1988 300TE - Misfires - Part #2
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I can't feel it as soon as I touch the accelerator even just a tad...but performance sucks in general. I can only "feel" it at idle....and at this point in time, its not that noticeable anymore. Problem is power + MPG. I figure that whatever is causing my power and MPG loss is also causing my minor misfire now.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream
Guys at another local shop said they wouldn't do it...
I'll have to keep asking around I guess.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream
Guys at another local shop said they wouldn't do it...I'll have to keep asking around I guess.
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Joined: Feb 2008
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From: Orland Park, Illinois
1994 E320 (current)
I can't feel it as soon as I touch the accelerator even just a tad...but performance sucks in general. I can only "feel" it at idle....and at this point in time, its not that noticeable anymore. Problem is power + MPG. I figure that whatever is causing my power and MPG loss is also causing my minor misfire now.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream Guys at another local shop said they wouldn't do it...
I'll have to keep asking around I guess.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream
Guys at another local shop said they wouldn't do it...I'll have to keep asking around I guess.
Super Member
Joined: Feb 2008
Posts: 844
Likes: 1
From: Orland Park, Illinois
1994 E320 (current)
I can't feel it as soon as I touch the accelerator even just a tad...but performance sucks in general. I can only "feel" it at idle....and at this point in time, its not that noticeable anymore. Problem is power + MPG. I figure that whatever is causing my power and MPG loss is also causing my minor misfire now.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream Guys at another local shop said they wouldn't do it...
I'll have to keep asking around I guess.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream
Guys at another local shop said they wouldn't do it...I'll have to keep asking around I guess.
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I did the coil about 30k miles ago when I originally bought the car. Plugs wire and coil were the first things on my hunt 
Does the M103 CIS use insulators on the injectors or is it just a seal? I am going to replace the injectors and grab a crank position sensor at the junkyard if the injectors don't fix it. I had someone point out to me that the amount of varnish on the inside of my intake manifold was suspect...I would put my money on injectors over a crank position sensor IMO.
Does the M103 CIS use insulators on the injectors or is it just a seal? I am going to replace the injectors and grab a crank position sensor at the junkyard if the injectors don't fix it. I had someone point out to me that the amount of varnish on the inside of my intake manifold was suspect...I would put my money on injectors over a crank position sensor IMO.
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From: Orland Park, Illinois
1994 E320 (current)
I did the coil about 30k miles ago when I originally bought the car. Plugs wire and coil were the first things on my hunt
Does the M103 CIS use insulators on the injectors or is it just a seal? I am going to replace the injectors and grab a crank position sensor at the junkyard if the injectors don't fix it. I had someone point out to me that the amount of varnish on the inside of my intake manifold was suspect...I would put my money on injectors over a crank position sensor IMO.
Does the M103 CIS use insulators on the injectors or is it just a seal? I am going to replace the injectors and grab a crank position sensor at the junkyard if the injectors don't fix it. I had someone point out to me that the amount of varnish on the inside of my intake manifold was suspect...I would put my money on injectors over a crank position sensor IMO.
I am not sure about the insulator/seal question. However if the CSP sensor is suspect I would do that before the fuel injectors. My theory is usually go with the least expensive likely issue. Either way those sound like two last things that are good possibilities.
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You are probably right. I should head to the junkyard first and grab a CPS before doing the injectors. If the injectors and CPS are fine...then realistically what else do I have left? The EZL brain and fuel pump? Isn't that it? But a fuel pump wouldn't cause a misfire would it really? If I had fuel supply issues wouldn't I have trouble revving higher up because it would be starving for fuel?
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From: Orland Park, Illinois
1994 E320 (current)
You are probably right. I should head to the junkyard first and grab a CPS before doing the injectors. If the injectors and CPS are fine...then realistically what else do I have left? The EZL brain and fuel pump? Isn't that it? But a fuel pump wouldn't cause a misfire would it really? If I had fuel supply issues wouldn't I have trouble revving higher up because it would be starving for fuel?
