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idjit 09-19-2012 09:36 AM

Is this typical of Vanos?
Now that the colder weather is back I have the same issue as I did last fall and winter.

At temperatures starting somewere below 15C-20C (60F-65F), when I start in the morning I get missfire on cylyinder 3 (with cutoff). Just #3. No other codes.

After warmed a bit an "off/on" will often completely clear the rough idle. If I just start driving, usually the light doesn't come on. If I idle for it to warm up it does. Either way it's missing. Sometimes worse than others

The plugs have been replaced since last year and I swapped the number 3 coil with number 1. Also a new DISA unit this summer and there are no vacumm leaks. Thorough smoke testing was done as hoses ccv, etc were all replaced last January.

Always #3 and never any other. Is that typical?

Thanks, -Bob

Flybot 09-19-2012 11:03 AM

Sounds more like a bad fuel injector or coil. VANOS will not affect just one cylinder. I cant remember if you get a code for an individule coil.

BentValve 09-19-2012 11:21 AM

If you unplug the vanos solenoid and the issue doesn't happen, then it's the vanos.

idjit 09-19-2012 01:56 PM

Ok, thanks. I've already ruled out the coil by swapping, so is there any trick to swapping injectors? Like how to not drop bits into the cylinder or something scary like that?

For the solenoid. Do I unplug it tonight and run it like that a couple days or do I wait till it's running bad and then unplug it to see if it fixes it (i.e. will it hurt to run it while unplugged).

I tried the unplugging when it happened before, but when it stopped I wasn't sure because if I turned the car off, reconnected it and re-started or simply plugged it back in it wasn't missing anymore.

Thanks -Bob

idjit 09-20-2012 12:16 PM

OK, I unplugged the intake solenoid on the vanos and it started fine. That may have been a fluke so I'll repeat it every day for a week to be sure.

Here's my theory:

I think vano's might play a part. It's not bad enough to be throwing codes except for cylinder 3 cause there is an issue there that does not show up on warmer days when the vanos does not come into play. I've swapped the coil and the plugs were change since last spring when I last had the issue so it's probably the injector. Of course compression could be a factor but I'd prefer to think I didn't say that.

Maybe vanos if fine and it's just the added bit of fuel from the cold start injector that tips it to misfiring (flooding). I assume the cold start injector is used on cold days? Maybe more so on cold days?

Once the computer senses the missfires, it shuts down the injector to prevent cylinder washdown and catalytic failure. Meanwhile, with the car running, things warm up a bit. Perhaps the vanos goes normal or maybe now the cold start injector is off or something other "cold start feature". Now missfire would be gone if not for the fact that the fuel remains shut off until computer reset. So I restart the car and all is fine.

So what can I do for less than $20.00 without getting my hands dirty?....

I'll keep checking the vanos for a week (as mentioned above). I'll try some "Techron" injector cleaner on the next fillup (if I can find it here). "Redline SI-1" seems to have a good reputation as does "BG-44K" (again...if I can find it). In fact I've read "BG-44k" might be the best. I know where I can get "Lucas" injector cleaner, another favorote from what I read.

Then, on the fillup after that I'll "seafoam" it if I still have the problem. Having owned a 1980 golwing I've learned to respect seafoam, but it's for a lot more than just injectors. Very gentle on seals. Lot's of cool smoke to impress people when taking off at green lights. Fun to watch in the rear view mirror as they fade away into the fog.

After that? I'll swap #3 injector with whichever other injector looks easiest to get at to see if the problem moves (now my hands would be dirty and $25.00 wasted).

After that? Ignore it if I can. Otherwise compression check or something.

I've read people suggest computer, but I highly doubt it. That theory seems to come from the fact that they have to reset, which I think is by design to protect the car. The shut off is a result of the missfire, not the cause of it. I don't believe being cold is going to repetively cause the DME to shut down the same injector.

I wouldn't doubt that my vanos is on the way out. Does anyone have an exchange program for vanos using the seals from ""?

Thanks for your helpful replies, I let you know....


poolman 09-20-2012 01:04 PM

If you want to swap Vanos units--Dr Vanos rebuild their units using the Besain seals--but if your going to all the work of swaping out the unit your far enough along at that point to just replace the seals yourself. Your looking at about 130 bucks plus your labor to do the job. The OEM seals start to go bad at the first 10k miles--you just don't know it until you replace them--then you will see what all the fuss is about

idjit 10-10-2012 08:30 AM

Well, I've run a bottle of injector cleaner and, on the next tank, a bottle of seafoam though it and nothing has changed.

It took a while to be sure, where it's a bit random in "when" or "how severe", but disconnecting the intake solenoid does not cure the missing problem. I have noticed that when it acts up it starts fine and then, very soon after, gets rougher as the temp needle makes it way through the blue area on the gauge. It smooths out about the time the needle clears the blue area.

