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190e 1.8 auto tick over
Hi i have a 93 k.reg 190e 1.8 auto this car was running a1 till last week when the tick over went up from 800-850 rpm to 1500rpm's and will not go down.
i have put new plugs oil and filters in this week but still the same. it's a right pain round town..please help if you need any more info just ask.. cheers all karl:confused: |
Take off the air cleaner and block the airflow meter inlet with something flat while the engine is idling. If the engine does NOT stall, you have an air leak, probably in one of the idle air hoses or a vacuum line.
Steve |
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I will try this tomorrow and let you know how it went.. Regards karl |
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Make sure all your throttle linkage is lubricated. Be sure it moves properly. Have someone push the accelerator pedal while you look at the linkage (take the air filter off) Watch for old and brittle rubber connecting tubes.
If brown telltale rust around the throttle linkage connectors, remove one at a time, clean and lube with something such as ATF. It provides lube but unlike a paste doesn't attract too much dirt. You can pop the bell cap ends off by using a 10mm wrench end. Keep us posted. Haasman |
Remove the electrical connector from the idle control valve to see if idle drops. If so, you may be running too rich. If not, the ICV may be sticking open, and should be cleaned. It is also still possible you have a small air leak - check all air hoses for cracks or loose fitting at connectors, and for vacuum lines disconnected.
Steve |
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Thanks for the info. I looked at all the linkage's today and it looks in very clean condition ie no rust i have lubed all the moving parts. but still runs the same. Cheers karl |
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I went out to my car and disconnected the idle control valve and it drops to a 850rpm spot on.But when i put it back on the engine revs to 1500rpm again so may be running to rich. It was getting too dark to check all the air hoses.will check tomorrow..I have the car booked in at a mercedes main dealer on 29th i hope they fix it quick as they charge £80 per hour labour..(robbing gits) Cheers Karl |
If the car is running rich, the ECU may increase the idle to compensate if the EHA is out of range. However, idle is still too high with the idle valve disconnected. This makes me suspect there is still an air leak.
Steve |
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car still runs the same:confused: they could put it on the computer they say it's to old. it's a 93.reg on a k.plate.....£178 later still the same I'm not a happy man....anyway got to go now and bash my head on a wall..... |
I would pull the electrical connectors off the EHA, and then the O2 sensor, and see what happens. If neither drops the idle, then check for air leaks on your own. see if the air hoses are soft and pliable when you pinch the gently. If they seem hard and don't give, then you probably have air leaks at all the interconnects, where they will fit loosely. Replace any such hoses.
Steve |
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cheers karl |
The Electro-Hydraulic Actuator is screwed to the firewall side of the fuel distributor, and the O2 sensor is screwed into the exhaust manifold (but not to be confused with the EGR valve, which has no electrical connector). This would be on my 2.3 - your 1.8 may be different.
Steve |
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Thanks for the info..it is eha that is dead.. I disconected this today and the revs go down to 500 rpm, then I rang mercedes main dealership and was quoted £348 + vat=$500 bucks for the part silly money ! am going to a breakers yard in london this weekend let you know how it goes and thanks again you've been a really big help kind regards karl (from sunny London) ps i think in the uk we call the 02 sensor the lambda sensor. and the eha is airflow sensor.. |
Just got back from london with some s/h parts for my car. First i fitted the air-flow sensor on the side of the inj unit and still the same. Then fitted the 2nd air-flow sensor and still the same.....Just in case 1 was bad i got 2 sensors. Then i fitted a mircoswitch (I got 2 of these as well) to the fuel linkage but same again still ticks over at 1200/1500 rpm's...
so please i need help asap ..... any idea's Steve regards Karl |
Karl, by pulling the plug on the EHA I was not indicating that a change in idle speed would indicate this part is bad. The fact that idle speed dropped once you disabled the mixture loop control device of the Bosch KE fuel injection simply indicates the computer is trying to increase your idle speed for some reason. This could be because your mixture is mechanically mis-adjusted, your O2 sensor is reading incorrectly, your mixture is leaned out due to air leaks, or a number of other things. At this point, correctly reading the diagnostic plug is what is needed, and I suggest you find a good tech to do that for you.
Steve |
Air leak
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Hi Steve, Wouldn't an air leak after the mass air sensor raise RPM without the ECM knowing about it and trying to compensate? The large air duct which connects the mass air sensor to the throttle body can be where such a leak exists. A little trick to find an intake air leak is to use a small propane soldering torch to direct the propane gas close to all suspect hoses, fittings and manifold gaskets... Once the gas reaches the leak, the engine will speed up immediately... Just hold the end of the torch within an inch or so of the areas being tested and see what happens. (NOT LIT OF COURSE):beerchug: |
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Steve |
I had a high idle issue on my 86 2.3L 190e. It was idling fine until I adjusted the ignition timing to spec, which made it idle around 1100-1200 rpm (the timing was retarded by a significant amount for some reason when I got the car). After adjusting the timing made it idle fast, I corrected the fast idle by simply turning the adjustment screw/knob on the Idle Control Valve. I know there are some vacuum leaks that I haven't had a chance to properly fix, and I think the adjustment on the ICV helped reduce the amount of air enough to drop the idle. If yours has the adjustment screw knob, you can try this--just make sure to keep track of how much you turn the knob so you can return to the starting point if necessary. Turning the knob so the screw "tightens" into the valve will reduce the airflow and help compensate for vacuum leaks until they can be repaired.
I would suggest actually looking for vacuum leaks by removing the air cleaner assembly and inspecting all the rubber hoses. Further inspection might be required to see if the rubber boot on the underside of the airflow meter assembly is torn, or if the Idle Control Valve hoses are brittle and loose/cracking. I personally don't see how the engine can run with the air meter blocked off as suggested earlier. Unless some air goes through the air flow meter to pull down the plate, all the fuel will shut off any time the plate is at the top of its stroke. There are a lot of possible vacuum leak points on this engine, and I wouldn't trust that airflow block-off test. Each hose and rubber part needs to be checked up close to know for sure. |
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Hi Steve, The ECM would enrich the mixture if a vacuum leak were present. That would allow the car to still have some pulling power instead of backfiring and stalling the way they used to do before the days of ECMs I would guess that the 02 sensor was working properly, thereby telling the ECM to enrich the mixture. Disconnecting the 02 sensor temporarily should lower the rpm and make the car act like an old one with a carb. (eg. backfire and stall when attempting to rev the engine under load). Is my thinking wrong? |
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I do value your input on 190e a great deal. Please keep it up.. regards karl |
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regards karl |
my 190e went to the garage 2 weeks ago for a new mot and it passed ok
On the mot they check the 02 sensor so this part must be ok ?... |
Adjusted the timing
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Hi Archie, Just curious... when you adjusted the mechanical timing, was that with the vacuum advance disabled and plugged? Isn't that the only way to get it right? What was the shop manual recommendation ? |
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Thing is, disconnecting the EHA should not cause the idle speed to drop if the only problem is an un-metered air leak, unless there are more problems. Such could include a bad control module, defective OVP, bad or misadjusted throttle switches/linkages. Steve |
There must be a plot in pollution control
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Thanks Steve, I think I am starting to get the picture better now.. Years ago, (in the mid 70's) we were told that having an air pump push fresh air through the EGR valve under the carb... I agreed that it would really help burn unburned gas as a way to reduce hydrocarbon emission.. Other pollutants might not be affected in this way... My theory was that the air pump would simply add more air to the exhaust volume and DILUTE the PPM of all the pollution that was being measured at the tailpipe.. Am I wrong in thinking that IF exhaust fumes were dilluted by 50% with the addition of air, then the tailpipe pollutants would measure about HALF of what they would be without the added air? Ron |
Ron, if by 'air pump' you are referring to an air injection reactor (AIR, 'smog pump'), my '91 2.3 does not have one, and on MB's that do, I believe they are only active during warmup, when the O2 sensor is ignored.
My '83 Chevy m'home has a 4bbl and the smog pump is active even after warm-up - but there is no loop control or O2 sensor. Steve |
todays job was to wire bridge 3 pins on the throttle body which i think is the idle control sensor. the revs went down to 750rpm's but 2'mins later the rev's went back to 1500rpm's. so i think i will need a new sensor for the throttle body...i can see the light at the end of the tunnel......
ps I got this little tip from a mechanic at mercedes...for free. |
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