missing on cylinder

[n/a]

Hello all,
 my 280sl is miss firing on a cylinder but also running rough as well,
I had a classic car mechanic look at it he has ruled out plugs and
leads and thinks valve gap and injectors to make it run on all six
it starts ok on six in morining and when at running temp above 2800Rpm
is O.K. has anybody any answers?

Pagoda Red. P.S where are all the jokes gone?

red kelly

[Benz Dr.]

Could be a vacuum leak at the intake manifold. Once the engine warms up the gap gets bigger and more air leaks in.
Over a certain speed the effects may go away because of the way the fuel and air mix at higher RPM's. Could also be in the IP.

 Or , I don't have a clue.

Daniel G Caron

[ja17]

Hello Red,
You need compression, gasoline at correct mixture and spark for combustion. If you are lacking any of these you will have a miss. Narrow your choices first. A miss at idle can be low copression check it first before you beat your self up on all the other possibilities. Find out which cylinder is missing. If this doesn't show up in a compression check pull plug wires one at a time at idle to find the culprit. (Use special pliars any NAPA store).
It is good to rule out things like spark plugs and cables but make sure you check them. These parts are fairly inexpensive to replace compared to many other items you may be looking at. An ohm meter check on the spark plug cables and popping a new spark plug in is inexpensive and easy. If you are suspicious of an injector, move it to another cylinder a see if the problem moves.
The entire ignition system should be checked if the miss is random.

A miss caused by improper fuel/air mixture is more difficult and you will need to check a lot of things like fuel volume and pressure, injection pump settings, vacumme leaks (thanks Dan), linkage, mechanical problems like valves adjustment, bad cam, etc,  etc.

Keep us up to date.


Joe Alexander
Blacklick, Ohio

[rwmastel]

quote:Originally posted by ja17

If this doesn't show up in a compression check pull plug wires one at a time at idle to find the culprit. (Use special pliars any NAPA store).

Joe Alexander
Blacklick, Ohio

Joe,

Can you describe these pliars so I can go get the right tool?  I could really use them right now.

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[n/a]

thanks all, but leads are o.k and when I pull them off one at a time
they miss more and put back on picks up o.k on each pot.

red kelly

[ja17]

Hello Rod,
These pliers have insulated handles and jaws to prevent shock. Most autopart stores should have them. Often times the jaws are angled also.

Joe Alexander
Blacklick, Ohio

[rwmastel]

quote:Originally posted by ja17

If you are suspicious of an injector, move it to another cylinder and see if the problem moves.

I am suspicious of a bad injector in my car.  I've got a miss in #4 because when I use my new spark plug pliars to pull the wire off the plug the engine behavior does not change.  If I pull a wire off any other plug the engine almost dies (running on 4 clyinders!).  I then swapped the spark plugs and wires between cylinders #3 and #4 and the problem remained with cylinder #4.

I've never removed a fuel injector, what's the proper way to do this and what tools are required?

Looking ahead, my MB 230 SL Spare Parts List shows the MB part number for the injector as 000 078 07 23.  The local MB dealer has MB part number 000 078 11 23.  Does anyone know the correct Bosch part number?  The local MB dealer wants about $118 each.  What's a "good" price for injectors?

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[A Dalton]

One can swap wires and move plugs and injectors around to narrow down skip problems, but after all is said and done, the best test before any is the compression test.. Once compression is eastablished , then you know what you are working with .
 The best is testing compression specs and compression leak-down for each jug..On a leakdown test, you will know if your valves are leaking, are too tight , and which ones ..etc..This test will also give the Tech an idea of overall engine condition ..
Then start your swapping..
 Another good tool for these old ignition vehicles is an ignition scope .. I see them on ebay for  $40-$50 and once you have one , you will wonder why it took so long to get one
 Between the compression test and ignition scope wave forms , you can diagnose all..
and , lastly , get yourself a nice , big vac gauge .. great for playing around with those IP adjustments...

