Car has no power. Maybe MAF issue, don't want to throw parts at it.... help meeeeee!

[Joester]

Hey guys, long time no post,

Anyways, my '02 golf with 220k miles on it has started acting up.

It throws a MAF code.

It has no power AT ALL, until I exceed some certain RPM and the default MAF values kick in. Then its driveable, but only just. I am not comfortable driving on the highway at either power level, default MAF values or not.

The only reason I don't think it is the MAF itself is that this pretty much happened over night. AFAIK, MAF failures happen gradually?

Here's some things that I've done in no particular order.

• Scanned car for codes, Only thing I have is a MAF error.
• Tried logging specified vs actual MAF but it just defaults to 550 or whatever so the logs are useless.
• my boost target is 23psi but I can only get to about 18 psi or so.
• Checked turbo actuator, feels fine, vacuum lines all connected and dont appear leaky or damaged
• When I have the ignition on but the car not running, MAF actual is 1275mg/stroke and when i start the car and idle this falls to either 10 or 5. Then upon revving the car this falls to 0mg/stroke assuming I dont exceed some RPM that kicks it over to the default values.
• I cleaned the MAF element with no change
• According to MyTurboDiesel, the MAF conector pin #2 should be 12V, which it is.
• MAF connector pin #3 should be ground... I see 12V across pin #2 and #3, but i DONT see continuity between pin #3 and the negative battery terminal OR ecu pin #4. I'm suspicious of this but if this is wrong, then why am I seeing 12V across this ground??
• MAF connector pin #4 should be 5V, which it is, right on the nose.
• I took off the ECU connector and according to MyTurboDiesel, MAF pin 3 should be connected to ecu pin 4, MAF pin 4 should be ecu pin 50 and MAF pin 5 should be ecu pin 52. Although I did find pins on the ecu that were connected to MAF pins 4 and 5, they weren't pins 50 and 52. I cant remember what they were, but the fact that i did find 2 pins that were connected made me feel like that was OK.
• I also nicked each wire coming from the MAF with a razor blade to be sure that the wire itself was connected to the pins in the MAF connector, which they all are. I've heard of the MAF connector failing or becoming oxidized but this doesn't seem to be the case.
• IQ is at 6.5, I don't think this is relevant but I checked it while I was in there with the VCDS.

So my first question is what have I missed?

Secondly, should I see continuity between MAF connector pin #3 and chassis ground? I feel like this could be my issue.

What else can I do to troubleshoot before throwing $115 at it in the form of a new MAF?


Thanks for all the help guys!

 

[Joester]

I've got a co-worker with a Jetta wagon TDI (ALH) and I'm going to try to convince him to let me borrow his MAF to see if it works in my car before I go dropping $115+ on a new one.

I can also test continuity between MAF pin #3 and chassis ground on his car and see if that should be or not.

Will update.

Anyone got any other ideas?

 

[Growler]

sounds like a good place to start..

also go into basic settings group 11 and see how smoothly your actuator control system is working.

if you are only seeing 550mg/stroke that is as if the MAF is disconnected. and if it is otherwise at 1275 then your tuner has your MAF essentially tuned out and is sending your ECU a GO BABY GO signal all the time so that it never pulls fuel back. would make for a smoky ride almost at all times unless your turbo is really working good.

can you clarify when you are seeing the two signals you mentioned above? with a stage 4 tune, did you have to change your MAP sensor and have your MAF values reconfigured to account for the extra airflow required?

 

[Joester]

sounds like a good place to start..
also go into basic settings group 11 and see how smoothly your actuator control system is working.
if you are only seeing 550mg/stroke that is as if the MAF is disconnected. and if it is otherwise at 1275 then your tuner has your MAF essentially tuned out and is sending your ECU a GO BABY GO signal all the time so that it never pulls fuel back. would make for a smoky ride almost at all times unless your turbo is really working good.
can you clarify when you are seeing the two signals you mentioned above? with a stage 4 tune, did you have to change your MAP sensor and have your MAF values reconfigured to account for the extra airflow required?

With the ignition on but the car off, I see 1275.

When I turn the engine on and let it idle, this drops to either 5 or 10.

