JonMac

Hi Guys,
thank you firstly for being such a resource for anyone with an MB...
I have a 2002 C240 (140k), always being serviced...
however a couple of days ago it started loosing power during drive and would stall when I slow to stop or at idle.
It will also idle really quite roughly and threaten to stall...
So feeling that it may have been fuel related, I used Seafoam to see if it'd help the situation but unfortunately didn't make it any better (or worse at least!) ...
After we had the seafoam in and it'd been idling there for about 10 mins, it just stalled on it's own and after that, I couldn't get it to restart even though the engine was cranking, but not firing... it sounded like it really should have... (the battery is like 2 months old and the alternator is really good) but nothing... left it alone after that for the night (got too dark)
So digging around and from the awesome guides and other posts on this forum, and from the symptons, I concluded that it was the Crankshaft Position Sensor and ordered it ... got it today... fitted it in.. and it's pretty much the same still. I thought it was better because after I fitted the CPS, and started it, it worked fine... but after about 10 mins of idle and driving, the non responsive throttle and rough idle and finally the stalls came back.
So now I've also got some Check Engine lights which read off an OBD gives a P0300 (random misfires), P0301 (cyclinder 1) and P0302 (cyclinder 2)... and whilst the engine has been used (warm/hot) it just refuses to restart. I'm almost certain that if I leave it to cool, it'll work again for 10 mins or so.
What else could this be? The items I've thought about, but not sure on...
1. camshaft position sensor? (but if it was that, wouldn't it throw an error?)
2. ECU? (but then it wouldn't wait for it to warm up.. it'd just not work if I my understanding of it is right)
3. MAF? (I disconnected it and it was no different, still wouldn't start... as per instructions from another post)
4. Fuel Lines? (again, if it was this, it wouldn't consistently wait for the engine to get hot to fail... or would it?)
5. Ignition Coils? (not sure how to test this but from the reading I've done, even if some were bad, it shouldn't be completely dropping power and stalling the car?)

Complete loss at the moment, I was so hoping that it was the CPS but I guess luck is not on my side today...
Any suggestions or course of action would be greatly appreciated...
thanks guys!
Jon

JonMac

Hi guys,
so this morning i went out and tried to start the car again and first time it didn't fire ...
then it fired up and almost immediately completely just died out...
this happened a couple of times...
then it fired up and stayed on and the idling adjusted itself a couple of times and stabilised and i let it sit there for about 5-7 mins and it sounded just perfect...
I took it for a drive around the block and immediately was evident that applying throttle didn't do much for it, it felt as if it wasn't getting any throttle or when it did, it would feel as if was going to stall and the engine was not sounding good.
If i played the throttle, or lightly try to increase it , it responded a little better but still not good. When it was moving, it tended to overrev before changing gear... when i got it home and put it in park, it went to idle quite contently, sounding as if nothing is wrong!
And while in park, if i apply the throttle, apart from a slight hesitation, it would rev up and back down quite happily.
So it feels like the issue happens when i'm in gear?
there's still no new Check Engine light (i cleared the P0300/301/302 from last night) but i plugged in and pulled a pending P0112 (Intake Air Temperature Circuit Low Input) ...
not sure what my next step or test should be at this stage... i know it's a matter of elimination so I'll take a close look at the coils and sparks in a little bit.
if you have any suggestions please let me know Thanks all!

LexBrett2

Had a problem like this with my former car. Was puzzled by the random misfire code, and checked all the sensors and everything ignition related. Turned out to be engine timing- the crankshaft cam was not properly torqued and slipped off teeth. But in my case I had just had an engine rebuild, so that's probably not your issue.

If you do have an manual available you probably have checked usual suspects such as plugs, couls, maf, o2 sensor, bad Ecu, and lastly timing?

Assume you also did simple stuff like reading you lambs codes and disconnected battery for at least five minutes??

Icebreaker

Please excuse my ignorance but what is a crankshaft cam?

Icebreaker

Have you check fuel pressure? Sounds like your fuel pump could be on it's way out. How many miles on your car?

Russell Ormerod

Easy fix!
Step 1 check fuel pressure must be at least 3 bar
Step 2 if fuel pressure is ok renew airmass sensor use ONLY bosch or mb parts!
Good luck!

JonMac

thank you guys ! i'll go check the fuel pressure first...
oh and Icebreaker, car has 143k miles... always serviced... actually 6.7k from a service B atm

Icebreaker

Mine has 129k. I was less fortunate in that my fuel pump went out at 80 mph in the fast lane on the highway. I was stuck for about an hour with people honking at me constantly ignoring the fact that I had my flashers on. If only it happened a block away from my house like yours, life would have been a lot simpler.....

JonMac

at lease you didn't get rear ended !
so i went and bought the CRC MAF cleaner... took out my MAF... confirmed that it's manufacture stamp is 01/11 so it would be the original (car is 2002) and drowned it in the CRC a few times and then waited for it to dry, reassembled it...
started up fine though with a bit of a longer firing sequence like it couldn't work out if it was going to actually start or not but did in the end.
Let it idle for a little bit, applied throttle on and off... heavy throttle made it backfire before it caught and revved. But after a few minutes it seemed to have settled so took it for a drive around the block...
Initially it felt almost like normal, slight hesitation on applying throttle (ie stop and go), but it definately drove longer and better than the last two days and after about 10 minutes (far longer than yesterdays efforts which lasted a few minutes) it started to not respond to the throttle again...
Ok, sorry for the long text.. but I am leaning towards it being the MAF...
1. it's the original part still... which makes it 15 years old now ...
2. the car (since i've had it 8 months) has always had bad fuel economy (mixed 17mpg, hwy 21mpg?) and i always felt it was high for the size of the engine? and since this saga began, i've read that a bad MAF can cause this (bad oxygen/gas mixture...)
3. the car has always had this slight hesitation before going when applying throttle, which i believe is another of the symptons of a bad/dying MAF ...
4. after i did it's 'clean' it drove well until (i'm guessing) the hot wire got to a temp where it's just failing now (which if it's another sympton, makes sense why it would be fine for the first few minutes until it got hot?)

i'll keep you guys updated once i get a new one in and fingers crossed it will do the job...
ps. if you guys have other thoughts or agree let me know? i'm still open to any suggestions until we get it resolved
Thanks!

