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Recently bought a used '89 190E 2.6....a newbie Mercedes owner, but am a decent mechanic.

Idle is erratic at times...tachs at 900 when in Park, otherwise 650 when in "D"...check engine light has been coming on fairly regularly and car seems to cough/choke/stall and then occasionally resumes normal power as light goes off.

This seems to be a very intermittent problem as sometimes its very easy to start and idles/runs fine, other times its very hard to start without the 1/2 gas pedal.

My question is...could this be a throttle plate issue, or a combination of injectors/throttle plate gummed up...??? I've yet to replace fuel filter.

How should I proceed? Someone on another thread posted something about coolant temp. sensor possibly being related to this issue? If so, where is it, what is the procedure to check for this? (I'm running blind awaiting the 190E 2.6 manual which was impossible to find in local auto parts superchains)

Thanks in advance...and if you'd rather email me the info, please do at [email protected]

KO
 

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Yes #1 cause of this type of symtoms is temp sensor and #2 is OVP relay. There are other causes Like vacuum leaks,pump relay, O2 sensor dirty air flow plate, so on and so on.

Dont know what manual you ordered but there are a lot on of origanals on ebay and you can get the cd rom with them all rapped up in one (except the trans repair) for about 100 bucks from the dealer or some private venders.

Sense you have some mechanical knowlage I would just replace all the temp. sensors and get it over with if there not bad now they will be soon.
 

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92 190e 2.6, 97 e320
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Then do the EHA if the above doesnt work. Check engine light probably the o2 sensor. The engine temp and the 02 are the only sensors which send info to the ECU which spits it out via OVP and to the EHA, all or one could be buggered and all have similar-ish symptoms as all effect function of the EHA.
You can check them by unplugging them an seeing if they much difference,
 

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1990 190E 2.6 Auto
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I think the electronic control unit for the ignition system goes into "limp home emergency mode" and this causes erratic idling. Control unit does this when one of the sensors goes wrong or is not sending info to control unit. Check that there are no air locks in your coolant system. The temperature sensor needs water / coolant in the system right at it to function properly. The car will turnover but not fire if this sensor is not functioning properly.
 

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1990 190E 2.6 Auto
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Oh and I meant to say, there is a cold start valve that adds fuel to this system on cold starts. This being faulty can lead to hard starting. I have read many posts about that on other MB sites. If you can notice a pattern in ambient outside temperature / engine temp and hard starting conditions then this could be a cause.
 
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