1988 300TE - Misfires - Part #2
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I think I may have stumbled across something...Of course thanks to my 260E for comparison!!
But first...
Fuel Pressure:
Upper is dead on
Lower is too low (AKA EHA, right?) Now...if I turn the EHA clockwise, that will raise pressure right?)
---
Check this out:
I noticed that my throttle plate is actually not sitting correctly. It is sitting far too low and won't go up any further even when pulling it....so I did some research and found that this little pushpin is the stop for the rest height of the throttle plate....well...compare it to my 260E...
See how it should look? It should be flush with the body...With that said...It could explain at the very least my horrible gas mileage as the body isn't shutting properly and allowing more fuel to enter the system. And it would (hopefully) explain why I only feel my misfire at idle and not at all as soon as I hit the throttle.
So then I went on to read this on the MB CD
Well mine is RECESSED by like 5 mm or over twice the thickness of the sensor plate!
That means that at idle the sensor plate is too low, and in turn that means the position of the fuel distrubuter metering is wrong too!
Any thoughts?
I ordered the plastic boot that goes on the bottom of the fuel distributor unit because its possible of being cracked...and to access that pin, I have to hit it upwards from underneath so that works out for me.
This may be it guys!! Won't keep my hopes up too much though. If I get the boot in today I'm gonna go for it!
But first...
Fuel Pressure:
Upper is dead on
Lower is too low (AKA EHA, right?) Now...if I turn the EHA clockwise, that will raise pressure right?)
---
Check this out:
I noticed that my throttle plate is actually not sitting correctly. It is sitting far too low and won't go up any further even when pulling it....so I did some research and found that this little pushpin is the stop for the rest height of the throttle plate....well...compare it to my 260E...
See how it should look? It should be flush with the body...With that said...It could explain at the very least my horrible gas mileage as the body isn't shutting properly and allowing more fuel to enter the system. And it would (hopefully) explain why I only feel my misfire at idle and not at all as soon as I hit the throttle.
So then I went on to read this on the MB CD
Check zero position sensor(rest position) of the sensor plate. The top edge of the sensor plate must be flush with the top edge of the cylindrical part on the fuel funnel. It is permissible for the plate to be higher, but not more than .2mm
That means that at idle the sensor plate is too low, and in turn that means the position of the fuel distrubuter metering is wrong too!
Any thoughts?
I ordered the plastic boot that goes on the bottom of the fuel distributor unit because its possible of being cracked...and to access that pin, I have to hit it upwards from underneath so that works out for me.
This may be it guys!! Won't keep my hopes up too much though. If I get the boot in today I'm gonna go for it!
Last edited by ps2cho; Mar 19, 2009 at 07:54 PM.
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1992 300TE 4matic wagon
You may be on to something there and it would certainly explain your dismal gas mileage. But as for that 'push pin'....I would be puzzled as to how it got in that position and I would make damn sure it doesn't get there again, after being corrected. From the pictures and from my own car, I'd say you're correct on the throttle plate...too low.
Kevin
Kevin
I think I may have stumbled across something...Of course thanks to my 260E for comparison!!
But first...
Fuel Pressure:
Upper is dead on
Lower is too low (AKA EHA, right?) Now...if I turn the EHA clockwise, that will raise pressure right?)
---
Check this out:
I noticed that my throttle plate is actually not sitting correctly. It is sitting far too low and won't go up any further even when pulling it....so I did some research and found that this little pushpin is the stop for the rest height of the throttle plate....well...compare it to my 260E...
See how it should look? It should be flush with the body...With that said...It could explain at the very least my horrible gas mileage as the body isn't shutting properly and allowing more fuel to enter the system. And it would (hopefully) explain why I only feel my misfire at idle and not at all as soon as I hit the throttle.
So then I went on to read this on the MB CD
Well mine is RECESSED by like 5 mm or over twice the thickness of the sensor plate!
That means that at idle the sensor plate is too low, and in turn that means the position of the fuel distrubuter metering is wrong too!
Any thoughts?
I ordered the plastic boot that goes on the bottom of the fuel distributor unit because its possible of being cracked...and to access that pin, I have to hit it upwards from underneath so that works out for me.
This may be it guys!! Won't keep my hopes up too much though. If I get the boot in today I'm gonna go for it!
But first...
Fuel Pressure:
Upper is dead on
Lower is too low (AKA EHA, right?) Now...if I turn the EHA clockwise, that will raise pressure right?)
---
Check this out:
I noticed that my throttle plate is actually not sitting correctly. It is sitting far too low and won't go up any further even when pulling it....so I did some research and found that this little pushpin is the stop for the rest height of the throttle plate....well...compare it to my 260E...
See how it should look? It should be flush with the body...With that said...It could explain at the very least my horrible gas mileage as the body isn't shutting properly and allowing more fuel to enter the system. And it would (hopefully) explain why I only feel my misfire at idle and not at all as soon as I hit the throttle.
So then I went on to read this on the MB CD
Well mine is RECESSED by like 5 mm or over twice the thickness of the sensor plate!
That means that at idle the sensor plate is too low, and in turn that means the position of the fuel distrubuter metering is wrong too!
Any thoughts?
I ordered the plastic boot that goes on the bottom of the fuel distributor unit because its possible of being cracked...and to access that pin, I have to hit it upwards from underneath so that works out for me.
This may be it guys!! Won't keep my hopes up too much though. If I get the boot in today I'm gonna go for it!
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^ Its funny because you can see the dent from whoever knocked it in...Probably the same person who removed the plug on the mixture unit I suppose?
----------
Well corrected it, then checked plastic boot for cracks...No luck -- Still have the rough idle....Unbelievable...
The next thing that is unexplainable -- I have two EHA's...One that gives 4.9bar and another that gives 5.15bar (lower chamber of course...upper was 5.5bar both times. Official MB specs state upper 5.5, lower 5.1). Why does the one that gives me 4.9bar have MORE power??? I don't understand.
I set the mixture the same both times.
I mean look at this throttle body...This engine is absolutely immaculate for its age, yet I have this damn unsolvable rough idle.
Thought for a minute that this mystery may finally be resolved...Guess not.
----------
Well corrected it, then checked plastic boot for cracks...No luck -- Still have the rough idle....Unbelievable...
The next thing that is unexplainable -- I have two EHA's...One that gives 4.9bar and another that gives 5.15bar (lower chamber of course...upper was 5.5bar both times. Official MB specs state upper 5.5, lower 5.1). Why does the one that gives me 4.9bar have MORE power??? I don't understand.
I set the mixture the same both times.I mean look at this throttle body...This engine is absolutely immaculate for its age, yet I have this damn unsolvable rough idle.
Thought for a minute that this mystery may finally be resolved...Guess not.
Last edited by ps2cho; Mar 20, 2009 at 02:04 AM.
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I never have any starting problems. Have to crank a few seconds in the mornings when cold...but not a huge deal. It starts hot very easy.
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Understandable, but I highly doubt it otherwise I'd have misfires upon acceleration -- which I don't.
The only thing that can be left at this point is the injectors. Would you recommend having them cleaned and flow tested, or buying a new set?
I am gonna try and grab some from the junkyard soon and test them...It will be obvious if there is a difference.
The injectors could not be closing fully or opening too early. They are pretty expensive new -- hense me wanting to get some from the junkyard first.
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I looked up the cost of having them flowtested and its not worth it. Its like $20 per injector compared to $21 brand new...Just bought 6 new injectors, seals and insulators for $179 at AutohausAZ.
I swapped out my CSV with one from the junkyard. Interesting enough my duty cycle went from 45% to 39% right after, but I didn't notice any difference in idle quality. Maybe it was leaking a little bit.
Will report back mid-week with injector results. This has to be it right here. I realistically have nothing left LOL!
Oh and BTW I bought a new set of ignition leads for my 260E, but for ****s and giggles I put them on my TE...no difference. Just kinda triple checking things.
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The reason I ask it's because people that have problems starting their cars when warm usually means they have a clogged fuel filter and/or fuel accumulator. It will start making noise too and that's when you know you need to change it. I'm going to change mine next weekend.
It doesn't affect idle quality because it's only for cold start enrichment. Do you have a check list of all the things you've done to it?
I swapped out my CSV with one from the junkyard. Interesting enough my duty cycle went from 45% to 39% right after, but I didn't notice any difference in idle quality. Maybe it was leaking a little bit.
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Hmm, dude that's like everything i did over 5 years to my car. Have you changed the fuel accumulator? It maintains pressure on the system for re-starts and if you have a leaky injector somewhere it might be the problem.
