Engine Wont Start C230 1997 W202 Auto Sport

[Ds24215605]

Problem: Car was running fine then in the morning came to start it - car wont start.

Actions taken so far by myself. Did the usual visual checks,nothing seemed out of place.

Called AA Home Start.

Actions taken by AA (Who were very thorough) to narrow down what the issue is:
1. Check fuel delivery - pump priming up and running.
2. All fuses in fuse boxes ok.
3. Fuel pump relay ok.
4. Check switching at injectors - ok.
5. Check key fobs remote working ok.
6. Car has fuel in tank.
7. Check for HT spark at plugs - ok.
8. Found that the plugs were dry like the injectors not opening?
9. Car would start if fuel manually fed into carb, albeit only for a short burst until fuel was used.

Unfortunately he didn't have a diagnostic checker to fit the car :-(

Anyone any suggestions what the issue could be, or come across this problem before. I am reluctant to have it transported into a Mercedes Garage for expensive diagnostics.

Conclusion. Is it the fuel pump not building up enough pressure to pump fuel into the injectors? I have only a limited knowledge of DIY on cars, the notes i have typed up from the AA Report.

 

[Will]

Could it be an immobiliser issue, I think the early 97 202 has the red/green LED lights in the rear view mirror? Have you got a spare key? I think from memory it uses both RF and IR so could be unlocking but not disabling the immobiliser.

Although the fuel pump primes does it continue to run when cranking over, is there enough fuel pressure on the rail when the injectors are pulsing?

The diagnostic socket is probably the round one under the bonnet, not the usual OBD type port for modern cars.

Where abouts are you located?

 

[Ds24215605]

Will,

many thanks for your comments.

1. Yes red and green lights. I have a spare key which the AA guy checked but i dont think he got a response from the IR yet as you say it unlocked the doors. ? Is there any way of checking if the keys are at fault or the immobiliser is still engaged? If not working correctly would it stop fuel going to the injectors?

2. AA checked fuel pump was initialising but not sure if he checked if it still run when cranked over he listened under the car when i turned it over so i presume thats what he was doing. I presume the pump has then given up? Do they just stop working or is there any warning signs, i didnt get any?

3. Yes ive found the OBD but AA didnt have a socket that fitted, wouold this show the fault if connected?


I live in Oldham / Manchester.

Thanks,

Derek

 

[Silestanix]

If the immobiliser had an issue it would make the red and green lights flash alternatively. If the lights go out whilst the key is in ignition position II then immobiliser is alright and your issues are elsewhere.

Do hope you get to the bottom of the issue though, good luck mate.

 

[Jimmas]

Could it be blocked fuel filter, I think it is fitted underneath the rear of the car.

 

[Ds24215605]

Ok the story so far.

1. Fuel going through to the front of car i took of the fuel pipe and checked.
2. Looked in the boot and checked all wiring, found some aftermarket wiring that goes from the unit shown in the picture to the fuse pump relay. reconnected that temporarily just to ensure its not that.
3. Renewed the Fuel pump relay fuse 30 amp in the boot of car.
4. power going to fuse pump relay ok.


Can anyone tell me what the small box with wires coming from it to the pump relay on top of the battery is?

Car still wont start - local Merc dealer doesnt have a STAR machine that will fit due to year. Round pinned type under bonnet.

 

[Ds24215605]

Could anyone let me know where the immoboliser is on my model of car?

 

[grober]

the two units most popular aftermarket immobilisers disabled at that time were either the fuel pump relay and /or the OVP overvoltage protection relay which powers the engine ECU among other things. The fuel pump relay is 2 stage first stage primes the system on ignition switch on---- the second stage needs an engine running signal to continue to pump fuel ---its a safety feature to prevent the system to continue to pump fuel if the engine is stalled with ignition on as might happen in a crash. The W202 electrics changed markedly in 97 and would have their own immobiliser built in. Before that its possible that the box is indeed an after market immobiliser which has gone faulty. You need to trace all the leads from said box to their origin.
ps your picture doesn't come up on screen.

