CombustoBird89

My bird runs like a B*%@(h from Hell,, but thats with MAF unplugged. Starts ok cold, but soon throws code 33...been like this for a long time. When warm, won't start easy or run decent until i uplug MAF. Replaced maf and relays, Coolent sensor, wiggle tested wires, Volt meter tested wires with engine hot (heard some wires punk out only when hot). I also heard code 33 has to do with it seeing a high flow of air at part throttle....i replaced stock filter before these issues...could higher flow of air i now have done this? Anyone ever heard of this? I hate to starve my bird of extra air if i don't have to....i'll switch filter out tomorrow and see....

Tuned Performance

iTrader: (92)

https://www.thirdgen.org/forums/tpi/...-pls-help.html

NY87Iroc

iTrader: (1)

I pulled my hair out for 2 years trying to figure out code 33, I ran all the tests and replaced everything and still had the problem until Tunedperformance solved my problem! Talk to him and listen to what he has to say!!

CombustoBird89

Tuned Perf has helped me before with wiring and other problems before...sounds like what he did for you is only thing left too try now... Yah, code 33 and rough running when warm has been a prob for a while now, until i uplugged MAF that is...Have installed new MAF and relays and ran all the tests i could...guess its time to re-program and put new chip in and run normally again.
I don't have aftermarket chip or new cam like NY87IROC did...i do have high flow air filter, shorty hooker headers, and cats...
Would be nice if someone could burn a new chip so reprogramming could make MAF happy and might as well get rid of VATS before it strands me somewhere......

Pajjen

iTrader: (1)

Tunedperformance really does a on this site!!!
He has helped me out on many things already. And hes a very nice person.

CombustoBird89

Yah TP has helped me before and am working with him now to fix MAF rough running problems.
So, Pajjen, you are from finland and have car like ours? Bet getting parts is harder than getting advice...
My moms' great grandparents immigrated from there about 150 years ago by the way...

Calixbwsx

I'm having a maf problem also I get code 33 and 36 I unplugged my maf sensor and runs good but I can't figure out the problem. If I plug in the sensor the car will stumble and die after 5-10 seconds. Please sOmeOne help bcus I don't wanna keep driving my car with maf unplugged. By the way I have a 1989 Iroc 5.0 tpi

CombustoBird89

What have you tryed so far to fix? Replace relays or MAF sensor...connector and wire tests...Troubleshooting trees? Many diffferant things can cause that...no mods like cam?

soarestransam

switch to speed density an ur problem will go away get a wiring harness from a 91-92 f body with a 5.0 or 5.7 along with the ecm an replace it thats one way to get rid of the maf sensor style

Calixbwsx

I can't really try to do the steps from the chevy manual bcus my car won't stay on and I have no mods

Calixbwsx

I just checked again and it gave me code 33 36 44 and the connection for the maf sensor is broken from the clip but it has good contact

CombustoBird89

Would have to check manual as to what codes 36 and 44 are...i''ve jZ had a 33.
Go ahead and use strap to secure wires from dangling and getting beat up more....they may already havve prooblems though..when using meter on wire tests, wiggle wires and connectors to see iif theres a break. Relays aren''t too expensive...u replaced those yet?

Calixbwsx

I just unPlugged the sensor relay and car ran good but it still gave me code 33 I'm gonna replace it tommorow and hope that that's it. But I did connect the Maf sensor so now it runs with maf sensor relay unplugged.

saldav420

Where in south Cali are you from? it seems like a lot of us have the same issue with code 33 & 36

Calixbwsx

I'm in the inland empire my code 36 went away since I unplugged maf power relay but I still get code 33.

CombustoBird89

Yah...by unplugging MAF, you are interupting circuit and whether iits a short or a break, a code 33 will come.
I've run my bird a while with MAF unplugged...other than reduced M.P.G. has anyone noticed bad effects on leaving MAF unplugged??

Tuned Performance

iTrader: (92)

CombustoBird89 can you datalog to see the maf grams per sec ?

CombustoBird89

yah, i can take picture with auto-xray again this week..but llast time i did that, it said 13gr/sec at idle..you want me to monitor that while driving next time?

Tuned Performance

iTrader: (92)

just curious when it hits 45 gps

CombustoBird89

So, you want to know what speed or RPM i'm at when 45 gps is reached? I will monitor that next time TP...so what would a good place to be look like?

