Importance the position of Ignition distributor intermediate sprocket m116 3.5?
 

Hello Everybody,
I'm experienced in timing problem despite my camshafts and crankshafts are in exact position.( Crankshaft 0 , first piston TDC, and both camshafts are in alignment with markings on camshaft bearings) . I also replaced chain due to extention, there was almost 10 degrees deviation on crankshaft while the cams were in alignment before chain replacement, changed chain tensioner, camshaft gears and chain guides.

Now looks like no problem with timing. But, I would like to ask, is there any position while installing new intermediate sprocket for distributor drive? Because according to book, intermediate sprocket should be placed in special position. I attached the picture from book. It will be perfect if anyone share information regarding to this question.

Service manual does not explain the reason of positioning sprocket in this way. Because, in any position of this sprocket, if the first cylinder is tdc crank is 0 and cams in alignment distributor rotor positioning 1 cylinder, engine starts.

I wrote all this, because, despite my engine timing is correct, we feel like, there is a tiny ignition timing deviations regarding to individual piston position during engine operation. At idle, its more noticeble, idle speed changes(fluctuates) +-50 rpm , also when I press accerelation pedal at idle, engine shakes little bit then become normal. There is a delay time.

Will be waiting suggestions to solve this issue.

Thank you very much in advance

Regards,

Kutluhan

J:

You are probably correct that it does not matter from a practical standpoint. Hypothetically, the rotor of the distributor could be just enough out of position that the amount of available rotation of the distributor body is not enough to achieve correct ignition timing. The small timing variations that you observe are due to slack and clearances in the gears and chain that drive the distributor, and also to wear in the distributor bearings/bushings and in the point cam.

Thank you very much Mr.Frank for your reply and information. Today I tried with my spare ignition distributor and idle problem still available. I have new MAP sensor tried with it and also checked the throtle switch, 20 clicks.Also nothing changed.

Still did not find the problem, do you think if the injectors are not equally spraying(as volumetric) this can be the reason?

If not what to check about timing? Except, ignition drive sprocket, all other stuff including chain guides were replaced new..

I run a fair amount of timing advance on these engines - around 8 - 10 degrees BTDC at idle.
I would check to see if you have any major play in your throttle linkage. Throttle position switch and throttle valve should move together and at the same time.

The delay in engine speed increasing sounds like your throttle position sensor is adjusted too far the wrong way, so that you're opening the throttle blade but the ECU is still thinking it's on idle stop. You can use a multimeter to verify. It should read open the split second that blade starts to move, as close to it as you can get.

As for the fluctuations, as Frank said, it's normal based on wear of the components and the harmonics of the engine. You can chase your tail all day trying to fix it. A way to reduce it is to switch to an electronic ignition system that doesn't rely on the points. The points result, even in a factory condition distributor, a tiny amount of pressure on the shaft that can explain these fluctuations, as cylinder 1 and 6, for example, can get different spark timing / gap.

Thank you very much for TomGuy,Benz Dr., Frank Rainer for your suggestions and detailed information regarding to issues I shared,

For delay approx 2 second in engine speed while pushing acceletration pedal issue , today I was able to recheck throttle switch with multimeter, it reads opens suddenly after blade is open and 20 clicks totally. Also switch is moving together with throttle blade.

Secondly for fluctuations in idle speed and sure while driving which is not noticeble due to high revs but sure available, I still did not find the issue, This fluctuations are too much for wear of the ignition sprocket or ignition distributor I think. Because, I have spare ignition distributor still same issue. thinking of shifting to Petronix ignition I but, would like know where 5Kohm spark plug heads and currend transistorized ignition coil is compatible with this system or not.

Also, this fluctuation issue emerged this year, winter times I don't use car. Did not have last year. For and information I recorded a video and decreased idle speed to min closer to end of video to realize this fluctuations better. Could you also watch and give me some additonal suggestions if you have?

https://vimeo.com/user89325525/review/288948546/ec584171cb

Thank you very much

Kutluhan

The video is broken. You said the RPM fluctuates by 50RPM, but do you maybe have the D-Jet "Surge"? If your idle is too high (1200RPM) you'll hit the fuel cutoff until it gets to about 700RPM or so, then it'll go back to 1200.

