Seanmay1

Well i have had some MAF codes before but not this one, i had cleaned the maf a few months back and they cleared up and car has been running great. Well as of yesterday my car will be driving fine and then just loose power for a few seconds and then its fine, it has done this about 15 times in the last two days. SES light finally came on so i pulled the code, got a 33 (MAF frequency too high) what all could the causes be, and what exactly does it mean

I think it is something to do with one of the sensors on the throttle body though, I had the throttle body off the car yesterday to clean it out (throttle seemed to stick a little) BUT i know not to get throttle body cleaner in the MAF and made sure it was all dry before it got put back together so i don't see what i could have messed up.

TPI

Code 33's are plagues, and for one reason. It is a hard code, itll stay there
until its rectified and cleared. I dread the thought of tinkering with the insides
on MAF sensors, the hot wire is very fragile.

First few things to check is your burn off and MAF power relays on
the driver side corner of the engine bay. Remove them and give them
a soft shake to see if anything is rattling around.

Another thing to check is the MAF connection, and the wiring that
disappears into the harness. If you look at the connector, 5 prong
slots should be in good condition and make tight contact with the
sensor prongs, the leading wires should be in pristine condition.

These codes are known to give quite the run around, but
these are the rudiment things to check.

The 33 is telling you the gm/sec signal is to high for a given engine speed,
the sensor could be picking up excess voltage from one of the two relays or
a bad wire.. OR the TPS is set way too low/high!

The object here is to not buy a MAF sensor until youve totally eliminated
every possibility.. because the price! If you are forced to buy one.. Id steer clear
of the Cardone remanufactured MAF's.. Every single one I obtained locally gave
me the dreaded 33.

I got so lost at one point, I took it to the shop and he stuck a brand new
bosch unit on there and the car ran better than ever. I tried to avoid loading
you down with electrical techno-babble, but MAF trouble shooting can get alittle technical.

TPI

I should stress since you removed and cleaned the TB that
you could have nudged the TPS out of calibration as well.

Id confirm that is it set between .58-.62volts!

Seanmay1

What do i need to check, and how do i do that? I have only had this car for a few months and never had a fuel injected vehicle before, so its a learning experience
thanks for taking the time to type that up lol i know it took you awhile, will check all the relays and wires in the morning. Im kind of thinking its the TPS like the other guy said since it started right after i put the throttle body back on.

TPI

https://www.thirdgen.org/tpimod2

PM me if you cant figure it out, Ill break it down alittle better.

TPI

Kind of funny, as I just noticed that but..


I AM THE OTHER GUY!

Seanmay1

ok maybe i don't need to try to respond when i been drinkin a little lol. I never really looked at who it was just the post lol. Man you might need to talk to somebody about the split personalities lol

Seanmay1

Well i finally got home to check the TPS voltage, was set at .31 Not its at .54 like the write up said. But not i get back on and see that u said .58-.62 Do i need to get back out there and change it?

TPI

.54 is fine, in fact maybe even prudent. But, to get the best possible
outcome.. I like the parameters of .58-.62v, some people go higher
than that.. Not so much for my liking.


Did the car's attitude change?

Seanmay1

Well when i can get my hands on the voltmeter again I will get it changed.

Also forgot to mention i did the other things it says with the TPS. Got 4.08 at full throttle and it looked good slowly opening the throttle. It usually takes about 20 min of driving after resetting the computer before it starts it again so i should know soon if that was my problem

It doesn't feel like its driving any different though. BUT I only drove 5 min up the road to get some food (can't say no to grand ma's cookin lol). Going to get on it pretty hard on the way home and see how she does though.

TPI

Sounds to me like a minor case of the code 33 blues, my car was so bad,
hardly idled, staggered, putted and so rich my eyes melted out of my skull
when idling in the garage with the door wide open!

Seanmay1

well mine wasn't no where near that bad lol. Just loss of power while driving that would last for maybe a second. But on the way home it had a slight loss for no where near a second. But never threw a code but i guess i need to get checking those relays

TPI

If the relay suggestion is a dead end.. I wanna add that it gets technical after this
stage, pinpointing the source requires a good wiring schematic of the car.. a six
pack of beer and your voltohmeter!

