A few days ago I was driving my C4 automatic with 65,000 miles on it ,and I really layed on it, basically Floored it. So i had my fun and coasted back down to normal throttle. Then i gently accelerated again to get up a hill and the car bogged out let me try and explain. It was like a hesitation or a Jerk. Almost like it had missed a gear or something. It only did it for like 1 sec and that was it. But know im affraid to floor it again. did any of you ever get some bad fuel with maybe some water in it, and the car hesitates? was something like that to.
Any help on what i should do, Or buy some feul injection cleaner or any other stuff like that.
Also some times when i start the car and put it in reverse it sounds like its going to stall out, and sometimes it idles funny
thanks
Bruce

 

Sounds like you blew some carbon build up through the system. Do you run this vette much at highway speeds?

The latter question, but both questions as well sound like you need to clean the throttle body and IAC. When you start up, do you let the engine stablize before you back up? I mean start it let it idle on its own never touching the throttle and when it gets to 103-105F then start moving? I assume your talking about a cold engine start. Keep in mind that the engine is going through a couple mode settings. Letting it idle and stablize means it cycles through start mode to run mode which is a valid transfer to the O2 data and computer controlling it via IAC. If the throttle plates have carbon build up on them they are not sealing properly and the engine is getting too much air for what the IAC allowed.

I would consider getting the vette back on the interstate and running it for 20-30 miles at highway speeds or at least 2100+ RPMs (without getting into trouble). Open it up a couple times (be careful). See how it does after that. The throttle body can be cleaned and IAC cleaned or replaced for just a few dollars. You'd be amazed at the differece. If your coolant is also in need of changing or flushing now is a good time, because you have to drain quite a bit of coolant to remove the hoses to the throttle body. So its a good time to consider it more of a project, meaning consider the coolant system hoses as well. If your going to have these things all off, now is a good time to re-install all new hoses, coolant, thermostat, and a fresh clean throttle body and IAC.

Opps almost forgot: The injectors on the LT-1 are self cleaning. I would not advise using fuel system cleaners or injector cleaners. The electronics of these injectors are immersed in the fuel and cleaners damage them.

 

thank you very much jetjocky for the info. Im not very good at working on engine
I mean i can change air filter, Brake fluid, PS fluid. ETC.

What is the IAC? Also where is the thermostate. Could it also be an old fuel filter. I bought this car in 1998 and never changed fuel filter. Also i was just outside taking out the coolant jug and cleaning it out, there was what looked like mud at the bottom of it. Can you recomend a good coolant (antifreeze) same thing right?

Also is it usually 50/50 with the coolant and water?
thanks
Bruce

 

It takes a fair amount of mechanical knowledge to clean the throttle body just because there are things that have to be removed to get to it. If you want I can highlight the steps.

You might try just removing the air duct and opening the thottle plates and spray it good with throttle body cleaner then see if there is any improvement. Don't use carb cleaner, throttle body cleaner. It comes in a spray at auto stores. Carb cleaner harms the coating on the throttle body components.

If you see some improvement and lots of black liquid gunk coming or going into the intake manifold while spraying it then your probably due for a thorough cleaning. You'd need the steps to determine if you think you can do this job.

The IAC is the idle air control valve. It determines the air amount entering the throttle body during idle operations and is controlled by data from the main computer. The computer gets it data from the O2 sensors and a few others inside the engine crank to set and control idle. It is located on the lower right (passenger side) of the front of the throttle body. Just below the intake opening.

The theromstat is inside that bell shaped inlet water hose connector. It is the lower right side of the radiator and comes up to just before the throttle body and enters the engine.

Rare that it would be the fuel filter. An indication of failure or clogging is total loss of power.

The anti freeze coolant to use is the green ethyoglycol as recommended in your manual. You use a 50/50 mix with distilled water. Or you can buy it already mixed now a days. I would just go with a standard Prestone type.

It's not mud, its sealant. The corvette coolant system has three tablets of sealant added upon coolant system refill. They are copper looking dry tablets of crushed material. Generally they are crushed up and added at refill. New tablets are larger than the older one's so it only takes three. It makes the coolant color change to a rusty looking color. It is suppose to condition and seal.

