W201 stopped whilst driving

[fangio_gg]

Hi, thought I'd share my issue. I haven't fixed it, but when I do, maybe it will come in handy for someone else.

Till about a month ago my 1.8l W201 1992 been problem free since I bought it about a year ago. Got 300000km on it. When I bought it, it ran good, but I took the time changing:

Rotor
Distributor cap
Spark plugs and wires
Fuel filter
And other bits, but non relevant AFAIK now

Then, a month ago, I noticed all the warning lights fading on and off on the dashboard. It then stopped whilst driving, had been going about 1hr in totalt from when I noticed the warning lights.

I was on the look for a voltage regulator being the issue here, measured the output and sure enough bellow 12V. But I found a complete alternator and bought one of those instead. Been doing long trips since then no problem. It has always been starting on the 1st crank and I keep the car tucked away from rain and moist.

Today, it stopped again whilst driving. As if one just took all the fuel out of the car. Got half a tank with 98. I think I could smell fuel after trying to start it after it happened. I have done no work on car since changing alternator a month ago. All electrics work, it cranks well and good but won't fire up, no warning lights. I think I can hear the pump priming, but gonna check it anyways in order:


1: Listen to fuel pump on turning ignition
2: Check for spark on spark plugs

Depending on outcome,

3: Bypass fuel pump relay and bridge pins 7 + 8 in the plug
3: Change ignition coil
3: Check fuses
4: Clean connectors

Q: Would a faulty camshaft position sensor cause the car to stall whilst driving? I know it could prevent the car from starting.

Q: I noticed drips of fuel from the fuel pressure regulator, probably still original, maybe the film inside been worn/clogged. Part of the problem?

Q: In my situation, where I don't expose the car for cold/damp or moist weather, can the cold start valve still be acting up?

What I also have in mind, but I don't want to throw parts at random, is EHA valve, fuel pressure regulator, but also that small fuel distrubitor filter screw. Change OVP and fuel pump relay. Possibly fuel pump.

Wish me luck

 

[fangio_gg]

Was ably to pry out the contact for the fuel pump relay. To my suprise I found this big gapping hole were pins 6 and 8 (female socket) should be and what appears to be the 12 volt cable melted its housing. It seems as some previous owner stuck it into place, because it was seated at the pin on the relay. But where is pin 8? Found no cable but I guess it functions as supposed to anyways.



Did bridge pin 7 and 8 heard the pump feeding continuously but engine didn't start. I didn't have any extra spark plug at my location so I went ahead and tried this first.

 

[fangio_gg]

So today I went ahead and checked for spark, no spark. Was to my local hardware/auto parts store yesterday to get extra spark plugs, found ignition coil for the cost for 4 spark plugs so grabbed one of those as well. Glad I did after checking the car today. Put everything together and it fired up after a few attempts and ran good stationary. I had it sitting and rev'd it for a good 10 minutes.

Then I went in to get some stuff for the car wash. It didn't start. Now I'm having issues with the car coughing on start and it took me maybe 10 attempts on cranking with jumper cables to get it going. I'm thinking either a new problem arised with the cold start valve or the fuel pump relay after all. Gonna do some more troubleshooting.

Funny thing is that the car did run well after change of ignition coil. Maybe the car good flooded due to bad CSV?

 

[fangio_gg]

I'm also getting white smoke coming through the throttle body as it coughs and stops upon trying to fire the car up. I turn the ignition key on, it cranks and coughs. Then as I release the key, it makes a final cough and puts some white smoke out through the throttle body plate.

Timing issues?

 

[LostKiwi]

Sounds like classic Crank position sensor issues.
The CPS is used to turn on the fuel pump after the initial prime and then provides timing information to the ignition system.

As always get codes read to be sure.

 

[fangio_gg]

SOLVED: I did some more checking for loose tubes etc if it was a vacuum thing. Everything was seated and connected, ordered a new crankshaft position sensor albeit not OEM. Was really cheap. Had read some horror stories getting the thing out, but the screw (torx in my case) was already loosened and movable by hand. Put my sleeves up was able to get my left hand and arm down in between the oil filter and the firewall. When I was going to put the replacement part in it was just going down half the way no matter what pressure I put and turned it. The plastic housing had some edges from production so I peeled them down with a knife and put a film of motor oil on it, then it sat perfect the old one had gunk and bits all over it, maybe it would have worked if I just cleaned the top magnetic surface off. Anyways now its starts on the first go just like before. Thanks a bunch!

 

[fangio_gg]

Well, things were all fine and dandy for 2 whole days! Yesterday when driving home from work, it started surging really bad once the engine got warm. On idle it would jump up and down sometimes coughing and stalling. Had to keep the revs up good sometimes coasting with the clutch and giving it throttle at lights to keep it alive. It's fine at highway speeds. This morning, the car cranks good but won't fire up, again, just like the original issue I had when starting this thread.

