbor is a Automotive instructor and teaches new mechanics how to really diagnose problems. Guess you need to find someone with a test center or try replacing plugs, cap, rotor, wires, and the 02 sensor. Clean the throttle body and change the PCV valve and I'll bet you will be good to go.

Randy

 

[tomtom72]

Hi all, I'm reading this with interest as I'm thinking about a 90 or 91 ZR-1. My question is about electronic engine management systems. Is it not possible to buy a hand held analyzer with the software specific to your model yr.? Are the C4 EEC systems not able to be analyzed by a chevy dealer? I assume that the EEC for the ZR-1 is different, software wise, from the rest of the C4's. Thanks for tolerating my intrusion and ignorance. I never owned a GM product other than a 72 vette. I've owned Fords and have never had a problem with EEC that a hand held and the ROM display couldn't get me going in the right dirrection to solve. Aren't GM EEC systems like that? Tom

 

[corvette66]

About the carb cleaner; I also heard from a mechanic that the carb cleaner has a sticky residue that will gunk up the fuel injection system even more. i use throttle body cleaner, Yeah I also tried cleaning the TB, but it really wasn't that dirty to begin with.

The diagnostic man seemed to really know his stuff, but he seemed to be to busy to bother with my old car. that was the impression I got. So he tried to hurry me along i think. Oh well it was free!!!!!! So im not complaining.

I thought maybe change the rotor, since I have already changed about everyhting else, but my car only runs rough when cold.

 

[G Winter]

Only runs rough when cold? couple of facts. takes a better spark to light the fuel when engine is cold. Takes more fuel to get it to light. I used to work on propaned powered engines. Propane needs a really good spark to light up. One of the things I learned from working on them is that the majority of the time rough running was an ignition problem. To close or to wide a plug gap can both cause similar problems.

 

[Ken]

About the carb cleaner; ... sticky residue

The reason for staying away from the old carburetor cleaner and use a cleaner designed for throttle bodies, is to prevent damage to the sensors, not to prevent a "gunk build-up."

 

[corvette66]

My Gap is good, new plugs and wires, maybe i need a new cap and rotor, not sure though. I'll run out of money one day, and that will be it. I'll drive it the way it is. getting fed up thats for sure. But i'll keep on plugg'n away till i get it.


your right ken.

 

[vetteboy86]

How long will it run rough? You say when cold, but is that just at start up and 30 seconds afterwards, or like ten minutes afterwards? I guess I would like to know your meaning of cold.


Good luck

Craig

 

[corvette66]

Well I would say "cold" is about 5 minutes. Ususally i have to run it around the block to get it nice and hot before it will idle smooth.