I have not found time and weather condition to take on swapping injectors yet. Meanwhile, I'm open for other ideas.

cn90 10-10-2012 09:39 AM

Did you check the wiring that feeds #3 coil?

idjit 10-10-2012 11:46 AM

No, it's so consistently only cooler days from a cold start that I didn't figure it could be something like that. Not always on cool days, but never when it's warm outside. Once the engine is warm it purrs. Never a misfire when the engine is warm. Knowing this, would you still suspect wiring? -Thanks

AnotherGeezer 10-10-2012 11:58 AM

When you pulled plug 3 (assuming you've already checked the plug to be sure it's not worn out) was it oily at the base?

doru 10-10-2012 12:15 PM

Could be one of a slew of things. Maybe a cracked rubber of the coil-on-plug? Anyways, here's a good read from the Fanatics, a bit overwhelming, but you know what you did and didn't do to your car.

idjit 10-10-2012 12:16 PM

No, Last winter that was checked by mechanic when new plugs were installed. In fact, shortly after being checked in January the oil separator did it's thing and took the valve cover gasket, hoses, all the usual with it. Those holes were all cleaned out when the new gasket was put in and this issue remained until the warmer weather. Later when I swapped coils I checked also.

idjit 10-10-2012 12:21 PM

Thanks, Doru, I'll read this in more detail tonight. Vacuum wise, it passed smoke test after lots of hoses and elbows and things got replace with the oil separator. Where this is one specific cylinder only lot's of things are not going to apply but there might be something in there.

Flybot 10-10-2012 02:41 PM

If your sure its one cylinder it almost has to be an injector or plug/coil. Since it gets better as your engine warms up, most likely an injector. If its not that, then your talking maybe a valve. But that is very unlikely.

idjit 10-10-2012 03:10 PM

Well "injector" stays as the next thing I try after a peek at the wire to the coil then. I don't think it's the wire cause it's too predictable with temperature. Plus you've pointed me at it twice :-) I've looked at the link from Doru, but I don't see anything that fits with my symptoms as close as what you said above. Makes me want to rush out and by a spare fuel pump though. -Thanks

DPP528 10-11-2012 08:31 PM

If the Idle is surges when it's cold out it's likely that the Idle Control Valve is dirty. I replaced mine ($140 part) and it's much smoother now. I overhauled my Vanos seals thinking that they were causing the problem and although it helped performance, the problem continued until I swapped for a new ICV. Very common problem with the M52.

idjit 11-01-2012 04:21 AM

Well I finally had a decent day to swap injector 3 and 4 allong with the O-rings. BTW all 12 O rings looked great.

Still throwing cylinder 3 misfire with fuel cut off.

To date...

The spark plugs have been replaced since last year and I swapped the number 3 coil with number 1. Also a new DISA unit this summer and there are no vacumm leaks. (Thorough smoke testing was done as hoses ccv, etc were all replaced last January.) ICV valve cleaned. Unplugged Vanos intake solenoid to rule out vanos. A can of injector cleaner, a can of seafoam. Injectors swapped.

Is there a cold start injector in this engine? Would it feed primarily into Cylinder 3? I'll have another look at the spark plug chamber before moving on to a compression check.

Always starts smooth then goes rough and then rougher as the idle drops then smooths out again about when the needle comes out of the blue.

Thanks -Bob

poolman 11-01-2012 05:48 AM

Change our the Vanos seals--my 2 cents

idjit 11-01-2012 06:31 AM

But why just cylinder 3? I thought unplugging the Vanos intake solenoid was supposd to rule out it being vanos. Is that a myth?

poolman 11-01-2012 08:45 AM

I thought that when you unplugged the vanos the problem didn't arise. If it did then it's not the vanos..You say that you replaced the plugs last year--try a new plug in the #3 hole and see what happens just for s--t and giggles. If it still has no effect-then try this-when cold and someone else cranking the car--have the cover off of the engine and turn on some butane out of a tourch and bring it over the point that #3 intake bolts onto the head. Lets see you have a small vac leak on your intake gasket that only occurs when the engine is cold.

Fudman 11-01-2012 08:54 AM

Two questions:

1. Are you erasing the code every time and then it comes back?
2. What spark plugs are you using now?

idjit 11-01-2012 09:18 AM

Yes, I am erasing codes.

Not sure of the spark plug. I had my mechanic replace them, but the issue remained on #3 after replacement.

idjit 11-01-2012 10:11 AM

Poolman.... that's a great idea. My mechanic had the intake manifold off when doing the CCV job, but that doesn't mean he checked the gasket. I suppose it's also entirely possble he didn't actually change the plugs when he said he did. I'll have to see what's in there first so I may as well check the electrodes for wear, gap and color and do a swap between cylinders first.

Is Propane OK?

poolman 11-01-2012 03:56 PM

Yeah Propane is the very thing to use--say he had the intake off --Hmm that sound like it could be the very thing happening--When cold there is a slight vac leak straight into that cylinder--when warm the heat swells up the gap and the vac leak goes away-Hmmm

idjit 11-02-2012 04:17 AM

Well the #3 issue existed before the intake manifold was off, but I suppose that really means nothing if the gasket is old. I'm hoping it dosn't rain all weekend so I can try the propane test. I'll let you know.

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