1990 190E NO START
 

Hi guys, I hate to become a member of this board because of a no start problem, it seems like thats how it always happens.:rolleyes:

I just recently bought a non running 190E 2.6 sedan. I really dont know the circumstances leading to it not running, but i took a chance.

It will crank over fine, but it wont start.

Ive checked the following:
It has blue spark- it seemed rather inconsistent on two cylinders though.

It has great compression- 140+/- in each hole.

It has fuel pressure up to the fuel distributor, I can also hear the pump cycling like its supposed to. -however, I opened the line at an injector and it wasnt much more than a trickle?

Ive replaced cap/rotor/wires/plugs.

Ive checked for TDC, even cycled the wires all the way around the cap to advance timing.

Ive shot ether into the intake, no luck.

only glimmer of hope came when I was advancing the timing, and i had #1 in the #5 position. while cranking it, a small bit of smoke came from the tailpipe indicating detonation.

given the slightly irradic timing, Im curious if this might be a crank sensor?

I'd appreciate your thoughts on this thing. :bowrofl:

Im really curious about the starting fluid thing. if it has spark, then why wouldn't it try to fire when I sprayed ether down the intake?

If it was a 350 it would've been running a long time ago....:rolleyes:

When you replaced the cap & wires, did you match the order they were in, or did you consult a manual? What did the old plugs look like?

A blue spark isn't quite as useful an indicator of adequate firing voltage as you might think - the initial voltage required to bridge the gap while firing is far higher when the plug is under compression. I'd use an actual spark tester connected in-line w/ the wire & plug - especially if you've got weak sparks on other cylinders.

If it won't run on starting fluid, that sort of (but not completely) rules out a fuel delivery problem. Did you check timing with a timing light? Have you checked for vacuum leaks and checked the airflow sensor? Have you taken any vacuum gauge readings?

Did you get any sort of history from the previous owner about how it "died"?

thanks for the reply, Dhj. I did make sure the wires were in the correct order- #1 at 1oclock etc.

im pretty limited on diagnosis tools where i am, ive got an ohmmeter, a comp tester, and basic hand tools.

I actually swapped out the coil with a new bosch unit to see if that helped, still no change.

i havent checked for vacuum leaks, nor have i checked the airflow sensor. how do you go about checking that?

I was told that the car ran fine until it just quit.
I really didnt put much stock into his evaluation.

My impression of the guy was it could have been sputtering for 6 months and it would be "running fine" as long as it ran.

You can get a used timing light on ebay for around $20-$30 bucks. It's a decent investment for older cars.

A cheap vacuum gauge you can pick up almost anywhere that sells automotive tools for around $15.

I've you've got a new coil, you probably can do without the spark tester.

You might try unplugging a few things and trying to start it, especially since you don't have many tools. If a particular sensor is causing problems/shorted/etc..., some cars will run if it's simply disconnected (may not work with MB's).

Is the check engine light on?

correct me if im wrong, but there isnt much need to check timing with a light if ive already confirmed TDC right?

check engine light: I couldnt tell ya; ive never had it running. all lights come on when key is in on position.

something I didnt note: the plugs I used are bosch supers, they are copper core which means less resistance in the plug. the old plugs looked to me like platinum plugs, but none were fouled out when I replaced them.

All an engine needs to run is fuel, air and a spark.

The timing light will give you a good idea of the existance of spark.

Having it run well is what the other stuff is for.

Clean plugs are essential for reasonable detonation. Pull at least three of them and make sure they're clean and dry. A little brushing with a brash bristle brush and simple green does wonders.

Thx -CTH

as stated, I have spark. timing is on, i checked TDC (TDC= Top Dead Center)
Ive pulled the plugs one by one and checked each cylinder for spark, and its there. They are new plugs, installed them yesterday. when i pulled them , they were clean, and smelled of gas so i know its getting fuel. Ive hit the intake with ether, so it should have fired if it was a fuel issue.

at one point, I had all the plugs attached to their respective wires, just laying in the plug hole. As it turned over, i saw each cylinder detonate 1-5-3-6-2-4. it almost seems they don't detonate in the chamber?

Could this be a plugged cat issue?

Have you checked the Crankshaft Position Sensor?
Mine reads 814 ohms cold and 900 ohms hot.

For voltage, it reads .842 v ac cold and .986 v. ac hot. You'll need someone to crank the engine for the voltage test.

Slk, thanks for the reply. do you know what the symptoms of a bad crank sensor would be? I'll check it with my ohmmeter. Im only able to get the cold reading, as it obviously wont start.

on the 2.6, is it located under the oil filter?

i had the same exact problem with my 1989 190e witch is the exact same car.... here is a cheap and easy way...that car is befor the obd sensor so go to pep boys with 20 dollars ask for a gm universal coil replace your old one with the gm......... and presso it will start and replace the crank sensor which is underneath the oil filter get one from the junk yard and test it with an oms metter it must read .700 or higher .... replace it and badda bing badda bomb the **** will start TRUST ME!!!:D


GM HELPING THE MERCEDES WORLD RUN!!!!!!!!!!!!!!!!