Icebreaker

Once it died, but before you try to restart, did you have a chance to check the fuel pressure?
My pump was still working, just didn't have the required pressure to keep it running.

Russell Ormerod

I have lost count of how many MAF sensors I have replaced on 112 engines. As I said if fuel pressure is good. Change MAF. Also renew airfilter when changing MAF. If you really want it to run well after a MAF replacement. Service the throttle body. Renew o ring behind throttle body. Reset self adaptation.
Good luck.

JonMac

Hi guys!
Got the new maf... installed... no difference (after my obligatory drive round the block a few times...it was fine idling for a while and then after a restart was very rough, pulled a cel p0301)
So got the fuel pressure tester and here's the results...
After plugging it inow, read 10psi
Cycled the ignition... 20psi
Cycled again... 30psi
Stable at 30psi
Started car...idling at about 28psi
In park, applying throttle, barely moved, sitting around 28psi... dropping to about 25psi...
After a couple of mins, idling is starting to feel rough... 20psi
Was slowly dropping, 18psi, applied throtle, 20 psi and little wobbly on idle...
Engine off... sitting at about 10psi
Restarted, went to about 20psi idling OK 700ish rpm.
So if I'm not mistaken, one of you pointed out 3 bars (43psi) should be normal but I'm getting less than half that?
And how do I tell if it's the pump or filter?
And does the length of time driving possibly affect the pumps performance? (Referring to the fact that the first 10 minstrel seems that the car drives generally ok...)
You guys were right on the money ... thank you for your help so far!

Icebreaker

I would replace pump and filter and test again. You may (slight chance) of need ing a pressure regulator too. As for MAF...I rest my case......
If your pump is going bad, could be due to working too hard pumping through a dirty filter, it could get hot the longer it works and thereby not pumping enough the longer you drive. I'll bet after you change pump and filter that you won't have high rpm miss either.......

JonMac

Hi Ice!
thank you so much for the suggestion... i was also browsing the forums (searching fuel pump issues) and ran into d1no's post (going back a couple of years now but still relevant) where, in the end, culprit was indeed a fuel filter...
I was inclined to go with a pump replacement but given what you've said and that other thread, i've just ordered a Mann-Filter WK 720 which i should get tomorrow and i'll swap it out and then test the fuel pressure again etc.
If it's still bad, then i'll go for the pump as well but if it turns out good, then i'd have saved myself $160...
Appreciate your input

Icebreaker

What worries me is the engine off pressure that drops all the way to 10 PSI, a clogged filter won't do that. My fuel pressure after 3 days (over the weekend) never dropped below 35 PSI. I hope you never get into my situation on the highway!

JonMac

Valid point and you'll most probably be right again (this is the first time i've dealt with fuel system in any car!) ... and i won't touch a highway until i get good readings (55psi constant) and have driven around a fair bit first to be safe
(not to say that i still wouldn't get a pump failure at 80mph *touch wood*)

Icebreaker

Yeah I actually had to call 911 and they sent out a State Trooper and he held all the cars back so he can push me across the highway to the right side. My wife was crying cos she was afraid all the cars whizzing past us would hit us. This was close to rush hour so there were a lot of cars on the highway. It sure as scary!! It cost me $450 to have it towed home.

Actually my other car (2000 Jag XJ8) I just changed the pump on that one a few months before but luckily this one wouldn't start right after I dropped my friend off at his house. I should've know bad luck comes in pairs!!

Russell Ormerod

That's why I said check fuel pressure first BEFORE changing MAF. They both troublesome parts

JonMac

another update !
ok so i got the new filter in... turned over a few and started fine, was a little hesitation... didn't have the gauge with me so i just drove it around a bit and then it came back shortly... heading for a pump now !

Icebreaker

Yeah usually the filter doesn't act like that. Pressure should stay the same but volume will be low. Pump is easy, there is a YouTube but it's in Russian (I think) but the video should be self explanatory.

Icebreaker

By the way it should be under rear seat under the right side panel (passenger side).

JonMac

Thanks again Ice .. i was wondering about that and wondering if i've ordered the wrong part ... ...
is there anyway to identify which side it's actually on once you look at the tops of the two sides? (i'm reading all over the place and find conflicting info to the point where it's best to 'listen' to which is holding the pump?)
THanks again
Jon

ok i just saw the video and can see the difference bdtween the pump and non pump ! thanks

Icebreaker

I actually got mine from here, much cheaper.

http://www.bigredautoparts.com/item....OBEST&weight=2

JonMac

FUEL PUMP !
she's running and purring along and so dam quiet at idle / stop that i have to remind myself engine is still on.
swapped out offending piece ... had the gauge hooked up once i got the pump lid down etc and cranked a couple of times and it sprung to the magical 55psi like magic ...
started up, purred, spluttered a little at 1200rpm but that went once it settled back to it's normal idle at 700rpm...
took it out for the block drive, pickup on corner / exit is flawless... went highway, just purring along now. Did about 10 miles mixed and i think it's better than i ever remember...
So thank you Ice and Russell for your advise and help... one of the great things about the mercs is the awesome community.
cheers!
Jon

Icebreaker

Congrats on a job well done and thank you for your update! Wishing you many more happy Mercedes miles!!
Alan.