Mass Airflow Sensor talk

[dworthy]

Try and ID that cylinder, or you can do a cold compression test to find it. I am thinking that you have a cylinder that the rings are sticking, and they can be freed up by dropping in some upper cylinder cleaner.

[snow663]

Try and ID that cylinder, or you can do a cold compression test to find it. I am thinking that you have a cylinder that the rings are sticking, and they can be freed up by dropping in some upper cylinder cleaner.

It's cylinder 2 I believe. When I was cranking the engine by hand after timing it with the valve cover off. I could hear a gurgling sound from the crank case on cylinder 2s compression stroke. There's quite a bit of carbon on the piston head in all 6 I think is a byproduct of the engine running with the timing off. Could be carbon in the ringland... it's going away slowly as the engine racks up hours. I start it every morning and get it up to temp and every day it gets more and more smooth. It probably just needs to be driven and get the cobwebs out of it. I got my tags today so the driving test will be tomorrow I'm driving it to work.

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[dworthy]

You can give it the old Italian tune-up too, that should help it to clear out the carbon. Also you can do a water vapor cleaning, just need to get the motor hot and a spray bottle with some water in it. Of course you have to be careful as water doesn't like being compressed, so it doesn't take a lot of spraying to get it clean either.

Well have fun driving the piss out of it, for that is always enjoyable too!

[snow663]

You can give it the old Italian tune-up too, that should help it to clear out the carbon. Also you can do a water vapor cleaning, just need to get the motor hot and a spray bottle with some water in it. Of course you have to be careful as water doesn't like being compressed, so it doesn't take a lot of spraying to get it clean either.

Well have fun driving the piss out of it, for that is always enjoyable too!

I've done the water vapor method on a Chevy SB it works well but like you said I've seen some motors get destroyed that way. I'll just get it some high rpm for a little bit on my way to work tonight and maybe put some seafoam in the gas. I am a true believer in seafom, I usually use it in the crank case bout 1/2 pint to a whole oil fill about 500 miles before an oil change. It'll polish up everything inside that engine. This is my engine at 206k miles I used seafoam on it a year ago. The golden brown layer of varnish was stripped from even the vanos housing.

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[dworthy]

Yeah, seafoam does work quite nice, but I like to use ATF. Cheap, easy and you can use it anytime. I have always puts some in the motor before an oil change and it does wonders at keeping my motors clean. This is my wagon at 110k miles:

[snow663]

Yeah, seafoam does work quite nice, but I like to use ATF. Cheap, easy and you can use it anytime. I have always puts some in the motor before an oil change and it does wonders at keeping my motors clean. This is my wagon at 110k miles:

I've also heard that in emergencies the military used diesel fuel in the oil to clean the engine out too. It actually evaporates out of the oil leaving you with a clogged ass filter. What do you think of pulling all the plugs and putting some ATF in the cylinders overnight?

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[snow663]

Today I finally got to put her on the road and my Lord it takes off so much easier than before. It doesn't buck or anything. But I still felt a slight hiccup at 5500 rpm once I got on the highway. And I feel like it could still make some more power but then again I may just be expecting more than what I'll get out of a 2.5. Also once I got to work about 22 miles I noticed the idle still drops low coming out of gear then goes up to about 1000 then to idle not really a problem but I know it shouldn't do that. The engine bogs slightly under electrical load too. But I can't find any electrical problems. It's got a brand new IACV and I know that works right. I think I'll smoke it for vac leaks since I just took it apart.

Update: after driving home from work I feel like my cams are still a bit advanced. The boost of power I used to get at 4k is now 3.5k and it still struggles in the vanos range but now it only struggles at 75% or more throttle. Is it possible the mark on my balancer vs the mark on my front cover are not 100% accurate. Can I set it just to the right of the mark on the cover and square up the cams again? Or am I gonna be playing a brutal game here. Is there any way I can accurately degree the crank?
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[dworthy]

I don't think ATF in the cylinder would work very well, like adding it to the oil. Diesel fuel I have not heard of, but kerosene yes. It would be very similar to Diesel, as it would be between Gasoline and Diesel.

As for the timing, you did lock the crankshaft? That should be the only timing mark you would need on the crank IMO.

[snow663]

I don't think ATF in the cylinder would work very well, like adding it to the oil. Diesel fuel I have not heard of, but kerosene yes. It would be very similar to Diesel, as it would be between Gasoline and Diesel.