Picture of IAC (used and new)
http://home.cfl.rr.com/laniplace/images/old-new_iac.jpg

 

[QUOTE=93JetJocky]It's not mud, its sealant. The corvette coolant system has three tablets of sealant added upon coolant system refill. They are copper looking dry tablets of crushed material. Generally they are crushed up and added at refill. New tablets are larger than the older one's so it only takes three. It makes the coolant color change to a rusty looking color. It is suppose to condition and seal.
QUOTE]

do i need to add the tablets? or are they already in there
also if you could provide the steps for cleaning various things it would be greatly appriciated. im learning more and more from people in here, cool!!
thanks
bruce

 

I found instructions for cleaning the throttle body, in Tech Tips.

My 94 has 80K on it, and I cleaned my t/b a few weeks ago, it was filthy! I dont' know if any previous owners had done this, or not. I bought the t/b spray cleaner and a gasket at Autozone; that and an old toothbrush got the job done very nicely. It's not difficult at all.
Good luck!

 

are u talking about you bought a intake manifold gasket?

 

No I believe he is referring to the gasket between the throttle body and intake manifold. You must replace that when its removed.

I agree the actual work is rather easy.

In a nutshell, you basically remove the air cleaner and duct, drain down the coolant system about 4 quarts. Disconnect the throttle cable, coolant hoses, vacuum hoses and electrical connectors. Remove four bolts holding the throttle body on and remove it. If your replacing the IAC then just remove the old one. Place in a area you can spray it well and clean it all up using a tooth brush like mentioned earlier. Make sure all gasket material is removed from throttle body and intake manifold. Install the new or cleaned IAC. Install new gasket and cleaned throttle body to manifold and torque bolts. Then if your replacing any coolant hoses, do that as well if your replacing the thermostat now is the time. Remove the two bolts and hose connection. Lift it off and replace thermostat. Observe its position before you remove it and put the other one in the exact same way. Secure with the bolts and torque. Reconnect all hoses, electrical connections and vacuum hose. Besure at all times to protect the opti spark. Its best to stuff towels down all openings to the opti spark and cover it from the passenger side. Coolant is deadly to an optispark. Refill the coolant reservoir. There is a step by step on this and then you bleed the system at the two screws near throttle body and thermostat.

Those are not specific step by step, they are just general. That will give you an idea of what is entailed.

Also, try disconnecting the negative battery cable and let the computer clear the stored parameters. Then reconnect, torque the battery connection 15Nm and let it idle for 3 minutes. See if that doesn't improve the behavior some. It will take a day or so to relearn all parameters for operations. I have a pdf of the steps. I'll look for it in a bit.

The tablets are added after you have stabilized the coolant level. Then they are crushed and poured into the reservoir. Depends on how much coolant your adding doesn't sound like your adding that much by cleaning out the overflow tank so I wouldn't worry about it now, just when you drain it down and refill it.

Tablets are purchased from GM Chevy parts. There is a new part number now but they know what it is when you ask for the coolant system sealant tablets for the vette.

 

im confused. where is the reservoir tank, is it the same as the overflow tank the big white jug i pour the antifreeze in?
i cleaned that out once before about 3 years ago and filled it half way with 50/50 antifreeze. And all that muddy looking stuff appered at the bottom of it. And i didnt add any tablets. How much are the tablets?
and do they go in the coolant tank?

thanks

 

The overflow tank, the one you cleaned it is located forward the passenger front tire. The reservoir is the black plastic fill tank up by the passenger side firewall.

You only need to add the tablets when you do a flush or drain most of the coolant and/or replenish it. You don't need to add them when your just topping it off. There is some in there now as you describe. I wouldn't worry about it until you plan to drain the system. Then pickup a package at Chevy parts and add them when you do a refill.

When you get ready to do the throttle body you might want to consider it then since you have to drain so much coolant.

The overflow tank is just that, when the coolant gets hot it expands and 'overflows' into that tank up front. When it cools down it siphons back into the system. You really only need to add to that overflow tank if the coolant level is below the add marks on the dip stick when its cold.

Also with a cold engine, open the reservoir fill tank cap (slowly) and verify the coolant is at the throat of the neck. If not top it off with a little 50/50. You can then start the car with the cap off, let it come up to temp you can tell when the thermostat opens and coolant starts flowing past the opening. If it drops down some add a little more to top it off, then secure the cap.

 

Dumb question... Tablets to be added to the coolant system??? Why??? I'm thinking about down a flush. I take it that a Vette has a special system?

 

fuel filter.