3.2 starting issues

[Mark300SL]

After a few ideas really

M104 3.2 HFM engine from a 1993 S320 fitted to a 190E

(Sat) I drove it back from Devon after it had sat for about 3 years SORN.
The drive back was nothing short of perfect - not an ounce of trouble or even a hint that there might be something amiss.

(Sun) The following day I gave it a good clean and afterwards added something like 150 miles. The clean included checking plugs (so removing coil packs etc) as well as the MAF and crossover pipe.

(Mon)The following day I picked up the turbo kit and put a further 200 ish miles on the clock just driving. Nav tried it and it seemed OK

(Tue) - took it to work and to a job covering a few more miles (50ish)

(Wed) As above

(Thur) - - Went to start it to take it to work again - and it was very hesistant (see later), finally started after 15 mins - and all was good. On the return trip it was again hesitant but only for 10 seconds or so and then appeared normal again.

(Friday - went out early - and it was not going to start - took the astra and left it.
Came home after work and had another look and it displayed the following symptoms

1. Turn over on the key and after 6/7 seconds it will "catch" - run for 3/4 seconds and die. Any attempt to touch the throttle in this period will kill the engine dead. I checked every connection I had touched/moved to no avail

Then at around 9.00pm it just started and ran perfectly after an hour of me looking at it

Took it for a very local "spin" to put some life back in the battery and it was perfectly well behaved. Took a chance and stopped for a coffee as to this point I had assumed it was a cold start issue. - Well it wasn't and I was stranded outside the "Wild Bean" for 25 mins - then it started and drove very roughly all the way home it idles between 500-1200 rpm but doesnt die even in gear and stationary.


Sat

Took everything apart again , checked the engine harness very very carefully, no cracking or breakdown and all wires still flexible.
Every connection under the camcover cover was spot on. All fitted properly, alll leads making contact. Changed the plugs for new NGK and again checked all connections. Also checked the connections at the front for the cam sensor
Despite my best efforts under the bonnet it took an age to start (doing the crank / fire run for 4 sec /die routine ) and when it did start it very quickly re-established the 500-1200 idle routine running really badly.

Sun - well today it has made it to just about not starting, this is a blessing as I should now be able to cure it once and for all!

Symptoms
Crank it over and after a while (anything from 4 to 8/9 seconds) it will fire and run for 5 seconds max. (possibly fuel pressure dropping off?) - It cant be revved at this point or it will die instantly.
After firing the street is enveloped in a dirty cloud of unburnt fuel that you can really smell.

Car runs or not without the MAF with no difference
This year appears not to have an OVP relay and this is bourn out by the wirining diagrams I got with the car from when Ben built it. A lot of web wiring diagrams show the HFM system WITH an OVP. The actual original MB drawing Ben used to wire the car show no OVP relay.
I was leaning towards CKP sensor - (but I think this cut injectors if it were faulty ??) but the massive overfuelling makes me doubt this diagnosis./
Base control unit only uses 2 fuses when fitted to the 190- these are intact


A chat on the phone with Ben didnt reveal much other than he never had problems with it over many years - Having driven it back I can only agree that it was perfect.

I have a Multiplexer and Carsoft 7.4 arriving early next week anyway to help with any future problems (bought for turbo install) but I am just after any ideas to try before this arrives


If you got this far - thanks for reading

If you have an idea - even better !


Mark

 

[Will]

Well, it sounds like an intermittant electrical issue. I'm guessing a dry joint/poor connection somewhere?

Fuel pump relay? Can you hear them prime when you put the ignition on?

Will

 

[television]

Does it have ABS as it seems that the OVP relay was only fitted to cars that had

If you need any voltage pin outputs to check I can look it up for you.. The CPS would cut the fuel and spark. but I can double check that as well

Do you know the next 3 numbers after 104

 

[Mark300SL]

Well, it sounds like an intermittant electrical issue. I'm guessing a dry joint/poor connection somewhere?

Fuel pump relay? Can you hear them prime when you put the ignition on?

Will

Unfortunately the fuel pumps prime. I intentionally "short cranked" it for about a second a few time just to hear the pump prime - and it is VERY rich smelling when it does fire. However giving it any throttle at all will result in it not firing.

This has taken hours of searching and checking - but it really is a totally new engine to me and I need to work my way thorugh it more logically.

