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Understanding MAFs and their part numbers

34K views 79 replies 10 participants last post by  FRR35H 
#1 ·
Hi All,

Not sure how relevant this is to most of you folks but I had some issues recently with my MAF.
I kept getting told by many very knowledgeable people that any MAF will work regardless of year or model. Every thread I read said the same thing. However...... my car is a JDM TT so what has been said on all these threads appears to be correct for USDM models ONLY.
I had some issue which I suspected was my MAF. So in all my wisdom I cleaned my MAF with electronic parts cleaner. This made my car undrivable as it stumbled and lurched constantly. I cleaned it again and it came good for about a week. Then back to the same issues. Then one day it threw a CEL pointing to code 12 air flow sensor.
I bought a replacement going on the above rule that any version will work.
I had a 165 which I replaced with a 337. The stumbling issues was gone but now I had a different CEL. Code 25 this time Barometric Pressure Sensor. I had the seller send me another one just incase it was a dud. Next one was a 789. Same issue.
Ran through diagnostic process in the service manual and confirmed wiring is all OK.
Did more reading and searching on ASA/CAPS on both JDM and USDM versions and found the part numbers listed for both are the same.
I then had a light bulb moment and worked out what the numbers mean. The 3 digit number is actually the last 3 digits of the part number.

So:
165 = MD170165 [1st gen TT/VR4]
618 = MD183618 [2nd gen TT/VR4]
337 = MD357337 [NA]
338 = MD357338 [NA]
055 = MD151055 [NA]
789 = MD187789 [NA]

From this brainwave I realised the 2 parts I had tried are both from an NA version.

I then sourced another 165 and fitted it tonight and car is back to normal. No CEL.

So... moral of the story is. If you have a USDM 3S then you should be able to use any MAF version. However even 3sx sell a different part number per version so I would attempt to locate the correct part number.
If you have a JDM GTO then you MUST use the correct part number.
I can only assume this is due to the differnt ECU used. I am yet to check the ECU part numbers for Europe yet as I haven't installed EU ASA. Once I have done this i'll check back.

These are the threads I had running incase it's helpful to anyone.

http://www.3si.org/forum/f1/issues-using-alternative-maf-part-number-502142/

http://www.3si.org/forum/f1/cel-code-25-barrometric-pressure-sensor-501593/

http://www.3si.org/forum/f155/australia-anyone-got-1st-gen-maf-spare-502208/

Sorry about the length but hopefully it will help someone in need.

Cheers,

Joe
 
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#2 ·
Glad you solved the puzzle Joe, sorry I couldn't be of more help.....

Bob. :)
 
#4 ·
According to JDM ASA it's for a Pajero V6. According to USDM ASA it's for Pajero, L200, Diamante and FWD NA 3S.
I actually thought this might get more hits than it did considering all the peopel that told me any version would work. Cost me $100 to work this out LOL.
 
#6 ·
Thanks for that! I just completed my TT conversion, using a JDM ECU and got trouble codes 12 and 25... I shall pull the ECU tomorrow and read the numbers so I can source the proper MAF sensor! :)
 
#8 ·
This is exactly what this thread was about. Every time the Americans tell up any maf will work but that is NOT true with JDM cars. You must have the correct number or you will get a CEL.

Sent from my GT-I9300
 
#10 ·
Only thing you can clean on the maf is the IAT sensor (the reisistor just behind the vortex column), if you spray anything into the maf at best it will do nothing; at worste it will ruin it.

Good info on the numbers, some cars have less wires going to the MAF connector so it makes sense some MAFs doint have all the sensors..
 
#13 ·
Okay then, I just purchased a 165 MAF since I am using a '93 TT ECU. Thanks a lot for all that info!
 
#14 ·
This is a JDM issue ONLY when doing a conversion. Took me a little while to work it out but here is the fix....


You need a 7 wire MAF plug which is TT only on JDM cars..from my research ALL USDM cars are 7 wires..both NA & TTwhich is why they don't have this issue.

The two missing wires from your harness are a green wire and an orange wire.


I needed to run a wire from Pin 1 (green)of the MAF plug to PIN 61 of the ECU and another from Pin 2 (orange) of the MAF to pin 65 of the ECU.

It didn't make any difference whether I ran my NA maf or my TT maf. The codes only cured when I fitted the missing wires. :):)
 
#15 ·
Shoot, I already spent $100... Oh well, at least I know how to fix the problem for sure now. I would have been stumped after installing the 165 MAF and discovering that the engine light was still on! Oh well, now I will have two spare MAFs... Thanks for that info!
 
#16 ·
If you are running a first gen ecu then you would have needed the correct maf anyway. Sounds like he is on the money with your issue with the 2 CELs but you would have still had 1 CEL left. I have tried an NA maf on 2 first gens (90+93) and both had the same issue. Perhaps later model ecus don't have the same issue???

Also my apologies. I should have picked up that it was something else since you had the 2 error codes. I assumed you had swapped in a TT engine bay wiring loom.

Sent from my GT-I9300
 
#17 ·
It's okay, I will swap the MAF first and see if the codes go away and if not, I can do the additional wiring. I can always sell the additional MAFs I have, but I prefer keeping a spare just in case, because our cars are getting older and parts getting more scarce...
 
