M44B19 misfire at idle - SOLVED

[Statek 87]

Hi guys,

I've got a 1998 Z3 which has a weird misfire at idle. It feels absolutely fine while driving, but it vibrates at idle. It's been slowly getting worse, or at least more noticeable. 
The revs at idle are at around 650rpm, which seems ok. If you stand by the exhaust pipe, you can hear it misfiring maybe once every few seconds though.

What I've done so far:
- New spark plugs
- New PCV valve
- Cleaned throttle body
- Cleaned IAC valve
- Visually checked for vacuum leaks - all hoses are like new, the car has <60,000kms
- Replaced the coil with one from another car

Cleaning the throttle seemed to help a little, but definitely still has the intermittent miss.

My 318ti has a similar issue, but that car is a 'race-car-in-progress' so (A) the shaking doesn't bother me there, and (B) it doesn't tend to sit on idle for much of its life.

Any pointers as to what to look for?

Cheers, Kris.

p.s. Not sure if related, but it tends to get around 10L/100km (or 10km/L if you prefer), which seems a bit high for a 1.9 which doesn't get driven all that hard.

Edited April 4, 2018 by Statek

[BM WORLD 1283]

I was gonna say pcv , but I see I have done it ,

there are vac hoses attached to the injectors , check those for splits,

remove top half of the manifold to get to them.

also the hose going to the PCV perish with oil going through them and split .

try spraying some engine start or brake cleaner , wd40 around the the intake system see if the idle picks up.

could be a bad MAF.  can scan for you if you bring it around.

bad engine mounts can cause vibrations on these.

fuel economy sucks on automatic m44 m43 m42 engines

as they use a 4speed GM box (like a holden trimatic with a overdrive)

5spd manuals will use far less fuel , more like 7-8l per 100km

 

[Statek 87]

Thanks for the leads Brent, I'll check those things and see what I find. 
If nothing comes of it, then I'll get in touch to arrange a scan.

Cheers!

[Eagle 1662]

Does it misfire when cold and hot? DISA valves can leak and act up

Nothing beats a smoke machine for finding vac leaks

 

[Statek 87]

2 hours ago, Eagle said:

Does it misfire when cold and hot? DISA valves can leak and act up

Nothing beats a smoke machine for finding vac leaks

 

Yes, both cold and hot, although it is more noticeable when it warms up and the revs drop further. I'll look into that.

Yeah, the more BMWs I acquire, the more I think i'll have to look at making a smoke machine for myself 

[Statek 87]

Further checked:
- PCV hose
- Injector hoses
- Cleaned MAF (no change), swapped MAF with 2 spares (no difference)
- Checked DISA valve while manifold is off - looks ok, closes and opens when applying vacuum as expected

I'm not ruling out worn engine mounts for some of the vibration, but the engine definitely has a misfire at idle.

While the manifold is off, I've noticed the number 3 and 4 injectors have wet spots around the top. I'm pretty sure that leaking injectors could cause this misfire, although I'm not sure why it's only affected at idle. Thinking about it, it would also be increasing fuel consumption... Hmm..

Looks like I'm going to need some new o-rings, and continue tracking this down afterwards (although fingers crossed this might be the cause).

[dirtydoogle 383]

Super common to have cam timing doing this, the gears are adjustable and fairly easy to fix 

I have a timing tool cut for these for this reason 

[Statek 87]

38 minutes ago, dirtydoogle said:

Super common to have cam timing doing this, the gears are adjustable and fairly easy to fix 

Hmm... didn't think something like this would develop before the engine even hit 60,000kms. Good to know it's common though. I'll look into it, thanks!

[dirtydoogle 383]

The cam timing is set differently to different markets from what I can tell. Mostly a compromise with noise/vibration vs throttle response 

However eliminate everything else is always a good idea 

[Statek 87]

While waiting for the o-rings to arrive, I've been thinking (dangerous!). I was still very suspicious of the DISA valve so I pulled it out - easy enough.

Checked visually - it has a little play on where the lever holds the flap, but nothing terrible. Applying vacuum to (read: sucking) the little hole under the solenoid closes the flap. However, manually closing the flap and looking through the hole at the diaphragm I noticed that only around 3/4 of the rubber diaphragm move with the lever, and the rest remains attached to the housing. Looks like I may have found the problem.

I can't seem to find a rebuild kit for the M44 DISA valve... anyone have any leads?

I might pop up to pick-a-part on the weekend and pull them until I find a good one, as I don't really want to spend $400 on one just to find out it doesn't fix the issue.

Edited April 12, 2018 by Statek

[BM WORLD 1283]

1 hour ago, Statek said:

While waiting for the o-rings to arrive, I've been thinking (dangerous!). I was still very suspicious of the DISA valve so I pulled it out - easy enough.

Checked visually - it has a little play on where the lever holds the flap, but nothing terrible. Applying vacuum to (read: sucking) the little hole under the solenoid closes the flap. However, manually closing the flap and looking through the hole at the diaphragm I noticed that only around 3/4 of the rubber diaphragm move with the lever, and the rest remains attached to the housing. Looks like I may have found the problem.

I can't seem to find a rebuild kit for the M44 DISA valve... anyone have any leads?

