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S Chassis Technical discussion related to the S Chassis such as the S12, S13, S14, and S15.


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Old 05-12-2017, 10:53 PM   #1
gtrpryde
 
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Odd Limp mode Z32 MAF troubleshooting

SOLVED! After fixing my shoddy soldering job on the z32 maf plug wiring (replaced with a new wiring specialties version), it works! I had ignorantly cold soldered (melting solder with iron vs heating the wires) the wires years ago and it must have broke when moving the wiring around during this round of maintenance that I did. I had a knock sensor code after, broken wire on the plug (old age), replaced that too and all is well!

Hi, so i've been scouring the forums looking for specific insight on what happened with my S13 kade-t.

Back story-

1. ka-t running a chipped ecu with Z32 MAF(no MAF issues prior)

2. Pulled intake manifold for a overhaul of all coolant and vacuum hoses, and replaced with S14 intake manifold and S14 throttle body.

3. Started car and it was in limp mode, ECU code 12 - MAF problem.

4. Car runs exactly the same regardless of whether the MAF is plugged in or not - about every thread I read said the car ran worse when the MAF was plugged in, indicating a bad MAF.

5. This MAF was working fine prior to this overhaul (it stayed plugged in but was moved out of the way during boost leak check). I don't think it was damaged...

6. Car idles strong at 1100-1200 RPMS, vacuum is a strong 20" and has been completely boost leak checked.

7. I made sure all the grounds around the intake manifold were reconnected.

Troubleshooting

1. Tightened pins on MAF harness and tried reconnecting (no changes)

2. Checked voltage on MAF harness (4 wires- 1.12V wire:1.2V with engine off, key on, 2. Ground, 3. Ground, 4. ECU signal 0V with both key on engine running or key on engine off.)

The last wire according to to the Jim Wolf diagram says 12V constant. I'm getting 0V and I don't know why. I even jumpered a 12V connection to this wire and no change, same code, same limp mode same super rich AFR ~9.2. EDIT: I just realized I read the diagram backwards when testing this and actually jumpered the ECU 0-5V signal to 12V power >.<

At this point I have no idea what is causing the MAF issue - the wiring or the MAF or the ECU (I didn't touch the ECU prior, only after to pull codes. Nothing looks amiss on the ECU.)

Questions:

1. What should the MAF harness be reading when unplugged?

2. Could anything else be causing this code?

3. Does the S14 throttle body have any effect on this? (I haven't checked TPS values or anything)

4. Does anyone have a link to testing the MAF (I heard it's possible but haven't found a procedure)

Thanks in advance for the help, I racked my brain for a few hours and couldn't figure it out. Hopefully a ECU/MAF/wiring guru on here can help!

Devin

Last edited by gtrpryde; 05-23-2017 at 11:52 PM.. Reason: Problem solved
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Old 05-13-2017, 10:38 AM   #2
OnTheChip
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When you connected 12V to the 0-5V signal wire, it probably fried something in the ECU.
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Old 05-13-2017, 01:22 PM   #3
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Quote:
Originally Posted by OnTheChip View Post
When you connected 12V to the 0-5V signal wire, it probably fried something in the ECU.
That may end up being the case, but I did that after the issue started, and thus far nothing has changed. Thanks
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