Need help om602 ELR not working
Need help om602 ELR not working
I've recently bought a european import 1985 190d with the 2.5L N/A om602. Engine runs well, with no excessive smoke and good fuel mileage. Just over 200k miles on the clock.
The problem is that when engine is cold it won't start unless the throttle is pressed at least 25% down. The throttle pedal has to be held that way for 30+ seconds or else the engine will stall. For the fist couple of minutes engine runs quite rough but then it smooths out.
I have checked my glow plugs and they are all ok. Although I have no way of knowing exact idle RPM (car does not have a tach) I believe my ELR system is dead because unplugging the ELR relay makes no difference on engine RPM, cold or warm.
I've replaced the ELR relay with a spare I had and there is still no difference. I've tested the crank sensor to be OK (more than 5V AC at idle and goes up to almost 18V at high revs). I also tried to test the ELR actuator itself by very briefly applying 12v to it as the manual says. What puzzles me is that instead of increasing, the engine RPM seems to drop when the coil is energized. I pulled the actuator off and tested on the bench, the plunger gets pushed out when voltage applied as it should.
Can anyone explain why the RPM drops with ELR energized? also what more can I do to test why ELR doesn't seem to work on its own? I tried to find wiring diagrams for the system to be able to troubleshoot more but I had no luck.
ponkokanada
02-01-2016, 10:06 AM #1Hi All
I've recently bought a european import 1985 190d with the 2.5L N/A om602. Engine runs well, with no excessive smoke and good fuel mileage. Just over 200k miles on the clock.
The problem is that when engine is cold it won't start unless the throttle is pressed at least 25% down. The throttle pedal has to be held that way for 30+ seconds or else the engine will stall. For the fist couple of minutes engine runs quite rough but then it smooths out.
I have checked my glow plugs and they are all ok. Although I have no way of knowing exact idle RPM (car does not have a tach) I believe my ELR system is dead because unplugging the ELR relay makes no difference on engine RPM, cold or warm.
I've replaced the ELR relay with a spare I had and there is still no difference. I've tested the crank sensor to be OK (more than 5V AC at idle and goes up to almost 18V at high revs). I also tried to test the ELR actuator itself by very briefly applying 12v to it as the manual says. What puzzles me is that instead of increasing, the engine RPM seems to drop when the coil is energized. I pulled the actuator off and tested on the bench, the plunger gets pushed out when voltage applied as it should.
Can anyone explain why the RPM drops with ELR energized? also what more can I do to test why ELR doesn't seem to work on its own? I tried to find wiring diagrams for the system to be able to troubleshoot more but I had no luck.
ponkokanada
02-01-2016, 01:21 PM #3I checked wire continuity between the ELR relay socket and the connector going to the electromagnet. It is OK. When the car runs the multimeter does not detect any voltage going to the ELR connector.
or in case your car has a A/C hooked at it and or take off assistance, wich being a w201 is hard to belive...
most probably u have a IP situation , wich one is will take assle to find out....
anyway try to actuate by hand the idle increase, take a screw driver and push it in the place were the actuator should push.
if your car is fitted with a ARA device make sure they were not interchanged , ELR is black or red cover.
then try to open the side of the pump , with the engine stopped the rack should be half travel , when the engine fires it reduces, will travel in the direction of the rear of the pump,
if the rack is aft and only goes fwd with throtle on , u may start disantling the IP ...
post back i´ll try to help u
FD,
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na... naana ... that is not a ELR problem, remember the system only actuates when engine core temp is below 28ºC ....
or in case your car has a A/C hooked at it and or take off assistance, wich being a w201 is hard to belive...
most probably u have a IP situation , wich one is will take assle to find out....
anyway try to actuate by hand the idle increase, take a screw driver and push it in the place were the actuator should push.
if your car is fitted with a ARA device make sure they were not interchanged , ELR is black or red cover.
then try to open the side of the pump , with the engine stopped the rack should be half travel , when the engine fires it reduces, will travel in the direction of the rear of the pump,
if the rack is aft and only goes fwd with throtle on , u may start disantling the IP ...
post back i´ll try to help u
FD,
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When you say try to actuate by hand, do you mean pull the ELR actuator off the IP and just press in where the actuator should?
I don't think I could do that because the actuator on my pump is placed on the very bottom and once taken off all of the oil drains from the IP so I don't imagine I could have the engine running like that. See the photo below (not picture of my pump but one exactly like it)
I am not familiar with ARA can you explain?
Suppose the IP has an issue with rack providing start up enrichment is that something that is adjustable/repairable by someone who's never worked on IP before? Am I better off just replacing the IP if I can have a used one for under $200?
ponkokanada
02-02-2016, 08:22 AM #5The car did come with factory AC but the compressor has been removed, the "KLIMA" relay is still present. I understand that the ELR shoudl only bump idle when engine is cold but it also works to stabilize the idle all the time doesn't it?
When you say try to actuate by hand, do you mean pull the ELR actuator off the IP and just press in where the actuator should?