#19 ·
Yes yet need to disconnect the battery to clear the codes. Also I would connect up the TT MAF or you might find it still has a cel after clearing. As for using the usdm wiring pin outs for a jdm car I'm not sure. Hopefully he can chime in and confirm the pins for you. Connecting them to the boomslang isn't an issue as the ecu will still get the signal.

Sent from my GT-I9300
 
#20 ·
I will try to clear the codes tomorrow and see if I get any luck with it. Thanks!
 
#21 ·
Well, I reset the ECU by disconnecting the battery today, but the check engine light still remains... Also, the car idles rough when cold and stalls, unless I give it some gas to keep it going for a bit. When it warms up, it doesn't stall while idling, but it does stall when I switch to let's say reverse and hit the gas and then release it repetitively to back into a parking space, for example. I have an NA MAF on the car at the moment, but since it was mentioned that the MAF is not what causes the issue, then I am assuming it is something else. I do have a TT MAF here, so I might just install it and see if that makes any difference, but I have a little faith in that... Any other suggestions?
 
#22 · (Edited)
I scanned the car with the HHH and found the same trouble codes as before 12 and 25 - barometric pressure sensor and mas air flow sensor. They are both MAF related. I also took a picture of the log so I can post it up here and see if anyone could notice anything wrong in it. What surprises me is that the log shows that the AC clutch is OFF and the AC switch is OFF while the AC is on. It also shows that the power steering is not active. Also, the idle with the AC on varies between 558-585 and with the AC off it actually goes up to 671-735. I can also hear the AC clutch come on and off when the RPMs increase or decrease suddenly. The last thing started happening when we recharged the AC system with Freon yesterday. When I turn on the AC, the RPMs do not go up, but actually decrease... The last thing I noticed is that when I turn the steering wheel at idle, the RPMs do not move at all. Here is the pic...

***EDIT***

1. How come the log shows front and rear oxygen sensor readings if the ECU is JDM and they only have one?

2. Is the injector duty cycle normal at 1%? I am using resistors for the TT injectors...

3. Is MAS airflow normal at 0.0Hz or does that value mean that there is no signal?

4. Is timing advance normal at 16 degrees?

I have checked the ECU before installing it a month ago and the car has not been driven, but from the shop to home since.
 

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#23 ·
I installed the TT MAF (165) and reset the ECU = still check engine light on... What should I do next?
 
#24 · (Edited)
Okay, I went to get an expert opinion form a certified Mitsubishi technician and got this information from him:

The ecu connections are the same, but the MAF and ECT should be on different locations unless the GTO has a completely different manufacturing structure than 3000s which is not very likely.

On a 95NA for example the ECT is wired into ecu 83 and 92.
On a 93TT the ECT is wired into ecu 63 and chassis ground.

On a 93TT the MAF wiring goes to ecu 19 52 61 65 70 and chassis ground
On a 95NA the MAF wiring goes to ecu 19 70 72 and MFI 12V


Again it could be that the GTO uses a completely identical harness structure that is different from US 3000s.... I doubt it though. I'm staring right at the schematics and unless these are all incorrect, the wiring is different.


Lots of MAFs "will work" since the connections are the same on most. All NA 3000s are the same MAF, which happens to be the same MAF used for 94+ twin turbo. 91-93 twin turbo uses a different MAF

How in the world did other people's cars worked fine after TT conversion was done with different years ECU is beyond me if all this is true...


***EDIT***

Okay, he was looking at California spec so the numbers above are not correct. Here are the corrected numbers and his suggestion:

Sorry I made a mistake on the 95NA ECT, it should be 63 and 72 (same data but sensing ground). The pins I quoted were for California spec.


Honestly it would be in your best interest to swap the harness over. There are only a few differences, however they are rather important. Specifically the sensed ground for certain sensors versus a chassis ground.
Of course since you are reverting to the old style set up this isn't as big of a deal since you can just wire in grounds manually..... you are still talking about some significant wiring modification. It would be a ton less work to just put the right harness in there.

I don't know what to do now. I surely do not feel like changing the whole harness though...
 
#25 ·
Some of that info is wrong. The 94+ MAF is not the same as the NA MAF. Is the current CEL [with the 165 MAF installed] the same as before?

Also I just looked up the dates for when the MAF part number changed over and after the 10th month of 1992 it changed to MD183618 [the 618 MAF] so I hope that's not what's causing the issues. What is the part number of the ECU you are using?
 
#26 ·
Well, I haven't scanned again, but the check engine light is still on and the idle is just as crappy...

Is that change for the TT or the NA MAF? I found one, but I am afraid of making another purchase that I don't need to...

I made the mistake of not writing the TT ECU number when I was installing it so I may have to take it off again and see it.
 
#27 ·
That's the tt ma I'm talking about. If the ecu you have is a 93 then you should have a 618 maf but I need to check the ecu part number first. The one thing I was unable to check was whether the 618 maf worked on my car or if a 165 worked on a newer tt.

But fastbikes says it worked for him once he did the wiring changes. Hopefully he can comment on the correct pins. Maybe send him a pm?

