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The E46 M3 Journal


DrLeadFoot

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The stock tune made a huge difference being that the car doesn't sound like a old ford pickup with a bad exhaust manifold gasket. The light still came on. After talking with Frank Smith from tuning tech we think the 2 cam and crank sensors should be replaced. I will order those tomorrow. I'm thinking that is why the car doesn't start on the first try. I also have replaced almost everything else that would throw the o2 sensor codes.

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Didn't take pics but I replaced the intake, exhaust and crank sensors.

Cleaner the throttle bodies and checked if they were adjusted properly.

Cleaned the inside of the intake manifold.

Cleaned the ICV.

Properly connected the SMG Reservoir line and topped it off with fluid. It was leaking.

Replaced what I think was the fuel relay.

Sent from my SM-G900V using Tapatalk

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Smoke test it for leaks in the intake track or such. Start there. Also gas cap will not cause those faults. Would be evap faults. I'm lost as to why you continue to throw parts at it and not have someone with the know how diagnose it properly. Just look at all the parts you installed that wernt needed.

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Timmy, it has been tested for vacuum leaks. I replaced the pre-cat O2 sensors w/OEM parts. I have 137K on the motor. Why not replace the cam sensors? New MAF due to the too lean codes.

What is the problem if you're so knowledgeable? Where would you start?

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I'd personally drop it off at Matts shop down the street from Concours and have him diagnose this issue. Without being there I cant really tell you what to do. Usually a bad maf will cause a rich mixture though not lean. What are the multiplicative and additive fuel adaptations values? Have you drove and checked fuel pressure? What about injectors starting to clog? Bad ecu? Exhaust leaks? Etc. All things that can cause lean mixtures. Without the car in front of me I can't diagnosis obviously. You sound like you don't know were to go as you are taking everyone else's advice and throwing parts at the issue. Also sure you have 137k on the motor...so what? Why don't you rebuild the motor then as "preventive maintenance" i mean were does it end? You know people at concours to. Why can't yout have them take a peek?

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There is value in learning about your car and increasing your diagnostic ability and engine knowledge by troubleshooting and working out problems yourself. You spend extra time and money doing so but valuable experience is gained.

Another reason to go at it yourself is the lack of trust and credibility a lot of shops have.

I use shops pretty much just for tire mounting and alignment since the required tools arent available for my personal use. Even then it gets difficult to deal with the incompetency of shops.

The last two experiences I had with shops were

-they didnt have the "special bmw tool" to do an alignment on my E30 which only has adjustable toe

-On a Nissan Versa they quoted an extra $39 for tire mounting to re-program the TPMS sensors "so the car will know which corner has which sensor". Re-install the wheel from the same corner you removed it from then???? "Nope it just doesnt work like that"

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Matt at Urban Motorworx has no clue why it is throwing the lean code. He has to warranty a leaky valve cover gasket job that he did when he resently adjusted the valves next week. He will do a "bunch of tests" to it and try to find the issue.

I just did the exhaust manifold gasket as well. Brake cleaned out all the studs, blue loc-tite'd them back in and installed an OEM gasket due to the old ones being blown out. Something Matt didn't catch.

Also, I'm throwing parts at it to do a while I'm in there approach. I wanted to clean the throttle bodies and ICV and those sensors are accessible with the intake manifold off. My wife and I are taking a road trip to California this year and I need a bulletproof cross country car. The last thing I want to be thinking when I'm on the side of the road in Nebraska with my hazards on is why did I listen to Timmy and not replace a small, cheap and easy replaceable part while I was right next to it when I had the manifold off.

Sent from my SM-G900V using Tapatalk

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No vacuum leaks.  Burger hooked it up to a fuel gauge and figured out the no start issue.  The fuel pressure stayed right where it should be.  Then they found a no spark situation.  They let the car sit for 15 minutes and they said that that is when the ECU automatically resets and replicated the situation again.  So, he is testing the ECU just to make sure that it is the problem before I order a new one $$$$. 

 

A new ECU will fix the no start issue but they can't guarantee the too lean/too rich codes will disappear.  I figure if the ECU is causing a no spark situation at start-up it probably is doing the same thing while driving. 

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It's weird that it's going back and forth between rich and lean. That's the only part that has me scratching my head a little. But you said you checked cimpression and it was ok? if compression is ok it very well could be ecu issue. Burger to the rescue! Hopefully you get the issue sorted though. At least you didn't bring it to the people who worked on your e30. Haha.

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