'95 W202 C180 (no MAF) hesitation and hard to start after warm

[Mo420]

Hello all!

Im looking to get some advice regarding our trusty old W202 Merc. Its an early (1995 model) C180, with the M111 engine that came without a MAF sensor. Its just turned over 300,000kms on the clock not so long ago.

Here's the issue - car would do a cold start during mornings just fine, however for subsequent starts after that, the engine will crank for a good 7-10 times (around 3-4 seconds) before it finally fires up, rather reluctantly.

Another thing is (maybe related or otherwise) the car seems to hesitate for a few seconds when taking off, for example, starting at a green light, with moderate to full throttle input, the car would jerk for 2-3 seconds as if the engine is cutting out, and then would only accelerate normally after that.

Both symptoms have started intermittently but now its progressively worse, now occuring every warm starts (long cranking) and when pulling away (jerking, hesitation).

I've trawled through the forums to no avail as most W202 C180s, unlike ours, are equipped with MAF which usually is the culprit in such scenarios. I doubt its usual stuff like plugs or coils since the car drives ok otherwise. We're currently leaning towards the fuel pump because recently the car ran out of fuel (our fuel gauge is bad hence unable to know exact fuel level) so we think probably some of the gunk thats settled at the bottom of the fuel tank is now clogging the fuel intake, does this seem like a sound theory?

We're planning to take the car into an indy's soon, so would like some ideas on what may be wrong beforehand if its possible. Car also isnt equipped with an OBD2 port so I cant get my scanner to pull out codes.

Thanks in advance for your responses.

Regards,
Mo420

 

[Nasco12]

I understand that a broken crank position sensor can cause the engine to stall when warm.

I would have thought that the fuel filter would prevent any gunk from getting into the engine. If not, what's it there for?

 

[hfmscan]

It is necessary to check the leakage of fuel through the injector, through a pressure regulator, through a check valve fuel pump.
The most typical - a pressure regulator on the ramp passes through the fuel outlet of the vacuum (disconnect the vacuum hose from the pressure regulator when the engine stop after run and watch the drops of gasoline). Just check the pulsation damper (if installed) on the ramp.

Read your engine error - please see Mercedes,Diagnose,USB KKL,M111,M104,W124,W202,W210,W140,G320,OBD,OBD2,ELM327,HFM-scanner,HFM,PMS,Android,Torque
but with this problem does not help. Only if the crankshaft position sensor failure

PS: fuel system on your car - PMS

Mike

 

[Mo420]

Hi all, thanks for your suggestions. Have been quite occupied with work so didn't get a chance to reply earlier.

I understand that a broken crank position sensor can cause the engine to stall when warm.

I would have thought that the fuel filter would prevent any gunk from getting into the engine. If not, what's it there for?

I've looked into this and seems like a probable culprit. Car does not stall randomly when warm though, its just trouble starting up after its been all warmed up. Any ideas on how to test the CPS?

The fuel pump itself is connected prior to the fuel filter hence Im guessing it might've been filled with gunk due to running our of fuel (twice) last few weeks. Yeah hopefully none of that nasty gunk surpasses the filter and gets into them injectors.

It is necessary to check the leakage of fuel through the injector, through a pressure regulator, through a check valve fuel pump.
The most typical - a pressure regulator on the ramp passes through the fuel outlet of the vacuum (disconnect the vacuum hose from the pressure regulator when the engine stop after run and watch the drops of gasoline). Just check the pulsation damper (if installed) on the ramp.

Read your engine error - please see Mercedes,Diagnose,USB KKL,M111,M104,W124,W202,W210,W140,G320,OBD,OBD2,ELM327,HFM-scanner,HFM,PMS,Android,Torque
but with this problem does not help. Only if the crankshaft position sensor failure

PS: fuel system on your car - PMS

Mike

This is also quite interesting, I'll have a look into the fuel pressure regulator... question, can you explain more on the 'pulsation damper'and 'ramp' and where I can find these two? Sorry for the newb question and while we're at it, I dont know if you were serious or ptherwise (forgive me if indeed you are serious, Im finding it hard to pick your tone right there) the fuel system 'PMS' you were saying, is that some kind of sensor, or are you just merely stating the system is in some kind of distress

 

[Mo420]

Just an update on the car,

So yesterday I took the car to the indy's..

