News:

The Org - Serving W116 Enthusiasts since 2004!

Main Menu

D-Jet 450SE progress Team116 car #2

Started by 13B, 18 January 2008, 04:45 AM

13B

Those of you who have been reading my other thread on the car know that it doesn't run right - its not running on all 8 cylinders.

Study of trouble shooting info on D-jet indicated the likely problem was trigger points but I've since today changed the distributor to a known good one with no change in engine behaviour.

Other changes I made today which resulted in no change in engine behaviour consisted of:

No. 4 fuel injector: it was leaking
Fuel damper (regulator?): it was leaking
ignition coil: for no particular reason (thought maybe a weak spark)
ignition amplifier box-thingy: for no particular reason (thought maybe a weak spark)

Because I'm an idiot and only had an hour I didn't follow proper engine diagnosing sequence and didn't check for any of the following first: fouled plugs, spark at each plug, fuel pressure, firing order, and any number of other simple little things - so they are next. 

On the way home I kicked myself because I have a 2nd map sensor and forgot to plug that in, which is crazy of me, its a 10 second job...

I went home because the battery was flat by then.  After a re-charge I'll go back and try some other stuff...

Does anyone think it could be ECU or injectors?  I guess I can replace them as well.

(I've pulled a complete D-Jet system off a car I saw running properly on all 8 cylinders - Noel's 450SEL - its being parted out in the Shop section here.)

Ian.

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

Nutz

Have you tested the wiring?

Main relay;

1)There should be 12 volts at pin # 24 of the ECU.

2)If not,check for 12 volts at pin # 24 of the relay.

3)If 12 volts is not present at the relay but it clicks,replace with a new relay.

4)If there is 12 volts at pin # 24 of the relay,repair
# 24 wire between relay and ECU.

5)If the relay does not click,inspect the wire from the main relay pin # 45 to ground.

6)If the ground is good and 12 volts at relay pin # 38
when the engine is cranked,replace the main relay.


Trigger points;

1)With the engine not running and ECU harness disconnected from the ECU,check the resistance between
ECU harness 12 and 21,then from 12 to 22.One should show a low resistance and the other should show an open circuit.

2)Rotate the engine 360 degrees and check the resistance.They should have an opposite reading now.

3)If not,perform the same test at the trigger points themselves.This will tell you if it a component or wiring fault.


Temperature sensor 1

1)With the engine not running and the ECU harness
disconnected from the ECU,connect an ohmmeter between
ECU harness pin # 1 and 13.At an ambient temperature
the reading should be 200 ohms.

2)If the resistance is well above 200 ohms,check resistance at the sensor itself to determine if it is
a component or wiring fault.

3)Check resistance of all the terminals to chassis ground.There should always be an open circuit.


Temperature sensor 2

1)With the engine not running and the ECU harness
disconnected from the ECU,check the resistance between harness terminal 23 and ground.The resistance should be 2000 ohms at ambient temperature.

2)If the engine is near operating temperature,the resistance should be below 1000 ohms.


Throttle switch

1)Test the throttle switch with the key on,engine off.

2)Slowly open the throttle,and as it opens the injectors should alternately click.You should hear
20 evenly spaced clicks.

3)If this is not met,place a 0.016 in.(0.4mm)feeler
gauge between the throttle stop and throttle stop screw.Connect a voltmeter to terminal 17 of the throttle switch.The voltmeter should show voltage while the ignition key is in the on position.Remove the feeler gauge and the voltmeter should show no voltage now.

4)If this fails,loosen the screws and rotate the switch until it meets these requirements.

5)If they can not be met and voltage is always present no matter where you position,replace the throttle switch.

6)If the voltmeter reads no voltage,ensure voltage is
being supplied to the switch.If so,replace the throttle switch.

7)If no clicks are heard while performing test 1 and 2,check wire numbers 20,17,14 and 9 for continuity end
for end from the ECU to throttle switch.


Pressure sensor

1)With the engine not running and the ECU harness
disconnected from ECU,check the resistance from ECU
harness terminal # 7 to 15.Should be 90 ohms and then check the resistance between # 8 and 10.Should be
350 ohms.If this is not met,test the sensor itself.