Alot of dudes just throw parts at the car, at the end of the day hes spent
close to 300 bucks and more than likely still has the same problem.

I definitely dont want you to be one of those guys because of my advice!

Seanmay1

Well I don't have $300 right now lol, so i won't be one of those guys. I will be checking the relays tomorrow. Where are they exactly and what am i looking for?

TPI

Driver side corner near the brake booster, different years and models
vary but.. one should be an oval weather protected type (MAF power) and
the other should be your fuel pump/MAF burn off.. and that is black & squarish iirc.

There is pictures posted up of the most common found relay order
somewhere, I can only identify them by the color of the wiring sometimes.

Look for corrosion or an abundance of grease at the terminals, & how
the wiring is seated into the plastic connector. A soft shake and a rattling
noise doesnt really prove that the relay is toast either, your meter will!!

Seanmay1

Ok, and u said to shake them a little right

TPI

one little Mexican maraca shake wont hurt anything!

Seanmay1

I think i can handle that lol. Thanks for all the help man

TPI

I wont lie, but I spent more money than I should have. If I only
took the time to calm down and work the problem, its kinda weird
what a little age can do.. but im still a kid!

I wanna credit the mod Vader and the rest of the board for much of
what I know, he walked me through it at 19 and tried to save me money
as well.

Seanmay1

Well i appreciate u helping me so far, lets hope u can save me some money like they tried to do for you lol. Will post about the relays tomorrow morning

TPI

You sound like your confident and intelligent enough to
find the issue, at least eager to learn it.

If it doesnt help, getting into the techy stuff is pretty much
mandatory if you dont wanna pay someone to do it for you.
All the info is here on TGO, so why not give it a shot!

Seanmay1

Im pretty sure that with the right information i can get this figure out. This is just my first FI car. Always messed with older cars with Qjets so a lot of this is new to me lol. But the SES light came on again today so whatever is there is still there. Haven't checked the code yet but im sure its still 33. Bout to head out there now to check the code and those relays. Well atleast i have got my TPS set right now lol

Oh and I refuse to pay anyone to do anything other than machine work or mounting tires lol

Seanmay1

well i checked the relays. Two oval shaped ones and one square one bolted to the firewall right? None of them had any rattle when i shook them. So i guess let the fun begin lol. I need to find someone with a good MAF that will let me borrow it for a hour lol. One thing though the problem doesn't seem to happen as much since I adjusted the TPS though

TPI

The thing that concerns me is how good your car seems to run, Usually big
MAF problems occur right at start up.. 2-15 seconds or so into idling.

Imma have to break out my swapper guide or search the boards for
the steps and voltages of testing your MAF, and relays.. I wish I
had the stuff memorized.. like quite a few people here!

Plus, Im not the best helper on the forums, my brain rambles! hahaha

There is 2 oval relays, but the one you want should have a single fat
orange wire, and the square should have a tan/white pretty easily seen.
Could be mistaken, I should go out and pop my hood!

Seanmay1

these videos were made last week, car still runs great

TPI

Holy crap! I wanna live where you live! nice dig too, gotta love when
you got two fat rubber streaks tainting the streets for a few months!

Seanmay1

lol thats over at my grand parents house, about 5 min from where i live, if i did that on my street i would be sitting in county right now lol. We do a lot of dumb things out there though there is a gas station right up the street from there with a big parking lot and they hate when i come in lol

TPI

Prolly be even worse with a bandit jacket on or even a hasselhoff leather! LOL

Seanmay1

lol

Seanmay1

so, what all do i need to start checking out before i decide that its the MAF

TPI

Besides the buried wires/harness and all the relevant grounds? lol

Ill get back to you.

Well, I got a great guide from Alldata online in paper with wiring schematic
and a concise step by step how to. Now, the challenge is getting my brain to
scribe/translate it properly.

You got a fax machine or something?

