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M35 Running Rich

Dane

By Dane,
in Four Door Family & Wagoneers

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Dane Enthusiast

Dane

Posted
Posted (edited)

Hey guys

my 2002 m35 is running rich

This all started when my AFM died on the m2 a few weeks ago

was replaced with a scotty AFM (thanks mate) and i knew they run a little bit more rich in the higher rpm...

At the time of replacing the AFM i stupidly loosened the BOV spring thinking it might protect the car a bit more -recircing-as the car compressor surges ALOT. Well of course this caused the car to run extremely rich due to what i assume was a massive boost leak with the spring so soft. I did like 200kms to a tank and fouled my plugs

Tightened the spring back up as much as i could and economy came back (a bit) but due to fouled plugs i knew i had to change to see if i can start getting 400km to a tank again..

Replaced my plugs a few days ago with a fresh oil change.. Feels much better - however under load , say at 3000rpm at 80kph mostly up a slight hill, I get belowing black smoke from exhaust.

Car has Impul ECU - TBE - Front mount. BOV is turbosmart plumb-back

I could go and buy a genuine AFM - but i have a feeling i may have a boost leak ? I am in talks with another user who lives nearby and our plan was as soon as i have changed the plugs to try his really good working AFM and see if the problem dissapears - failing that a smoke test machine to see if any leaks....he hasnt logged into the forum for a little while so i thought i might also ask you all - am i missing anything - all advice welcome. Just had the oil changed and the PCV valve was inspected and seemed to be ok.

Edited by Dane
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https://www.sau.com.au/forums/topic/438649-m35-running-rich/
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nickcorr Proficient

nickcorr

Posted
Posted

This is identical to what I had...

Scotty fixed it, after pressure testing my intake (which was fine) and changing out my discusting plugs, by getting me to put the old AFM sensor back in...

If that had not worked, next stop was O2 sensor and seeing what Consult said.

He did suggest that my inlet was good, partially because I am on stock intercooler, and nothing has been touched, so that might be a good starting point.

Good luck with testing!!

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Sorry to hear Dane, Do you still have the stock ecu to test? Has the Impul been reset?

These faults can be tricky as there are so many parts that can make the car run rich. 3k is almost full torque load on the stock turbo, so it is a point where the fuel would be dumping in on the Impul map, but hopefully it is just a leak.

Do you have the stock bov to put back on, plumbed back?

Dane Enthusiast

Dane

Posted
  • Author
Posted (edited)

Hey Scotty,

The Impul has been reset yes - cleared all codes

I BELIEVE i was given the stock ECU with all the parts...what would we be testing exactly ?

yes at 3k the boost is pretty much 15psi -the accelerator is probably about 25%? depressed when mildly accelerating up to 80kph...i thought only really high RPM would cause an excessive dumping of fuel but i often drive with the pedal depressed at 25% to get to 80kph, i think everyone does !

I might have the stock BOV - thats a good idea.

Edited by Dane
scotty nm35 Grand Master

scotty nm35

Posted
Posted

I BELIEVE i was given the stock ECU with all the parts...what would we be testing exactly ?

The impul map might be richer in that area, and as peak torque is around that point, it is the richest point of the map usually.

Time for an Emanage?

  • 1 month later...
Dane Enthusiast

Dane

Posted
  • Author
Posted (edited)

UPDATE !!!! a very good one.

Turned out the BOV that i was tightening was slowly becoming loose over time and leaking boost because i didnt lock the vac nipple against it once adjusted! I was wondering why it seemed to fix the issue but then came back!

So on the drive to work this morning - the car felt way better, sounded way better, and no black shit unless I Really, really gun it. BOV is on its hardest setting. anything after a few twists and it leaks boost badly.

Edited by Dane
Brick Mentor

Brick

Posted
Posted

Is it worth abandoning the aftermarket style BOV & returning to a new OEM?

The drivability against the stock ones never seems as nice.

Great to hear you solved it though. :yes:

I found mine drove heaps better with much better high-end pull since changing to the turbosmart kompact. The stock one is too soft once your up the boost at all.

Daleo Grand Master

Daleo

Posted
Posted

I found mine drove heaps better with much better high-end pull since changing to the turbosmart kompact. The stock one is too soft once your up the boost at all.

That doesn't necessarily point to the OEM BOV being no good;

Just that a 12 or 13 year old one might be no good.

For sure there a gains to be made, but I really don't like the "shunty" nature of the throttle response with aftermarket styles.

It would be interesting to see whether there is enough meat in the body of a Turbosmart to run the bleed port; or a slightly smaller version of it to allow the slight bleed off that you have with the OEM.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

That doesn't necessarily point to the OEM BOV being no good;

Just that a 12 or 13 year old one might be no good.

For sure there a gains to be made, but I really don't like the "shunty" nature of the throttle response with aftermarket styles.

It would be interesting to see whether there is enough meat in the body of a Turbosmart to run the bleed port; or a slightly smaller version of it to allow the slight bleed off that you have with the OEM.

Not required after tuning, as the 'shunt' can be tuned out.

I have seen a 2-3 psi gain at standard boost on customer M35's, I would hate to know how much I would lose on high boost.

DaveM35 Collaborator

DaveM35

Posted
Posted

Yeah but broz the stockie one doesn't make it do the hectic shhhhtututuuuu

when I'm dosin' it around my streetz ain't nothin sicker.

It's worth almost head butting the steering wheel before the power kicks back in.

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