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4 to 6 wire MAF conversion (need info)


Yokohama
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I know there have been a few people who said they have converted a 4 wire MAF (86 back) to use a 6 wire 87-89 MAF. I have searched a lot on the forums, but there is no write up/wiring diagrams as far as I can tell.

 

Also, I know that the 83 has been converted to use the 1G MAF, but are the stock MAF pinouts the same for 83-86 4 wire MAF's or are the 83's using a different MAF pinout from the 84-86's?

 

I have the connectors and MAF from an 89 so I plan to make an adaptor harness so I don't have to cut into the stock 86 harness.

 

Thanks!

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When you swap, you don't use the "Temp sensor B/baro" circuit. The 86 has an external sensors for this so you won't need the DSM parts.

 

Check the FAQ/How To's, lots of info there:

http://www.starquest...hp?showforum=55

 

Or check the Engine and Performance Mods section (would be easier to search without all the questions that don't belong in there, I cleaned up some but there's a lot lol):

http://www.starquestclub.com/forum/index.php?showforum=15

 

Here's the one specifically related to your question:

http://www.starquest...showtopic=28050

86 AFS: ------------------- DSM AFS:

 

green/red ----------------- green/orange

red ----------------------- green/red

black --------------------- green/black

white/black --------------- green/blue

new > A 16 ---------------- green/yellow (Run from pin A16 on the 86 ECU "B" connector)

new > +12 Switched -------- red

n/c ----------------------- green/white (NO CONNECTION NEEDED)

you just need 2 wires of 14-16 gage and run them from the ECU "B" connector to the MAS, you'l have to poke through the fire wall for that, but there are several places to go though. If you look on the 86 wiring chart, you can find the nessesary +12 v and ground to use for this DSM MAS.

 

Also here it says to leave the green/yellow disconnected:

http://www.starquest...?showtopic=8874

Ok guys, I don't want to post this like it was a simple job. -It took a lot of work to figure it all out but now I know what to do it should be easy for all of you 86 guys to get this to work. -Keep in mind the only way this would really benifit the 86 guys is if you have some mods and you are running a Fuel Cut Defencer. -I will list my mods just so you can get an idea:

 

86 AFS - - - - - - - - - - - - DSM AFS

grn/red - - - - - - - - - - - - grn/orng

red - - - - - - - - - - - - - - - grn/red

blk - - - - - - - - - - - - - - - grn/blk

wht/blk - - - - - - - - - - - - grn/blu

N/C - - - - - - - - - - - - - - grn yel

New +12 Volt switched- -Large Red

N/C - - - - - - - - - - - - - - grn/wht

 

N/C means you will not hook these up

**** -I would not even try hooking this up without an A/F guage. -You need to be able to monitor your readings while you are doing the process.

 

What's the reason you want to swap to the 1g MAS?? It won't get rid of the fuel cut for higher boost.

 

-Robert

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What's the reason you want to swap to the 1g MAS?? It won't get rid of the fuel cut for higher boost.

 

-Robert

 

I don't want to use the 1G MAF. I want to use the 87-89 6 wire TSi/ESI-R MAF because my earlier 4 wire MAF (flatbody) has gone bad. I also already have the parts from an 89.

Edited by Yokohama
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Yes, I do have an 86, with the dual MAF/MAP system; I can run MAF-less, and it does great. But, with the old MAF connected the idle would fluctuate and it would surge as I remember.

 

I used the above information and the write-up of the 6-wire to 1G conversion to figure out the connections for the 4 to 6 wiring. However, when I ran it, it would buck, had no power, would bog down, etc. So, I had to disconnect it. I did not use the A16 pin as according to the ECU pinout I have there is no pin 16 on the B connector. There is a pin 16 on the A connector, but that is the diagnostic pin. Also, according to what you said, the barometric sensor for the 86 is external to the MAF.

 

I know that the 89 I got the MAF from was a driving car.

 

Any ideas?

 

Thanks!

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The idle issue sounds like a TPS/ISC problem. Did you ever do a reset on those?? If so, were they sweep tested??

 

I posted some pinouts somewhere... I'll see if I can find them. Are you 86 widebody or flatbody??

 

Flatty:

http://home.comcast.net/~DriftAbility/images/Komeuppance/1986NOICECU.jpg

 

Widebody:

http://home.comcast.net/~DriftAbility/images/Komeuppance/1986ICECU.jpg

 

-Robert

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The idle issue sounds like a TPS/ISC problem. Did you ever do a reset on those?? If so, were they sweep tested??

 

I posted some pinouts somewhere... I'll see if I can find them. Are you 86 widebody or flatbody??

 

 

I have an 86 Flatbody. It is the model that came with all the mountings (bolt holes, etc.) for the IC, but did not come with one installed at the factory; I have since added an IC from a TSi.

I did a test and adjustment of the TPS some time ago, but after the MAF was removed. I had just dismissed the MAF as being bad after it was removed and it started running well using the MAP only,

 

As to this conversion; I had also thought that it would be good to go to the easier to get 6 wire MAF versus the older 4-wire.

Edited by Yokohama
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I'm very doubtful of a bad MAS, unless they are broken/dirty. Those pinout instructions for the conversion were for widebodies.

 

Plug the stock MAS back in, set your timing to 10btdc warmed up, remove and block the vac advance vac line and follow the TPS/ISC reset procedure to the letter:

http://www.starquestclub.com/forum/index.php?showtopic=27979

 

Let me know how this goes. Make sure you can hear the ISC motor move.

 

-Robert

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You mentioned issues with the idle, and that is tps isc related. Did you follow the rest of the instructions or are you only looking for a quick fix...

 

Gonna need more info, bogging down at what rpm, under boost?? Have to be detailed in describing issues.

Have you checked your ic hoses/piping?? Boost leak test??

 

-Robert

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The 4 wire mafs are more sensitive to modifications too. If the cardboard star is removed, they have more of a tendency to hunt at idle especially when stopping after highway speeds.

Upgrade flow air filters can cause it too, such as the K&N.

They don't normally respond well to removing the honeycomb either, and that can cause it to be verry erratic with no appearant explanation as to why.

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There are no mods to the MAF, stock boost, stock intercooler. The bogging down is at low speeds. It just bogs down and stays that way until I let out the throttle.

 

It is fine running MAP only.

 

I will just run MAP only or get a 1G Turbo MAF, or rewire to use the later CPU/injectors.

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