m104 twin-cam takeover/timing

[aka$h]

Ive been looking into the hesitation on my coupe some more, and it seems to stall at around 3800rpm, which is when the 2nd cam kicks in. The hesitation lasts around 1 sec, and thereafter it performs correctly.

What could the cause of this be?

Cam timing?
Cam position sensor?

Or am I barking up the wrong tree?

 

[Mark300SL]

Cam position sensor?

Or the wiring to it ?

 

[aka$h]

Or the wiring to it ?

Checked the wire, and its not shorting. The issue is too specific to be wiring IMO.

 

[grober]

You have 2 variables on that engine which might be involved. On is the variable valve timing actuator on the inlet camshaft and the second is the two solenoid operated flaps of the variable length inlet manifold. A malfunction or hesitancy in the action of either might be the problem. I did post a short time back the RPM's the flaps opened/shut but can't find it tonight.

 

[aka$h]

You have 2 variables on that engine which might be involved. On is the variable valve timing actuator on the inlet camshaft and the second is the two solenoid operated flaps of the variable length inlet manifold. A malfunction or hesitancy in the action of either might be the problem. I did post a short time back the RPM's the flaps opened/shut but can't find it tonight.

Thanks, Ill try to find it.

 

[television]

I am reading up what I can on crammys engine right now.

If anything fits the bill I will put it up

 

[television]

I need some more info.

Does the engine cut completely and instanly, if so its ign or electronic.

If it splutters as it cuts its fuel being cut off, this is so nesr the 4k pump cut off point.

There first post that I ever did on a forum was a 126 in Oct 05 that died at 4k and sputttered as it cut. after some 30 post, and I was a newbie, and that made it hard it was found to be the incorrect fuel pump relay.
Thats the only reason I still do it, sad am I not

 

[aka$h]

The engine does not sut out, just just hold power back for a bit over a second. So the rev needle stops rising. The difference is more apparent if you have kicked it into a lower gear, ie hard acceleration. Altought this is a 3.6 amg engine, the priciple is the same as a 280 or 320 m104. However the exact rev band of the variable valve timing actuator on the inlet camshaft and variable length inlet manifold, mentioned by Gollom may be different.

Cheers Malcolm

 

[television]

The engine does not sut out, just just hold power back for a bit over a second. So the rev needle stops rising. The difference is more apparent if you have kicked it into a lower gear, ie hard acceleration. Altought this is a 3.6 amg engine, the priciple is the same as a 280 or 320 m104. However the exact rev band of the variable valve timing actuator on the inlet camshaft and variable length inlet manifold, mentioned by Gollom may be different.

Cheers Malcolm

You have 2 fuel pumps why not take the live off each one in turn. and see if the car runs on each, one at a time

Thats very simple to do and meaningful

 

[television]

I have been looking up 104 engine faults for 2 hours today for you and crammy, there is nothing listed for the cam sensors, and I cant see why one should fail at just that RPM.

Start with more basics like I said above and so simple to do

 

[aka$h]

The other thing i thought of was lamda probe, I do remember at MOT time the lamda was taking a very long time to respond.

To clarify the problem is not a rev limit, once the hesitation us over it will continue to rev through to 6500rpm (into red line)

 

[Dave Lewis]

A different idea altogether - an ignition misfire will display the same symptoms, since the injectors are shut off on a non-sparking cylinder. If you can get hold of some substitute new or known to be good coil packs, it's a 10 minute job to swap them. Coils do fail in time.

 

[television]

Not easy then, the cam sensor is easy enough to change, the O2 does not behave in this way,so not that.

Its beyond me and nothing anything like this fault listed

 

[nick mercedes]

The other thing i thought of was lamda probe, I do remember at MOT time the lamda was taking a very long time to respond.

To clarify the problem is not a rev limit, once the hesitation us over it will continue to rev through to 6500rpm (into red line)

Variable valve timing not quite right?

http://www.mercedesshop.com/shopforum/showthread.php?t=144720&highlight=cam+timing

 

[aka$h]

A different idea altogether - an ignition misfire will display the same symptoms, since the injectors are shut off on a non-sparking cylinder. If you can get hold of some substitute new or known to be good coil packs, it's a 10 minute job to swap them. Coils do fail in time.

Tried that already, I swapped all the coil packs and ht plugs\leads over from my other e36 (which runs perfectly), and the fault was exactly the same.

 

[Dieselman]

The cam timing device is a magnetic coil that pulls a helical gear forwards to advance the timing.
Try either disconnecting the 12v feed or clamping the return to Gnd so the device is either always actuated or never actuated.

This will either prove that variable timing either is or isn't the problem.

It may just be coincidence that it happens near the point the cam timing changes.

 

[grober]

Finally!!! found the thread detailing the inlet manifold resonance flaps engine RPM's switching points. It actually refers to a diesel but may well be applicable to petrol engines also. they are 1200,2800,3800 rpm for the diesel engine.
http://mbclub.co.uk/forums/showthre...owthread.php?t=49287&highlight=manifold+flaps

 

[Dieselman]

Different arrangement.

NickMercedes has it in post #14.

 

[grober]

Different arrangement.

NickMercedes has it in post #14.

Just following up what I said in post #4

 

[television]

Engine missfires above 4k = transmision overload protection not operating though this is in the CIS list, is there one on the KE