300E runs fine when cold; stutters on low refs when motor heating up up
02-28-2013, 02:46 PM
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89'300E mercedes
300E runs fine when cold; stutters on low refs when motor heating up up
Hi guys i have this problem My 89'300e runs fine on start-up but when motor heats up on low refs it stutters on pull a ways but runs smooth again when refs pick up. By simply putting it in drive and keeping the foot on the brake will make the motor runs extremely rough as if 2 or more pistons does not get spark from the plugs.Ive replaced the distributor cap and plugs plus plug wires and also the crank censor please help
03-01-2013, 06:18 PM
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E430 4Matic
It sounds like you have focused on one of three possibilities. Now look at the other two, fuel and air. Fuel flow could be an issue but indirectly because you said it runs better at higher revs. Check your air filter and the plumbing for the intake all the way to the manifold. Leaks or clogs can result in a fuel air mixture mismatch. Vacuum leaks can also cause rough idle and stumbling. Is there some sort of automatic choke that may be stuck closed since its starts fine but runs poorly when warm? May be restricting the air when it should be full open.
Last edited by flattops; 03-01-2013 at 06:21 PM.
03-03-2013, 02:13 PM
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89'300E mercedes
Thanks for the reply I understand what You are saying but it would not account for losing spark on 3 cylinders when it heats up;I am going to replace the oxygen censor next to see if it will have an effect it can also account for the high fuel consumption by oversupplying the motor with fuel.I will also check the auto choke and the plumbing. thanks for the advise.I will Keep U posted on the results