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1994 E320 Dragon Wagon
I think his injection system is a more of a mechanical "distributor" affair. Where the injector nozzles and the distribution device(s) are suspect. The 104's are more conventional solenoid/fuel rail style. But we have the mysterious actuator. Looks like both systems are a bugger to troubleshoot.
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Off to the junkyard today! Gonna get the crank position sensor, some window motors + regulators, maybe a coil if they have one (because I bought a used one to replace mine...better triple cover my base on something as important as the coil).
A few days ago I reset my mixture to 50% as it was sitting at like 80% and the misfire is a little worse now...Maybe what I have here is a lean misfire if when reducing the mixture from something which in real terms is very "rich" caused the misfire to get worse.
On monday I am going down to the dealership and getting the fuel adapter that plugs into the distributor so I can test fuel pressure.
A few days ago I reset my mixture to 50% as it was sitting at like 80% and the misfire is a little worse now...Maybe what I have here is a lean misfire if when reducing the mixture from something which in real terms is very "rich" caused the misfire to get worse.
On monday I am going down to the dealership and getting the fuel adapter that plugs into the distributor so I can test fuel pressure.
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1992 300TE 4matic wagon
In the Bentley book, they talk about an adapter to test fuel pressure back on the pump. I'm interested then, in this fuel adapter you're talking about, the cost and maybe a quick pic? The book says that if you tweak your fuel psi a bit higher, the cars will run better overall. Then of course the fuel air mix has to changed as well. What are you using to test your fuel mix percentage?
Kevin
Kevin
Off to the junkyard today! Gonna get the crank position sensor, some window motors + regulators, maybe a coil if they have one (because I bought a used one to replace mine...better triple cover my base on something as important as the coil).
A few days ago I reset my mixture to 50% as it was sitting at like 80% and the misfire is a little worse now...Maybe what I have here is a lean misfire if when reducing the mixture from something which in real terms is very "rich" caused the misfire to get worse.
On monday I am going down to the dealership and getting the fuel adapter that plugs into the distributor so I can test fuel pressure.
A few days ago I reset my mixture to 50% as it was sitting at like 80% and the misfire is a little worse now...Maybe what I have here is a lean misfire if when reducing the mixture from something which in real terms is very "rich" caused the misfire to get worse.
On monday I am going down to the dealership and getting the fuel adapter that plugs into the distributor so I can test fuel pressure.
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http://www.ps2cho.net/downloads/MB%2.../07.3-1603.pdf
Part numbers are listed.
-------------
Just got back from the junkyard with a nice collection of goodies:
EZL off 88 300TE
Jetronic Brain off 88TE
2x Fuel Pump Relay (1 off 300E, 1 off 300TE)
2x Multipurpose relays (the long one to resolve my faulty light error on dash)
2x fuel distributors
1x Cold start injector (forgot name)
Gonna do one at a time starting with the cold start injector, then the EZL, then the jetronic brain
EDIT: Okay, the long multipurpose relay fixed my bulb out light on dash
I did the jetronic brain first because it was the easiest...Car started up and we will see today if it made any difference. Gonna do one thing at a time so I can identify better.
Part numbers are listed.
-------------
Just got back from the junkyard with a nice collection of goodies:
EZL off 88 300TE
Jetronic Brain off 88TE
2x Fuel Pump Relay (1 off 300E, 1 off 300TE)
2x Multipurpose relays (the long one to resolve my faulty light error on dash)
2x fuel distributors
1x Cold start injector (forgot name)
Gonna do one at a time starting with the cold start injector, then the EZL, then the jetronic brain
EDIT: Okay, the long multipurpose relay fixed my bulb out light on dash
I did the jetronic brain first because it was the easiest...Car started up and we will see today if it made any difference. Gonna do one thing at a time so I can identify better.
Last edited by ps2cho; Feb 23, 2009 at 09:51 AM.
