hi all, ive been having problems with my 85' L98. it idles fine but when you floor it, it spuders almost like its hiting a rev limiter at like 4k. but if i only give it about 1/2 throttle it will rev clean to redline.

now here's where it gets odd. for some reason i unpluged the MAF, started it up and it ran fine no hesitation at all. now i turn the car off plug it back in and it went right back to the problem...

could this be the MAF going bad? iam not getting any trouble codes so i really dont know.

please help,
thanks,
mike

 

1985? L98? Somehow, those two don't seem to go together.

 

its an 85 corvette motor

 

I would go with what everyone here always suggests first, and that's to try replacing the MAF power and MAF burnoff relays first. They're way cheaper to replace than the MAF, and go bad fairly often. If this doesn't cure it, inspect the MAF sensor for any foreign debris around the sensing wire. If it's clean, and the sensing wire appears intact, then it probably has gone bad.

 

Have you switched the PROM or the "chip" with something aftermarket? or is it still the original one that was for that particular motor? Within the PROM it goes into a Power Enrichment mode after a certain throttle pecentage, maybe around 70% throttle opening, and adds fuel and spark advance. If the PROM is not the original, I wonder if the settings are working well below that certain throttle % and then the Power Enrichment is not right.

When the MAF is unplugged its not using the PROM at all, it goes to a default "limp home" mode, therefore a problem within the PROM will not be there.

maybe its not the PROM, especially if its the correct original one, but its somethign to consider..

 

thanks everyone,
the chip is a custom tuned one from tpichips.com. it did this with both the stock chip and the custom one . iam going to try the burn off relay first and go from there.

 

Is this a swapped engine? Did the 85 electronics go with it? If so... you're not going to find any burnoff relay. Might be time to look into repinning and going with a different ECM altogether, if the MAF or module is your issue.

Anyway, I'd check and see how your spark is doing.

 

well that makes sence.
its and orignal tpi 305, then is did the 350 swap using the orignal tpi ecm.
i didnt find anything that looked like a maf burn off.
is there any way to test my MAF? if not that then what could it be????

 

Have you recently relocated the battery? added some component to the ignition? Have you had this problem sence you first did the swap?

 

no i didnt relocate the battery, and yea i added MSD, but that all worked fine, until this problem started.(if it is the MSD). tomorrow iam going to take the MSD out and see if it will work with stock ignition.

 

also does it take alot to get your car started, like having to parellel or boost a fully chargered battery? when you disconnect the msd, have you noitced you can give the car more gas (closer to WOT) with out it sputtering at 4k?

 

well i took the MSD off, and got the same promblem. it seems like it about the same rpm also. this is getting old. i think i am have a charging problem too, could the two be linked? if so how. i dont think it is the MAF.

 

would you happen to have a volt meter? if so check the battery voltage then, check it with the car started. It should be reading about 14-15v if its the stock alternator set up. Once it has started let it warm up and turn on any thing and every thing, check the volt meter,is it holding it's voltage?

give it some gas up to 5k did it sputter?

-When you have driven the car before does it usually happen under load(123gear, etc...) when it sputters?

 

its not holding a full charge, it drops very slowly, the battery and alternator are new. the car ran fine up until this happened. i havent tried giving it gas while i had it on the volt meter thou.

 

please diffine "the car ran fine up until this happend" by what you were doing when it happend,

As for the battery you have a 12.5v battery on a 14.4 volt system, nothing wrong with this really just make sure you have the warranty(over charging leads to burnt plates which in the end hold no charge at all), but the 12.5 volt battery voltage will drop until it has reached its max possible charge 13.3v there abouts when the car is off.

As for your problems I'am sure you have a ground issue I'd get some nice thick cable don't invest much because it might be as simple as a loose ground. When connecting up the cable have one go to the body be sure to scratch the paint off, connect one to the block, and one to the fire wall.

Best of luck

 

the car ran fine until i put the new cam and intake runners in. i already checked the main grounds. but there is one on the back of the head that i do need to check to make sure.

 

which cam did you drop in?

 

crane Z cam 268 (218/230-.459/.482) < something close to that....

 

ok its the maf.. 99 times out of 100 its the actual maf.. nd not wiring.. not relays.. not anything but the darn thing is bad.. nd they go bad constantly.. i replace them all the time.. thats actualy one of the quickest ways to diag a car nd i do it often.. if u unplug it nd the problem goes away its that part.. so good job there.. honestly.. id just replace the darn maf