As for the timing, you did lock the crankshaft? That should be the only timing mark you would need on the crank IMO.

This time I did not lock the crank. Only the cams. Since the vanos was off it was easy to see the timing mark lined up perfectly. Then I verified it with a borescope. I have a motor swapped 318i. Unless the intake is off it's nearly impossible to put the flywheel pin in. Maybe if I put it up in the air and tried from underneath I could get it. I'll put the pin in tomorrow and see where it puts the mark.

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[bmwdirtracer]

Um, yes, you absolutely put the pin in from underneath. If you don't lock both cranks and cam, you have not set the timing. BMW gave you holes and tools you can lock, instead of marks, and you need to use them. That's the only way that you can rule out the timing being wrong, and proceed to other diagnostic paths.

I'm not saying your timing is wrong, I'm just saying that we need any potential error here ruled out. Then the smoke test, to try to find the idle issue.

It seems that you have "issues" at idle, then issues "in the vanos range", and then issues at ~5500 rpm. That won't be an intake leak, but certainly you need to rule things out, as possible.

Um, the electrical load thing: is the DME properly grounded? Is the engine properly grounded?

[snow663]

Okay so the cold start misfire I believe is a leaky injector, my oil is getting dark already and smells like paint thinner (my nose is not very good so i would guess this is actually fuel I'm smelling). It's probably washing the cylinder wall causing the miss I get on cold starts. As for the cam timing, I'm gonna wait a couple weeks, save up some tip money, and buy the more expensive BMW tools, I'm tired of fiddling with it and I'm ruling it out for good. I sat down and wrote down a list of everything and then I went back and pulled up all the info I've gathered working on this thing and the only thing left that I have yet to get real data on is fuel volume, the CKP sensor, and I cant truly rule out mechanical timing. Everything else is ruled out...

[dworthy]

If you have the time, it takes about a week for your injectors to get cleaned and returned. I have used these guys in the past for my M-42/44 injectors, and they really did help me find a running issue: https://www.rceng.com/

[snow663]

If you have the time, it takes about a week for your injectors to get cleaned and returned. I have used these guys in the past for my M-42/44 injectors, and they really did help me find a running issue: https://www.rceng.com/

I have a set of injectors I can swap out just need to find out which one it is, it's such a slow leak not even 8 hrs at work is long enough to cause a miss on the next start it cranks right up. It's gotta sit for like 16 hrs before it misses. Is there really any scientific method of checking which ones are leaking at such a slow rate, would I be able to see it by looking into the cylinders with a boroscope?

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[dworthy]

Well a leaky injector will tend to have a cleaner intake path, so you can look for that.

[snow663]

Well a leaky injector will tend to have a cleaner intake path, so you can look for that.

It was a sticky injector. It slowly got worse over the last few days then last night it dropped a cylinder. I got home pulled the codes, no codes were stored, so I pulled the plugs and Cyl 2 was soaked with fuel. Put it back together and started it. The miss was still there so I pulled the coils one at a time and I got a nice strong pop from each one including Cyl 2, Next I stethed out the injectors. Sure enough no2 wasn't clicking. When I pulled the fuel rail fuel was still dripping from the injector, I swapped it with one from my backup set and it seems my cold start issues have diminished. The engine is now smoothly idling and no longer surges when pulling out of gear.

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[bmwdirtracer]

I'd have to recommend sending 6 injectors off to RC Engineering for blueprinting; $25 per injector....best bargain in the automotive world !

[Aeko]

I just read up on vanos as much as I could and this is the general conception of what I've gathered. These symptoms line up to my car 100000%
The first sign of a failing Vanos unit is rattling at start up of the engine, more advanced signs are knocking sound from idle to 2000 rpms, leading to a surging feeling around 1800-2000 rpm. Overall loss of torque and power, particularly in the lower RPM range, < 2k. Bogging then surging at 2k RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, < 3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel consumption.
It seems my vanos is beyond rebuilding and needs to be replaced. I've already put new seals in it, and my performance seemed better for a while but not much better, which i expected due to the 500 mile break in but its been 5k miles since the new o-rings and performance has'nt increased significantly. could the actual cylinder bore be worn beyond its tolerance as well as the gear cup and its bearing components that rattle?

A little bit of an aside but I had a question here as I'm wondering if I am experiencing a similar issue. When the car is surging, does it feel kind of like the car is rocking back and forth? I'm also having issues with difficult takeoffs, hesitation etc, etc..