If I rev the engine it drops to 0mg/stroke.

If I drive the car and rev past some RPM (maybe 3k?) then it defaults to 550mg/stroke and goes from 25 horsepower to 50 horsepower.



I did change my MAP sensor a long long time ago when I got the tune, however I don't remember ever messing with the MAF.


The car broke overnight with no work or anything done to it. One night I was hauling rocks around on my trailer just fine, the next time I got in the car (maybe a week later) it feels like it has about 25 horsepower and throws the MAF code.

I mean, honestly, it could very well be a simple broken MAF sensor, as mine is 15 years and 220k miles old (its the original as far as I know) but it just seems weird that it would break overnight so I'd like to make sure, if I can, that its the sensor and not a wiring or ECU problem or something.

 

[piper109]

Check your vacuum hoses, all of them and the other bits and pieces in the vacuum system, check valve, valves etc. Split hoses hide pretty well so be thorough. Perhaps replace them all systematically if they are old. Its cheap enough.
Its likely that the MAF needs replacing however. Make sure you get a Bosch replacement.
I've been down that road with my wife's 2000 NB. 17 year old vacuum pipes can hide trouble. A new MAF ended up being needed for a complete cure.

 

[Joester]

Check your vacuum hoses, all of them and the other bits and pieces in the vacuum system, check valve, valves etc. Split hoses hide pretty well so be thorough. Perhaps replace them all systematically if they are old. Its cheap enough.
Its likely that the MAF needs replacing however. Make sure you get a Bosch replacement.
I've been down that road with my wife's 2000 NB. 17 year old vacuum pipes can hide trouble. A new MAF ended up being needed for a complete cure.

I visually checked them and even pulled a few off to check the ends, and everything looked fine. I replace my vacuum lines pretty religiously. I also checked by shutting off the car and then after a bit of time, pulled the line off the vacuum ressy and it had held its vacuum in there so I'm pretty convinced the vacuum system is fine, especially given the MAF code and weird MAF actual values.

Maybe I should just quit being a cheap-ass and buy a MAF, but this is not my primary car, I use it pretty much only for towing and Lowe's runs, so I'm not super fond of the idea of actually spending money on it, especially if I don't have to.

 

[BobnOH]

Swap with your co-worker, it couldn't be much easier to do. If feasible, follow him home and do it there.

 

[UhOh]

Unplug the MAF and go for a drive. You should have smooth but low power; readings should be up to default limp mode levels (you should be seeing higher than zero!).

MAF in the wife's car didn't really seem all that bad, FE readings were looking wonky, but car basically ran fine. Then one day it just plain started puking/bucking. With engine running, roughly, I popped the MAF connector loose and the engine settled down immediately and the car was drivable, though a slug. Popped in a spare marginal MAF and it was basically back to normal: ordered a new one and when it showed up dropped it in.

 

[Growler]

With the ignition on but the car off, I see 1275.
When I turn the engine on and let it idle, this drops to either 5 or 10.
If I rev the engine it drops to 0mg/stroke.
If I drive the car and rev past some RPM (maybe 3k?) then it defaults to 550mg/stroke and goes from 25 horsepower to 50 horsepower.

With this info, I am thinking either a bad MAF, or there is something flaky with the wiring to the MAF. almost seems like it is cutting out with a loose or frayed connection.

def try to swap with your coworker for a test.

 

[hughesjasonk]

After reading the thread...

Have you tried to disconnect the MAF all together, drive it around and see what it does? that right there will tell you if the MAF is your problem because the ECU will then have to rely on the MAP sensor. From there you can see if it's your MAF/Wiring/OrSomethingElse. If I remember correctly the Bentley manual will tell you what the resistance is supposed to be when you Ohm out the MAF. I can check to confirm if you like. If you do that test make sure that you do it right after everything is heat soaked then throw the MAF in the freezer for a couple hours and do it when it is super cold. If it checks out I would look else where like the harness and connectors for example.

I would also check all of your rubber connectors and plastic hoses IE Intake to turbo inlet. The reason being is that if the MAF is reading X and the MAP is reading Y it going to throw and MAF code as well for unmetered air.

