Cutting off still! PLEASE Help!

[flynbyu82]

Ok, I'm still having cut-off problems with my 82. I've recently replaced air filters, valve gaskets, suspension, u joints, and a new radiator. It was cutting off awhile ago, but then I made sure the expansion tank for the radiator was full and it stopped that. Now, I had the radiator replaced because it rusted through and was leaking.

When I start the car, it sounds like an exhaust leak with a tapping noise. It stops, but then when I'm cruising and step on the gas, you can hear it start tapping again.

I havn't been driving it too much, and I don't know if I'm just retarded, or something weird happened while it was at the shop, but it's only getting roughly 6mpg, and it should be getting around triple that.

I've put techron and gas treatment in the tank, and it's still acting up. I don't know if all these things are working toward each other, but the main thing is, it's cutting off. When I'm stopped at a light, not every light, but randomly willl drop from around 800rpms to around 400, and then cut off. It usually starts right back up, but I've gotten to the point of sitting on the gas alittle in neutral at lights to keep the idle up. It's been to the shop several times, and everything that ages with the car has been replaced, but it's still cutting off.

ANY suggestions I will be grateful for, I just can't figure it out, and with school starting soon, I will be driving it a lot more, and I really don't want to get stuck in traffic because my car shuts off, or get tboned pulling out infront of someone.

In advance, I appreciate any help.

Thanks
Shane

**And here's another thing I forgot to add in the post, if I put the car into park when the RPMs start to drop, it will jump back up to ~ 700 rpms, and sustain that longer than if it was in drive. I'm just throwing more information out there.

** My engine light also just came on, checked it, and it's flashing 13s, can anyone help me on that?

 

[black_81_vette]

First off id take to a shop that can actually read the data from the c4 style of engine computor thats on that car.Does the check engine light come on? If its only getting 6 mpg its running way rich. what has been replaced? Also any exhaust leak can throw what the o2 sensor sees way off IE it senses more air the computor dumps more fuel.first things first id have it checked with the proper scanner by a knowlegable mechanic first to see where the values are at.One more thing ive seen cases where the top plenum warps due to heat from the EGR valve on cross fire set ups like yours a vacume leak seems to be your issue. Id have that checked and make sure the EGR ect isnt sticking open ect. a very good tech with the proper skills can find the trouble much better than some kid off the street working at the local tire shop.Do your self a favor spend a few extra bucks on a good mechanic its gonna save you alot more in the long run.

 

[flynbyu82]

With the money I'm spending, I'm kind of angry it isn't fixed yet. But, the people that are fixing it for me are 'Corvette only' techs that run a shop on the weeknds. Right now, they have 2 ZO6s and a 62 Feul Injected C1. I geuss I will call around and see what I can do.

BTW, I checked for engine codes myself and it blinks constant twelves.

 

[chevyaddict]

This may be completely off base but what comes to mind is the timing is off. Did you take the distributor and put it back in one tooth off? I've done this int eh past and if you do and advance the timing enough it will still appear to run Ok but will knock when get on it and certainly may have some pinging noises at startup... this would also explain horrible gas mileage...

If you haven't done anything to that part of the system then i can't imagine the timing slipping on its own unless the chain is stretched... this probably isn't your probably but it never hurts to put it out there!

 

[flynbyu82]

I have not messed with the distributor at all. I recently just replaced valve gaskets, plugs and wires, radiator, and alternator. And here's another thing I forgot to add in the post, if I put the car into park when the RPMs start to drop, it will jump back up to ~ 700 rpms, and sustain that longer than if it was in drive. I'm just throwing more information out there.

 

[Alan76]

Shane

Bring it up to Cairo and I will help you

Alan

 

[flynbyu82]

Alan, do you have a shop or what? Please give me more information and avaliability and I would love to work something out.

Thanks
Shane

 

[Evolution1980]

...if I put the car into park when the RPMs start to drop, it will jump back up to ~ 700 rpms, and sustain that longer than if it was in drive. I

Hmmm...take a load off the engine and the RPM's creep back up. 700rpm is still low I believe, but if it's really warm out, it will idle low. But anyways, I think you have a 700R4 trans, so possibly you have a TV Cable problem. I'm not well enough versed in the TV setup though to say for sure. I'd still lean towards checking vacuum lines (as I mentioned in my PM to you.)

 

[flynbyu82]

Hmmm...take a load off the engine and the RPM's creep back up. 700rpm is still low I believe, but if it's really warm out, it will idle low. But anyways, I think you have a 700R4 trans, so possibly you have a TV Cable problem. I'm not well enough versed in the TV setup though to say for sure. I'd still lean towards checking vacuum lines (as I mentioned in my PM to you.)

Usually RPMs stay around 800-900, so 700 isn't normal, but it is higher than the 400-500rmps when it cuts off.

BTW, any tips on checking vaccum lines myself? Or if Alan get's back to me I may just have him take a look

Thanks all
Shane

 

[KANE]

I have not messed with the distributor at all. I recently just replaced valve gaskets, plugs and wires, radiator, and alternator. And here's another thing I forgot to add in the post, if I put the car into park when the RPMs start to drop, it will jump back up to ~ 700 rpms, and sustain that longer than if it was in drive. I'm just throwing more information out there.

IAC

You have a problem under load at idle- which is not uncommon for CFI.

 

[Evolution1980]

IAC

Idle
Air
Control

...did the 82's have 'em? Did think those came until later.

 

[flynbyu82]

Alright, how can this all work togethor?

Vacuum leaks, exhaust leaks, problem under load at idle...

Ultimatly, I would like the 6mpg to jump up to around 15, and for the car not to shut off when I'm stopped. What should I go about doing to fix these things, especially the IAC?

 

[Evolution1980]

Vacuum leaks, exhaust leaks, problem under load at idle...

I don't believe that exhaust leaks (if any) are going to cause the problems you are experiencing. An exhaust leak will quite possibly improve your performance due to the factory exhaust being so restrictive! :L :L
However, vacuum and idle problems travel in the same basket.

 

[flynbyu82]

But like the guy said earlier, wouldn't that make sense if more air was coming in, the o2 sensors could be telling the car to dump more gas then need meaning horrible gas mileage?

BTW, IAC are on 82s...

 

[Bob Chadwick]

When I start the car, it sounds like an exhaust leak with a tapping noise. It stops, but then when I'm cruising and step on the gas, you can hear it start tapping again.

Sticking valve/collapsing lifter affecting compression in that piston?

 

[Alan76]

Alan, do you have a shop or what? Please give me more information and avaliability and I would love to work something out.

Thanks
Shane

Yes I have my on shop, But I do not make my living this way

 

[flynbyu82]

Alan

Shop hours? Address? Avalability?

If you really think you can help me out, please PM me this information and I might be able to make it up there somtime soon.

Thanks
Shane

 

[flynbyu82]

My engine light also just came on, checked it, and it's flashing 13s, can anyone help me on that?

 

[Evolution1980]

My engine light also just came on, checked it, and it's flashing 13s, can anyone help me on that?

Check in the Tech Center on the site here. The codes might be there.

 

[flynbyu82]

Yup, O2 sensors. The last couple days this car is just crapping out worse and worse, right before school