I just finished a swap from a TPI 305 to a ZZ4. 58mm TB, Big mouth, runners, and chip for ZZ4, etc.

I just started seeing a code 33 (MAF high). It's intermittant. Usually it comes on after 3 to 10 minutes of driving.

Any suggestions for troubleshooting would be appreciated.

Thanks,

Larry

 

Will the car not rev above 1000 rpm's when the code comes on? How are your air filters? If they get clogged your car obviously cant breath and i got a 33. Try replacing the MAF relay on the passenger side firewall. Relay's dont last forever so it wouldnt hurt to swap them out. MAF sensors arent as fragile as some people are led to believe. There's a good chance it's something other than the actual MAF unit

 

The car rev's fine and the air filters are new. According to the manual I need to check the electrical connections between the dark green lead on the MAF and where it connects to the ECM. There's a 5V pullup resistor on the ECM side so any interruption in the connection (open) will drive the voltage high. I'm hoping someone else has successfully beat this problem. The down side is that the car runs in "limp home" mode once the code sets.

One other problem I'm running into is that the throttle is "sticky" at idle. It makes it hard not to break the tires loose from a stop sign. The throttle doesn't seem to stick when the motor is off. Any suggestions??

Thanks

 

Swap the 2 similar relays on the drivers side firewall. One is for the MAF and the other is for the fuel pump. If this solves the problem ,then you know you have a bumbed relay

------------------
1988 Pontiac Trans Am GTA L98 5.7L, Black on Black with 114,000kms.

Best ET 14.559 @ 95.25MPH
Custom 3" Stainless Exhaust Y-Pipe back (High flow Cat and Flowmaster Mufler)

 

Other than the 2 similar relays on the drivers side firewall, there's also another relay there that is the MAF burn off relay. Might as well replace it too... I think I remember reading someone say it was only $8



------------------
1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

Thanks guys. I'll check those relays out. Today the car ran perfectly but I know that the problem will return shortly.

Larry

 

yea code 33 is a b1tch. I actually paid 13 bucks for a new relay.

 

First do the above suggestions-relays, check wiring for shorts. Then adjust the tps volt. and adjust the throttle blades so that the iac valve is about 20 counts warmed up at idle. The usual procedure for min. idle adjust doesn't work too well when you start getting a lot of mods. If you still get that %#&*%^$ code 33; then it's time to get a chip with the code 33 parameter increased above the stock setting of 45gm/sec. With your 88 it'll be a 32b tdf- it's in the ecm constants-
MAF High diagnostic (code 33)threshold. Just increase it to about 75gm/sec- that way it'll still set a code 33 if there's a real problem; but eliminate the false codes. Hope this helps


------------------
86 406

 

ive have also found that larger Tb cfm can
cause code 33. in some mapping softwares you
can kill the 33. tunercat. the MAF is measuring
airflow, but when the TPS vs flow doesnt
calc, the code will pop. just for your information
if the above relays do not fix it.
airdeano

 

Again, thanks for all the info. I'm going to get the relays this week. I've done a careful look on the wiring and I've read the MAF on my XRAY scanner while the error has been set and before it set. I saw nothing unusual. The highest value I remember seeing was 55gm/sec so I think it's a spike of some sort. I don't think the scanner would display it.

The other thing that I'm hearing is that burning your own chips becomes something that you do as you get deeper into this hobby. Are there any general recommendations for the equipment?

Larry

 

55gm/sec will do it- The code sets when it sees over 45gm/sec at less than 2000rpm and less than 1/4 throttle. Check out the diy-prom board and read the article linked at the top of that page for prom burn info-great stuff there! If you're going to con't to mod things then it's definatly worth while to learn to burn!


------------------
86 406

 

They should put a Board up just for the "Code 33" LOL... But my problem was intermitent as well. It would go 2 weeks without a problem, then bang, the gutless bird was back. So I bought both relays. The next time the car ran like a bag and the SES light came on, I replaced the power relay, and never again... fixed it up. Its a very common problem, and unfortunately a lot of mechanics will get you to replace the MAF at a 300dollar replacement charge.. and the code comes back in 2 weeks, and then they say they can't take the new MAF back.... its horrible.

Good luck

------------------
1988 Pontiac Trans Am GTA L98 5.7L, Black on Black with 114,000kms.

Best ET 14.559 @ 95.25MPH
Custom 3" Stainless Exhaust Y-Pipe back (High flow Cat and Flowmaster Mufler)

 

Thanks for all the advice guys. Today I should get the answer. When I pulled the MAF burn off relay I found that the connector was trashed. It looks like quite a bit of heat has been generated at the connections but the wire looks ok going into the connector. This would tell me that either the relay is generating a poor connection and arcing is occuring at the terminals or I have a short. I think a total short would do a fuse and is low probability. I have the new relay and will pick up a new pigtail today. I'll post the results when I'm through.

Thanks again,

Larry

 

Ok, I put in the new relays and soldered in a new MAF Burnoff relay connector. I still have the same problem. I did manage to monitor the MAF flow in the driveway in park.
At idle it is around 7-9gm/sec. If I give the gas a stab I see numbers for an instant go up to 125gm/sec. The code doesn't set under these circumstances. The code sets after several minutes of driving and appears to come on after some fooling around at partial throttle. The car runs great until the code sets - then it's limp home and non ideal operating conditions. Any help would be appreciated this is the last problem I need to overcome for a nice ride.

Thanks.
Thanks

------------------
88 IROCZ28
ZZ4, Big Mouth, Lg. runners and BBK 58mm TB. 700R4 w/ corvette shift servos, 3.23 Borg Warner & posi.
B&M 2400 Hole Shot and MegaShifter. Random Tech Hi Flow Cat and 3" Catback system, Edlebrock headers - jet coated.

 

First check the seal around the edges of the MAF... make sure there is not alot of outside air coming in through the MAF. The only air that should pass through the MAF is the air coming through the breather box and through the ducting. If you MAF is pulling in outside air it will set code 33 while driving, mine did. If your seals around the MAF are ok and it's not pulling in a whole lot of outside air then you probably have a faulty MAF and you should replace it.



------------------
1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.