Replaced the fuel pump with a genuine BOSCH unit along with a Hengst fuel filter. Very much quiter now but still have the trouble starting when warm. Thought this cured it because it didnt happen yesterdat when I was testing it but happened today

The car also started vibrating at idle, besides the serious hesitation, which I think is due to one or more cylinders misfiring. Took a look at the plugs today, two of them were quite dirty so I replaced them with genuine BOSCH Super R6 (FR8DC+) - can anyone confirm if this is a compatible replacement?

Anyway after changing plugs, upon a cold start, car started fine, no more vibration at idle.

 

[Mo420]

Sorry - didn't finish my last post, anyway here's the continuation:

After putting in the new plugs, car started (cold start) fine, no more vibrating at idle. Took the car out for a test drive just up and down the street, car accelerates fine as it were, no hesitation. At this point I thought yay!! problem solved! Parked the car, shut off the engine.

Half an hour later, decided to take the car to do some quick shopping nearby - drove for about 10kms. At first car responded well when accelerating, did think it was a bit sluggish though but then I'm used to driving the CLK320 so I thought its probably normal. Halfway during the trip, car started hesitating again when accelerating from a stop This got progressively worse (as the engine warms up I guess?), barely accelerating 5-10 seconds after giving full throttle, very hard to accelarate between 1k RPM to 2k RPM range. I find it hesitates less/not hesitate at all when I really really feather the throttle with very light input when starting off. Also, it seems the hesitation is gone after 2k RPM or so, it feels like the power is immediately restored above 2k ish RPM. When in Park or Neutral, car revs fine, only hesitates when in gear, at low RPMs.

I also realised the RPM fluctuates a tiny bit when idling, but still idles fine, no vibration. Checked the vacuum hoses in the engine compartment for leaks, so far it looked ok. I don't know if this is related or not, but this car has had its central locking (vacuum operated) completely failed lately - which I am assuming a faulty auxiliary vacuum pump since I dont hear it operating anymore.. however I understand this vacuum system and the engine vacuum system is separate?

Anyway, as a summary:
-Replaced fuel filter, fuel pump and plugs
-Car still hesitates especially at low RPM and full/moderate throttle
-Still prolonged cranking when restarting engine after it has been fully warmed up and left shut off for a while.

Any more ideas on what I should look at next? I know there's lots of possibilities... don't know where to start to be honest. Will look at the fuel pressure regulator and CPS as suggested. Other than that, HT leads look like they haven't been replaced yet but still appear in good nick, contacts look clean. My gut feeling tells me problem lies in the fuel delivery, as the hesitation feels like fuel starvation. Possibly a clogged injector... is this a pretty common part to fail? Normally the MAF sensor is the classic culprit, however I can't find one along the intake, am I right in saying this engine doesn't have a MAF?

I've also just noticed lately the exhaust seems to reek of oil and petrol, odor seems to be stronger than usual. Also, sometimes, the exhaust tone at low RPMs sounds abnormal, as if there's a hole/leak in the muffler. Don't know if that's due to the misfiring/hesitation that happens at the same RPM range.

Phew! Sorry for such a long post! Just wanted to give as much detail as possible. Any suggestions/comments welcome!

Cheers, Mo420

 

[BlackC55]

Look for a decent bright spark from the plugs.

 

[Mo420]

Look for a decent bright spark from the plugs.

Any suggestions on how to check for that?

Do I just simply remove the plug one by one, connect it back to its HT leads and then start the car while the plug is out? Wouldn't that harm the engine at all?

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[Mo420]

The most typical - a pressure regulator on the ramp passes through the fuel outlet of the vacuum (disconnect the vacuum hose from the pressure regulator when the engine stop after run and watch the drops of gasoline). Just check the pulsation damper (if installed) on the ramp.