So now what, change of OVP and/or fuel pump?

I'm going to start with putting the original ignition coil back in and check for cracks on hoses. Maybe something slipped when I installed the camshaft sensor. Or the fuel pump had enough from all spluttering and bad going.

 

[fangio_gg]

Also beginning to think that maybe that coughing and splutter maybe caused pressure up the system towards the air mass sensor, maybe enough to cause already hardened plastic parts to crack. I have a love and hate relationship to my Baby Merc

 

[LostKiwi]

Does this car have K-Jetronic or L-Jetronic? If it's K-Jetronic it will have mechanical fuel injection with a fuel distributor.

 

[fangio_gg]

It is indeed Bosch K-Jetronic (KE-Jetronic).

I'm shooting high and low now, but is it recommended to slightly loosen the lines going to the fuel distributor or is the pressure to high? Just to see if it's actually coming through there.

 

[LostKiwi]

Pressure is fairly low as injection is into the port (unlike diesels that inject into the combustion chamber). That said petrol is highly flammable so not the best thing to have squirting around an engine bay!

Do you have a catalytic converter? If so check the lambda output. OVP relay is also a strong suspect.

 

[fangio_gg]

Cheers. Yes it has. I grabbed OVP relay and fuel pumps from refurbished dealer, OEM. Not a big cost and it's fine for me, just want it running. I guess it's time to change the O2/lambda anyways since the car is almost 30 years old so I will grab a fresh one from the autoparts store. The fuel pump relay is a good €250 (€100 second hand) so I will change that as a last resort if the others don't check out. This is where I would like to be better as the common garage weekend hero to pinpoint the problem but hey you learn every day.

 

[fangio_gg]

SOLVED, AGAIN: Well I think my Merc is just toying with me. Today I went through all the tubes, pipes, connectors and greased them up good also putting some WD40 into them. Checked the EAH valve it held a good amount of fuel, noticed that since it shot straight into my face Took the idle air control valve aka ICV off and had a good shower of WD40 through it. I changed back to the original Bosch ignition coil. Removed the distributor cap, screws and casing was pretty loose actually... there was some buildup on the pins so I brushed them off with sandpaper as well as the rotor. As I took the out the spark plug wires, they had to be pushed down really hard with the other end of a screw driver to hear the "click" at the top of the distributor. The idle problems are gone and it does not surge anymore. Took it for a 20 min spin, was hesitant to even get near the city and red lights in case the old problems would reappear. Then went to my old folks and back total driving time of 2hrs. The problems seems to be gone for the time being. The idle is actually better then before. Overall I think the current flows better then before, maybe compensating for other faults. I get the feeling it just needed a run through like everything else to function, bit of love. And now I got a set of extra fuel pumps and OVP in case things turn sour again.

 

[fangio_gg]

Been two weeks going now and for the first week I had my idle deteriorating again. Not to the point of stalling, beside once, but it been wonky. Jumping up and down typically surging. It actually for two days had a fluctuating idle, you know when driving you can tell the difference between an engine surge and jumping RPM. I'm still awaiting new O2/lambda sensor and a air intake sensor (or IAT, the one inside the air box with the filter). It won't hurt. Also realized when I bought the car I forgot to change the ignition cable going from the ignition coil to the distributor, I changed the ones to the spark plugs. This did improve the idle but still not good. I also went over the throttle mechanism with PTFE-based lube. Making sure it is not sticky. Cleaned the idle switch (that clicky thingy when throttle are released). Also added extra ground from engine to the chassis. Right or wrong, I been driving the car for another week now, highways and city driving, with a good stable idle and this is what I did:

Spray bottle of water
WD40
Throttle body cleaner

Car is old, don't have any papers on it's history, so I figured there is all kinds of crap inside the throttle body and valves. So starting with the water, I wanted to clean out deposits I went through good half a spray bottle taking my time and listening to how the engine responded. I was able to run it down with a tip around the air mass sensor plate. The ground turned black where the exhaust points. Then onto the WD40. If the throttle body was sticky the idea I had was to clean the surroundings of the plate and movable parts, at first I sprayed down some with the engine off. So it would dissolve crap by sitting at the top of the plate maybe working its way around and underneath it. Again started the car put my thumb on the throttle so I could blow it through. Used maybe half a can.

Finally I used a can of throttle body cleaner, since it is alcohol based, I wanted to get rid of any residue left by the WD40. And this last step is what really seems to have done the trick, I could hear a clear difference on the exhaust note after like a minute. I used half a can with the car sitting on idle. Went out for a drive pulled over and emptied the remaining can through and over the air mass sensor. It makes everything look really clean and dry, and I hope that what it looks like down bellow as well.

I'm skeptic to these procedures and it feels like cutting corners doing it, but if it does make the engine run better I'm fine. Maybe in different circumstances it wouldn't have done any good and maybe even harm, worked out this time.