 

[Mark300SL]

Does it have ABS as it seems that the OVP relay was only fitted to cars that had

The 190 has ABS, the S320 had ABS, the wiring diagram for the S class shows no OVP. This is confirmed by Ben

If you need any voltage pin outputs to check I can look it up for you.. The CPS would cut the fuel and spark. but I can double check that as well

Any values - voltage or impedence for the Sensors would be good please

Do you know the next 3 numbers after 104

Unfortunatley no - I should really go and physically check on the engine itself, but I don't have the logbook back yet (yes it is all on the logbook)

Where on the block is it likely to be ?


Thanks again


Mark

 

[television]

Where on the block is it likely to be ?


Thanks again


Mark

I need some more info as cant see a 126 or 140 S320

There is an oblong flat just under the exhaust manifold, very hard to see. its not on the near side of the block as seen in the link.

If one can find the exact car that it came from or something otherwise I do not know where to start looking

http://www.detali.ru/cat/oem_mb2.as...507722.605&CT=M&cat=520&SID=01&SGR=012&SGN=03

At least with the next 3 numbers I would know what goes with it

 

[Mark300SL]

Its definately a 1993 140 S320

Other than that I won't be able to see it tonight

I have a whole folder of wiring info from Ben - but no engine number

 

[television]

Mark I have found wher the number is can you PM me with an E mail address, there is one empty PM space

Ok found the 140032 and 033

 

[Mark300SL]

Done thanks

Unfortunately its just too dark out there now - and my LED torch doesnt do quite enough

I know ir will be simple when I find it - its just frustrating not even having and LED tool to read codes with. If the multiplexer doesnt arrive tomorrow I will prob make one anyway

I'm more and more sure its an ignition fault just bacuase I can smell the fuel
either tha or it is flooding whilst cranking and then not feeding fuel after it catches.

Again it could be CKP "playing up" but I dont want to start guessing this one as I need to fully understand it if the turbos are to work properly
Its really frustrating as I totally understand Honda PGMFi - I almost wrote the UK handbook on it!


"DING"
If this were a Honda I would go straight to the main engine earth on the thermostat housing. This provides injector earths, ECU earths etc etc - Is there a similar earth I could have distrubed whilst "cleaning" the top end ?

I will also check the battery earths in the boot as the battery was moved there to allow the 3.2 ECU housing to be located where the battery normally lives. That said it does crank over VERY well and all electics work at normal speed.

 

[KLP 92]

I doubt its a crank postion sensor.

I've had many M104s with CPS failing and its always when the engines hot and intermittently cuts out at random. It never stutters, or starts and then dies, either it works or it doesn't.

It was fine when i drove it (honest i didn't break it ). SOunds more like an issue sue to the car being stood for long periods.

I would check the basics, check the MB Diagnostics first, if no joy check the fuel pressure as that will give you a good idea of what is happening.

MAS comes to mind, disconnecting it isn't a 100% accurate way of testing. Other than that check the top intake pipe, following from the MAS over towards the throttle body. You'll come accross another small sensor of the passenger side of the intake pipe, i believe its a temp or o2 sender and this again is critical to the running of the car. Check that sensor as well.

Other than that check as WIll stated the fuel pump/relay and fuse (gets corroded).

 

[Ian B Walker]

Spark plug extensions cause this type of issue.

 

[grober]

MAS comes to mind, disconnecting it isn't a 100% accurate way of testing. Other than that check the top intake pipe, following from the MAS over towards the throttle body. You'll come accross another small sensor of the passenger side of the intake pipe, i believe its a temp or o2 sender and this again is critical to the running of the car. Check that sensor as well.

.

Air temperature sensor as KLP said. A lot of earths to be found at the top of the nearside side front strut turret 3 separate bolts on a w124 at least.

 

[kth286]

Mark300SL

Well, a very important sensor for fuel is the coolant temperature sensor in the head at front.

They often go out of spec and I suspect it may currently be stuck on the hot end of the scale (it alters resistance as temperature changes).

 

[Mark300SL]

I doubt its a crank postion sensor.

I've had many M104s with CPS failing and its always when the engines hot and intermittently cuts out at random. It never stutters, or starts and then dies, either it works or it doesn't.

Thanks for that - it does look like a bit of a mission to get to!

I would check the basics, check the MB Diagnostics first, if no joy check the fuel pressure as that will give you a good idea of what is happening.

Yep - going to look for a fitting for my FP gauge

MAS comes to mind, disconnecting it isn't a 100% accurate way of testing. Other than that check the top intake pipe, following from the MAS over towards the throttle body. You'll come accross another small sensor of the passenger side of the intake pipe, i believe its a temp or o2 sender and this again is critical to the running of the car. Check that sensor as well.

