I just purchased my first vette a couple of days ago, and already having troubles. The car runs great under a load when over 1500rpms. If I try to mash the throttle from an idle, the car sputters and falls on its face. The idle is also hunting a little between 67 and 7300rpms.

I put my buddies Snap-On scanner on it, and got a code 33 fault. MAF sensor(signal voltage high) so I decided to replace it the next day.

Upon reading my shop manual, I learned that I should have disconnected the ECM for 10secs. to clear any previous stored codes. I did so and now I have no codes. I have put the scanner on about 10 times and still no codes. Yet the problem is still there.

The exhaust is very rich and there is next to nothing for throttle response. When it bogs off idle it makes a big noise which sounds like it is taking a big gulp of air. Could the MAF be bad and not be detected for some unknown reason? I just installed a new cap, rotor, Rapidfire plugs, wires, and a Supercoil.

The car has been in storage for the last seven years, and has only 65000 on the clock.

Upon reading some of the posts in this forum, I gather that there are many members with great knowledge of these cars, so I hope someone can help.


Sturtzy



[Modified by sturtzy85L98, 2:50 AM 2/26/2003]

 

Welcome to the club.. :cheers:

Do you know any modifications that have been done to the car?
I also have an '85 vette, and a few years ago had an issue where
'sometimes' when I floored it from a stop, the car bogged, and you could hear a sort of 'sucking noise' from the front like you are describing.
It turned out to be a lower intake manifold leak. But all I did to 'fix' it was to tighten all the bolts on the intake and the runners/plenum. Since then it stopped happening.

The erratic idle between 670-730rpms is actually normal for an '85.
See if you can track down a vacuum leak too, that could cause a jumpy
idle too.

Good Luck

 

It has full Flowmaster exhaust, 373s, air foil, K&N, And a Max Performance chip from Mid America, and Friday it is getting a new centerforce dual friction clutch installed.

Can I install a modified MAF or should I stick with a stock Bosch replacement??

I will check the intake bolts and make sure they are secure and check for any other possible vacuum leaks. Thanks for the advice and keep it comin.

I need all the help I can get. I have owned many carbed hotrods, but this computerized stuff still has me baffled.

Thanks again

Sturtzy

 

yes you can install a modified unit and that probally is your problem if you are going to mod it yourself i would install it stock first to make sure that is the problem once you mod the maf it could go bad there is a very thin wire in there that is easily broken so be carefull :cheers:

 

do yourself a huge favor bring the car to a shop with a full diag. scanner if you start chasing the problem you can end up spending alot of unesesary money that you could be spending on high perf addon's :cool: when you get the problem figured out let us know :flag

 

I have an '85 and it did the same thing that you are discribing for years, but it was very intermittent. It would run very rich and blow black smoke with no throttle response. I tuned it up, cleaned the throttle body, played with the IAC and TPS with no success.

I took it to a good Vette Chevy dealer and they couldnt find it. Like I said it wouldn't act up all the time. I took a shot at it being a bad MAF. That's what it was. It hasn't acted up since.

I later was told that if you unplug the MAF that the computer goes into a pre-programmed MAF setting and doesn't get its info from that sensor. If the car runs better by unplugging the MAF then the MAF is bad. I was not aware of this before I replaced the MAF.

MAF are pretty expensive. Get a Bosch unit to be safe. I bought a new one from TPIS for around $270. Put it in stock first then just take out the screens if all seems well.

Good luck