[328 Power 04]

A little bit of an aside but I had a question here as I'm wondering if I am experiencing a similar issue. When the car is surging, does it feel kind of like the car is rocking back and forth? I'm also having issues with difficult takeoffs, hesitation etc, etc..

Is your check engine light on, and what codes? Vacuum leak is most common problem to cause what you describe.

[Aeko]

Is your check engine light on, and what codes? Vacuum leak is most common problem to cause what you describe.

No lights or codes. I have a thread on this issue I just made today: https://www.bimmerforums.com/forum/s...r-acceleration

[bmwdirtracer]

Wow, I've just got to say that you got some really damned stupid answers at that other forum. Some dip$#!+ declaring, outright, that you have a bad flywheel ???? Another stating your "traction control solenoid" is bad? Do yourself a favor, and ignore that BS. You need more information, not idiots.

Do you have access to a scan tool which can watch live data from all the computers? Personally, I'd start with looking at wheel speeds, just to rule out the ABS....I do not think this is your issue though.

As Abel (328Power) indicates, a fuel/air mixture issue is likely to be the cause. A smoke test of the intake system would be a good first step (using a professional smoke machine). If you have access to a good BMW specific scan tool, you might also want to try disconnecting the MAF, then starting and driving the car, to see if the issue changes dramatically. (This will set a code, which you'll need a scan tool to clear.)

[Aeko]

Wow, I've just got to say that you got some really damned stupid answers at that other forum. Some dip$#!+ declaring, outright, that you have a bad flywheel ???? Another stating your "traction control solenoid" is bad? Do yourself a favor, and ignore that BS. You need more information, not idiots.

Do you have access to a scan tool which can watch live data from all the computers? Personally, I'd start with looking at wheel speeds, just to rule out the ABS....I do not think this is your issue though.

As Abel (328Power) indicates, a fuel/air mixture issue is likely to be the cause. A smoke test of the intake system would be a good first step (using a professional smoke machine). If you have access to a good BMW specific scan tool, you might also want to try disconnecting the MAF, then starting and driving the car, to see if the issue changes dramatically. (This will set a code, which you'll need a scan tool to clear.)

I had a feeling people didn't thoroughly read the description the first time and jumped to conclusions... to put it nicely. :P

Currently I have only a standalone OBDII code tool and I ordered a Galletto 1260 off eBay to see what I can do with it as far as live data / tuning. This is all learning experience for me, but I can grab and set up whatever tools and software I need to get this figured out. I already downloaded INPA and I'm getting it set up on my spare laptop that has a real serial port.

I'll see where I can get the smoke test done. FWIW I did clean the MAF with actual MAF cleaner I had left over and there was no change.

[Aeko]

It's cylinder 2 I believe. When I was cranking the engine by hand after timing it with the valve cover off. I could hear a gurgling sound from the crank case on cylinder 2s compression stroke. There's quite a bit of carbon on the piston head in all 6 I think is a byproduct of the engine running with the timing off. Could be carbon in the ringland... it's going away slowly as the engine racks up hours. I start it every morning and get it up to temp and every day it gets more and more smooth. It probably just needs to be driven and get the cobwebs out of it. I got my tags today so the driving test will be tomorrow I'm driving it to work.

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I just did a compression test on my M52 and I also noticed carbon buildup on my piston heads. I also have noticed what you mentioned a few posts back about intermittent misfiring at startup and then it runs smooth. In my case cylinder 5 came back as low compression but I re-tested it several times and the compression kept increasing... I'm wondering if it's really dirty valves. (232,000 miles should be a clue). There's also a really strong burning oil smell.

[bmwdirtracer]

I've answered your PM, Aeko.

In fairness to the OP, Snow663, I have to suggest that you start your own thread at this particular forum. You can copy and paste the relevant posts from the other thread, and also my PM, if you like. There are a lot of damned good people at this forum, and you'll get the best responses from them, using your own thread.

[snow663]

My issue was solved by simply replacing a worn out plastic splicer in the hose that runs from the radiator side tank to the back of the cylinder head and heater core. It was old and had a hairline crack that caused air to enter the cooling system, interestingly enough it wasn't leaking coolant externally until it finally popped, replaced it with a metal one and all my issues went away. Apparently it was causing a fuelling issue and that fuelling issue was causing my startup issue.

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