I was of the assumption that removing the MAS would make some difference though - on or off it performs exactly the same. Same as the Air temp sensor - on most systems air temp just provides a correction factor for incoming air temps. Most of the engine temp sensing is by coolant temp sensors - please correc tme if I am wrong

Other than that check as WIll stated the fuel pump/relay and fuse (gets corroded).

That was my next port of call - to see if the pumps are running when the engine is running.

Once I can read the codes properly I will have a better idea, unfortuantely I was back too late to picjk up an LED and resistor tonight, its a long day tomorrow (brum and back) so it will likely be wed/thursday before I can get back on this with a vengance ( and hopefully Carsoft + Multiplexer)

Spark plug extensions cause this type of issue.

I did wonder as I did disturb them - but unless I have killed all 3 by removing them just twice then I would at least expect it to run on 3/4/5 cylinders - again I am open to suggestions but this is not like a missfire - much more like a fuel/spark dropout.

Mark300SL

Well, a very important sensor for fuel is the coolant temperature sensor in the head at front.

They often go out of spec and I suspect it may currently be stuck on the hot end of the scale (it alters resistance as temperature changes).

Can it run with a default value if the CTS is disconnected ?

Time for some specs and a multimeter I think




Mark

 

[television]

Thanks for that - it does look like a bit of a mission to get to!





Yep - going to look for a fitting for my FP gauge



I was of the assumption that removing the MAS would make some difference though - on or off it performs exactly the same. Same as the Air temp sensor - on most systems air temp just provides a correction factor for incoming air temps. Most of the engine temp sensing is by coolant temp sensors - please correc tme if I am wrong




That was my next port of call - to see if the pumps are running when the engine is running.

Once I can read the codes properly I will have a better idea, unfortuantely I was back too late to picjk up an LED and resistor tonight, its a long day tomorrow (brum and back) so it will likely be wed/thursday before I can get back on this with a vengance ( and hopefully Carsoft + Multiplexer)




I did wonder as I did disturb them - but unless I have killed all 3 by removing them just twice then I would at least expect it to run on 3/4/5 cylinders - again I am open to suggestions but this is not like a missfire - much more like a fuel/spark dropout.





Can it run with a default value if the CTS is disconnected ?

Time for some specs and a multimeter I think




Mark

The CPS measure 1k Ω when good. Intestingly we had a thread where the CPS was I believe going parcial short circuit last week, and we are waiting for the answer

I do have all the details now of that engine, its a 104990

 

[Mark300SL]

The CPS measure 1k Ω when good. Intestingly we had a thread where the CPS was I believe going parcial short circuit last week, and we are waiting for the answer

I do have all the details now of that engine, its a 104990

Good job - because I came in relatively late and then spent 1/2 hr on the phone to Ben. Unfortunatley I was in a white shirt and couldnt get under the car to remove the lower shield panels!

There is a fuel pump relay, but I cant actually find it due to the mixed 1903/s320 wiring looms Its not in the stock 190 location so I will have to hunt this one out


I am actually really enjoying it now as perverse at that might seem. I have learned more about this engine in a couple of days than I would have over several weeks otherwise! As it now wont start at all I will know I have cured it properly when I eventually find the fault.


At least the car went to me - I have visions of someone else being less then pleased with a car that only lasted a week - whereas I am actually enjoying the challenge!


Thanks for all the ideas so far guys


Mark

 

[grober]

Faulty ignition switch? Is it the original 190's?

 

[television]

Faulty ignition switch? Is it the original 190's?

I have been thinking of you earlier post on the common ground wiring spades, the car has got new paint, and as you say the ign switch is another.

I should have time tomorrow to look up the control unit plus connections so a somple test will check that out.

To test the ground spades/wires, just put the meter neg lead on the neg of battery and the+ probe onto all of the spades with ignition turned on

 

[KLP 92]

Check the throttle body as well, may be slightly sticky.

 

[Mark300SL]

Quick update of - not a lot

Due to work I was unable to get out there for the last couple of days, but now I have a bit more time

1. Muiltiplexer is here so I can at least read codes
2. Battery is now recharged
3. New fuel filter is sitting on my desk at work ready for me to fit tonight
4. fuel pressure gauge adapter is made - so I can verify fuel pressure whilst cranking and running.

Engine number - is a 104 994



Mark