Seanmay1

you could fax it to my moms job tomorrow lol

TPI

I wanna admit, I feel guilty.. Im just another lazy American.

Not really, its alot easier when you can have the information in
front of you while your in the car, and the fact it is pretty technical.

PM me!

TPI

Tried sending it over, ill try again later on in the morning. Hopefully it
gets through, and yea.. scan the info for anybody cruisin' the thread
if you can, you are the man with the game plan.

TPI

Well, since you gave me the wrong fax number and wont get it till monday...
Here is quick rundown.. ull probably need to find a schematic on the boards.

Or, wait for the fax.

sept. 1988 code 33 high diagnostics.

"Some vehicles may experience a SES light
with code 33 that is not easily diagnosed.

-Code 33 is set when voltage at pin B12 of the ECM exceeds 2.2 volts for
a second or more either at start-up OR when the TPS is less than 20% and
the RPM is than than 2000rpm.

-The ECM provdes a 5 volt signal @ B12 through a pullup resistor, this voltage
should be brought down below 2.2 volts by the MAF circuitry during the
conditions explained above, or the Code 33 will set."

A condition whereby the MAF circuit cannot accomplish this is as follows.

-A open or internmittent connnection in circuit 998 (dark green wire from
ECM pin B12 to MAF sensor pin C.)

A condition causing voltage @ MAF sensor pin D during crank/run such as:

-A short or ground in circuit 900 (black wire from ECM pin D12 to MAF burnoff
relay pin F)

-A faulty or incorrect burnoff relay.

-A short in circuit 994 (dark blue wire from pin A of the burnoff relay to
pin D of the MAF sensor.)"


I cant type it all out.. The latter half of the guide has even more, flow charts,
a schematic, and more explanations/symptoms. But, since your car is running well..
I posted a jist of it.. It is really written up well.

It will more than likely overwhelm you right now, without a schematic of the car.

Seanmay1

LOL this isn't going to be easy. Im going to end up having to sit there and study that fax for a few days before i even look at the car

TPI

Its not as hard as you think, playing the wiggle wire game and
some meter work are all that is really done. Not massive overhauls
of anything.

You can go to the autozone website and pull up a schematic
from them, but the nice guide will be there on monday. If you
gotta friend with a good MAF sensor, id call him as well.

tpis15

I also had a code 33 problem. I posted on here for help but got none. The guys on the corvette forum were much more helpfull with this http://members.shaw.ca/corvette86/Code%2033.pdf. With this flowchart I was able to easly pinpoint my problem.

TPI

That is bascially what is contained in the fax, but with concise
directions. Should be at mom's work now... But, nice addition tpis15!

That is for a '86 Y-body, might be slightly
different. You trying to say I wasnt helping tpis15?!!

TPI

She went through Sean, 5 pages + cover sheet.

You might wanna print out the schematic tpis15 posted, that
is alot bigger than the one contained in the fax, but ..the info
provided is what I want you to have!


Happy hunting!

tpis15

TPI, I was just saying that nobody helped me when I had the same problem, probably because I don't have a thirdgen. But I do have an s-15 loaded with thirdgen parts. You've been a big help to Sean .

That schematic matched my 87 f-body harness, so I'd say there the same. For future reference chevythunder.com has the same flowcharts for all of the various trouble codes. Just go step by step slowly and see what you come up with. Do this before you buy any parts. No need to waste money, especially these days. Good luck!

TPI

Well said!
and yea, I knew where you were coming from.. I was just playing with ya!

Thanks for the backup and the links!

Seanmay1

now if only i can get out there and put the info to good use. Should have the papers in my hand tomorrow and soon as all the rain this week stops i will be able to get out there and figure it out

Seanmay1

Here is the fax TPI sent me if anyone else is having these problems

TPI

Sweet deal, looks great!

Thanks Sean!

TPI

Sorry to kick what I hope is already a dead horse, how'd you make out?

Seanmay1

well the days that i have free time it seems to rain lol, then today its not raining and i have to go pull a motor for my uncle lol. Im hoping to try and work on it this weekend