DannyT

Thought I'd post this here too:

According to my AutoXray my MAF is registering 3228gr/sec with the MAF unplugged and the car running or not. I've heard that the AutoXray can be inaccurate but I'm wondering what readings others are getting with it unplugged. Please let me know what type of scanner you are using also. Thanks.

DannyT

ttt
anyone?

DannyT

Wow, I know people have scanners. Maybe I'll rephrase the question.
If I am getting improper MAF readings (3228gr/sec) with the sensor unplugged is it more likely that my scanner is bad or can the PROM have the wrong values on it?

ski_dwn_it

I guess I would have to ask, why you trying to scan the car when the MAF is unplugged? What values do you get when its plugged in?

DannyT

All of my readings are out of range from what everyone else is getting. I'm getting readings in the 13000 gr/sec range with it plugged in around 3000 RPMs and someone suggested that I unplug it to check the default reading.

Mangus

sounds like a bad MAF to me, based on your plugged-in readings.

DannyT

But how would that explain the off the chart readings with it unplugged?
I thought the max reading was 255 gr/sec? Someone else suggested a bad ECM or scanner. I just wasn't sure if AutoXrays were notorious for data errors.

Mangus

I've never had a problem with my AutoXray.

And although I'm no expert, asking "what about the reading when its unplugged?" is like asking "why doesn't that light bulb work when its not plugged in?".

A quick, free way to find out is to find someone else with a 3rd Gen MAF car and swap them out for a minute. Takes about 10 minutes to and from.

DannyT

Um no, that's not the same. I didn't say "Why doesn't my MAF work when it's unplugged".
My MAF readings when it's connected are off the chart. Instead of a max of 255 gr/sec I am getting readings in the 1000s whether it is connected or not.
Someone suggested that I unplug it and check to see what the scanner sees and that the default reading should be 255 gr/sec. I'm just wondering if that is true or not.
If you want to help me you could unlpug your MAF and tell me what your Auto Xray says.

ski_dwn_it

How does the car run?

I would try to find someone elses car to scan and see what they get. If you get funky numbers again. Its the scanner. If they are right, then you have some trouble shooting to do. I suspect if the car is running well, then its most likely the scanner. Call AutoXray and see what they say.

Gold86Vette

I would say if the car runs and feels right then its the XRay data. If it runs rich all the time check the MAF for a short or replace the computer. P.S. what year is your car? I have 2 extra ECM's due to the fact that my AUTO XRAY wouldn't comunicate with my 1986 ECM. TUrns out I am missing pin "m" in my aldl. I am still unsure about that issue. I can scan data when the car is set up as 1985 but at a slow speed of 160 baud. Its better than nothing. If you want to borrow an ECM let me know they are 165's.

DannyT

I get an occasional code 33 "MAF high". When the code comes on the car starts running really rough, almost like it's running out of gas. It's fine at WOT though.

BTW it's an 89 L98

Grumpy

The 165s are notorious for having problems.
They just didn't use enough solder.

Autozone, as well as a few other stores used to have what's called a break out box, where you could plug this devise into your car and check all the sensors.
I'd do that first.

If it passes that then get a junkyard ecm and try it.

Does it set a code with the MAF unplugged?.
If it doesn't then that would sure seem to indicate the ecm is bad, assuming the wiring is intact.

Always the chance of several things at once being wrong.

And it's always a good idea to have a known good MAF and 165 around.

Gold86Vette

Danny what is up with code 33? I have had this code intermitently more often than not recently. WHen it is lit the car runs like crap. It won't even rev higher than 5500 in first 4500 in second and even lower than that in third. The O2 sensor leans right out to 0 mv. ANy Ideas what would cuase it to light? It has been off only 3 times in about 50 trips. Its quite annoying feeling like you are going to stall at part throttle and having no power at full throttle.

DannyT

It could also be a bad MAF connection. It usually only does it at very light throttle and even that is intermittent. It has only happened once at about 75% throttle and the car coasted for a good 4 seconds as if the spark/fuel was cut then came back on and ran fine.

Gold86Vette

We received a code 33 (Mass Air Flow sensor high). When talking to Myron for the second time, he asked if the car was driveable. Apparently when a code 33 reveals itself, these cars normally go into a limp mode, locking the car at 22-degrees of timing, which causes terrible driveability. Interesting, but that wasn’t the case with us. CC

This is from an article in car craft.
I wonder If I am in limp home mode 95% of the time.

Gold86Vette

Just got back from a LITTLE test drive where the code 33 wasn't on (after resetting the ecm) . Can you say throttle respnose?????
well it didn't last too long , about 2 minutes into it the code came back and the car barely made it home. The MAF only reads a max of 165 when the code 33 is present. any ideas????