 

[Joester]

After reading the thread...

Have you tried to disconnect the MAF all together, drive it around and see what it does? that right there will tell you if the MAF is your problem because the ECU will then have to rely on the MAP sensor. From there you can see if it's your MAF/Wiring/OrSomethingElse. If I remember correctly the Bentley manual will tell you what the resistance is supposed to be when you Ohm out the MAF. I can check to confirm if you like. If you do that test make sure that you do it right after everything is heat soaked then throw the MAF in the freezer for a couple hours and do it when it is super cold. If it checks out I would look else where like the harness and connectors for example.

Driving with the MAF disconnected is better "50hp" mode instead of "25hp" mode.

However, the car defaults to the same thing after driving for a bit, even with the MAF connected, as soon as I exceed some certain RPM around 3k it defaults to 550mg/stroke which is the same as if I didn't have the MAF connected at all.

I have a Bentley but haven't looked at it yet. I don't know why I didn't think to do so. If you want to give me some helpful page numbers that'd be super cool of you to do!

 

[shift957]

I just went through a similar experience and tried twice to clean the maf with no success. I have an '02 with 235k on it and a stage 3 tune. It just went bad, no hesitations.

I replaced it just the other day and immediately the car ran great again. I had to cycle the ignition each time the CE light came on while driving. It took 4 times and the CE light quit coming on -- done within 4 miles.

 

[Joester]

I just went through a similar experience and tried twice to clean the maf with no success. I have an '02 with 235k on it and a stage 3 tune. It just went bad, no hesitations.

I replaced it just the other day and immediately the car ran great again. I had to cycle the ignition each time the CE light came on while driving. It took 4 times and the CE light quit coming on -- done within 4 miles.

Good to know they can just fail like that. Thanks!

 

[Joester]

UPDATE:

I just went ahead a bit the bullet, have a MAF sensor coming to me via Amazon prime. If it doesn't fix it I can just return it with no hassle.

I will update with the results. Should be tomorrow evening.

 

[wonneber]

[*]According to MyTurboDiesel, the MAF conector pin #2 should be 12V, which it is.
[*]MAF connector pin #3 should be ground... I see 12V across pin #2 and #3, but i DONT see continuity between pin #3 and the negative battery terminal OR ecu pin #4. I'm suspicious of this but if this is wrong, then why am I seeing 12V across this ground??

I had to look at a diagram for this.
Pin 2 is the power feed so it's OK.
The other 3 pins go into the ECU not to a ground unless it's grounded inside the ECU.
Pin 4 and 5 of the ECU are grounded G608 at 'center of firewall'

 

[Joester]

I had to look at a diagram for this.
Pin 2 is the power feed so it's OK.
The other 3 pins go into the ECU not to a ground unless it's grounded inside the ECU.
Pin 4 and 5 of the ECU are grounded G608 at 'center of firewall'

This contradicts the info on myturbodiesel's site and confirms what I saw in my car so thats a bit of a relief.

Thanks!

 

[Joester]

A new MAF fixed my car.

I'm pretty embarrassed that I made such ado about nothing, lol.

Thanks for all the help everyone!

 

[wonneber]

A new MAF fixed my car.

I'm pretty embarrassed that I made such ado about nothing, lol.

Thanks for all the help everyone!

Don't look at it as 'such ado about nothing'
Its diagnosing the problem to replace only part(s) needed.
It gets expensive guessing at the correct part.
I will admit I did a bit of guessing myself with fairly inexpensive parts.
Look at it as a learning something new thing.

 

[UhOh]

$100 fix. And the time to do it was a matter of perhaps 10 minutes. Relish this fix, as there are MANY others that fall on the complete opposite end of the $$ and time spectrum.

 

[Joester]

$100 fix. And the time to do it was a matter of perhaps 10 minutes. Relish this fix, as there are MANY others that fall on the complete opposite end of the $$ and time spectrum.

Amazon prime has genuine Bosch MAFs (sold by Bosch) with prime shipping for $76!

https://www.amazon.com/Bosch-Origin...TF8&qid=1505136637&sr=8-1&keywords=0281002757