How bad is the misfire anyways?
How bad is the misfire anyways?
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Its not that bad nowadays...At some points I can hardly feel it...but its there and I want it perfect. It's just at idle of course.
I did some reading on the fuel accumulator and like you said, its only function is to maintain pressure after the engine is shut off. When I did the fuel pressure test, it held 3BAR for over 30minutes before I let it off. It meets specs so its fine.
I did some reading on the fuel accumulator and like you said, its only function is to maintain pressure after the engine is shut off. When I did the fuel pressure test, it held 3BAR for over 30minutes before I let it off. It meets specs so its fine.
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Ok, so that's not it. This might sound crazy but have you checked your fan clutch?
Take a long screwdriver and listen to the engine with your ear...
Take a long screwdriver and listen to the engine with your ear...
Last edited by YNVDIZW124; Mar 23, 2009 at 10:09 PM.
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Nah the clutch is fine...That wouldn't have anything to do with the misfire...
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Oh heck yes. SOLVED. Injectors was the problem. They must have been leaking all the time.
The engine no longer shakes in its mounts like before!!
The general idle from inside the car can still be felt slightly....but I think there is much fine tuning at this point now.
How "smooth" should a perfectly running M103 be?
Very happy I finally found the culprit!
The engine no longer shakes in its mounts like before!!
The general idle from inside the car can still be felt slightly....but I think there is much fine tuning at this point now.
How "smooth" should a perfectly running M103 be?
Very happy I finally found the culprit!
Last edited by ps2cho; Mar 26, 2009 at 01:14 AM.
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Cool, they must have been leaking or clogged and the CSV too. You're gonna love the way your car is going to run now. It should be smooth but you should still feel the engine when warm. I usually don't even feel the engine when cold but after it gets warm you should feel it like any regular car.
I always say, get it dialed in and leave it alone
I always say, get it dialed in and leave it alone
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Cool, they must have been leaking or clogged and the CSV too. You're gonna love the way your car is going to run now. It should be smooth but you should still feel the engine when warm. I usually don't even feel the engine when cold but after it gets warm you should feel it like any regular car.
I always say, get it dialed in and leave it alone
I always say, get it dialed in and leave it alone
Exhaust is blowing...and rear control arms so I put my Monoblock II's on! Don't want to put them on until I fix it because the tires are geting worn on the sides due to no alignment...But of course it's pointless getting an alignment when I need the control arms doing. I have them all ready to go on...just was getting around to it.
Based on how I read your post, I'd say my idle is still a little rough...but as I said, I need to fiddle with the mixture and swap back the EZL with my old one as the part #'s are different. Want to make sure everything is exactly how it was now I isolated the problem.
It's nice to know that I can now start getting aesthetics taken care of. Got a few dings I would like taken care of...front windows need a tint...monoblock II's on as I said above...then maybe new springs to get her a little lower. Then I'll be set!
Last edited by ps2cho; Mar 26, 2009 at 01:30 AM.
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1994 E320 Dragon Wagon
Not a parade rainer by nature but I gotta remind you way-back, across two MB sites, when you first started this ordeal. The progress went from ignition to valve seals to vacuum when several helpful posts recommended injectors. Considerable time and parts have gone by (read buy) before you revisited this. Not such the break-through, more like random elimination.
You demonstrate a scientific approach and researched effort but allowed your budget to guide the next step. The key to troubleshooting is logic and discipline. Not to mention the "pros" that didn't have a clue.
You demonstrate a scientific approach and researched effort but allowed your budget to guide the next step. The key to troubleshooting is logic and discipline. Not to mention the "pros" that didn't have a clue.
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Not a parade rainer by nature but I gotta remind you way-back, across two MB sites, when you first started this ordeal. The progress went from ignition to valve seals to vacuum when several helpful posts recommended injectors. Considerable time and parts have gone by (read buy) before you revisited this. Not such the break-through, more like random elimination.
You demonstrate a scientific approach and researched effort but allowed your budget to guide the next step. The key to troubleshooting is logic and discipline. Not to mention the "pros" that didn't have a clue.
You demonstrate a scientific approach and researched effort but allowed your budget to guide the next step. The key to troubleshooting is logic and discipline. Not to mention the "pros" that didn't have a clue.
