Bugly87

First code is the TPS sensor..The next two are MAF too high and MAF too low. In the process of dialing in the TPS now but it was pretty close. I will report back with the results

Bugly87

Just dialed it in...It was pretty close initially at .52. It is now set at .54 Started it up and it ran rough for a few seconds then straightened out. The SES light then came on again. Still has a miss. Idle between 600-700 in park. I will see if I can have the codes read again and report back. I assume I will see the MAF and TPS agin. If so should I swap out the MAF?

Thanks for any help

Kevin

JackDidley

Unplug the MAF and start it up. If it runs better you likely need a new MAF. I'd probably replace the relays first.

MK 82

I would run the chart in the FSM.. It's free.

Eddie

Bugly87

Update...I swapped out both MAF relays with new ones...No difference, the SES light came on within 3 seconds. I carefully took out the MAF sensor and checked the inside. It is undamaged and I can see the thin wires inside so it appears to be intact. I will check the codes tomorrow and post results. Here is another question... While looking at my cowl that holds the air filter in place I noticed that one of the side ***** are broke, causing the air filter to pull away slightly on one side. Could this create a vacum leak and throw the MAF out of whack and thus a code? Just reaching as I am rapidly running out of ideas.

Thanks again for all the help

Kevin

Cliff Harris

Do what JackDidley suggested: run it with the MAF unplugged and tell us the results.

On my '86 the two MAF relays are different. If you get them swapped the MAF burnoff won't work and the wire will become contaminated. I know they changed the wiring in later years so that both relays are the same, but I don't know when they did that. Are both of your relays the same?

jsinga

A car that's been sitting a long time.....
New fuel filter
check fuel pressure
Put in a bottle of Techron fuel system cleaner.
Sometimes when you get a lot of codes they are caused by low or varying fuel pressure. The ECM is trying to compensate and can't handle the up and down.
Fuel filter is in front of the passenger door along frame rail.
Fuel pump will come out the gas door. Can be replaced in 1/2 hour. Getting the hardened up rubber boot in and out will be the biggest headache.
And Yes! and air leak after the MAF will drive the ECM nuts.
Also look for other rotted vac hoses.
If you can keep a Fiero running you'll do fine. Same GM stuff..

JS

neat

Because this is an obvious reference to the late, great, CFI EFI, I feel compelled to correct you.

FSM stands for FACTORY Service Manual. Not FIELD Service Manual.

Thanks for playing, and try to disseminate correct information from here on out.

-RACE ON

neat

The techron is a horrible idea. The dirtiest part of the fuel system is by far the tank. Why you would want to loosen debris/dirt from there, send it through your pump, pray that the filter catches it, and hope that somehow the techron can clean something else in the fuel system on it's way though is beyond me. Tank additives are a terrible idea in nearly every scenario, regardless of what commerical or Internet drivel you've seen.

If you want to clean the intake, there are some good fogging products out there, but that won't help with dirty injectors. If you can't find the issue, and suspect dirty injectors, you can test them fairly easily with some basic shop tools.

Removing the injectors is a pain on the TPI, but once that is done find a clear jar with a plastic lid. I've had good luck with empy mayo jars. Drill a hole in the lid that will accept the injector, and is slightly smaller than the injector seal. Then attach a 10 foot rubber hose to the fuel inlet on the injector and clamp it. Set up your rig so that the injector is lower than the hose, and the hose has slope from one end to the other. Fill the hose with fuel.

Regulate your compressor down to approximate fuel pressure. Stuff your blow gun in the high end of the hose, clamp it, and zip tie the trigger down.

You now have a small reserve of fuel pressurized at approximate running pressure pushing against the injector.

Use a 9V battery and some short wire leads to actuate the injector. Watch the spray pattern in the jar.

It's not a standardized flow test or anything, but it'll let you know if you have injectors that are clogged, struggling to open or close, etc...

Bugly87

My Corvette is a 1987. I researched and determined that the relays are the same and are interchangeable. So the ones I purchased are the same. I did unplug the MAF and it did seen to run better but I am not soo sure because it doesnt run too bad with it connected. The longer I drive the better it seems to run. I checked the MAF and the wires are intact

Bugly87

Thanks for that information. I will replace the fuel filter next day off and will do a tune up. Began the first treatment of Techron the other day. will continue to do that. I will rig the cowl to get rid of the air leak until I can get another part.
Thanks for the Fiero insight...I do see that they are somewhat the same

Thanks again

Kevin

PLRX

Here you go

-wipe on

Bugly87

Ok..Still no change in the performance of the vehicle so I jumped the A and B terminals and get a single code...33 Searches indicate a MAF issue. I have replaced both relays with no improvement. I checked the inside of the MAF and the thin wires appear to be there. I saw a diagram before on what the inside of the MAF looks like. Can someone direct me to this diagram so I can check to see if mine is right? Should there be 4 wires or only 3..or how many? And finally... How can I test to be sure it is bad before I take out a loan and purchase another one.

Thanks again for all the help..It would be impossible without your help

Kevin

Sweeride39

Be ready to change out those outdated injectors. Car had been sitting, and those injectors go bad fast after start up.

Bugly87

Thanks for that suggestion and that is on my list as I do have a ticking from 1 or more injectors. Would this cause a 33 code, either directly or indirectly?

Kevin

MK 82

The book for my 96 is simply called the "1996 Corvette Service Manual."

Sparkytfl

Not a vacuum leak, but still undesirable. My own is broken the same way; the lid is now held on with bungee cords.

Bugly87

Fresh gas, new fuel filter, new MAF sensor, and a rebuilt throttle body and I am back on the rode. As luck has it another issue has arisin. The car sat since Hurricane Irene (about 4 weeks) and when I went to take it to the Mechanic the battery was dead. Got it jumped and got the above items fixed. I mentioned this battery discharge and the mechanic said that a battery in a C4 could go dead in as few as 7 days. Back in the garage and now 5 days later the battery was dead again. This battery is brand new. I now have a battery tender but it seems odd that the battery can go dead in 5 days. Is this at all possible? If not what are the leading culprits to track down.

Thanks for the help
Kevin

jaa1992

In my 92 the battery goes flat in 3 - 4 weeks (new battery)
I hook it to the charger a few days before an event so its fully charged.

Draining in a few days means you have something on all the time.
Could be a light (interior or even the light near the spare tire). I know if my glove box isn't shut all the way the light stays on and the battery might last a couple days.

Electrical gremlins are a lot of work. Use the FSM and start there.

engle1147

Dirt nap or is he just MIA?