2)on occasion,the sensor resistance will check out,but will not hold vacumm.Using a hand held vacumm pump perform this test again (step #1)


Injector circuit

1)With the engine not running and the ECU harness
disconnected from ECU,check resistance of ECU harness
pins # 3,4,5,and 6.All should have less than 25 ohms.

2)If the resistance is greatly higher or lower than
25 ohms,test the injector itself.

3)If the injectors pass,repair the wiring harness.

oscar

Quote from: 13B on 18 January 2008, 04:45 AM
I didn't follow proper engine diagnosing sequence and didn't check for any of the following first: fouled plugs, spark at each plug, fuel pressure, firing order, and any number of other simple little things - so they are next. 

Absolutely!  Anything you read on d-jet will say don't blame the d-jet up front.  Check the basics first.

You have to make sure the ignition system is good.  No leaking sparks from ignition leads and suppressors to block and clean and correctly gapped plugs.  Visual confirmation of spark whilst plug removed doesn't guarantee a good spark when it's screwed back in.   I've been dumbfounded in the past with all 8 plugs sparking and connected to ignition leads whilst cranking but removed from block and sitting on an earthed metal bar.  A change of leads and new plugs might make a big difference.  Been caught out here a number of times whether old leads and plugs, but moreso dirty plugs. 

Whilst you've got it idling on how ever many cylinders, have you worked out which ones are missing??  eg pulling a lead off a plug one at a time.  Also listen to the injectors by way of stethoscope. 

Vacuum leaks - other than a leaking MPS, a decent vac loss elsewhere may also affect operation of MPS.  Try and clamp or plug up the ancillary vac systems and see if there's improvement.  Then move onto the  Nutz's suggestions.
1973 350SE, my first & fave

13B

I suppose this will give me the chance to fit NGK plugs that I prefer to run anyway...

I see the local wrecker here has 4 116s, three of them with K-jet V8s so I must remember to grab all the leads, dist caps, rotors, etc.  What is the test procedure for leads anyway?

My reading seems to indicate d-Jet to be a very robust system and easy(ish) to diagnose once you know what all the things do (I do now), and have a testing sequence (thanks Nutz!). 

At the moment its not idling on any cylinders :( However I will be trying all this stuff when I get back there in a week.  I'll also have someone with me to bounce ideas off and make sure I don't forget anything.

Will report back next week.

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

oscar

Quote from: 13B on 18 January 2008, 07:55 PM
What is the test procedure for leads anyway?

That's a bugger it's not running.  Re, leads, I thought you might know more about this then me so I didn't elaborate but you might have seen in scraf's thread about my mention of leaking sparks as well and my preference of NGK plugs over Bosch.  Leak detection can be hard to detect and nigh impossible on a non running engine.  This is what I've done before.

Firstly, do a visual check at the same time looking for tracking, burnt marks, or physical damage or possible breaks in the wires especially at joins at either end of the wires. .

Secondly using a multimeter measure the resistance and check for continuity of each wire from one end to the other.  For the life of me I can't remember if it's supposed to be 1kΩ or 5kΩ for this car.  It should match what's stamped into the supressor, but all suppressors should be the same and correct rating for the 450.

Lastly, (with engine running unfortunately) there's two ways you may discover a spark leak.   At night time whilst very dark, or in a very darkened garage, open the bonnet and look for sparking or arcing around the suppressors to block, wires on distributor, wire to block or rocker covers etc.  The leak is more obvious whilst dark. 
However, some arcing is nearly impossible to hear and or see even in the dark, especially if the arcing or leak is occuring within the suppressor to the block or to the outside of the spark plug.  The only way I've discovered this happening is by pulling the wire off the plug slowly.  About a few mm movement would see the spark go through the plug rather than around it to the block and rpm's increase a little.  Push the suppressor home and the misfire would occur again.  This happened particularly with bosch plugs but also with dirty or plugs needing regapping.
1973 350SE, my first & fave

13B

Ok so I got back to it today - its a pain with the car 50min drive away from my house at the moment.  Hoping to get it mobile soon so I can get it home and work on it more frequently.

its getting closer to running properly now.  Today we replaced the spark plugs, checked the firing order, made sure the rotor button pointed at lead #1 when the engine was at TDC.  And woohoo!  We got it to run for 5 seconds on all 8 cylinders...

