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What Causes Poor Power

Started by calvin streeting, 13 November 2010, 12:59 PM

calvin streeting

ok.. it stopped raining for a little while.. and everyone stoped bugging me to do other things...and i re did the checks..
(I even took some photos, but someone had played with the camera and lowered the image quality to its lowest setting  :( )

Quote from: s class on 15 November 2010, 10:36 AM
Firstly, Can you confirm that in the picture of the crank damper, it does indicate about 6 deg BTDC (photo not that clear for me).
Yes about 6 BTDC

So i aligned the left cam (as per sitting in the car) and you are correct the damper was pretty spot on to 0, and the right cam was just past the mark.

I am right in thinking that this is so close it wouldn't realy cause much of an issue..? and thus my power problems are either incorrect tunning, and or, a vacum leak somewhere.

many thanks.. its realy helpfull to have people to talk to about this, as no one here understands me when i start talking cam timmings etc..in fact most just say scrap it and by a new car.. they don't understand how nice it is to drive these old girls..

s class

If the left cam is spot-on, and the right cam is a little early, I would leave things as they are.  As the chain and sprockets bed in (and as wear occurs over the next many thousands of km) the right cam will gradually retard, so its better to start out with it timed slightly early rather than slightly late. 

And yes, the small timing errors we are dealing with here are not the cause of your poor performance problems. 

Have you checked the throttle linkage for correct range of operation?

Have you done a fuel system/control pressure test? I can talk you through this with photos if need be. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

calvin streeting

Quote from: s class on 17 November 2010, 01:21 PM
If the left cam is spot-on, and the right cam is a little early, I would leave things as they are.  As the chain and sprockets bed in (and as wear occurs over the next many thousands of km) the right cam will gradually retard, so its better to start out with it timed slightly early rather than slightly late. 

And yes, the small timing errors we are dealing with here are not the cause of your poor performance problems. 
Good...

Quote from: s class on 17 November 2010, 01:21 PM
Have you checked the throttle linkage for correct range of operation?
yes all moves ok. and i did oil it

Quote from: s class on 17 November 2010, 01:21 PM
Have you done a fuel system/control pressure test? I can talk you through this with photos if need be. 

I take it i need to get a pressure tester first...

s class

Yes, you need a pressure tester, but it doesn't need to be anything super fancy.  You can buy them online from about US$100 and up.  Some years ago I needed one in a hurry, and couldn't wait for shipping from the US or UK, so I made my own using various bits and pieces from the local hydraulics supply outfit.  Total cost was like US$40.  The rig I've made up is more complex than need be, because I've made it multipurpose to allow other tests on other types of fuel injection systems as well.  Basically all you need is :

1 x tee piece
1 x pressure gauge (fuel-compatible, 0 to 10 bar range)
1 x ball valve (fuel compatible)
assorted hose barbs
length of fuel hose (internally braided, high pressure type)
some decent hose clamps
1 x female fitting to screw onto the port at the top of the fuel distributor
1 x male fitting to screw onto the steel line that originally went to the port at the top of the fuel distributor

The last two are the most difficult to source, as the thread diameter and pitch appears not to be one in standard use in the hydraulics industry. 

I will get some photos for you over the weekend. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

calvin streeting

thanks..
I have been trying to get bits for a preasure tester for some time. (in UK testers can get realy expensive £200 upward).

I have fuel Pipes, Guage, and valve (hopefull fuel safe).

your right about last two conectors, as far as i can tell they are metric threads (typical germans :) ). I have various pipes from a few other mercs, and considering sacrefising for a greater cause.

If from what i have read you connect in the location you sugested, and watch the preasuer while it warms up. with the valve open you measure the WUR preasure (known as the control preasure), and then shut of the valve and measure the preasure from the fuel distrabutor (System preasure).

And to adjust use spacers in the fuel distrabutor, and either adjust the WUR, or overhall (with new seals, springs), or just replace.

is this right.?

calvin

P.S I am also thinking of geting my enderscope and looking under the Kjet at the seals to check the seals. wasn't it you with a 350se and a leaking seal, if so how did that run/not...

s class

OK you are doing fine - sounds like you have a good understanding of what is to be done. 

Check this guide in our library :

Link

Not sure it was me with a 350SE with those troubles, I've got several 450's, 1x 350 and 1 x 500 that I'm fixing fuelling problems on at the moment. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

calvin streeting

will look at the link..

this is the one i ment

http://forum.w116.org/mechanicals/350se-poor-idling/

Quote from: s class on 14 November 2010, 01:09 PM.

This morning I started poking around, and I found that the rubber boot between the throttle body and the air meter housing was displaced.  The upper of the two clamps had slipped down, and the boot pulled away, leaving a gap of a few mm for false air.  Now that's quite a vacuum leak!


but this had a bad idle problem. but i asume it drove ok ish.. this is why i want to look under the K-jet

s class

Yeah, that's me - that 350 is the latest in-need-of-help project I'm working on. 

And no, it doesn't run too great.  Won't idle at all, one can get going by heel-and-toeing it, but performance at speed is very limp .


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

calvin streeting

mine will idle, but not realy smothly.. i can rev the engine fine.. sometimes get inlet backfire (I asume fuel/ignition  settings have been tampered with) but when in gear and put you foot hard to the floor it will not beat a predestrian of the lights.. :)

I am going to do fuel flow test, check FD filter, reset ignition, preasure test. and reset fuel ratio..

P.S i have also noticed that sometimes the idle screw dosnt effect the engine much. well not as much as my old W123 280E. so thats why i will look for air leek. and as i have looked every else i will look under k-jet.

13B

#24
How about next time you go for a drive you shoot us an in-car video and put it on youtube?  Contrast your video with other peoples W116 in-car videos for acceleration.  Oscar I'm pretty sure has some in car acceleration vids for both the 350SE and 280S.

Here's one I shot for the 450SE:

Link

This is Oscar's one I was thinking of, compare accaleration times with yours...

Link

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

calvin streeting


Quote from: 13B on 18 November 2010, 04:31 PM
How about next time you go for a drive you shoot us an in-car video and put it on youtube?
good idea.. i will try and record the engine startup

but as " it will not beat a predestrian of the lights" means i can WALK faster. let me do a preasure test first.

s class
Quote from: s class on 17 November 2010, 01:41 PM
you need a pressure tester,

managed to build/hack some connectors to the k-jet to standard fuel lines.. how dose this look..

click for image

hope it dosn't leak :)

s class

That looks very good! certainly less home-made looking than mine. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

TJ 450

I agree, nice work with the fittings! 8)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

calvin streeting

when that worked.. i did a preasure test..
1. on start up 1.2 bar (in tolarance)
2. steadly rising to 3.9bar (removed WUR and cleaned screen and got it to 2.8bar in tolarance)
3. system preasure 3.9bar (low add 0.9mm of washers, and got it to 5.5bar, so thats better)

my co2 tester decided today was it last time on earth and died... bloady tipical...

so set the timing (without vacum at 0 TDC)

tested fuel delivery 1.1lts in 30sec

still a bit gutless but now dose pull away. so i think it just needs tunning.. any one got gidance on setting a k-jet.. sounds etc..


s class

OK are those all system pressure values?  Measured with the valve in your instrument closed?

What is the system pressure doing?

Are you getting enrichment when you remove the vacuum connection to the WUR?


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL