The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support Morrison Fabrication

MAF or MAS test / check

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Artago

15+ Year Contributor
2,090
26
Nov 30, 2006
North Vancouver, BC_Canada
Hey all, I was wondering if anyone had a link for a MAS / MAF test? I need to check mine out and make sure it's working correctly.

I don't have any CEL errors but I'd still like to make sure it's metering air properly. Does anyone know how to test it? Or maybe have a link to a test procedure write up?

Thanks,

Tom
 
A logger like a palm or dsmlink would most likley tell you if its working. But if your honeycombs are fine, and its a stock MAS and no cel, it should be fine.

Thanks for the reply. So there is no way to test a MAS (which is not throwing a CEL) without a logger?
 
I am also curious about this, aside from popping it in the car and driving around to check the airflow, is there a way to test it with a multimeter?
 
Backprobe terminal 4 of the connector with the positive probe of the voltmeter and connect the negative to the ground. Turn the key to on but do not start the engine if the voltemeter does not read around 12v. If so check the circuit back to the MFI relay and fusible link.

Backprobe terminal 3, it should read 4.8-5.2v with the key on. If not check the circuit to the ECU.

Backprobe terminal 5 with an ohmmeter and measure the resistance. It should be less than 2 ohms. If not, check the circuit from terminal 5 back to ground.

If none of the above work, the MAS or ECU is dead. Replace it.
 
Thanks for the information. I will check the 5 maf sensors I have tomorrow.
Where did you find this information?
 
Also when idling terminal 3 is a square wave but should average 2.2-3.2V. And terminal 7 should be 0-1V at idle and 6-9V at 3000rpm. There are also intake air temp and atmosphere sensors in there which if you really really want I can specify.
 
Unless it is not in the manual then please let me know. I have a bunch of mafs kicking around that I was hoping to test without swapping into the car. If I can just plug them in and turn on the key then take a few readings that would be great.

Thanks
 
I was looking for this info for a 2g maf so this is exactly what I need.

Thanks
 
Ok again for 2g:
- Barometric pressure sensor: With key on, pin 2 should be 3.7-4.3V at 0' altitude and 3.2-3.8V at 3937' altitude.
- Air temp sensor: see attached picture.
 

Attachments

  • Air temp sensor test 2g.jpg
    Air temp sensor test 2g.jpg
    66.7 KB · Views: 1,052
Also when idling terminal 3 is a square wave but should average 2.2-3.2V. And terminal 7 should be 0-1V at idle and 6-9V at 3000rpm. There are also intake air temp and atmosphere sensors in there which if you really really want I can specify.

Can you please specify how to test the air intake temp on the maf with a multimeter?

Im trying to break down on cracking down my stock boost gauge issue.

yes i have a manual boost controller, but my problem is the stock boost gauge is metered by how much air is read going into the intake. Now i have no boost leaks, and on light throttle the stock gauge skyrockets up, while my manual gauge builds no boost... I almost have to floor it to start building boost. Once again, no leaks, Pulls hard at WOT but extremely laggy and reading high air intake volume if anyone understands that.

EDIT: Im surprised i didnt see it.. i feel dumb.
 
Last edited:
Backprobe terminal 4 of the connector with the positive probe of the voltmeter and connect the negative to the ground. Turn the key to on but do not start the engine if the voltemeter does not read around 12v. If so check the circuit back to the MFI relay and fusible link.

Backprobe terminal 3, it should read 4.8-5.2v with the key on. If not check the circuit to the ECU.

Backprobe terminal 5 with an ohmmeter and measure the resistance. It should be less than 2 ohms. If not, check the circuit from terminal 5 back to ground.

If none of the above work, the MAS or ECU is dead. Replace it.

Just did this test. Everything was within range. Resistance at terminal 5 was around -12 ohms.

I've been doing research because I have a P0105 that came up yesterday right before I was about to hop on the rollers to get smogged. EVAP passed just fine, but the tech said he didn't think it was going to pass because my car took up the entire time allotted for the 1st portion. He was cool enough to let me know he could stop the test and take it home to fix whatever was going on. I don't think it had to do with the fact that I cleared the CEL right after I noticed it because I have a 1995. Apparently they didn't start doing the OBDII monitor deal until 1996.

