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1996 C280 W202
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Discussion Starter #1
Hi everyone, after searching quite extensively through various forums (including here) I haven’t found anything that matches my situation exactly.

Occasionally if I pull away from a stop, let it change gears once (1-2) and then brake suddenly car will idle erratically and is only remedied by applying throttle. There is also a distinct vibration from car at rest in all gears (seats vibrate visibly)

Recently car randomly stalls at low speed, and two days ago would not start, fuel pump relay works (tested by auto electrician) fuel pumps run when cranking, have spark as well. I suspect crank position sensor. I am also replacing intake temp sensor.

NB: car doesn’t have EGR, no o2 sensors (no emissions equipment) no CEL in cluster.
1996 W202 C280 M104.941 (Nov 1995 build)

Any guidance welcome and appreciated.
 

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1996 C280 W202
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13 Posts
Discussion Starter #3
Why did you remove the emissions equipment?
Never came with it, it seems, the early South African 202’s (94-97 at least) did not have any o2 sensors, EGR, air injection pump... They also did not have a CEL or ambient air temp sensor (cluster gauge is a blank) never had electric seats the whole model run too (94-00) they weren’t very high spec...
 

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w163 02 ML500 W210 97 E50Amg w202 99 C230K w124 - need more space, time to build again
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1,719 Posts
No CEL, but have you scanned for any saved codes?
No CEL, does not mean there are no saved error codes.
 

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1996 C280 W202
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Discussion Starter #5
No CEL, but have you scanned for any saved codes?
No CEL, does not mean there are no saved error codes.
For what it’s worth it was hooked up to my mechanics computer somewhat recently and he claimed there were no error codes whatsoever, and the vibration and surging idle issue were present at that time, so I’m not sure.

Don’t have the money for a diagnostic right now, as I’m in-between paychecks, can only afford new cps at this stage, it’s cheaper by a fair margin. Do you think the Crank sensor could be a culprit or am I just wasting time with that idea?
 

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w163 02 ML500 W210 97 E50Amg w202 99 C230K w124 - need more space, time to build again
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For what it’s worth it was hooked up to my mechanics computer somewhat recently and he claimed there were no error codes whatsoever, and the vibration and surging idle issue were present at that time, so I’m not sure.

Don’t have the money for a diagnostic right now, as I’m in-between paychecks, can only afford new cps at this stage, it’s cheaper by a fair margin. Do you think the Crank sensor could be a culprit or am I just wasting time with that idea?
If you choose to replace the cps, make sure you get the genuine Bosch part.
The most common failing CPS symptoms: increasing starting problems when engine is warm, increasing sudden immediate stalls - no other CEL's.
 

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1996 C280 W202
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Discussion Starter #7
If you choose to replace the cps, make sure you get the genuine Bosch part.
The most common failing CPS symptoms: increasing starting problems when engine is warm, increasing sudden immediate stalls - no other CEL's.
Thank you for the advice, I aim to do so, I’ve never trusted the cheaper parts, I replace most parts with Bosch, established brands or oem, buying “cheap” always bites one later on and ends up costing more.

I do sometimes battle to start the car if it has been out in the sun or if I’ve recently driven it. Stalling happens occasionally at low speed. Car cranked but didn’t start the other morning when it was very cool, then suddenly started hours later when testing for spark (plugs are brand new oem) but had noticeable vibration.

Did test mounts by revving engine in D & R previously, no significant movement, tested g/box mount with pry bar, flex disks have no cracking obviously visible.

If I did do diagnostics would Star at the dealer be best? Not a lot of good diagnostics available in my town.
 

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1995 C220
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I would say that it is never good to just throw parts at it, but I do understand your situation which makes it tough. Idle issues however can be caused by many things, including spark/ignition, vacuum lines, idle control valve, etc.

My first thought is if you throw parts at it, throw a good set of plugs and wires on it, as that is something that is regular maintenance anyway. I would not recommend Bosch for the plug wires however, as the ones I have used in the past are as junky as the cheaper brands. NGK makes a fantastic set of plug wires for our cars which is a much better option.

I would also invest in a good vacuum tester and check your vacuum lines. Given the age of the car it is possible you have some leaks to address. This is where looking at some live data would be nice, because you could see if it is running rich or lean when the problem occurs. Seems really odd that they do not have o2 sensors in the car. That would tell some of the story in how it is running.
 

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1996 C280 W202
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Discussion Starter #9
I would say that it is never good to just throw parts at it, but I do understand your situation which makes it tough. Idle issues however can be caused by many things, including spark/ignition, vacuum lines, idle control valve, etc.