Combined with the "Delay" in hitting the gas, it leads me to believe maybe your aux air valve is too far open. Your mixture is too lean to get off idle. Close your idle air speed screw a bit and see if that helps.

If we could see the video I could tell if it's the D-Jet surge or not.

Actually video link looks like working for me but strange. I will upload video from other website. Closer to end of video at it's more noticeable as I decreased idle speed to 400rpm.

https://streamable.com/j2mgu

I will try to describe the problem. The 'surge' I know. If the piston of aux air slide valve got stucked 'remain open' too much air entering to engine and rpm increases till 1500 or 2000 rpm even then ECU cuts off fuel like you expained to decreases replt to 750 or Idle speed and this loops continues till warm up or sometimes forever if the aux slide valve borken or defective.

But my case, when I listen exhaust sound, engine runing normal but there is a'pıt' 'pıt''pıt''pıt''pıt''pıt' sound intervals during idle operation or cold start. It looks like some injectors are not working or imporperly spraying or not inorder with timing if so how can it be?

Sorry I can describe sound like this, normal exhasut engine sound ''mmmmmmm then pıtpıtpıtpıtmmmmpıtpıtmmmmmmpıtpıtpıt''unstablility or interruption like wrong timing but I have ignition gun, checked timing is stable no deviation..

As a notification, at cold start, engine does not run high speed, normally it should work around 1200rpm at least as the weather aprrox 18 degrees now. But my case engine runs around 900 rpm at cold.

I don't think so that this problem because of ignition, because when acceleration no interruption(misfire). Everything is normal, but I'm sure this tiny idle speed misfiring is somehow related with fuel suppy.

For this case I also checked fuel pressure , it's stable at 2bar at idle or when push acceleration but this problem still available .

Checked trigger points cleaned nothing changed, tried spare ecu same, tried with new MAP which I keep as spare same, checked with other distributor same.. Just did not try with other set of injectors as I don't have 8 spare.

It sounds like a misfire. While idling, pull the plugs from your injectors one by one. Ex: Pull cylinder 1, then plug it back in. Pull 2, then plug it back in. See if any of them change idle speed.
Then do the same with your ignition leads if you can't pinpoint a cylinder. BE CAREFUL since you can easily get zapped doing this. The safest way would probably be to wrap a copper wire around the lead that's grounded to the engine somewhere before you pull it, and then make sure to wear thick insulated rubber gloves as you pull the leads.

If it's a miss, one of them would result in no change, or a much smaller change if it's a small miss. Have you verified all of your valves are properly adjusted? If one is too tight it won't get proper compression, and can result in not a complete miss but lower power from that cylinder, which would be most noticeable at idle as a near-miss.

Today I was able to check all injectors and sparkplug supressors for operation when the engine is running. I connected tachometer to chech the rpm reduction while removing injector cables. Most of the injectors rpm reduction is about 25. Except 2. 2 injector very little effect noticeble but not like other 6. Also checked out for ohmic values of each suppressors, all of them between 5k to 5.16k. I removed each suppressor, except one, most of them has noticble effect, engine misfires when removing suppressor, one of them has little effect but not bec of suppressor error, I removed spark plug of this cylinder and replaced with new one. But still this cylinder sometines misfires little bit, we remade all ignition cables by using beru copper silicon cable previous year.
Also I noticed that while the engine is running I put screwdriver to each suppressor cable connection end, at 3 of 8 cable, I noticed spark flux from suppressor dust cover cap to screwdriver. Do you think this is normal?

About the exhaust sound pıtpıtpıt situation, I found the reason, the ignition cable plugs on distributor cable was wrongly plugged. #1 was plugged instead #2 , #5 was placed instead #1 therefore I replugged each cable with the next one (shifted right). Problem solved.

About the problem when I give full throttle at idle, there is a delay and stall approx 2 secs, then rpm increases. I give full throttle when removing distributor vacuum line, engine does not stall at first for a sec or no delay. Do you think vacuum box defective? But when I remove vacuum hose at idle, idle speed increases to 1000 rpm from 750rpm.