 ..this is not to say that the plug/wire/injector swappings are not a good DIY tecnique. We use them all the time ...but for perfection sake , with a couple of standard test tools, you can make these 113s singgggggggggggg......

[n/a]

Just did this on my 280 SE. Swapped everything from a good cylinder to the bad one with no luck. Found two loose injectors in other cylinders in the process and fixed that. The real problem showed up when I checked the valve clearance on the offending cylinder. One of the exhaust valves was so tight it was staying open all the time. Adjusted the rest of the valves while I was in there and she purr's like a kitten now.

quote:Originally posted by pagoda red

Hello all,
 my 280sl is miss firing on a cylinder but also running rough as well,
I had a classic car mechanic look at it he has ruled out plugs and
leads and thinks valve gap and injectors to make it run on all six
it starts ok on six in morining and when at running temp above 2800Rpm
is O.K. has anybody any answers?

Pagoda Red. P.S where are all the jokes gone?

red kelly

Mikey

[A Dalton]

Mikey's post is a perfect example....  
A comp/leak test would have pin-pointed the tight valve condition right from the get-go.....

[rwmastel]

Mikey,
Thanks for the tip.

A Dalton,
I understand what you mean about doing these test, but I can't do them at home.  If I move injectors and the problem remains with #4, then it must be a FI Pump, valve, or distributor problem.

How do I swap injectors?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Cees Klumper]

Rodd - I remove injectors with a crowfoot wrench, the same one that I use for setting valve clearances, 17 mm I believe. They are not in too tight. There's a thin washer beneath the injectors, that sometimes stays behind, so make sure that on installation, there is only one washer beneath each injector.

A. Dalton: how do you use a vacuum gauge to adjust the IP (or maybe I misunderstood what you wrote)?

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[A Dalton]

<<A Dalton,
I understand what you mean about doing these test, but I can't do them at home. >>

 The main point of my post was to point out the importance of checking the engine compression before swapping out parts..
 I do not know why one can not do a simple compression test at home ..
 I won't even touch a car for a tune without comp specs.

 The remainding parts of the post/test are just mentioned for those interested in fine tune abilities and are not considered as driveway procedures.

 As I stated , nothing wrong with searching out a problem by changing known good parts for comparision, but a simple comp test sure does save a lot of swapping and sure does give a solid base for diagnosis... not just for our 113 , but for any make..
 We all know the   "It's gotta be fuel or spark" , but we never consider the most important basic of the engine - Compression.
 So, my preferance is to always start there...mainly cuz I'm lazy.

[A Dalton]

<A. Dalton: how do you use a vacuum gauge to adjust the IP (or maybe I misunderstood what you wrote)?>>
 A vac gauge  is a simple measureing tool that tells one how well the engine is working with the fuel and ignition settings.
  Changing any of these settings and the vac efficiency of the engine changes...so, with a little gauge hooked up to the engine intake system, one can get the most effective tuning of their engine by monitoring the vac. [ prob next best monitor to gas analyzer]
 Experienced Techs  can do these tunings 'BY EAR'  and come close , but I use a gauge cuz I like things right ON.
 Unlike the compression testing, gage readings take a little knowledge , but if you get one , they come with Instructions and Pic comparison charts to help in understanding what conditions they are displaying.
 If you have A Haynes Manual, there is a small section in there on IP setting using the vac gage for a/f mix. Sec 24 , I believe.
 I do have some other articles on this, but I am currently in a moving process , so my scanner and equip are not avail at this time , but will be when I settle in.
I will then post that info, just so members can print them out for 113 info/library accumulation...
 

[rwmastel]

quote:Originally posted by A Dalton

I do not know why one can not do a simple compression test at home ...

Because I've never personally done a compression test or a leak down test before and I don't own any tools to do said tests.  I don't even own a timing light, if that tells you anything.  I'm just trying to do what I can before enlisting any help from others.  If you come to the 2005 Tech Session in Ohio this July, you can come see my garage and how void it is of tools!

How much do the tools for these tests cost?  Are the test procedures in the BBB or Haynes manuals?  I don't mind trying something new.  Everytime I attempt to fix something on my Pagoda, it's a new experience for me.

In the mean time, it looks like I'll be buying a 17mm crowfoot wrench today.  And yes, that means I've never adjusted my valve clearance at home either.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[A Dalton]

R
 Having read some of your replies , I just thought of you as a DIYer.
 We have to get some tools in that garage.. a Garage ain't for the car, it's for toooolz.
 A compression tester is just a gage tool and short money.. they also come with simple instuctions and once you use it , you will be happy to have one..
 Same goes for a vac gage.. cheap and real handy ..you will sometimes see cars with a vac gage right on the instument cluster.
 Back when I first learned cars , it was common practice to pull the plugs and drop them in the correct # hole in a board . Then you did a compression test and marked those PSI #s down for each hole..
Doing the compression test once the plugs are out is simply putting the gage in the plug hole and turning the engine over to see how much pressure that piston will attain.
 With this info, one can READ the plug and compare each jugs compression spec and get a  good idea of how this engine has been running and what condition it is in..
 In a tune , a even balance accross  both compression specs and plug conditions  are what one is looking for.  These little test/observations will give you this info..
 And a timing light is nice to have to get the spark where spec design would like it to be.
 This setting is critical for Mechanical Fuel Injetion and can not be done without one, even for the best ear tuners.
 You quite often see these three items sold as a Tune Testing Kit , with all three as a PAK.. again , not big $$$$
 Get one .. you will love youself for it..

[rwmastel]

A Dalton,

I can see how you might get that impression.  My problem is that I have lots of information, but little practicle experience!  I've read darn near every post on the W113 Yahoo Group since it was started until this Group was started (3 years).  I've probably read about 95% of the posts here.  I retain quite a lot of what I read, but I don't have the time/money to make use of it on my car.  I just pass the info on to others.

I bought a set of 10 metric crowfoot wrench extensions today.  They are the kind to be used with a 3/8" ratchet.
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00904363000
I'll use this tonight (if I get the last of the house painting done!) to swap injectors #3 and #4.  If the problem does not follow the injector, then I'll bite the bullet and get the other tune up tools and go that route.  My birthday is in a few weeks, sounds like the wife will be buying me an early present!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rwmastel]

Are these the products I need?

Compression Testers

$25 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00902171000

$50 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00947089000

Timing Lights

$35 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00902137000

$50 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00921027000

$70 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00921023000


Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rwmastel]

quote:Originally posted by cees klumper

There's a thin washer beneath the injectors, that sometimes stays behind, so make sure that on installation, there is only one washer beneath each injector.

Cees,
Silly question:  Can this washer be reused, or is it a crush washer like on the oil drain pan?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[bpossel]

Rodd,

Make sure to re-tighten the injectors, fuel lines and injection pump fittings to the correct torque lbs.  I have heard 18 lbs, but have also read in the BBB that it should be 25 lbs.

Does anyone know the correct torque lbs?

Bob

quote:Originally posted by rwmastel

A Dalton,

I can see how you might get that impression.  My problem is that I have lots of information, but little practicle experience!  I've read darn near every post on the W113 Yahoo Group since it was started until this Group was started (3 years).  I've probably read about 95% of the posts here.  I retain quite a lot of what I read, but I don't have the time/money to make use of it on my car.  I just pass the info on to others.

I bought a set of 10 metric crowfoot wrench extensions today.  They are the kind to be used with a 3/8" ratchet.
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00904363000
I'll use this tonight (if I get the last of the house painting done!) to swap injectors #3 and #4.  If the problem does not follow the injector, then I'll bite the bullet and get the other tune up tools and go that route.  My birthday is in a few weeks, sounds like the wife will be buying me an early present!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

bpossel
Memphis, TN.
1971 280SL
1997 E320

[A Dalton]

