Hoosier240sx

I just picked up a 1990 190e 2.6 with the automatic transmission (sucks..) I drove the car the past 3 days, ran fine (Dies 2 seconds after starting just need to give it gas) until last night when I went to shut my car off.

I turned the key completely to the off position, and even pulled it out and my car kept running. All the electronics, everything. I pulled the #2 relay from the box at the driver side firewall and nothing happened. So I stalled the car on purpose since I live on a hill and the engine died but the fuel pump still kept going and all the other electronics stayed on. My friend said it could be the ignition switch or something related but I heard diesels have this problem and its due to vacuum lines. I also have suspicion because on my first 240 the vacuum lines we're bad and it had a rough "loping" idle like this car does only on cold start. This also happened after I put seafoam in the gas tank. Any ideas?

I've been in the drift game 5 years and have rebuilt numerous 240s but when it comes to these I don't feel like messing with it. Bought it as a daily and don't plan on making mistakes to keep it inoperable for any length of time.

Bob338

The setup for shut-off is totally different in the diesels than in yours. No similarity. In the diesels there is a vacuum line connected to the ignition switch. Vacuum actuates a valve near the injector which shuts if off. Yours is totally electric. I'm certain your switch needs to be replaced. It's a simple job but a real hassle to get in back of the dash to reach it. Your instrument cluster has to come out and you have to unscrew the switch behind the key and replace it. I did my diesel with the use of a mirror to find the three screws recessed and among the electrical connectors.

vanir

Bob answered the electrical issue, sounds definitely like the switch to me too.

For the stalling just after start, and rough idle for a few seconds on cold (or if the car has been sitting for a bit), mine does that and I've been gradually fixing it. When I pulled the plugs I found a lot of corrosion on them, and didn't like cheap NGK ones anyway so swapped these out for new Bosch F7-6 ones. The fact that helped it a bit and returned a little extra grunt up hills it must've been losing, convinced me this particular issue was spark related. If the plugs were that corroded, the rotor button will be too so I pulled off the distributor cover and found the cap is cracked. So I also need a new distributor cap, o-ring and rotor which I'll get soon (just spent a wad on other stuff for it). I'm pretty confident that'll fix the start/stall and occasional rough idle (which is from misfiring, I'm used to it from another car I had that used a totally vacuum operated fuel delivery system, always misfired after starting until the vacuum had time to work the carbs properly).

I like the auto by the way, but you have to manually select third a lot during normal driving in hilly areas to keep the engine speed up in the torque band. The stock programming is for upshifts under 2000rpm and it's got no grunt under 3000, maximum torque is up around 4800rpm, so this engine needs revs to drive spritely. It's pretty simple to just move the handy knob shifter back and forth between 3rd and 4th, just hold it back to 3rd whenever accelerating under conditions you want nice engine response and upshift so 4th isn't under 2000rpm. That's the bit that kills them, 4th upshifts way too soon making it accelerate like a small four. The M103 loves revs and mid range, not low engine speeds.
By contrast, switching into sport mode by selecting the dogleg 2nd changes the programming for high rpm upshifts (and engages the high ratio 1st gear not normally used). Do that with the foot to the floor and that little six really gets up and boogies for its class, easily chirping a little wheelspin on the upshift. It's just the normal driving mode that understates the engine for the driver, just remember to manually shift 3rd-4th whenever you want to put any loading on its acceleration but still want to drive sedately, I do that and it has no problems keeping up with fairly quick ultramodern traffic in normal driving, like the latest quad-cam V6s and 6.0 V8s everyone's driving these days, it's actually a fairly quick car driven right. I kinda like the auto, which is unusual for me.

DocWalla

intake manifold gasket can cause the engine not to shut off?

Bob338

No way if the electrical for spark is turned off. That has to be an electrical failure which could also be brought about by mechanical failure in the switch. How would the plugs fire without spark? A blown intake gasket in a gasser will allow air, lean the mixture and increase the idle, but it still has to have spark to run.