The car was non-op for the past 1.5 years or so, and I did notice that one of the recent time I started and drove around that the stock boost gauge needle wasn't moving at all. It also was hesitating really bad around 2.5k keeping me form boosting. After arriving home the same day and starting it back up, the problem went away. I think the MAF might be on its way out, but is testing fine at the moment.

I also had a injector #1 code (forget the actual code) but that hasn't come up in the last few days after I had sprayed some cleaner and made sure the connections were tight. I'm still considering having the injectors cleaned and tested though.

I'm going to check out the plugs and check the resistance in the wire tomorrow to rule those out. I was really hoping to have my car legally on the road since I haven't driven it in so long.
 
Have you performed a BLT recently? P0105 is BARO Pressure Circuit Malfunction. OBDII testing was federally mandated in 1996 requiring all vehicles to be compliant... Some companies were ahead of the deadline.

I just read this revived post a few days ago when I had troubles, Hope you figure it out. Gotta love Cali emissions!
 
12 ohms on terminal 5 is a little high (you must measure this resistance with key off otherwise you get bogus results, like a -12 ohms for example - if that's what you did). It is a sensor ground which should be connected to ground ONLY inside the ECU through pin 92 (should be less than 2 ohms). Or you can measure voltage on this pin with key on (should be less than 0.2V).

You can clean the injectors yourself: http://www.dsmtuners.com/threads/cold-weather-engine-issues.448803/#post-153136134.

P0105 is Barometric pressure sensor - see post 12.

And post 8 for couple more tests while running.
 
12 ohms on terminal 5 is a little high (you must measure this resistance with key off otherwise you get bogus results, like a -12 ohms for example - if that's what you did). It is a sensor ground which should be connected to ground ONLY inside the ECU through pin 92 (should be less than 2 ohms). Or you can measure voltage on this pin with key on (should be less than 0.2V).

You can clean the injectors yourself: http://www.dsmtuners.com/threads/cold-weather-engine-issues.448803/#post-153136134.

P0105 is Barometric pressure sensor - see post 12.

And post 8 for couple more tests while running.

Yes, I was following post #5 and the first two steps mentioned turning the key to "on," so I figured it was the same for that last test.

I guess I'll just try accessing pin 92 on the ECU.

Update: So I did the MAF test and checked the reading before and after I provided heat from a blow dryer. With the voltmeter set to 2,000 testing between 5 + 6 was around 1600 (with ambient temperature at the time around 80 degrees). With heat applied it dropped to about 1,000 so it looks like based on the test the MAF is fine.

I also re-did the ground test and it tested around 1.6 ohms. I did the backprobe method again.
 
Last edited:
Have you performed a BLT recently? P0105 is BARO Pressure Circuit Malfunction. OBDII testing was federally mandated in 1996 requiring all vehicles to be compliant... Some companies were ahead of the deadline.

I just read this revived post a few days ago when I had troubles, Hope you figure it out. Gotta love Cali emissions!

Last time I did a boost leak test was some time ago, but the only leak I recall was a small one at the TB (was worse before I replaced the o-rings on the TB plate).

I'm currently waiting on my injectors right now. I have them with a local vendor performing cleaning/testing. Since the failed smog, I've replaced the plugs with fresh BPR6ES gapped at .28, new Taylor 8mm plug wires, and a Wix 33288 fuel filter. It looks like the MAF tested okay and the coil tested fine too. I'll update you guys on the injectors once I give the guy a call tomorrow.
 
Last edited:
I am trying to determine why my car is running like it has a blown IC coupler, and I am getting P0100 code, and probing Pin 5 to battery ground I am getting 125-180 Ohms of resistance.

Should I unplug the connector and see what the resistance is? I really hope it is a bad Maf and not a burnt sensor ground. I've run out of possibilities now.

Gonna check my data stream and see if my other sensors are reading something that indicates they are functioning in the morning.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top