 

[Dec]

Is this a flip out key?
Dec

 

[Dec]

 

[Ds24215605]

Dec, Yes it is a flip out key. Your image did not show?

The box i located turns out to be the tracker that was fitted by the owner before me. (for some reason it wouldn't let me upload the picture. That is what was wired into the fuel pump relay.? Now removed and wiring as it should be, hopefully.

The symptoms you mention Grober would explain why i am getting fuel to the injectors but its not firing. It makes so much sense now with your explanation. I need to find the immoboliser though not a clue where it could be.

I think it now narrows it down to the immobilisor or the keys although the lights in the wing mirror seem to be as though its working ok, ie should be allowing me to start the car?

Derek

 

[grober]

I may have misled you on the immobiliser thing in so far as your description included a black box-leading me to beleive you had the simpler electronics setup and an aftermarket unit. After 97 the W202 went on to an early form of vehicle networking and used this as a basis for their DAS drive authorisation system. In this a transponder on the steering column reads a chip in the key and sends the data the DAS unit N54/1 which in turn sends an authorisation signal to th engine ECU allowing it to operate. A decent code reader should be able to check if this system is operating correctly.

 

[Dec]

w202 immobeliser chip - Google Search:
Was the key opened up or could the immobeliser chip have been dislodged from its location below the Red lens on the key.
See above link.

My picture is that of your picture of your battery from the other forum, the picture shows for me ok.
Dec

 

[Dec]

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The immobeliser...N54/1 in Grobers picture... is the smaller of the two Black boxes in above vidio, located under passenger footwell foot rest, see 3 plastic nuts when you pull back carpet.
Dec

 

[grober]

Transponder chip location in flip key.

 

[Dec]

Thanks Grober, could not get that picture of hand to show at all.

Dec

 

[Ds24215605]

Grober, Dec many thanks.

I have 2 flip out keys and a Wallet type key for the car.

I will check the keys properly although i get a red light on the key fob when i press the open button on the fob, and all lights on the rear view mirror operate in correct sequence.

I will have a look at the immobilisor and check for loose wires etc...

Grober you mention a decent code reader should identify if it the immobilisor is not functioning correctly? where do these plug in or is there a simple way of finding out if its not working correctly. Dec, thanks for the video that helps i`ll have a look this morning and see I presume in the video the guy bypassed the immobilisor?


Really appreciate the help.

Derek

 

[Dec]

No, the guy dident bypass the imobeliser, the immobeliser was integrated into an aftermarket alarm which became faulty so he removed the faulty alarm wiring from the immobeliser and rejoined the White immobeliser wire so as to put the immobeliser back to it's factory condition.

See if any wires have been tampered with at the immobeliser just like in the vidio.
Dec

 

[grober]

W202 Fault Code Scanner / Fault Reader - which of these shall I get?
the socket is the 38 pin socket under the bonnet.
without direct knowledge of which scanner works well on the later W202 I would hesitate to recommend a particular one. Sometimes there are cabling /adapter dificulties- some only interpret engine OBD codes and not other chassis systems. Only person to know for sure is someone with a later W202 and a scanner they know works 100% sorry.
ps Mercedes Star System in the right hands will do it of course not that I suggest you buy one of course- in general the more you pay the more functionality you get out of any diagnostic setup. there rapidly comes a point were its cheaper to pay someone with the right kit- [and experience interpreting results] to help

 

[Ds24215605]

Guys you are not going to believe this i just rechecked the fuses in the front of the car and changed the fuse in slot 27, Bingo, the Car turned over and started straight away !!!!

All the fuses where checked by the AA guy, and myself must have been condensation or some gremlin in the system in any case its working ok now, all for the sake of a 10p fuse.

Thanks for all your help, it could have turned out to be a costly affair if i had gone down the route of having it moved to a garage for "in depth" diagnostics.

I have posted the solution in case anyone else has the same problem

At least the only damage financially is a new 30 Amp relay switch, at least ive got a spare now.

I`ll post some pictures of the motor when i get it washed....



Thanks again.