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Gonna put the cold start valve in tonight and try that. I read a while back that it could be leaking fuel all the time instead of closing...worth a try.
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Interesting deal on the cold start valve. The one I pulled from the 1988 300TE was slightly different. Mine had a longer nozzle and did not have an MB star on it...
...So I swapped them and beforehand I read my duty cycle and it was sitting at 38% idle. When I swapped it and checked it right after, I was 31% idle. Interesting...but still the misfire pursued.
Swapped EZL, no difference.
So that takes off a number of items as the cause....Anybody need an EZL and Jetronic brain ? Probably list it in the classified section. Must work fine as I experienced no difference in driving at all.
---
Next up is testing fuel pressure. Gonna try and get a cheap gauge and adapter.
...So I swapped them and beforehand I read my duty cycle and it was sitting at 38% idle. When I swapped it and checked it right after, I was 31% idle. Interesting...but still the misfire pursued.
Swapped EZL, no difference.
So that takes off a number of items as the cause....Anybody need an EZL and Jetronic brain
? Probably list it in the classified section. Must work fine as I experienced no difference in driving at all.---
Next up is testing fuel pressure. Gonna try and get a cheap gauge and adapter.
Last edited by ps2cho; Feb 24, 2009 at 01:08 PM.
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Maybe there is a chance we have the same problem going on and can work towards a resolution for the both of us. When I bought the car at 64k miles I had the same misfire...so both our models have a low number of miles on them.
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Joined: Apr 2004
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From: Boston, MA
1988 300E
Well, Like I say, it's subtle but it's there. And it's annoying. Comes and goes, no effect on driveability, just at idle and warm or semi-warm start can be a bit longer than it should be. I've replaced tgh OVP, plugs and fuel filter only. Checked and cleaned cap and rotor and run Techron thru the sytem a few times.
I'm thinking it's either lean at idle or a leaking or erratic spray injector. No vacuum leaks to be found anywhere. It's been this way since we got it 5 years ago with 19K miles.
I'm thinking it's either lean at idle or a leaking or erratic spray injector. No vacuum leaks to be found anywhere. It's been this way since we got it 5 years ago with 19K miles.
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1992 300TE 4matic wagon
Thanks....did you buy that gauge set? And if so (assuming it's an MB set), where did you get the best deal?
Kevin
Kevin
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...but it looks like you can use any gauge that has two outlets. I am scanning ebay for a cheap CIS gauge and then all I need is that little adapter which was pretty cheap. Gotta watch my bank account after buying new Monoblock II's and a new snowboard this month
So may have to put fuel testing on hold til I get my tax refund through next week Thanks IRS!
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1992 300TE 4matic wagon
Let me know what you find on the gauge/adapter. Yeah, the MB kit was astronomical, unless you do that everyday for a shop.
We talked once about that MB Service Manual CD set for our car. You gave me instructions on how to incorporate some better instructions/directions into a folder....that makes the CD's incredibly more user friendly....my PC crashed shortly after that. Would you mind linking me to that conversation again?
What board did ya buy?
Kevin
We talked once about that MB Service Manual CD set for our car. You gave me instructions on how to incorporate some better instructions/directions into a folder....that makes the CD's incredibly more user friendly....my PC crashed shortly after that. Would you mind linking me to that conversation again?
What board did ya buy?
Kevin
The gauge is incredibly expensive...
...but it looks like you can use any gauge that has two outlets. I am scanning ebay for a cheap CIS gauge and then all I need is that little adapter which was pretty cheap. Gotta watch my bank account after buying new Monoblock II's and a new snowboard this month So may have to put fuel testing on hold til I get my tax refund through next week Thanks IRS!
...but it looks like you can use any gauge that has two outlets. I am scanning ebay for a cheap CIS gauge and then all I need is that little adapter which was pretty cheap. Gotta watch my bank account after buying new Monoblock II's and a new snowboard this month
So may have to put fuel testing on hold til I get my tax refund through next week Thanks IRS!