Years ago we discovered you can run a car engine on SuperCheaper Auto $2 engine de-greaser by spraying varying amounts into a throttle body.  A good shot of degreaser and 1/4 throttle and off she went... and then it stalled and the battery was too flat from all our prior mucking around to start the engine again... :(

Some things to ponder: the ignition leads are 5k Ohm whereas the ones I bought from Noel's 450SEL are 1k Ohm... Its still got the 5K fitted at the moment, but I want to know which it should have and why? 

I changed over the map sensor while I was at it and while I didn't get the engine running on its own fuel supply, it did seem to blurt into life much more happily that before.

Nutz I have yet to do your checks outlined below but thats next on the list because I firstly wanted to make sure there was sparks at the right time on all 8 cylinders.

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

CraigS

Quote from: 13B on 03 February 2008, 03:48 AM
Some things to ponder: the ignition leads are 5k Ohm whereas the ones I bought from Noel's 450SEL are 1k Ohm... Its still got the 5K fitted at the moment, but I want to know which it should have and why? 

The 6.9 should be 5k and the M117 1k
[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

13B

Note to self: save the 5K leads for the 6.9 and use the 1K leads

The 5K leads currently installed don't look any longer than they need to be - it stands to reason that a lead set for the 6.9 would have some leads substantially longer...

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

WGB

I think the leads on a 6.9 are similar in length and there is only one lead that is longer  than a 4.5.

When I queried this last year I was told that a 4.5 set will fit but one cylinder is a tight fit - not sure which one as I purchased a new set of 6.9 leads from autohausaz which were actually cheaper than what I was quoted for a set of locally made 4.5 leads in Perth.

The difference is in the resistance which in turn affects the spark characteristic as far as I know.

Bill

SELfor50

Quote from: 13B on 03 February 2008, 03:48 AM
Ok so I got back to it today - its a pain with the car 50min drive away from my house at the moment.  Hoping to get it mobile soon so I can get it home and work on it more frequently.

its getting closer to running properly now.  Today we replaced the spark plugs, checked the firing order, made sure the rotor button pointed at lead #1 when the engine was at TDC.  And woohoo!  We got it to run for 5 seconds on all 8 cylinders...

Years ago we discovered you can run a car engine on SuperCheaper Auto $2 engine de-greaser by spraying varying amounts into a throttle body.  A good shot of degreaser and 1/4 throttle and off she went... and then it stalled and the battery was too flat from all our prior mucking around to start the engine again... :(

Some things to ponder: the ignition leads are 5k Ohm whereas the ones I bought from Noel's 450SEL are 1k Ohm... Its still got the 5K fitted at the moment, but I want to know which it should have and why? 

I changed over the map sensor while I was at it and while I didn't get the engine running on its own fuel supply, it did seem to blurt into life much more happily that before.

Nutz I have yet to do your checks outlined below but thats next on the list because I firstly wanted to make sure there was sparks at the right time on all 8 cylinders.

Ian.


That's classic bout the degreaser dude!

I'm confused why the engine wasn't / wouldn't run on it's own fuel supply??  Is that cause it didn't run long enough to draw on it?

Those bottles of degreaser will come in hand at some point then i'm guessing.......don't suppose I could just spray a heap of them in the fuel tank if i run outta gas??   :D

13B

In hindsight we didn't achieve much but I reckon we could have sorted it out if the battery didn't die on us.

All we've really established was that the firing order is correct, the ignition timing is "in the ballpark", the spark plugs are no longer fouled (4 were dry 4 were wet) and that if there is a fuel source fed into it (in this case degreaser) then it will fire on all 8 cylinders...

How difficult is it to remove plugs 3 & 4?  You shoulda heard me swearing at it... !!

Next we well perform Nutz series of eletrical connection tests and take it from there... and also change the leads for the right 1Kohm ones.

Tell you what, its got a killer exhaust which will sound awesome on full song...

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

WGB

#11
One problem I have had with my 450 during it's extended storage was plug fouling.

I like to run it every week or so just to pump up the airconditioning.

It would slowly drop off one cylinder at a time with each cold start until it refused to run. Cleaning the plugs only brought temporary relief.

This was never an issue when used in normal driving but became a problem with moving it around the shed and prolonged idling.

My neighbour suggested different plugs and I changed from NGK BPR6ES to BPR5ES (I think) and have had no further problems with clean starts and prolonged low speed running while I finally finish the bodywork.

Bill