Hi all,

So just an update regarding the issue.... following up on Mike's reply, I decided to check the fuel pressure regulators. Started the car, drove it around the neighbourhood for a while, then inspected the FPRs. Lo and behold... after pulling the vacuum hose off one of them (there were 2) drops of gasoline were dripping out...

So I guess this confirms the FPR being the culprit... should I just replace one or both? (the other one seems quite dry)

 

[hfmscan]

regulator must be replaced, which flows. one

 

[Mo420]

regulator must be replaced, which flows. one

Hi good day sir,

I've just gotten back from the garage.. so I've replaced the 'leaking' FPR with a genuine Bosch unit just now..

After taking the car for a 15 min test drive, I can say the hesitation (feels like fuel starvation) is dramatically improved.

I can now say light to medium throttle input, there's no hesitation/starvation at all.

However, at full throttle, the hesitation is still present. Could it be that there's still air in the system? Do I need to bleed the fuel lines after replacing the FPR and any ideas how to do this?

Cheers,
Mo420

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[hfmscan]

Hello,

it is important to have a clean fuel filter, clean the filter in the socket (input fuel into the fuel rail)
the catalyst does not have to create a large exhaust resistance (it is difficult to verify).
may still be many causes of bad dynamics engine

 

[Mo420]

Hello,

it is important to have a clean fuel filter, clean the filter in the socket (input fuel into the fuel rail)
the catalyst does not have to create a large exhaust resistance (it is difficult to verify).
may still be many causes of bad dynamics engine

Hi,

Thanks again for your suggestions

Fuel filter was recently replaced (last week) along with a new fuel pump and spark plugs. All genuine Bosch.

So there is a filter just before the fuel rail input? I didnt seem to see one earlier, I'll check again tomorrow morning.. Any pictures/clues on where I will be able to find this filter?

Regards,
Mo420

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[Mo420]

By the way,

So if this questions seems a bit daft, but I was wondering if the new part was supposed to be installed just as, or should I have taken out the green plastic bit at the end before I install it?

I was thinking plastic n fuel dont work together quite well, but then I measured both new and old part heights and its similar with the green plastic bit on... maybe MB has updated the part between now and 1995? I've also noticed the new part has a smaller diameter hole on the input nipple than the original I've replaced...



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[hfmscan]

By the way,
So if this questions seems a bit daft, but I was wondering if the new part was supposed to be installed just as, or should I have taken out the green plastic bit at the end before I install it?

I was thinking plastic n fuel dont work together quite well, but then I measured both new and old part heights and its similar with the green plastic bit on... maybe MB has updated the part between now and 1995? I've also noticed the new part has a smaller diameter hole on the input nipple than the original I've replaced...

i don't know.

about filter on rail.

 

[Mo420]

Hello,

Thanks for sending me the photo.. I've checked mine, seems ok.. however I realised my other fuel pressure regulator (as mentioned earlier mine has 2) is also dripping.

I noticed from your photo, your car only has 1 fuel pressure regulator.. no regulator on the incoming side as I see no vacuum lines going out of it... Is yours a C180 as well with the M111.920 engine?

Cheers,
Mo420

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[hfmscan]

Hi,
from the interior of the car is the fuel pulsation damper. This is only set for the first batch of the engine 111, then it no longer install.
if it drips - set a new one.

Mike.

PS: it is not my photo. i found this on internet

 

[Mo420]

Hi Mike, thanks for that info!

I thought that was also a FPR all along, makes more sense now!

I cant seem to source a new pulsation damper for my car, any idea if I can modify my fuel rail to remove this damper, like the case in those latter M111s?

By the way, any inputs on whether the FPD could contribute to my hesitation/stuttering problem?

Cheers,
Mo420

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[Mo420]

Hi all, just thought I'd share how (finally) I got this resolved. Took me quite a while (hectic schedule at work) but anyway glad to have the 202's back in service!

Misfiring was due to bad HT ignition leads, combined with a coil on its way out (such a pain to replace btw!) and fouled plugs.

The hard starting was due to the fuel pressure regulator and fuel pulsation damper.

Regards,
Mo420

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