Weak spark, or no spark. One end connects to the Ignition Control Module that is mounted on the driver's side wheel well and the other end goes behind the oil filter at the flywheel.
Disconnect it at the ICM to check your measurements.

http://i179.photobucket.com/albums/w...Sensor300E.jpg

http://i179.photobucket.com/albums/w...ed/300EICM.jpg

Confirming TDC only means that the #1 cylinder is at TDC when the crank mark is at zero; that's not going to give you any information at all about when the spark plug is actually firing on that cylinder, hence the timing light. Did you at least confirm that the rotor in the distributor was pointing at #1 spark plug when you were at TDC on the compression/power stroke? That'll get you close, but even a 1/4" twist of the cap can change timing by 5 degrees or so.

Have you verified that the rotor is even spinning?

ok, mine reads at 794 ohms cold. when cranking the engine, the voltage is VERY spiradic, reading anywhere in the low teens to mid 40's.

and thanks for that photo, it was very helpful!

Voltage should be sporadic. It's a square wave form best viewed with an oscilloscope.

When you say mid 40's, do you mean 40 volts or .40 volts? Do you have your meter set on AC or DC?

i just realized that, doh....:o

If you're only getting around .1 - .4 volts AC at cranking speed, that's not good.

Checking around, it should be around 1 - 1.5 volts AC.

you mean at the crank sensor right?

ok, i plugged the CPS back into the ICM, and hit the key just for kicks. It actually tried to fire. im going to see if theres a bad connection somewhere in the vicinity of that plug i may have bumped.

crank sensor is reading 2-3 VAC on the 200 VAC setting.

according to shop manuals, the sensor is within spec at 794 ohms cold.

tried fooling with all the wiring around ICM, im not able to get it to pop off at all now. not really sure why it did to begin with.

Im about ready to throw in the hat, Ive been under this hood for 3 days.
I just dont understand what is going on. Evidently, there is no way to tect the ICM, other than replacing it. those suckers are $1000 at the dealer.

Before spending any money, how about checking the vacuum hoses on both sides of the Idle Control Valve to make sure they are securely connected and follow them to each end connection. Verify that the lower hose is connected to the bottom of the air intake boot and not cracked.

First check to make sure the rotor is pointed at the #1 plug when the #1 cylinder is at TDC on the compression stroke (both valves closed).

Then, get a timing light to make damn sure #1 is firing when it's supposed to.

You bought the car not running. You don't know if the previous owner tried to fix it himself or not; the distributor could be 180 degrees out of phase for all you know.

GOT IT RUNNING!!
 

WooHoo got it going! the P.O. had installed a new cap/rotor. I have had it off at least 10 times in this process, as it turns out, the rotor diode was severed in half underneath the plastic!:eek:

That would explain the irratic spark! Man, Ive been in/under/around this car for 3 days, had that cap off 10 times, oh well issue solved...

Thanks for the help guys, Ive become quite intimate with this benz in the last few days.

Incidentally, I bought it non running, never driven it or heard it run.
It drives beautifully, maybe the nicest benz Ive ever driven. it purrs so quiet I can stand at the hood and not hear it.


dhjenkins, slk230, thanks for all the help!

DHJ, the reason I didnt think it had anything to do with top dead center is because the 2.6 engine doesnt have a conventional distributor. the cap bolts to the engine, the rotor bolts right to the end of the camshaft. there isnt any way to set it 108 out, except by advancing the wires along the cap-which i tried too...

so, I went out this morning to start it, guess what.... no start. it tried to, then it then it went back to cranking.

Ive checked the OVP using the test written by max on here. im getting current and ground when/where I should be- I didnt check it with load but I assume its fine.

I did notice my ABS came on a couple times while driving, thats why I assumed the OVP.

I tried shooting the intake with ether, didnt change anything.

I pulled all the plugs, let them sit out and dry out, came back and still nothing.

checked the 4 pin coolant sensor for resistance, it measures 4000 at 50deg F.- so it appears to be good.

I rechecked the crank sensor, still measures fine.

I popped the fuel line off what looks to be an intake injector, it has plenty of pressure.I can hear the pump cycling, so it works.

WTF is the deal here?

If the ABS is coming on, it could be your OVP relay. Jump it with an in-line fuse and see if that starts her up. It could also be your ABS system.

When you say you hear the pump cycling, do you mean it's coming off and on?

Also, just because you have gas out of the fuel line doesn't mean you have plenty of pressure; granted, I don't know much about MB's, but there are plenty of domestics that won't run or start if the pressure is 55lbs instead of 60.

Again, with the ether not starting it up or running it, it makes it sound like it's still a spark issue. Get a timing light!

I did this test on my OVP, (with the exception of the load test) and it checked out fine.

http://www.peachparts.com/shopforum/tech-help/177089-testing-ovp.html?highlight=testing+ovp


By cycling, i mean i can hear it come on when i hit the key, and when i pause during cranking. I figured if there is a fuel issue, shooting ether down the intake will get it to fire.

so far, ether has gotten me jack.

When I got my W126, it had a bad FP, blocked tank strainer & blocked fuel return. I was able to start it and keep it running (at a smooth idle) with just ether/starting fluid (had to have someone else turn the start it).

