I downloaded the ECM error codes and it Says the Mass Air Flow Sensor is Bad along with the Throttle Position Sensor.
(Symptoms are consistant with what the manuals say for the Mass Air Flow) Been looking online & both are $$$ Spendy! Does anyone have any knowledge on testing these to confirm they have gone bad? And/or any leads on the best place to source replacements.
Thanks for the help!
Bob

Not sure exactly how to test it but this is what I found so far...


Here's what it shows for testing the Air-Flow Sensor (pg 14-84 of the 89 Factory Service manual...)

Page 14-75 simply shows the tester so that reference is pretty useless.

Maybe someone more knowledgeable can explain how one of these puppies works so you can figure out how to test it.

Test the TPS with an ohmeter (ign off) or voltmeter (ign on), looking for smooth change in values as the throttle is moved. voltages are 0.4-1.0v, resistances are 3.5K-6.5K ohms.

No clue on testing the MAF. Its a Karmann vortex generator type, which uses an ultrasound beam to "count" the vortices generated in the air flow, and the number of vortices is proportional to air flow. The ecu reads the frequency of the detector to get the air flow, and I gues you'd need a Mitsu "multi-use tester" or a frequency counter to test it. I'd hit the junk yards and try to find a 3.0 air can.

Also remember most of these problems are not with the sensor itself, but with the wiring and harness - clean the terminals good and reset the ecu by disconnecting the battery - for 15sec., and retest.....

Hey dude,
For some reason, the last time I assembled my engine and cranked it for the first time it threw those two codes too. Dunno why - shut everything down, they tested okay, reset the computer, and I've never heard a peep out of those codes since! Try resetting the computer first to see if the codes reappear. If they do, I can post how to test them. <img src="/forums/images/graemlins/wink.gif" alt="" />

where do you find these codes? can you actually hook a computer to the car??? I thought these Gen1-2's were too old for that kind of thing. if not then where do you hook up the computer? I would like to see if mine throws any codes.

Spend 19.95 and subscribe to alldatadiy.com. Both the sensor tests and harness tests for all the sensors are described in agonizing detail. Investment more than pays for itself on your first use.

Thanks guys,
Ray,
Thanks for the reference. I've got the Hayes, Chiltons & Mitsu manuals too, Looks like I'm going to learn how to use them more effectively <img src="/forums/images/graemlins/smile.gif" alt="" /> an excelent opportunity for growth.
Fasteddy,
I'll be trying this today. I'm definately a novice @ this...but with the help of y'all I'll get there.
Doug,
I did the power-down reset of the ECM a while back in responce to the check engine light comming on, It came back on that's when I downloaded the codes. I've just got that feeling they are telling the truth with the symptoms, loss of milage (currently @ about 13 mpg) running rough ect.
StockRaider,
Yes you can. There is a Tech Article by Phil that explains this so that even I could understand.
Lochabay,
Thanks for the link, I'll have a look.

Monty's having some other issues too, need to change the PCV valve, messing with the plenum scares me, but, here I go wish me luck...
Local NAPA man quoted $487. for a Beck Arnley MAF sensor w/ $63 core,
Cheapest I've found online is $230 w/ $56 core <img src="/forums/images/graemlins/barf.gif" alt="" />
Happy Trails
Bob

I have an early post here describing my problems with my ECM. The 89 is slightly differnet than the 91, but I would bet on the ECM being the problem. Those codes were the ones mine was throwing before the ECM failed. I checked the sensors and found both of them ok. 89 ECM I believe also contains caps that leak and destroy the ECM. I would pull the ECM and look for CAP leaking. You can reset the ECM by disconnecting it the battery for 5 minutes or so. Once reset you should see the 5 5 codes with nothing wrong. You can hook an analog meter up, there is a post to show you how.
You can drive around with someone monitoring the meter to determine when the codes get set.
Good Luck
<img src="/forums/images/graemlins/cheers.gif" alt="" />