DocWalla

i was reading the repair manual for benz servicing because im about to do my engine mounts on my 190e and i am going to take off the intake and clean it and replace the gasket on the way to the mount. it said if the gasket is bad enough the engine may not shut off and may require removal of batty lead to stop the engine. idk why, but thats what it said.

Bob338

I suppose if the engine and something in the combustion chamber is hot enough it might start to diesel but that will stop pretty quick.

vanir

If you've got a vacuum leak say from a leaky intake gasket a hot engine can keep coughing and spluttering after shutdown, essentially it's trying to keep running without spark. I'm guessing something about the KE-J injection system panics and starts supplying spark on its own if this happens. It's not quite like a fully electronic injection that would use the ignition like a master switch.

I still agree with Bob on the OP problem being a faulty ignition switch however. It's the simplest possibility, but sure if that is examined and found working, then since the service manual mentions intake gasket, sure then I'd replace that rather than pull my hair out. It does sound weird but if the manual mentions it, has to be something to it (hence my conjecture as to how it might be relevant).

Bob338

I think the OP was a one time poster!!

Hoosier240sx

Sorry guys I'm not a one time poster at all. Thanks for all the advice I do appreciate it.

However, I replaced the ignition switch; same problem. I can pull out the battery and the car will still be running even with the key out of the ignition. In order to shut the car off, I have to remove the ignition coil wire from the distributor. If I pull the ignition coil wire from the distributor WITH THE BATTERY IN, the fuel pump still keeps sending fuel and all the idiot lights come on the gauge cluster and will do so until I remove the battery.

I did find a short in the wiring since my car keeps blowing a fuse in front of the driver side fuse box (it is it's own little unit with a blue 15 amp fuse in it) I can't figure out what that is if anyone knows that'd be awesome...

Also, after replacing the ignition switch I can't get the car out of park even by pressing the brake pedal. Is there any type of shift lock on this car? From what I have read via Google search, on other Mercedes-Benz models of this era there is a line that runs from the back of the brake pedal to the transmission and on the transmission there is a button which will unlock the transmission if you press it.

And finally, after replacing my ignition switch it is an absolute PITA to get the key out of the barrel. Even when turned in the off position the key gets stuck in there. Where as before the key would come out smoothly.

Really starting to regret buying this car as a DD. My 330 hp 240sx is more reliable than this thing...and that's saying something.

DocWalla

could be there is a short or something wrong with the distributor/coil. check the dist. rotor too.not just the cap. could be something thats not grounded right as well which would explain the blown fuse. if the old ignition worked put it back in and return the new one to fix your key sticking.

DocWalla

or your w201 is haunted.. lol

Bob338

Can't address your other problems than the ignition switch. You've obviously installed the switch (as opposed to the key and tumblers,) incorrectly. There is no relationship to the key other than as a vehicle to turn the switch and there should be no difference in the key turning and releasing. Best I recall, the switch itself has a mechanical connection to the key and tumblers. Those two aren't mated correctly. If put in correctly there should be no difference in the key turning to enable the switch to connect.

The car shouldn't run without the battery. It would indicate that your wiring out of the alternator allows power to bypass the battery. Your challenge is to trace the wiring so that it is as original.

Hoosier240sx

Well Bob I didn't put the switch in, my friend who just graduated from lincoln tech did the job for me. I know 240's inside and out, but not German cars such as this. There's only one way to put the electrical part of the switch in, nothing else of that whole assembly was touched. The old switched was removed by the 3 screws and the new one was installed. The key comes out, I just have to push in and pull out once and it will pop then release the key.

But I sent the car to a shop today to have everything taken care of since I can't seem to rely on someone who graduated from his school with a 4.00. Whatever though, just costs me more money and he wont get the paint job I promised him.

DocWalla

I would second the alternator having shotty wiring. In my w201 it is in somewhat close proximity to the exhaust manifold. If the heat shield is missing from the alternator harness that runs up to the battery, it could have melted. Ive heard of the headlight harness melting its self where it connects to the bulb as well, and that doesn't have nearly as much currant passing through it as the alternator harness does. I would recomend figuring out what that fuse that blew goes to as im betting if you find the wiring diagram for what that fuse goes to and follow its signal flow, you will find your short.