Sent from my GT-I9300
 
#28 ·
So, let me make sure I am understanding this right - the TT MAF changed from the 165 to the 618 in late 92? If that's the case, then that could be the problem with my car. Tomorrow I will pull the ECU and get the number from it and post it in this thread so you can check it. Just remember that my ECU is JDM if that matters at all.

I will send PM fastbikes and hopefully he will respond.
 
#29 ·
Yes that's correct if your jdm ecu is from a 93 model then it should be a 618 maf. However fastbikes said it didn't matter on his after he added the new wires. But also he was using a different ecu from you. Both jdm though.

Sent from my GT-I9300
 
#30 · (Edited)
What ECU was he using?

By the way, the Mitsu specialist told me that all the cars produced June of 93 and later were considered true 94 models and had the 618 MAF. He thinks that since my ECU is 93 then I need a 165 MAF for it. And yet, I have it installed and the problem still persists... Also, I can't seem to locate a 618 MAF easily and the few that I saw were around $400... If all the TT cars produced after June of 93 came with 618 MAFs, then how come they are so hard to find?

***EDIT***

After some research, the Mitsu expert retracted his previous statement and said that:

"I just pulled the cross reference for every 3000 model I can find......
When talking about US market models, correct TT MAF went to 618 in June of 93. When talking about far eastern markets (not specifically Japan, but Asia/NZ/Aus) 165 is used through September 1992 and 618 is used from October 1992 which matches the information you received prior too. Further, (unrelated most likely, but interesting none the less) UK market MAF is 618 for all years 3000GT."

He also said that:

"The order of the wires will not change on the MAF.... Again my comment about the adding wires complicating things is not at face value.... it is what the fact represents. The JDM NA ecu is wired differently enough to not have those two wires (so you had to add them for the JDM TT ecu).... what else might be different? Maybe nothing, but unless we can find a JDM NA and TT schematic set to compare we can't say for certain."
 
#31 ·
Actually, I find many MAFs that are listed under the MD183618 part number, but when I see the pictures, they have a different three-digit number, such as 609... Could it be that the three big numbers on the MAF are not necessarily part of the part number?
 
#32 ·
No the 3 numbers on the maf are the last 3 numbers of the part number. If the picture says anything other than 618 then it's not the correct part. Or the picture is wrong. However don't buy anything until I check your ecu part number. It might not be a 93. Need to confirm 100% first.

Sent from my GT-I9300
 
#33 ·
Okay, I will do that tomorrow. I can't find a 618 MAF for a decent price anyway. If I am going to spend $400 on a MAF, I might as well buy a different ECU instead...
 
#34 ·
On MY jdm car I can run ANY TT ecu without any problems...I can also run an NA or TT maf without any problems.

The two issues I had is if I ran a 91 to 93 ECU I couldn't log as the protocols are different, but if I ran a 94 to 99 ecu it works perfect and obviously I can log fine too.

Running both a NA maf and TT maf gave me a CEL with AIT and BARO codes but the car started, drove and idled PERFECTLY. the only cure for that was too add the two missing wires form the NA harness back to the ECU.

My car is a 97 JDM NA manual and as such the JDM TT ecu plugged 100% straight in with absolutely no wiring to change (well apart form the two maf wires I had too add).

I cant really help anymore as your car is an auto and I simply don't have any knowledge of them at all :(
 
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#35 · (Edited)
Well, I followed big tyla's thread about wiring up a jdm ecu on an atx and there he says that it is of utmost importance to cut the wire going to pin 71 in the ecu and grounding one of the ends or the ecu will get damaged... Now I am thinking that this may be causing my problem if your car worked perfectly with all the wires staying intact. I might try that. Also, my ecu is a 93 so that may be the reason. Are the mk2 jdm ecus also three plugs?



***EDIT***

I can log with my HHH, because someone made me a cable with OBD II connector and OBD I software on it. That way it plugs into the OBD II port in my car and then communicates with my JDM OBD I TT ECU...
 
#36 ·
Here is the number of my ecu.
 

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#39 ·
I am starting to wonder if an o2 sensor can throw these codes...
 
#40 ·
The way asa list the production period is strange so it's problem June anyway. That ecu was used for all early cars so I suspect that in June they changed the cas and maf which required a new ecu revision. It's possible that the cas issue is causing the rough running. You might need to change the cas wiring. If you unplug your maf do you then get 3 codes? And 2 when plugged in? Is it possible you wired them to the wrong pins?
Fastbikes also used a newer ecu from memory so it's possible the pins are different between yours and his.

Sent from my GT-I9300
 
#41 ·
If this ECU is for the earlier cas and cam sensors, this means that the guy who sold it to me cheated me. This annoys me very much, because I traded him my LED tail lights that I had bought for $500... On the other hand, wouldn't it throw codes for those sensors if that was the problem?
 
#42 · (Edited)
Screw this! I will just buy another ECU. I will get a USDM one this time since I have no idea where to find the correct JDM one and what number it should be... How would I go about rewiring the sensors anyway? I will need to go back to the old sensors which are probably more expensive than the ECU...
 
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