I don't think I could do that because the actuator on my pump is placed on the very bottom and once taken off all of the oil drains from the IP so I don't imagine I could have the engine running like that. See the photo below (not picture of my pump but one exactly like it)
I am not familiar with ARA can you explain?
Suppose the IP has an issue with rack providing start up enrichment is that something that is adjustable/repairable by someone who's never worked on IP before? Am I better off just replacing the IP if I can have a used one for under $200?
I've attached a link describing it in a bit more detail.
http://www.w124-zone.com/downloads/MB%20...1-1856.pdf
Duncansport
02-02-2016, 08:45 AM #6I may be wrong here, but the actuator on the bottom is the ARA and not the ELR, it's used as an anti jerking device for manual transmission cars. So activating it would indeed cause a reduction in engine speed (as long as i understand it correctly)
I've attached a link describing it in a bit more detail.
http://www.w124-zone.com/downloads/MB%20...1-1856.pdf
Duncansport
02-02-2016, 08:47 AM #7Some more info -
http://www.w124-zone.com/downloads/MB%20...1-2009.pdf
the pump in the picture has a Pneumatic idle increase device, that is the vertical capsule, but the cover has the place where the ELR could be assembled, but inside there is no push pin for it, in that pump above the idle increase is atained by adding vac to the capsule. turning the capsule out will increase idle speed , til a certain amount.
the ARA device in the botom , grey colour, when energized moves the rack limitation to a "less rack" position than it is aloud to be when not energized, basically cuts fueling directly on the rack, by implication cuts fuel on acceleration and on the torque capsule ability.
anty jerk , well it may help but, only in stock pumps .... kiling the jerk is like turning a square in a circle maintaining the same área.
basically u can run the engine with the back cover off, u might loose half a liter of oil after one hour , nothing much.
if your pump is like the one in the picture , u have to see if it does react to vac in the capsule. if it does it might be a piping problem or the temp switch.
if not do as i said , watch the rack from engine stop , it should exibit at 1.5 cm movement when it fires .
changing the pump .... maybe but most pumps on junk yards are not in condition to install in a flick of a switch.
good luck
FD,
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nananan, again u both of u are all wrong, sorry to say!!!
the pump in the picture has a Pneumatic idle increase device, that is the vertical capsule, but the cover has the place where the ELR could be assembled, but inside there is no push pin for it, in that pump above the idle increase is atained by adding vac to the capsule. turning the capsule out will increase idle speed , til a certain amount.
the ARA device in the botom , grey colour, when energized moves the rack limitation to a "less rack" position than it is aloud to be when not energized, basically cuts fueling directly on the rack, by implication cuts fuel on acceleration and on the torque capsule ability.
anty jerk , well it may help but, only in stock pumps .... kiling the jerk is like turning a square in a circle maintaining the same área.
basically u can run the engine with the back cover off, u might loose half a liter of oil after one hour , nothing much.
if your pump is like the one in the picture , u have to see if it does react to vac in the capsule. if it does it might be a piping problem or the temp switch.
if not do as i said , watch the rack from engine stop , it should exibit at 1.5 cm movement when it fires .
changing the pump .... maybe but most pumps on junk yards are not in condition to install in a flick of a switch.
good luck
FD,
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(02-02-2016, 09:24 AM)barrote nananan, again u both of u are all wrong, sorry to say!!!
the pump in the picture has a Pneumatic idle increase device, that is the vertical capsule, but the cover has the place where the ELR could be assembled, but inside there is no push pin for it, in that pump above the idle increase is atained by adding vac to the capsule. turning the capsule out will increase idle speed , til a certain amount.
the ARA device in the botom , grey colour, when energized moves the rack limitation to a "less rack" position than it is aloud to be when not energized, basically cuts fueling directly on the rack, by implication cuts fuel on acceleration and on the torque capsule ability.
anty jerk , well it may help but, only in stock pumps .... kiling the jerk is like turning a square in a circle maintaining the same área.
basically u can run the engine with the back cover off, u might loose half a liter of oil after one hour , nothing much.
if your pump is like the one in the picture , u have to see if it does react to vac in the capsule. if it does it might be a piping problem or the temp switch.
if not do as i said , watch the rack from engine stop , it should exibit at 1.5 cm movement when it fires .
changing the pump .... maybe but most pumps on junk yards are not in condition to install in a flick of a switch.
good luck
All go info, but the OP says when he applies voltage to what he thinks is the ELR the RPM drops....so it sounds like he is indeed not looking at or working with a ELR and rather the ARA.
