Error code 34- Low MAF signal issues

[TurboBob]

As I'm sitting ther waiting for the tow, I used turbolink not direct scan. I thought now the TPS was screwed up or something. Now with the key on and engine off the MAF sensor goes up in tandem with the TPS!!!!??? WTF???

At WOT 4.62 TPS the MAF goes to 255. THE damn engine is not even running!!

This has to be some of the screwiest stuff I have ever seen.

This is a symptom of no MAF signal getting to the ECM.

Even with the engine off, the MAF still produces a signal. If this is not reaching the ECM, the MAF will follow the TPS...... even with the engine off.

Chase out the power and ground wiring to the MAF.

B

 

[turbobob924]

OK thanks Bob, How many volts should the signal B wire at the MAF sensor have?? 4-6volts or 2.7x?

I can giggle all the wires and the ground and bat/12 volts at the sensor do not change.

I can disconnect the ECM and the B6 wire at the ECM plug seems to have good continuity?

I assume the ECM sends this low voltage for the MAF to send a Hz frequency back?

 

[TurboBuRick]

Any luck with that damn thing yet? LOLO By the way I tested my B wire at the maf plug And I get 5v.

I got my fast times today and you and your Porsche are on the front cover. Congratulations!

 

[TurboBob]

OK thanks Bob, How many volts should the signal B wire at the MAF sensor have?? 4-6volts or 2.7x?

I can giggle all the wires and the ground and bat/12 volts at the sensor do not change.

I can disconnect the ECM and the B6 wire at the ECM plug seems to have good continuity?

I assume the ECM sends this low voltage for the MAF to send a Hz frequency back?

Check voltage on the 12 volt wire, and resistance to the engine block on the ground wire.

The ECM does not send anything to the MAF. The MAF gets 12 volts to power its innards from the power distribution wiring and sends a frequency signal to the ECM.

Troubleshooting with a voltmeter is not effective.

Bob

 

[turbobob924]

Thanks Rick87GN! Yeh I like the article, I should have sent them better pictures as it is a little fuzzy blown up on the cover.

I had less problems modifying the hell out a stock harness to put in the hybrid!
Since I sometimes have 6 volts and sometimes 2.7 volts at the wire B, something is FUBAR.

I got the wheel well opened up last night and starting yanking the harness for bench inspection. I really had not planned on spending $500 for a new harness from Caspers!

 

[BEATAV8]

I really had not planned on spending $500 for a new harness from Caspers!

Hey BOB-O! salt for the wound.... $500 is way too cheap for a fella with your disposable income.

https://www.casperselectronics.com/...Product_Code=109030&Category_Code=8687GN_Perf

 

[TurboDave]

Since I sometimes have 6 volts and sometimes 2.7 volts at the wire B, something is FUBAR.

Ummm, pin B is the MAF's output signal wire correct?

Not what Bob said in the post above

"The ECM does not send anything to the MAF. The MAF gets 12 volts to power its innards from the power distribution wiring and sends a frequency signal to the ECM.

Troubleshooting with a voltmeter is not effective."

 

[turbobob924]

Ok so what do I do to troubleshoot this sucker then??

I was going to pull the harness and bench test it for shorts bad wire from the ecm B6 To the middle b MAF connector?

I replaced the ECM and checked the pins
I replaced all the wires and the 2 big plugs to the ECM.

I thought I checked the wire and found no shorts to ground or bat on the signal wire.

 

[TurboBuRick]

Bob,
When your checking the wires are you ohm-ing them out or just checking for dead short? A corroded wire or connector will show resistance on a ohm meter. You prolly know that but I thought I would throw it out there.
Try to run a temporary wire from the ecm to the maf plug and see what happens. Keep us posted.

 

[turbobob924]

Rick,

Yep, I ohmed them like a test on the coil packs. Using the 200k scale no issues!

Are you going to the midwest challenge? I will bring the harness with me!

I'm not going to drive either buick based car now.

 

[TurboBob]

Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......Ground.......
Ground.......Ground.......Ground.......Ground.......

Measure the voltage on the GROUND wire to see if the ground is open or high resistance.

1. set the DVM to read DC volts
2. connect the black wire to the engine
3. turn the key on
4. with the harness plugged into the MAF, measure the voltage on the black/white wire. This can be done by "backprobing", i.e. push a paperclip into the backside of the connector, past the seal to make contact with the pin while its plugged in.

Let me know.

B

 

[turbobob924]

Good ideas Bob!

Here is what I tried before totally yanking the harness....

I by passed all 3 MAF sensor wires and ran a new separate wire to B6 at ECM from B (middle connector) at MAF. I ran the ground to a near by ground. I ran the pnk/blk to a relay for full 13 volts when key on.

Car runs like total crap! Turbolink shows same code 34 but the MAF readings at idle and goosed throttle in park look pretty normal. MAF goes from 4 to 12 at 1700 under no boost.

 

[turbobob924]

Oh and the voltage at B is the same, 2.71!

 

[TurboBuRick]

What the?

 

[turbobob924]

UPDATE!!

Well, it appears that it is not a wiring problem. Seems that the translator plus has issues, both LT1 MAF's, all 3 stock MAF's all have issues!

I put everything back to the way it was when I bought it including a necked down MAF. Bam, seems like it is now running OK.

I am still not sure about test drives but I also switched out to a different ECM ( have have tried 3) and a joe lubrant chip rather than the extender that I had.

I am taking a break from all this fun as I have to go out of town this week for work.

 

[turbobob924]

MAF issues update

Well I am still farting around with this!

I reset the IAC, Base idle and TPS. Now I don't have the code 34 but scar still runs like crap!

There appears to still be "noise" or something in the MAF signal??

I have replaced all 3 wires to the MAF, still has same issues. Now I am running the following;

Stock 87GN except:
TE44
MSD50s with extender chip
translator plus w/ 3" LT1 MAF
stretched IC

new ECM connector blocks
3 different ECM's
2 different LT1 MAFS

Here are 2 screen shots with the noice and the DS file

Anymore help is appreciated!

 

[turbobob924]

Tt

 

[TurboBob]

you need to find someone with an oscilloscope to look at the signals.

The voltmeter tests are not good for a frequency signal.

there may be 2 circuits shorted together or something else odd.

double check all the grounds on the back of the engine, measure the voltage from the ECM case to the engine

Bob

 

[turbobob924]

Solved!

Thanks to everyone who tried to help.

It turned out to be the MAF sensor connectors were just a little loose, enough to cause havoc on the computer.

Pulled the 3 wire connectors out and "fixed" them. Cars runns pretty good now with stock MAF and red armstrong 93 chip.

you screw around with cars long enough and sometimes the simplest stuff gets in the way!

 

[BEATAV8]

Captain Devastation to the Rescue! :tongue: