EGR del and CEL, new quick fix

NarfBLAST · July 17th, 2008, 20:27

Has anyone else tried this?

In order to prevent P0402 EGR Excessive Flow errors I have attenuated the signal from the MAF not by any sort of electrical means but simply by rotating it in the housing. I allready had the EGR adaptation but was still getting the CEL after my EGR delete. I used VAG-COM and rotated the MAF until the readings for actual and requested MAF matched at idle. I used to have to clear the code daily with my Scangauge.... I've been running for three weeks with this setup, no codes, great economy, no difference in power (reads over 850mg/stroke at 3000rpm allthough maybe because it is a 2.0L GAS MAF)

NarfBLAST · July 18th, 2008, 18:32

Here are some pictures to illustrate what I did. The 2.0L GAS MAF I am using looks like the old style on the left. The one on the right can not be rotated as far, but it can be swapped into the old style housing easily (once you get rid of those annoying security screws) and it doesn't change the VAG-COM reading too much as far as I can tell.

The part numbers (2.0GAS MAF not shown, it is hapily working in the car! Available upon request)

The sensors are a bit different, the old style has a straight mesuring chamber, the new style has an angled measuring chamber

Airbox side (air goes in this side of housing) note the original style has a metal screen but the new style is all plastic and has some crazy flow alignment vent area (the smaller cylinder in the larger cylinder) to align the flow to the angled part in the sensor.

Engine side (air comes out this side) with sensors sitting in their normal straight position:

And here is how far I rotated the one on the left. The one on the right can only be rotated slightly due to the housing.

The old sensor came with the car and died around 100,000km. The new sensor works, but I haven't tried rotating it in an old style housing yet. I will have to get around to this one day, because if that new TDI sensor requires less rotation to get the same reading as the old GAS sensor then it would block less air flow when rotated. Anyway. Still no CEL and loving it!

puter · July 18th, 2008, 20:04

it really seems to me like this would cause problems since the amount of boost is determined based on maf readings.

NarfBLAST · July 18th, 2008, 20:26

Quote:

Originally Posted by puter

it really seems to me like this would cause problems since the amount of boost is determined based on maf readings.

The weird thing about this mod is that it lowers the MAF reading at the low end when EGR flow is expected but it doesn't seem to affect readings at high end when there is lots of flow and I am making boost.

Also, I think you are wrong about the ammount of boost being determined based on MAF readings. On the ALH engine there is a MAP (manifold air pressure) sensor that determines boost. I have an analog boost gauge that I have checked against the ECU boost reading from the MAP (using digital ScangaugeII) and the boost behaves pretty much the same before and after this mod.

Actually, you are right, a reduced MAF reading will reduce fueling which will reduce boost. But like I said this mod doesn't seem to affect the top end MAF readings. This mod would be for those people who are not looking for maximum performance, just a cure for the EGR delete CEL without having to get their ECU reprogrammed.

Also, modifying the MAF reading is nothing new... I'm just proposing a simpler way to do it, a possibly better way for the reasons described above.

puter · July 19th, 2008, 10:08

Ah, ok.

I was going to question you on saying that the maf doesn't affect boost

...if it didn't affect boost you wouldn't get an overboost condition when it is under reporting

Anyway, I just wasn't familiar with changing what the maf was reporting and it seemed a bit dangerous to me.

fahrfrompuken · July 19th, 2008, 11:08

narf,

I just did the EGR delete and cooler delete a couple of days ago. I immediately got a CEL (P0401) and verified that today with a scanner. I also had P0672 (Glow plug #2). I fixed the glow plug problem - I had put anti-sieze compund on the threads of the glow plug and had a consistent CEL for quite a while. I cleaned the threads of the glow plug and also cleaned out the glow plug harness connectors and the top of the glow plugs with carb/choke cleaner and all is well with the glow plugs now.

Now, back to my P0401 CEL issue. I put in the kit per dieselgeek's instructions. Unfortunately, he does not tell you what to do with the actuator solenoid vacuum line and electrical connector. He also doesn't tell you what to do with the EGR vacuum line. Right now the solenoid is hanging there on a cable tie still connected as usual and the EGR vacuum line is plugged up with a piece of rubber.

Questions:
- Do I unplug the electrical connector from the solenoid valve or leave it connected?

- What do I do with the vacuum lines? Plug them up?

I just drove to the auto parts store and no CEL yet, but the engine barely reached temp and I was just going through the neighborhood so no high speed or load driving yet. Hopefully

Help anyone! Please!!!

puter · July 19th, 2008, 11:40

you used the kit that blocks the exhaust coming into the egr?

my guess is that you just plug the vag line into the egr. You get the error I think because the ecu can tell that the egr isn't there. Since the exhaust is already blocked off, allowing the egr to open won't affect anything.

caveat: I have not done this procedure so I am just guessing.

NarfBLAST · July 19th, 2008, 22:38

Farfrompuken,

You must plug the vacuum lines to prevent vacuum leaks. You must keep the EGR solenoid electrically connected to prevent a CEL that says the solenoid is missing... but I'm not sure what that one is.

You are getting P0401 is EGR Insufficient flow? That is the exact opposite of what most people get P0402 EGR excessive flow? I think you need to check for vacuum leaks and plug that N18 solenoid back in.

fahrfrompuken · July 20th, 2008, 06:38

I will double check the vacuum lines (I was thinking about replacing all of the lines out any way as a preventative measure).

Not sure what the N18 solenoid is. Can someone please explain?

NarfBLAST · July 20th, 2008, 16:15

Quote:

Originally Posted by fahrfrompuken

I will double check the vacuum lines (I was thinking about replacing all of the lines out any way as a preventative measure).

Not sure what the N18 solenoid is. Can someone please explain?

N18 is on the other end of the fat vacuum hose from the top of the EGR valve. It converts and electrical signal from the engine control unit (ECU) into a vacuum signal to the EGR valve.

No offense, but these questions are answered elsewhere on this site and in the service manual. The purpose of this thread is to talk about this specific way to adjust the MAF signal to prevent the EGR delete CEL as stated in post#1 and #2 and to find out of this has been done before or if it is a new and viable fix for everyone who doesn't want to get their ECU reprogrammed when removing the EGR system.

Jarmstrong · July 24th, 2008, 09:59

so what is the general concensus on this? Does it work with no adverse effects?

thanks
Jason

puter · July 24th, 2008, 12:58

Quote:

Originally Posted by Jarmstrong

so what is the general concensus on this? Does it work with no adverse effects?

thanks
Jason

The general consensus is that it works fine with the exception of a possible CEL.

The only other thing is that it's not really necessary. You may get a slightly increased MPG, but not if you're chipped, and the "new" diesel, in the US at least, doesn't really cause intake clogging so you won't really be helping with that either.

I personally did a quick and dirty delete by removing and plugging the vag line to the EGR. no CEL yet, but I'm chipped.

NarfBLAST · July 24th, 2008, 19:42

Quote:

Originally Posted by puter

The general consensus is that it works fine with the exception of a possible CEL.

There is no general consensus as I am the the only person who has ever tried rotating the MAF to my knowledge!

The point of the mod it avoid the "P0402 EGR Excessive Flow" Error and CEL you get when you do an EGR delete on a STOCK ECU (NOT CHIPPED).

My experience is that this mod works perfectly with a 2.0L GAS MAF and my stock ECU... its been over a month and 5000 or so km with no CEL. used to clear the cell every other day.

puter · July 25th, 2008, 05:55

Quote:

Originally Posted by NarfBLAST

There is no general consensus as I am the the only person who has ever tried rotating the MAF to my knowledge!

The point of the mod it avoid the "P0402 EGR Excessive Flow" Error and CEL you get when you do an EGR delete on a STOCK ECU (NOT CHIPPED).

My experience is that this mod works perfectly with a 2.0L GAS MAF and my stock ECU... its been over a month and 5000 or so km with no CEL. used to clear the cell every other day.

Sorry, I missread his post, I thought he was asking about general consensus of a delete

blktdi · July 25th, 2008, 19:38

Can you just block off the exaust side at the manifold and make a plate with a filter on the egr side to pull in fresh air whenever the egr opens? This way the maf is still reading the difference in air quantity as it would with the egr intact (hence no cel), when really you are getting more air and no exhaust.
Maybe a hose from the egr to the air box or have a seperate filter on the end.