He needs to address the idle speed as described for his pump (if he in fact has the pictured pump)
Duncansport
02-02-2016, 10:12 AM #9(02-02-2016, 09:24 AM)barrote nananan, again u both of u are all wrong, sorry to say!!!
the pump in the picture has a Pneumatic idle increase device, that is the vertical capsule, but the cover has the place where the ELR could be assembled, but inside there is no push pin for it, in that pump above the idle increase is atained by adding vac to the capsule. turning the capsule out will increase idle speed , til a certain amount.
the ARA device in the botom , grey colour, when energized moves the rack limitation to a "less rack" position than it is aloud to be when not energized, basically cuts fueling directly on the rack, by implication cuts fuel on acceleration and on the torque capsule ability.
anty jerk , well it may help but, only in stock pumps .... kiling the jerk is like turning a square in a circle maintaining the same área.
basically u can run the engine with the back cover off, u might loose half a liter of oil after one hour , nothing much.
if your pump is like the one in the picture , u have to see if it does react to vac in the capsule. if it does it might be a piping problem or the temp switch.
if not do as i said , watch the rack from engine stop , it should exibit at 1.5 cm movement when it fires .
changing the pump .... maybe but most pumps on junk yards are not in condition to install in a flick of a switch.
good luck
All go info, but the OP says when he applies voltage to what he thinks is the ELR the RPM drops....so it sounds like he is indeed not looking at or working with a ELR and rather the ARA.
He needs to address the idle speed as described for his pump (if he in fact has the pictured pump)
Since the car is an automatic and had AC from factory, I suspect that this injector pump is not original to it. There are no vacuum lines or switch installed on the engine so the vacuum actuator on the pump has no way to bump idle up when cold. Whoever installed the pump just plugged in the ELR connector to the ARA. The vacuum capsule has nothing plugged into it.
I'm going to try and apply vacuum to the actuator tonight and see if the idle speeds up. If that works I will plumb in a vacuum system with a thermo switch to get the system running on its own. If not then I will look into opening the pump and observing the rack.
thanks for the help so far
ponkokanada
02-02-2016, 11:08 AM #10Wow, that is interesting. I do have a theory now:
Since the car is an automatic and had AC from factory, I suspect that this injector pump is not original to it. There are no vacuum lines or switch installed on the engine so the vacuum actuator on the pump has no way to bump idle up when cold. Whoever installed the pump just plugged in the ELR connector to the ARA. The vacuum capsule has nothing plugged into it.
I'm going to try and apply vacuum to the actuator tonight and see if the idle speeds up. If that works I will plumb in a vacuum system with a thermo switch to get the system running on its own. If not then I will look into opening the pump and observing the rack.
thanks for the help so far
i´m not expert in auto trans , but usually when the box need to change gear a reduction in fueling is needed , that is usually acomplished
by a cable wich reduces THR ... as i said never one and i´ve seen many MB pumps and serviced them ...
the ARA device should have no role when the engine is at idle speed , unless a lot of things are out of place inside that pump...idle control is separate from max thr position.
anyhow , the pneumatic idle increase is bit tricky to fix nothing that a vac diagram wont explain ...
in w124-zone.com u have those diagrams
regards
FD,
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the think with the ELR is that, that device can do a lot more than just increase idle a bit, it actually can charge the engine to face T/off in a Hill for instance... if we aplly 12 volts to it the fueling may increase as 50% obviously the idea behind is having pulses or 4 or 5 volts so that it can electronically increase idle and load.
i´m not expert in auto trans , but usually when the box need to change gear a reduction in fueling is needed , that is usually acomplished
by a cable wich reduces THR ... as i said never one and i´ve seen many MB pumps and serviced them ...
the ARA device should have no role when the engine is at idle speed , unless a lot of things are out of place inside that pump...idle control is separate from max thr position.
anyhow , the pneumatic idle increase is bit tricky to fix nothing that a vac diagram wont explain ...
in w124-zone.com u have those diagrams
regards
FD,
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I hooked up a hand vacuum pump to the pod on the IP and surprise surprise: the idle speed responds to it as it should.
Since none of the vacuum plumbing is present on the car I had a brilliant idea to temporarily hook up the IP to the vacuum line going to my euro headlight aim adjusters. It works quite well and I am actually able to adjust my idle from the cabin using headlight aim switch. The regulator switch only allows for up to ~5psi of vacuum so I can't get the idle quite as high as I could with full vacuum pressure available but it is nice to have for now.
Since the engine was warm when I worked on it last night I could not verify is applying vacuum to the pump would solve my cold start issue. Unfortunately when I tested it this morning the car was still hard to start and keep going even with nearly full vacuum applied to the actuator with a hand pump.
I think tonight I will pull the cover off the IP and observe how the rack travels at cold start up.
ponkokanada
02-03-2016, 08:17 AM #12Update:
I hooked up a hand vacuum pump to the pod on the IP and surprise surprise: the idle speed responds to it as it should.
Since none of the vacuum plumbing is present on the car I had a brilliant idea to temporarily hook up the IP to the vacuum line going to my euro headlight aim adjusters. It works quite well and I am actually able to adjust my idle from the cabin using headlight aim switch. The regulator switch only allows for up to ~5psi of vacuum so I can't get the idle quite as high as I could with full vacuum pressure available but it is nice to have for now.
Since the engine was warm when I worked on it last night I could not verify is applying vacuum to the pump would solve my cold start issue. Unfortunately when I tested it this morning the car was still hard to start and keep going even with nearly full vacuum applied to the actuator with a hand pump.
I think tonight I will pull the cover off the IP and observe how the rack travels at cold start up.
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