Thumper

I have been getting a code on my '89 lately and I didn't know what it was. I just pulled them and it said I have a "Code 33"--Mass Air Flow Sensor Circuit. What is that? Where is it located on my '89? And how do I fix it?

JAKE

The MAF sensor is located at the front of the engine, sandwiched between the air filter housing and the accordian which leads to the throttle body. It's rather rounded in shape and is about five inches long. Should have the word Bosch or Delco stamped on the top along with some other identifying info.

From the passenger side you can see a plug in connector on the underside of the MAF.

It could be that just the connector is loose and only needs to be pushed in tightly. Wiggle the connector as you push on it.

If this doesn't solve the problem there are a couple of easy things you can do to check it.

With the engine idling, use the handle of a screwdriver and tape the bottom of the MAF, remember, TAP, DON'T GIVE IT A HARD BLOW.

If the idle flucuates, the sensor is bad and will need to be replaced.

The second thing is to remove the MAF. This only requires disconnecting the two clips (using the tip of a flat blade screwdriver) that hold it to the air filter housing and loosening one screw clamp. Unplug the sensor connector carefully.

Once removed, look through the wire screen to see if tany of he very thin wires near the center of the MAF are broken. If broken, you'll need a replacement MAF too.

If the wires are okay and the idle speed didn't flucuate when you tapped the MAF, it's got to be in the wiring. I believe the burn-off relay gives a different code, but I don't have my manual to verify this.

You'll need a Service Manual in order to test each wire connection.

Hope this helps.

AKS Racing

Thumper,
A code 33 indicates that the maf has detected excessive airflow based on the RPM and load requirements of the engine. This is a common code for larger displacement engines still utilizing the factory ECM. The MAF in your car is a Bosch unit. I would imagine that the code sets when you are running down the road at a continuous rate for longer than 6 seconds. Mine have always set in this manner.

This problem will have to be addressed in programming.

BTW, I am getting a code 33 on my '87. I used to get a code 34 (which is the opposite) every time I blew the inlet tube from the blower to the TB. Don't have this problem anymore, now fight the code 33.

That's all I have at this time. Maybe some of the tuners can chime in. Formato has fixed this in the past for me.

Aaron

Marcho Polo

Code 33 is a pain. If you get a chance to come over tomorrow I can help you with it. I'll be home all day removing the intake and re-installing, so feel free to swing by. When a code 33 sets, the computer runs in limp mode and the car runs like crap. Your car might be the relays..... I had a spare MAF, but I gave it to Chef since I didn't have a MAF car anymore :(


But I had a bad problem with code 33 on my '85, and pretty much know that entire circuit by heart. Did you know that your Torque Converter Clutch Solenoid is on that circuit? If it shorts out, you'll get a code 33. Check your 'guages' fuse, too.... if it blows, you'll get a code 33.

99% of the time it's the maf relays or the maf, but there are other things on that curcuit that can be misleading....

AKS Racing

Marcho Polo,
Are you saying that the code 33 does not relay to excessive air through the maf relative to RPM and load? I have understood that this was my problem in several stroker applications. Please correct me if I am mistaken.

Thanks,
Aaron

Thumper

Thanks for the reply's, this is very helpfull. I thought this had something to do with me still having the stock programing on my 383, but when I spoke with someone at 2 diffrent tuner shops and told them how the car was acting they both said they had never herad of that problem. It's definately pulling more air in through the super ram and 383 and it usually happens at highway speeds, although it has happened twice when I was accelerating away from a stop light. Someone mentioned to check the MAF on Tuesday so I disconected the conector and hooked it back up. The car did run better after that so it may have just been loose. I pulled the MAF off today and the wires on the inside looked OK although the screans are removed. Tomorrow I'll reset the computer and do the "tap" thing to see what happens. I'll drive it around a little also and then check to see if it throws the code again.
Craig--I'll give you a call tomorrow. If possible it might be better for me on Saturday.

drive it

First rule out any possible problems as Craig said above; relays, fuse, bad connection etc. Then since you've modified the maf and have more cubes I'd say it's time to burn a chip- (been there, done that) The ecm sets the code 33 when it sees over 45gm/sec at less than 1/4 throttle and less than 2000rpm. Under ecm constants there is a "Maf high diagnostic (code 33) threshold" it's set at 45gm/sec in a stock program-just increase it to 75 or so and it will eliminate the false code 33, but still set it if you have a real failure. Hope this helps :)

Marcho Polo

Oh, you're not mistaken... you're correct in the code. Most of what I said is when dealing with a stock or near stock motor. I forget that Thumper has a stroker. I've heard of people with 383's that don't have a problem with MAF's and code 33, but it's entirely possible that a stroker could suck too much air past the MAF wires. With too much air going past the MAF wire the resistance is too high and that could set a code. Code 33 is definately a tough one to narrow down sometimes.

Mr. CJ

Sounds like its time for a custom chip, the stock one, although very good, has its limits with such mods as yours.

Juliet

For what it's worth - While I was diagnosing my 32/34 code issues I ran the car with the MAF sensor plug completely disconnected. The car ran like crap, but ran, and gave a code 33. When I reconnected it / reset the codes I never saw 33 ever again. Maybe it's a simple clean out the connector deal? :seeya ~Juliet

Thumper

Well after resetting the codes it hasn't happend again...yet.
drive it--Thanks for the input, I'll have that changed so hopefully everything will be fine.
Craig--I'm still looking to hook up with you but it's just been real hectic for me lately.

89 Bob L

I have found that it is usually the simple items regarding the MAF, poor connections or time to change the relays ( located behind the battery on the firewall.