1990 560SEC Checking ignition timing?

[Mikesmerc]

Any one know the procedure for the above?. Have timed older mercs but these had points and seemed more straight forward.
Regards
Mike

 

[guydewdney]

according to autodata, its 14-18 degrees BTDC at 600 rpm, with vacuum connected - use the little pointer at the front of the engine that lines up with the flywheel. - and a strobe connected to No1 cylinder (No1 is the front most o/s one and i think the lead is the rearmost one on the dizzy))

 

[Mikesmerc]

Cheers Guy, will check it over the weekend. Dont think I have a vacuum connection to the distributor. Would it be advanced and retarded electrically? Its a starting problem I have, she runs backwards (for a short time )about ten times before she starts. Happened overnight and cant believe that the distributor moved to advance itself, so I just want to check if the timing is out.
Thanks again
Mike

 

[Mikesmerc]

Got my strobe light out, connected it to No 1 (marked on cap)idle at 600rpm and all I could see on the pulley was the No. 2. Loosened the bolt which secures the dist. and rotated it while running, made no difference whatsoever, it would always stay at the No 2. It would seem that the ECU or some other bit of equipment is compensating my efforts. There seems to be a green wire supplying an electrical coil wrapped around the rotor shaft which I presume advances or retards the rotor.
Any more suggestions/comments would be appreciated.
Regards
Mike

 

[guydewdney]

sorry - bit of a cock up there - its 7 - 11 deghrees BTDC - and is not adjustable...

the crank should have 0, 10, 20, 30 etc written on it - theres a sensor (TDC) bolted to a small plate with a pointer on it, at TDC the pointer ponts at 0, then with the stobe it shoudl point roughly at the 10 degreee mark..

not sure what the No. 2 mark is...

 

[Mikesmerc]

Cheers Guy, just had a quick look at the pulley again, its 20deg not 2 BTDC at the pointer. Got a bit confused with the mark between the 2 and the zero. The sensor is a bit further on around. Any ideas what has advance this?
Regards and thanks
Mike

 

[guydewdney]

things taht affect ign timing:-
engien temp
engine speed (supposed to be 650 rpm)
knock sensor (if it has one) = fuel quality
rich / lean = lambda sensor
throttle possistion (check the thottle switch is right)

what exactly do you mean by 'running backwards' - it cant - its a four stroke...
do you mean it backfires? if so - id look more at there being an air leak / exhaust leak

 

[Mikesmerc]

Yes Guy it backfires when trying to start it or when trying to accelerate quickly. She idles about 650 so could I eliminate an air leak? Checked the pipes a while back when I was having idle air valve problems. I found two engine temp senders near the thermostat housing, one seems to power the guage(single pin) and the other seems to power the AC fan(two pin). Where abouts is the Lambda sensor and how is it checked.
Cheers Guy
Mike

 

[guydewdney]

the two pin one is also the fuel injection one..

double check those pipes again - AND!!!! check that you have done the idle valve correctly - it should idle with no air con on, and minimal electrical load (ie lights etc off) at 650 with the pipe from the idle valve blocked - i.e. so that it only uses the ICV to INCREASE the air flow when needed... set the idle with the throttle plate / vlave.

check those pipes again, and all the seals at the manifold (geta friend with a rag or somthing to try to block the exhaust pipe and any leaks will become clear.

an old trick is to use wd40 on all the possible places where a leak can be (old pipes split....) - with engine idleing, spray a bit of wd40 on the selas / gaskets / pipes etc - if the revs change then thats where the leak is. (esp without the ICV connected...)

 

[Mikesmerc]

The high idle problem occured after the hard starting/backfiring problem, think the backfiring may have effected the old valve. Replaced valve and now idles OK 600-650 Guy with no load on, will she still run with the the pipe from the idle valve blocked?

 

[guydewdney]

it should do - there is an idle adjust screw surely? use this (with idle pipe blocked) to get idle set. this means that with air con off etc etc that the idle valve is shut- as it should be...

haynes manual?

 

[Mikesmerc]

Still in the office, just popped out to have a look, no idle adjust screw visible, unless its hidden under the air cleaner. Have one on my old 350sl ok. Must get one of those manuals, have ones for my other cars but not this one, typical. Leave it with me a while and I let you know how I get on.
Looking back on my old posts Talbir mentioned that the EZL control unit governs advancing and retarding ignition, could this be faulty or is it just reading info from the other bits you mentioned?
Regards
Mike

 

[guydewdney]

i dont believe its an ign timing issue tbh.. do the wd40 thing tomorrow - also - fire it up in the dark and check for any visible sparks from the leads shorting to the engine... just to be sure (to be sure, ted..

 

[OlafMaxwell]

Mikesmerc.....I see you are in Cork too.....do you know Reisers down at Minanebridge? I have found a few people recommending him....have you ever used him? Do you know anything much about him? Seems like a lot of German Merc owners here are using him and recommending him.

 

[OlafMaxwell]

One car we had an air leak problem.......was fine at idle, but on power the engine was moving under load and opening up a bad air filter pipeline connection.....Combination of torque reaction....you should have plenty of that...and faulty engine mountings.

Other one to look for is air leak in fuel line, I have had that too. That can mean air leaks in aluminium casings, filter body etc.

 

[Mikesmerc]

Thanks Guy, will have a look and try it out, just getting time in the daylight is a problem.
Just over the road from yourself Olaf, havent heard of this Reiser but will certainly look into it if all else fails.
Thanks
Mike

 

[Mikesmerc]

Thanks Guy, will have a look and try it out, just getting time in the daylight is a problem.
Just over the road from yourself Olaf, havent heard of this Reiser but will certainly look into it if all else fails.
Thanks
Mike

 

[Mikesmerc]

Spent about two hours at the car last night. Used almost a can of WD over the air pipes, joints and injectors with no change in rpm. Sits at about 700rpm. No sparks in the dark either. No sign of an idle screw either. That two pin sensor that serves the fuel injection also serves the AC fan. With all air con/htg turned off and ignition at position 2 ,if I bridge the two pins the AC fan comes on, is this supposed to happen, is it to provide extra cooling to rad?
One thing I noticed is when ignition is turned to position the two you can hear the fuel pump priming and usually cut out after a few seconds, but sometimes it doesnt cut out at all. Could this be linked to my problem?.
Regards
Mike

 

[guydewdney]

sounds like fuel pressure then - if the fuel pump doesnt cut out it could either be that the system doesnt pressurise up (leaking regulator - cottonreel sized thing on end of fuel rail, with a vac pipe on it) is dead - OR the fuel pump relay is sticking - id go with the first tbh.

oh well - at least we have eliminated air leaks!

 

[Mikesmerc]

Will have a look Guy.
Cheers
Mike