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2000 E39 M5
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Discussion Starter · #1 ·
Hi all,

First of all I want to thank all people sharing information about troubleshooting of the issues all M5 owners faced. I read the forumл I read the forum regularly and have applied quite a few of the fixes shared here. Thank you people for sharing this tons of information.

Please, excuse me for the very long post, but I'm trying to describe chronologically and with maximum details the issue I have and what conclusions I made from my experience!

Unfortunately, a moment has come when I have to turn to you for help and advice. First the information about the car. It is produced 09/2000 bought from me 4 years ago with 177 000 km on dash. The car was not driven for four years and it's condition was not perfect. For me to restore such a car is worth the money, more over based on the experience with my previous car '02 E39 530Da where I spent about 7-8000 $ to made it the car I want.

Anyway, what makes me think this is the real mileage of my M5 is that the rod bearings were not changed I replaced them immediately after I get the car along with water pump, thermostat (not OE which was a mistake, that I fixed lately), oil and all filters.
When I started to drive the car I had an issue with the idle when the car is hot, it worked bad and turns off. It turned out that was the one MAF which I replaced with new one (BOSCH) and the issue disappeared.
After that I decided to go with the rattling noise from the engine when powering off the car. The first thing I changed was the hydraulic chain tensioner which improved the things a bit but the rattling was still there, though less so.
Next thing in the list was retrofitting the VANOS pressure accumulator with valve which is installed on the late M5s, mine just had the connector tapped under the plenum. This solved the rattle issue.
Next I decided to change the spark plugs as there were no information if and when they were replaced. I used NGK BKR6EQUP LASER PLATINUM spark plugs. When did the procedure I used the moment to take a look in the cylinders with fiber optic camera and I'm pretty sure that there were carbon build up. (1st thought for the problems I have now)
Then after some time, I get a CPS error and decided to replace all them with non OE but VNE ones bought directly from the producer. During the replacement it turned out that two of the CPS were already replaced (the thick ones) and two were the old ones. Anyway, after the replacement was done, the car runs perfectly.
Next there were replacements of the radiator fan clutch with OE, electric fan with aftermarket (Hella/BEHR), engine coolant temperature sensor with aftermarket one.

Last year I decided to continue with the restoration/upgrading as follow:
1. VANOS boards maintenance with the BEISAN kit and some additional OE o-rings that were needed for the procedure. When the car was assembled back I had an issue with one of the solenoids which was replaced lately with one from E46 M3. No problems since then.
2. Exhaust system: Replica of Supersprint 4-1 headers, cats removed and substituted with resonators, X-pipe and aftermarket back mufflers (FOX)
3. KW V3 coilovers with OE support bearings, full replacement of the suspension bushings with polyurethane ones for street use (not the hardest composite)

Note: When did the VANOS boards maintenance we noticed that the timing marks are not aligned, but decided not to do the timing again as afik the VANOS can compensate such small divergences. Please, correct me if I'm wrong.

After these major procedures finished the car runs flawlessly until the second MAF reached its EOL. It was replaced and everything was ok.

This year I decided to track down an issue I have since I have the car, the rich mixture at idle. The car is with stock software (updated to the last version when I bought the car) disabled SAP and O2s sensors after the cats (hw removed), burble and pop feature enabled and top speed limiter removed all with the Ecuworx Modification & Remap Tool.
What I did is to replace pre-cat O2 sensors with BOSCH ones which didn't solve the issue, then replaced the fuel pump with Walbro GSS342, the fuel filter and the fuel pressure regulator along with the vacuum hoses under the car and under the plenum. No change, the smell behind the car can tears you and if you are close to the exhaust can feel the raw gasoline droplets on your hand if placed in front.

I started to do the MAF tests just and every time on 3rd speed I got 111 l/h as per the dashboard info. I tried with unplugged MAFs and hit 163 l/h on 3rd gear WOT. I test every time on the same road at nearly same air temperature about 26-8 deg C. Nothing changed after the installing pre-cat O2 sensors and fuel system components.

One day last week I read the ECU with the Ecuworx DME utility and the result made me think about checking the ignition coils.
Cloud Sky Font Gadget Communication Device


As you can see that there is a noticeable difference of the Ignition adaptations between 3rd and 7th cylinders and the rest 6.
Afaik the firing order of this engine is 1 - 5 - 4 - 8 - 6 - 3 - 7 - 2 which means after 7 cyl is after 3 cyl and the similar values may mean 7th compensate somehow 3rd. Not sure about that.
I run INPA RU measure and here is the result:
Computer Personal computer Font Gadget Output device

First thing I did was to exchange the ignition coil of 2nd and 3rd cylinders as well as 6th and 7th cylinders. Nothing changed. What is important to notice here is that I measured the resistance of the ignition coils I exchanged (as described in the DIY section) and the results were 1.0 Ohms for all four, from the DIY I understand that it should be 0.8 Ohms. And from here my thoughts are bigger resistance means less charge which leads to rich mixture. Please, correct me if I'm wrong.
When nothing changed after the exchange of the ignition coils I decided to focus on cylinder 3 based on the Run Unrest measurements from INPA and exchanged the spark plugs of 2nd and 3rd cylinders but this didn't change anything.
The only thing that left as of per my knowledge is that there is carbon build up and somehow this is the reason 3rd cylinder not to work as expected.

Thank you for your attention and please, excuse my bad English.

AsenZo
 

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Have you done anything with the fuel injectors? It's possible you have leaky injectors. Some people have good luck with having them cleaned, others don't. New replacements are expensive though.