Thread Starter
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Let me know what you find on the gauge/adapter. Yeah, the MB kit was astronomical, unless you do that everyday for a shop.
We talked once about that MB Service Manual CD set for our car. You gave me instructions on how to incorporate some better instructions/directions into a folder....that makes the CD's incredibly more user friendly....my PC crashed shortly after that. Would you mind linking me to that conversation again?
What board did ya buy?
Kevin
We talked once about that MB Service Manual CD set for our car. You gave me instructions on how to incorporate some better instructions/directions into a folder....that makes the CD's incredibly more user friendly....my PC crashed shortly after that. Would you mind linking me to that conversation again?
What board did ya buy?
Kevin
http://www.ps2cho.net/downloads/MB%20CD/W124/Main.html
All laid out for ya
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1992 300TE 4matic wagon
Thanks, dude!
Kevin
Kevin
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1994 E320 Dragon Wagon
Ahhhem... Alright Mr. PS2 let's get back on the Misfire Mission. I get excited thinking we'll finally see the awesome, breathtaking, revelation - suitable to publish in the Automotive Journal and we get NOTHING!
This is killing us, back to work with you. Smooth idle or Molotov gas rag time.
This is killing us, back to work with you. Smooth idle or Molotov gas rag time.
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From: San Jose
300TE / 300E / 300CE
I can't feel it as soon as I touch the accelerator even just a tad...but performance sucks in general. I can only "feel" it at idle....and at this point in time, its not that noticeable anymore. Problem is power + MPG. I figure that whatever is causing my power and MPG loss is also causing my minor misfire now.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream Guys at another local shop said they wouldn't do it...
I'll have to keep asking around I guess.
I didn't know it was a legal issue for exhaust shops to hollow out the precats even though I have a brand new one downstream
Guys at another local shop said they wouldn't do it...I'll have to keep asking around I guess.
I'd like to have my pre-cats removed, they are in the way of the manifold flange bolts and could improve performance. I don't see how an exhaust shop can accurately remove and replace them with a straight pipe while keeping them aligned. I had an '85 300E grey market import that had an aftermarket pair installed, see:
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You know I "realized" I have a missfire on my white sedan but was ignoring it. It's definitely there at idle and the only nagging thing is it may affect my mileage suffers: 16-18 mpg. What are you getting? This car's head was professionally rebuilt but I had to fix the high idle and the hack things the shop did like add a helper spring and disconnect the ICV. They also screwed up the head thread for the water temp sender's and even left a Sharpie drawn arrow to it as if to remind them to fix it. They also left a water line loose that worked it's way toward the alternator pulley that eventually cut a leak. That's another reason for doing the work yourself, shops seem to cut corners at their convenience. It was done in another state so I couldn't go back to them.
I'd like to have my pre-cats removed, they are in the way of the manifold flange bolts and could improve performance. I don't see how an exhaust shop can accurately remove and replace them with a straight pipe while keeping them aligned. I had an '85 300E grey market import that had an aftermarket pair installed, see:
I'd like to have my pre-cats removed, they are in the way of the manifold flange bolts and could improve performance. I don't see how an exhaust shop can accurately remove and replace them with a straight pipe while keeping them aligned. I had an '85 300E grey market import that had an aftermarket pair installed, see:
----------
Found the right adapter for the fuel pressure gauge set I have. Gonna test fuel pressure on the 300TE this weekend so we can rule that out!!
I had a thought though...How time consuming is it to remove the air intake block to access that plastic boot underneath it? I was looking at one I grabbed from the junkyard and I saw it had a crack in the bottom. I didn't realize the bottom of the air intake was plastic that attaches to the manifold...I should really check mine is okay. It "could" possibly have been missed by vacuum leak tests. All the rest of the plastic hoses in my car have been replaced apart from this one.
It would have to be one hell of a leak though...but I should really cover this if the fuel pressure turns out to be okay. Its a $29 part.
