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l28ET z31 ecu/maf problems...Car wont idle/run


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I saw in your video your ECU "going through the modes" the link says it all.

Turn switch fully clockwise...when the LED's flash 3x, immediately turn the switch fully counterclockwise...now you're in mode 3 and you can check for stored codes.

Green LED counts "tens" red LED counts "ones" (one green flash followed by 4 red flashes is code 14, 2 green flashes followed by 1 red flash is code 21 etc.)

Codes will cycle over and over again, so if you miss one, it'll come around again. Once you have all the codes, turn the ignition off and it'll be back in mode 1 automatically once you turn it back on, OR, turn the switch clockwise again and let it "go through" modes 4 and 5, then once it's back in mode 1 (1 flash of both LED's simultaneously) turn the switch CCW again and you're locked back into mode 1.

I don't know what codes will get stored with the car not really running, but I've instructed you on how to enter mode 3, so check and report back with your codes.

Easy enough?

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Sorry Domsz, but that info is false. That is just the ECU going through modes 1-5 waiting for the user to select a mode. Mine does not have a single green flash after mode 2, but regardless, those are not "codes" just modes.

Edit:

Just for clarification I'm running a JWT 450HP modded 88 or 89 ECU, but the code retrieval is the same. And FWIW, my ECU always stores codes 14 (vehicle speed sensor), 21 (Ignition signal), 22 (fuel pump circuit), and 42 (fuel temp. sensor). And my car runs just fine. Buy after I drive it a couple times, the codes always come back (indicated by a solid red LED when the car is running or ignition is in "on" position) viewing the codes in mode 3 makes the red LED go away, but as I said, it comes back on after a couple drives.

Personally I wish I could figure out the ignition signal code (21) but I guess that's just the way it is.

Edited by billseph
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Sorry Domsz, but that info is false. That is just the ECU going through modes 1-5 waiting for the user to select a mode. Mine does not have a single green flash after mode 2, but regardless, those are not "codes" just modes.

Edit:

Just for clarification I'm running a JWT 450HP modded 88 or 89 ECU, but the code retrieval is the same. And FWIW, my ECU always stores codes 14 (vehicle speed sensor), 21 (Ignition signal), 22 (fuel pump circuit), and 42 (fuel temp. sensor). And my car runs just fine. Buy after I drive it a couple times, the codes always come back (indicated by a solid red LED when the car is running or ignition is in "on" position) viewing the codes in mode 3 makes the red LED go away, but as I said, it comes back on after a couple drives.

Personally I wish I could figure out the ignition signal code (21) but I guess that's just the way it is.

Maybe you are right . I was using Mitchell 1 Ondemand for info. I also have an 84 turbo and haven't had much problems with it , thank God , so i don't have much experience with the car . Thanks .

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in the FSM it says something about the first round of flashes (different modes) actually telling you what mode you need to be in. Is the single green light maybe indicating I need to be in mode 2?

 

I've never reviewed the actual full FSM, just the link I provided. If I were you I'd enter mode 2 and see what codes flash (if any). Your car oughta run at idle with the MAF disconnected, so I'd bet you're just running rich as all hell, but since I'm not there seeing what's happening, I can't guess very well.

You can pull the fuel rail with the injectors and fuel lines still connected and set it on top of the motor to see what they're doing when you crank it, maybe they are stuck open, maybe they're just putting out hardly any fuel. Kind of a pain, but when things ain't working, you gotta check the basics.

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A quick check shows that 44 is "no malfinctioning in circuits" . Is this safe to assume then that im getting a bad signal from the maf or cas? When there is a malfumctioning circuit is this only referring to its continiuity and not a signal itself?

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Not familiar with this swap . When you said cas , are you using 300zx  dist. or external cas ?

 

with a z31 ecu and maf you need the z31 optical crank angle sensor.  It's an ET dist. with a z31 degree wheel and sensor.

 
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Well I did some more testing..

 

its not the ECU as I tried an 86 turbo... Its flashing a CAS code but Im wondering if this is from a different car.

 

The Crank angle sensor is getting + voltage and with nothing interfering the light/reciever it puts out around 5 volts on the signal wire.  With the sensor interfering it drops down to basically nothing (This indicates a good CAS, that is of course if the 5 volt signal is correct)

 

Also with the CAS by moving the degree wheel through and out of the sensor i hear an injector or two clicking as well as the coil firing

 

I got some resistance values of the MAF by just ohming out some of the different pins and recorded the readings and then got the same readings at the ECU connectors which cancels out my wiring. 

 

This is leading me to believe the MAF itself  is the problem.   Am i missing anything here people?

 

And anyone with a working z31 maf, would you mind getting resistance values of pins:

 

A-B   I got .58 k-Ohms( 580 Ohms)   

 

A-C   I got .51 K-Ohms (510 Ohms)

 

A-E-  OL

 

A-F   9.88 Ohms

 

B-C - 73.8 Ohms

 

Thanks guys

 

 

 
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Any possibility that the "auto clean" wire is more important than you thought.  Maybe it needs to be connected, maybe it's not just auto clean, maybe it's not auto clean at all.

 

Unless the ECU just needs to see some continuity, I don't think it would affect anything as + voltage is only applied to the F position wire when the ECU gets a specific signal from the Speed sensor and maybe another sensor or two.  As per the write-up guys have a push activated switch to + for the clean mode and it is otherwise an open circuit.

 
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