It doesn't seem like you have a bad coil, but at the age they are, it might be a good idea to replace them all. For the longest time I was in the camp of don't replace as PM since these coils are very good. Now that they are going on 20 years old, age may start playing a factor. I replaced mine with Dinan's new coil sets. I'm very happy with them so far. The introductory price was very good as well. Not sure what they cost now.
 

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I started to do the MAF tests just and every time on 3rd speed I got 111 l/h as per the dashboard info. I tried with unplugged MAFs and hit 163 l/h on 3rd gear WOT. I test every time on the same road at nearly same air temperature about 26-8 deg C.
Exactly how did you do that test? Left the MAFs plugged in did the first test, then unplugged the MAFS and did the second test right after with no time in between? You have done that a number of times so lets fast forward, to the next part of the test. Unplug the MAFS and drive the car for a day or two but at least 50 miles to get it to adapt to the MAFless condition and do the tests again. Do the MAFs unplugged test then plug them back in and do the test again. My bet is your numbers will be totally different.
My suspicion is you have a bad injector seal or maybe a loose clamp on the throttle to plenum gasket on cylinder 3.
Side note you should re-enable your post cat O2s unless you had a very good reason to turn them off. Post O2s play a role in the fuel trims. The burble pop feature is another thing that could be playing a roll in making this harder to diagnose. All that does is NOT turn off the injectors during deceleration. Do you see how dumping fuel into the engine during decel might mess up your trims? Do this after we find where your problem is, making any change now will be counter productive.
 

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2000 E39 M5
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Discussion Starter · #4 ·
Hi,
Thank you both for the quick responses!

Have you done anything with the fuel injectors? It's possible you have leaky injectors. Some people have good luck with having them cleaned, others don't. New replacements are expensive though.

It doesn't seem like you have a bad coil, but at the age they are, it might be a good idea to replace them all. For the longest time I was in the camp of don't replace as PM since these coils are very good. Now that they are going on 20 years old, age may start playing a factor. I replaced mine with Dinan's new coil sets. I'm very happy with them so far. The introductory price was very good as well. Not sure what they cost now.
For the injectors I used fuel additive Bardahl - Injector Cleaner 6 in 1 twice with no noticeable result. My mechanic have a ultrasonic cleaner bath which I can use to clean the injectors. As for the coils my thoughts are more like your current opinion, 20 years are a lot I think. That's why I'm changing some parts that are not giving signs for problems, as the fuel pump for example. I think there are mechanical parts in it that wears in time. I found a set of BREMI ignition coils on a very reasonable price. What makes me hesitate is that nowadays BREMI are made in China. Alternative is BOSCH made in Slovenia at 30% higher price of the BREMIs. Anyway I will go with the cleaning of the injectors first.

Exactly how did you do that test? Left the MAFs plugged in did the first test, then unplugged the MAFS and did the second test right after with no time in between?
You've got me. I was in the countryside and decided on the way back to home to stop by the road and unplugged the MAFs. After 10 KMs I stopped again and plugged in them again. I agree I approached impatiently on this test.

You have done that a number of times so lets fast forward, to the next part of the test. Unplug the MAFS and drive the car for a day or two but at least 50 miles to get it to adapt to the MAFless condition and do the tests again. Do the MAFs unplugged test then plug them back in and do the test again. My bet is your numbers will be totally different.
I will do this as you said and will provide feedback.

My suspicion is you have a bad injector seal or maybe a loose clamp on the throttle to plenum gasket on cylinder 3.
Side note you should re-enable your post cat O2s unless you had a very good reason to turn them off. Post O2s play a role in the fuel trims. The burble pop feature is another thing that could be playing a roll in making this harder to diagnose. All that does is NOT turn off the injectors during deceleration. Do you see how dumping fuel into the engine during decel might mess up your trims? Do this after we find where your problem is, making any change now will be counter productive.
As I wrote in answer of @technician117 a little above I plan to do an ultrasonic cleaning on the injectors and will order new seals before install them back, of course.
As for the post cat O2s, unfortunately they are hardware removed along with the CATs during the headers upgrade.
I will turn off the burble and pop feature and drive the car without it for a while. I keep that in mind it may contribute to the rich mixture, but I had this issue and before remove the post O2s and get the software to enable burble and pop, which makes me not attach such importance to these two things.

Thanks again for the guidances! I will post an update as soon as I have one.

AsenZo
 

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As for the post cat O2s, unfortunately they are hardware removed along with the CATs during the headers upgrade.
If you deleted the cats then you had to turn them off. The burble has proven to be bad for those that have tried it in the past. I have never tried it, I am too cheap to waste gas on decel, I want it all for accel.
You are sort of missing my point. You have had this problem from the first day of ownership, even though you did not notice it. You started replacing 1 maf even though in all likelihood you had two. The way the MAFs work replacement of 1 will fix half the problem, in most cases the car can adapt and adjust for that. It most likely is not MAFS alone it will be 3 things all adding up.
The general rule is don't mod a car unless it is running perfect, that way it adapts well. These mods that you have made to a sick car are complicating things and will make it much harder to find the third thing that might be wrong. The third thing is very hard to find on a stock car because they adapt so well. You will get it to where you are happy though.
 

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I would recommend two tests to narrow down the issue, cylinder leak down and injector balance. If you aren't familiar with either of these tests you can find a lot of videos on youtube. Both are fairly easy to do on this car. For injector balance you can get a fuel injector driver for ~$30 on amazon. You don't have to buy an expensive brand one, just something that will pulse your injector 50 or 100 times will do.
 
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