Again - timing light!

Well, stuck a new OVP in there, still nothing. The local parts store is allowing me to test fit parts and return them, right now they are ordering me a new MAF control unit. should be here tomorrow at 10am.

That's nice of them - see if they'll loan you a timing light.

ok, I'll check the timing. there isnt any way for the timing to be out of line. if the cam turns, and the cam is in time with the crank...

:vbac47679

That's only valve timing. I'm talking about ignition timing. I'm not saying your cam or crankshaft aren't sync'ed properly - I'm pretty sure they are given your compression readings. What you need to make sure of is that the #1 plug is firing when it's supposed to, which it might not be, due to the distributor, the ignition control module, ignition wiring, crank sensor, etc...

I getcha.

I checked it, timing was on, firing when it was supposed to. there is no distributor, the rotor MUST land on #1 as it is screwed to the end of the cam. there is no other electrical there besides the coil/plug wires. in other words, as long as the coil is firing consistant power at the cap, there will be spark in time with valves.

I checked the oil today, it appeared to have a sizable amount of gas in it. given how long it sat before I got it, and as much as it was cranked over, no doubt alot of fuel seeped into the oil.

So I had a thought. what if the oil/fuel was washing the cylinders so it effected compression?

SO I did an oil change, threw new plugs in there, guess what, fired right up.
So now it runs again, im going to pull the plugs later this evening to see if they are fouled out.

incidently, the ABS light is now on fulltime, so i stuck a new OVP relay in there and it fixed that.

DHJ, I appreciate your help, And I respect the ASE certs youve got. in no way do I mean to downplay your opinon. without seeing the car, you cant possibly see the whole picture, so you start with what you know, and I totally understand that.

Glad you got it running! Congrats on the cylinder wall washing idea - most people would have never even have thought of that; heck, there's many a tech that wouldn't have thought of that.

Like I said, I'm no benz expert (yet :)), and the info available in alldata & mitchell is often conflicting (and WIS isn't exactly user friendly). I just wish I could have been more help!

Ha! no start again this morning! pulled all the plugs out, the were wet(fouled?),
cleaned them off, reinstalled....still nothing.

I cycled the key about 15 times, and it sputters to life. once it started, runs perfect- no miss, no hesitation when I throttle it, just a perfect idle.

I let it run for a sec, shut it off and restart, fires right up.

bump to the top, really need some help guys, the last post sums up my issues.

it wont start when sitting over 8 hrs. the last three days it hasnt even sputtered.

I pulled the cold start injector, it has a nice spray when the engine is turning over. looks like its working fine to me.

I pulled a few random injectors, they also have a good spray, but only when i press down the "intake plate". looks like that is what they are suppose to do.

bottom line, it looks like im getting fuel pressure.

what the hell could my problem be?

Blow into the fuel return line (or use shop air). If you don't hear a gurgling in the gas tank, you may have a faulty check valve in the tank which is clogging the return fuel line.

Odd that it won't start/run on starting fluid, though. Almost sounds like it's spark related. Maybe you have a bad ignition switch...

Is it damp where you are?(vancouver Wash...I will bet very damp)...

I have had a lot of problems over the years with less than perfect "new" distributor caps, just when you think you have eliminated that as a problem. My issues of hard starting were always when the car sat for a few hours or days in damp weather.

There should be an "O" ring that seals the cap, and it get's hard with heat and time, and will not seal the cap any longer...Most new ones (aftermarket Bosch) do not come with this "O" ring...This "O" ring sits under the plastic disc behind the rotor, so both the rotor and what's behind it must be removed to change the "O" ring...it is part of what makes sure the dist. cap is sealed from atmosphere. Also note that some of the aftermarket Bosch caps cannot seal..some of the detents formed into the caps allow air into the dist cap, even with a good "O" ring...

Best solution..get an OEM cap and "O" ring right from MB and inspect it carefully before installing...they should be OK..I always got the right stuff from them, at least for my firing system, and swap...Sounds distinctly like you are getting moisture under the cap..which is going to cause exactly the issues you are battling. Would also help explain why the contact in the rotor burned through (extra resistance..been here seen all of the above).

Note: I am not pushing OEM parts because of any allegiance to the "stealer", but because there are so many discrepancies in aftermarket Bosch stuff....They can be made in any of maybe 20 different places, and they have no particular allegiance to "quality control" in some of these countries...I purchased at least three caps for my 2.6 over the years which were wrong for multiple different reasons...but ultimately most had the same issues...they did not seal the dist. cap....Have also seen cap and rotor combinations where the clearance between the cap and rotor center contact point was too great and allowed the spring loaded contact in the cap to fall out..I do not remember if this was a cap or a rotor dimension problem though

I actually went back to the spark thing too. I tested the coil power going in and also the output power. 12 volts on both sides of the coil, even when cranking. like you say, Ive seen an ignition switch dilute the current too...

What exactly is that valve/chamber that is inline on the fuel return line? it sits right next to the fuel dist.

I'll blow air into the return line and see what I get.

Merry christmas y'all!