Just a basic Inductive light is all you need .  Variable timing lights are not needed for the old style ignitions.
 The advantage of having the Inductive pick-up is you never have to pull a plug wire to hook the light up [ it just clamps over the plug wire and senses the voltage through induction]
 The first Sears one is perfect.
 Another advantage to the induction light is , besides using it to do ignition timing, you can also clamp it over each plug wire and tell if that plug is firing without even pulling a wire or plug. You just look at the lamp for even blinking.  So, if one has a skip, you can just go down the line and spot the dead plug/wire in about 10 seconds..
 On the comp gage , the first one is good as it has a 14mm hose and a relief valve .. that's all you need ..the others are for many applications , but you do not need that .. a Plain Jane gage like that is fine. There are cheaper ones that you hold a rubber nipple in the plug hole, but that takes another guy/hand to turn the engine while you hold the gage and they tend to POP out with the compression.. so , get that one and you can do it by yourself..
 These two tools will give you a good reading on the internals of your engine and the ability to time the ignition to specs along with the ease of spotting the cause  of skips  without swapping plugs and wires , etc..
 I hope you find that your injector suspicions are founded with that swap, but once you have the tools, a quick check for compression and ignition will save you a lot of time on diagnosis..
 Good Luck

[rwmastel]

quote:Originally posted by bpossel

Rodd,

Make sure to re-tighten the injectors, fuel lines and injection pump fittings to the correct torque lbs.  I have heard 18 lbs, but have also read in the BBB that it should be 25 lbs.

Does anyone know the correct torque lbs?

Bob

Thanks for the tip.  I have tried to order the Technical Data Book, which would have this info, but it was backordered and I've not seen it yet.

A torque wrench is something I do own, but seldom have a need for it.

quote:Originally posted by A Dalton

Just a basic Inductive light is all you need ...

On the comp gage , the first one is good as it has a 14mm hose and a relief valve .. that's all you need .... a Plain Jane gage like that is fine.

OK, I'll get the cheapest ones and learn a new "skill".  It should be fun.

I didn't get to the injectors tonight, I just got done painting at 10:30pm and needed to catch up on the computer!

Thanks for the tool suggestions.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rwmastel]

Hay Dalton!  Time for compression check!

1.  Establish main symptom.  Start engine, pull spark plug wire boot from spark plug 4 and rough running engine does not change.  Pull a boot from any other plug and engine just about dies in 2 seconds.  It's a cylinder-specific problem.

2.  Completely swap the electrical side (plugs, plug boots, wires) between cylinders 3 and 4.  Start engine, same results pulling boots off plugs.

3.  Swap fuel injectors (Bosch DC8C45R1) between cylinders 3 and 4.  Start engine, same results pulling boots off plugs.

It's not spark, unless there's a problem with the distributor delivering voltage to position 4 on the distributor cap.  It's not fuel, unless there's a problem with the F.I. Pump delivering fuel to the #4 cylinder.  I'll be buying a compression tester tomorrow on my lunch hour.  I'll assume it comes with instructions!

More to come .....

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[A Dalton]

Yeah..
 Now you can see why we do a compression test first..
 I suspect you have a tight valve, just like Mickey had further down on this same thread..
 
 You may want to pull the cover a take a peek, but the test is in order...
 If comp is good , you are down to possible fuel pump plunger at 4 .

[A Dalton]

<<<<I'll assume it comes with instructions!
>>>

 It will, but I will give you a couple of tips that it will not have , as they pertain specificly to a 113 comp. test procedure...

 Take the wire OFF the CSV, so you do not pour raw fuel into the engine while turning it over to build up the compression.

 Take the coil to cap primary ignition wire off the car so it can't start while you are turning it over .

 Try to turn the engine the same amount of time [ turns ] for each reading so they are uniform

 and , lastley , hold the throttle plate slightly open so the engine can get some air to compress... this one is seldom done, but makes a difference in total reading... many guys think they have a low compression engine all the way across all cylinders cuz they did the test with the throttle plate all the way closed ..which means the engine had to get its intake supply of air from the idle bleed screw . gasp..gasp..gasp...