Tuned Performance

iTrader: (92)

I havent done to much work with maf more sd, but from information from a few guys I have helped 45 gps was seen at a light highway cruse and Im thinking around 2k rpm. A friend of mine had a mild cam and after he installed a bbk 52mm tb he saw up to 90 gps. The programing theshold is 45 gps once that is hit you will go in limp home mode.

CombustoBird89

I was going to ask if free flowing air filter could bbe making thiis happen, but lately it goes into limp home 33 even when idling right after startup...Hmmm....thatt doesn't sound like too high of threshold then..the replacement MAF is one oof those miicrotech that consolidates from 85 to 89 tpi...what is thhis sounding like too you TP?

Tuned Performance

iTrader: (92)

I don't think its a air filter issue, Its just really odd that the reading you get at idle or even start up is dropping it into lhm. Since you are seeing the actual reading on the auto-xray im thinking its a bad ecm. I don't want to guess wrong at your expense though.

CombustoBird89

I'll get some gps readings at Hwy cruise and recheck wires etc; and then decide what direction next.
What bad effects on car beside bad fuel economy, would just leaving MAF uplugged have?

Tuned Performance

iTrader: (92)

it depends on how rich it is running, washing down the cylinder walls will increase cylinder wear.

Calixbwsx

I had unplugged the maf power realay and cOnnected the maf sensor and it ran good for a day the next day it stalled out and died at startup but once I disconnected the maf sensor I ran good again.

Calixbwsx

I just put in a new Maf power relay and still stumbles and dies at start up. Damn this is frustrating

Calixbwsx

I just read on the manual that if the maf is unplugged it will give u a code 33 if a code 34 resets then the wiring or the ECM is at fault. Help with this?

88I-ROC

I'm having similar issues, but with intermittent code 34.
I was data logging with Tunerpro RT and I'm getting MAF values of around 7.5 gr/sec at idle in closed loop....Is that normal?
What would be the normal air flow values while in idle?

fletchusmc

Good morning, I have a 87 Corvette L98 and have used this site for a lot of info. I recently had issues similar to yours and posted my findings on corvetteforum. Hopefully not breaking any rules but here is the link to that post and how I finally fixed it. Hope it helps!
http://forums.corvetteforum.com/c4-t...ng-thread.html

88I-ROC

I read the thread, very interesting, I was particularly interested in the last MAF you got, I never seen a design like that, might be the answer to all of our problems.

Calixbwsx

can someone help me diagnose maf sensor circuit.im trying to find out if ckt 998 is open but do i just check that wire or what do i test?

Tuned Performance

iTrader: (92)

circuit 998 is just the maf signal to the ecm pin c on the maf and b12 on the ecm. B12 koeo 2.5v running from .4-1.0 depending on air flow.

Calixbwsx

i kno but how do i test it to elimate the 998 from being open.

Tuned Performance

iTrader: (92)

are you saying you cant figure out how to back probe a weather pack connecter ?

Calixbwsx

the 998 has 4 connections right?

Tuned Performance

iTrader: (92)

Calixbwsx

i meant to say is the 998 on the burn off relay or power?

Tuned Performance

iTrader: (92)

maybe the picture above will help you. Im not sure what your referring to

Calixbwsx

i cant see the picture i just want to know how to check it and where its located at.

Tuned Performance

iTrader: (92)

please look at the picture 998 is the maf signal

Calixbwsx

theres no picture there lol

Tuned Performance

iTrader: (92)

post #37 , 998 is the dark green wire on the maf sensor it goes to pin B12 on the ecm.

Calixbwsx

its not showing nothing its a black post

Calixbwsx

so how do i check the voltage

Tuned Performance

iTrader: (92)

Tuned Performance

iTrader: (92)

a vom

Calixbwsx

thanks brotha

Tuned Performance

iTrader: (92)

CombustoBird89

Hi fellow Bird lovers....been away from forum a while as u can see in previous post...jz wanted to tell everyone what was throwing maf and 02 sensor codes....I tried everything in the book to solve this...and there r many things that can cause this gremilin... S000, I have fuel pressure gauge cuz fuel pump wuz old and I knew it would fail not too long from now...thought it would fail slowly with pressure reducing over time....not so...one day it read 0 on gauge...I limped in to shop and had it fixed...ran a scan...no codes at all! Is running a little rough at idle so I will do the iac dance with that...and maybe think about access cutout over fuel pump for a future day...so, all those years...the codes were caused by a weak fuel pump...the pressure was around 40psi all the time...on to da next prob....hehe...