My 300SL ticks over nicely when cold in both Drive and Park but once the engine is up to temperature it gets very 'lumpy' when stopped in Drive . Moving to Park smooths everything out. I have replacement the vacuum pipe to the R/H side of the autobox (it was found to be squashed). Any help would be most welcome.
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Poor tickover - Feels like it's going to stop
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Malcolm Brown
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Poor tickover
Do you mean slightly lumpy or very lumpy? Mine is slightly lumpy under those conditions - something I've noticed but not been too worried about. It seems like the revs dip slightly every 10-15 seconds or so.
Do you mean slightly lumpy or very lumpy? Mine is slightly lumpy under those conditions - something I've noticed but not been too worried about. It seems like the revs dip slightly every 10-15 seconds or so.
Poor tickover
Could be the A/C- it was in my car.
You know, when the A/C is on the engine revs will drop everytime the A/C compressor engages. Problems with the A/C system can cause it to click in and out very often, which is most noticeable as an eratic idle, especially when in "Drive" as there is then a little more load on the engine too.
Otherwise...
...there is also a cold-start fuel enrichment device, which takes care of a cold engine. When the engine is warm, it will rely on the main idle jets, so could be a fuel injection problem. However, if it only happens when Drive is selected it might be a a problem with the Torque Converter of the gearbox.
(Edited by Arnie at 1:34 pm on July 2, 2002)
Could be the A/C- it was in my car.
You know, when the A/C is on the engine revs will drop everytime the A/C compressor engages. Problems with the A/C system can cause it to click in and out very often, which is most noticeable as an eratic idle, especially when in "Drive" as there is then a little more load on the engine too.
Otherwise...
...there is also a cold-start fuel enrichment device, which takes care of a cold engine. When the engine is warm, it will rely on the main idle jets, so could be a fuel injection problem. However, if it only happens when Drive is selected it might be a a problem with the Torque Converter of the gearbox.
(Edited by Arnie at 1:34 pm on July 2, 2002)
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Poor tickover
Malcolm/ Arnie
Thanks for your help
Its ?lumpy? enough to course concern and worry the wife! The revs drop by about 200+rpm and this I believe is the main problem. Could be that if the ?Park? tick-over was dropped to this level the same ?lumpiness? would be felt. I also own a 280SLC auto (in bits at the moment) this doesn?t exhibit this problem and since the 300SL is a new acquisition I have something to compare it with.
The Aircon is switched off during this exercise and I believe Arnie may be close to target regarding the injection side. I once read in Car Mechanics about a ?modulator? in the auto box and wonder if the 107's have such a devise. Another point is that the front driveshaft coupling is worn and this may be contributing to the problem.
I?m sure the engine is not going to stall so I think I?ll take Malcolm advice and live with it.
Malcolm/ Arnie
Thanks for your help
Its ?lumpy? enough to course concern and worry the wife! The revs drop by about 200+rpm and this I believe is the main problem. Could be that if the ?Park? tick-over was dropped to this level the same ?lumpiness? would be felt. I also own a 280SLC auto (in bits at the moment) this doesn?t exhibit this problem and since the 300SL is a new acquisition I have something to compare it with.
The Aircon is switched off during this exercise and I believe Arnie may be close to target regarding the injection side. I once read in Car Mechanics about a ?modulator? in the auto box and wonder if the 107's have such a devise. Another point is that the front driveshaft coupling is worn and this may be contributing to the problem.
I?m sure the engine is not going to stall so I think I?ll take Malcolm advice and live with it.
Poor tickover
Presumably, you've checked all the simple things such as spark plugs and distributer condition.
For an auto box, revs should be around 700-800 rpm on idle (P) and these will drop to about 600 in Drive. If lower than this, the engine will probably idle a bit lumpy. It is quite straight forward to adjust the idle speed, if necessary.
Try also cleaning the fuel system with some injector cleaner additive (redex or STP) in your next tank of fuel.
It's probably best, though, to have a specialist look at your fuel system, if the above doesn't help.
Presumably, you've checked all the simple things such as spark plugs and distributer condition.
For an auto box, revs should be around 700-800 rpm on idle (P) and these will drop to about 600 in Drive. If lower than this, the engine will probably idle a bit lumpy. It is quite straight forward to adjust the idle speed, if necessary.
Try also cleaning the fuel system with some injector cleaner additive (redex or STP) in your next tank of fuel.
It's probably best, though, to have a specialist look at your fuel system, if the above doesn't help.
Andy
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Poor tickover
Hi Barry
There is no manual adjustment for the tick over. Sounds like something on the electronic side of the fuel injection. Although you need to check the basics, including emmission readings. The "modulator" as you have called it. Adjusts the quality of changes of the gear box. I doubt this has anything to do with it.
The tick over can drop to 500rpm also.
Hope this helps
Regards
Andy @ www.mercedesservicing.com
Hi Barry
There is no manual adjustment for the tick over. Sounds like something on the electronic side of the fuel injection. Although you need to check the basics, including emmission readings. The "modulator" as you have called it. Adjusts the quality of changes of the gear box. I doubt this has anything to do with it.
The tick over can drop to 500rpm also.
Hope this helps
Regards
Andy @ www.mercedesservicing.com
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