I might pop up to pick-a-part on the weekend and pull them until I find a good one, as I don't really want to spend $400 on one just to find out it doesn't fix the issue.

got good ones in stock

 

[Eagle 1662]

Just replaced the parents one (again) which had the same issue, it was creating a small vacuum leak out the rear pipe fitting and the shitty flap was rattling as well. 

DISA prices keep increasing in price it seems, the last one years ago was $350 NZD, this one was over $600 with shipping and GST added.

Edited April 12, 2018 by Eagle

[Young Thrash Driver 1020]

Could just rip the flap out and be done with it. You wont notice any lack of torque or reduced response from a M44, will you?

[Statek 87]

14 hours ago, Eagle said:

Just replaced the parents one (again) which had the same issue, it was creating a small vacuum leak out the rear pipe fitting and the shitty flap was rattling as well. 

DISA prices keep increasing in price it seems, the last one years ago was $350 NZD, this one was over $600 with shipping and GST added.

Try www.partsouq.com for parts next time. I've ordered quite a few bits from them, some genuine and some aftermarket, almost always cheapest on the market. The genuine BMW DISA valve from these guys, including shipping would end up around $380.

[Statek 87]

11 hours ago, Young Thrash Driver said:

Could just rip the flap out and be done with it. You wont notice any lack of torque or reduced response from a M44, will you?

It's an idea. The automatic gearbox will compensate for the lack of torque... 

[Eagle 1662]

9 hours ago, Statek said:

Try www.partsouq.com for parts next time. I've ordered quite a few bits from them, some genuine and some aftermarket, almost always cheapest on the market. The genuine BMW DISA valve from these guys, including shipping would end up around $380.

Yeah i found a few places in Europe that had it for around that but shipping times were 2-3 weeks and i needed it asap. The GST was the big hit as the valve its self was just over $400

[Statek 87]

Kept trying to sort the issue out.

- Scanned ECU - no codes, diagnostics didn't show anything interesting
- Replaced DISA
- Swapped cam sensor with one from another vehicle
- Unplugging the O2 sensor didn't change anything, so replaced the O2 sensor with a new Denso sensor (only around $40US, so worth a shot)

I've had several friends use the car, and nobody noticed anything wrong, so I'm beginning to think I'm being overly sensitive.
If it keeps bothering me, I'll attempt the timing, but I'm overly busy at work recently and don't really have time/desire to mess around with it.

Edited July 16, 2018 by Statek

[gjm 3258]

Have you tried swapping the cam position sensor?

[Statek 87]

30 minutes ago, gjm said:

Have you tried swapping the cam position sensor?

Yes

Sorry, I've done quite a few things in the last few months and no longer remember them all. I'll add that to my previous post.

[dirtydoogle 383]

You're certainly it's a miss and not broken down engine mounts? The 4 cyl mounts are fluid filled

[Statek 87]

12 hours ago, dirtydoogle said:

You're certainly it's a miss and not broken down engine mounts? The 4 cyl mounts are fluid filled

Yep, replaced those too  

¯\_(ツ)_/¯

[B.M.W Ltd 950]

The M44 had an inherent rough idle issue which could be overcome in most instances by a  mod to camshaft timing. Have a look...just google : " E36 BMW M44 camshaft timing modification"

[Statek 87]

2 hours ago, B.M.W Ltd said:

The M44 had an inherent rough idle issue which could be overcome in most instances by a  mod to camshaft timing. Have a look...just google : " E36 BMW M44 camshaft timing modification"

Thanks Glenn, I have read quite a few posts about this mod. It's an option, I was a bit iffy about doing anything to the timing due to the cars low mileage - surely it hasn't been like this from factory? 

In a couple of weeks, once I've replaced the blower fan on my friends Mini and clutch on my sister's Corolla, I might attempt adjusting the timing. My 318ti has a similar feeling idle, but it's done 260kms and the idle doesn't bother me since it lives near the redline when it's being driven. Might experiment with this car first.

Edited July 18, 2018 by Statek

[Statek 87]

On 7/19/2018 at 6:38 AM, B.M.W Ltd said:

The M44 had an inherent rough idle issue which could be overcome in most instances by a  mod to camshaft timing. Have a look...just google : " E36 BMW M44 camshaft timing modification"

You were right Glenn, that's done it!

Copy pasta from http://www.318ti.org/forum/showthread.php?t=21403

Quote

VIBRATIONS AT IDLE SPEED. PARTICULARLY NOTICEABLE WHEN IN THE SEAT WITH THE VEHICLE STATIONARY. Its says its due to " differing levels of residual gasses in the individual cylinders at idling speeds. This effect occurs at irregular intervals with differing intensity. Retard the intake cam timing by 6 degrees (=12 degrees crankshaft) to 116 degrees crank angle. Changing the valve timing in this manner does not lead to any perceptible drop in torque or output"

Interestingly enough, when you take off the rocker cover it looks like only the exhaust camshaft is adjustable, but that's due to the camshaft sensor pickup wheel being installed on top of the intake camshaft sprocket - both camshafts can in fact be adjusted.

All in all it took about 30 minutes to do, and the car is SO much smoother when idling.

I'm still surprised that this is what it took, have all M44s came out of the factory with this issue?

[dirtydoogle 383]

Yeah its not particularly uncommon but most people are plebs and don't notice these things like you have