My first thought is if you throw parts at it, throw a good set of plugs and wires on it, as that is something that is regular maintenance anyway. I would not recommend Bosch for the plug wires however, as the ones I have used in the past are as junky as the cheaper brands. NGK makes a fantastic set of plug wires for our cars which is a much better option.

I would also invest in a good vacuum tester and check your vacuum lines. Given the age of the car it is possible you have some leaks to address. This is where looking at some live data would be nice, because you could see if it is running rich or lean when the problem occurs. Seems really odd that they do not have o2 sensors in the car. That would tell some of the story in how it is running.
Thanks for the advice, it is very appreciated. I did recently replace my spark plugs with oem branded beru 14F8DU4 non-resistor plugs as I could not get F8DC4 plugs, or the champions...previous plugs (fitted by previous owner) were NGK BKR6EK’s which were covered in oil from valve cover gasket leak, which I also replaced.

I suspect my coils are either original or old oem replacements due to their visual age alone, some of the rubbers of the plug connectors have slight tears but not close to where it connects to plug, is Beru any good for leads if I can’t find the NGK’s? And who makes a reliable coil?

I know I have a leak in my drivers door element (hissing during unlock) which I will resolve ASAP, I am waiting for a new vacuum block I ordered to arrive from Germany (no local stock) due to the infamous split at the ball bearing, all vacuum lines are connected as far as I can tell but that doesn’t mean there isn’t a leak, I am trying to source a vac tester locally (things are hard to find in SA, I envy the USA)

It is odd, I’m not even sure if I have cats, as the engine/plug info sticker on the front crossmember states “non catalyst” (I might be wrong) there is not even a CEL, not that it doesn’t come on, it doesn’t exist on the cluster, just illuminated blanks.
 

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1995 C220
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I would think that even if you have no cat, there would have to be at least 1 o2 sensor in order for the engine management to be able to tune the car.

I have used Bosch for coils and I think they are fine, I am just not a fan of the coil wires from them.

I havent seen the Berus'. They may be fine. The key is that the connectors inside the plug boots make a nice solid connection and arent loose at all.

I was also going to suggest looking at your engine wiring and make sure it is in good shape. Easiest place to check it at is where the fuel injector connectors are. This is where I noticed mine crumbling apart.
 

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1999 C280, 2000 C280, 2000 C230K,2011 C300
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All 95s had that rotting wire harness problem so if yours has not been done, this could cause a whole host of problems.
 

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1996 C280 W202
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Discussion Starter #12
I would think that even if you have no cat, there would have to be at least 1 o2 sensor in order for the engine management to be able to tune the car.

I have used Bosch for coils and I think they are fine, I am just not a fan of the coil wires from them.

I havent seen the Berus'. They may be fine. The key is that the connectors inside the plug boots make a nice solid connection and arent loose at all.

I was also going to suggest looking at your engine wiring and make sure it is in good shape. Easiest place to check it at is where the fuel injector connectors are. This is where I noticed mine crumbling apart.
Thanks for the input george and glenmore, I’ll get a price on the Bosch coils when I order my crank sensor next week at the Bosch parts dealer here.

My cable harness was rebuilt by an auto electrician (previous owner, he gave me the invoice with the car) but to be honest I’m not sure it’s the worlds best job, there’s no exposed copper or anything, just doesn’t look too professional, and it wasn’t cheap either...

The o2 sensor thing is interesting, I checked below the manifolds and underneath along both exhausts which connect to a muffler looking part under gear shift mechanism “2024912801” which doesn’t come up on EPC, after this part it looks a bit “custom” with booger welds joining the sections to the muffler, no blanked off sensors or dangling cables around anywhere.
2610422
There is also a part missing on the third coil where harness connects (compared to first and second coil) would this be detrimental or is it just visual?
 

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1996 C280 W202
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Discussion Starter #13
I would think that even if you have no cat, there would have to be at least 1 o2 sensor in order for the engine management to be able to tune the car.

I have used Bosch for coils and I think they are fine, I am just not a fan of the coil wires from them.

I havent seen the Berus'. They may be fine. The key is that the connectors inside the plug boots make a nice solid connection and arent loose at all.

I was also going to suggest looking at your engine wiring and make sure it is in good shape. Easiest place to check it at is where the fuel injector connectors are. This is where I noticed mine crumbling apart.
Alright, I replaced the crank sensor and intake temp sensor tonight and...still cranks with no start...I am no longer getting any spark off leads from coils 1 and 3 (I did before) coil 2 lead still works....Do you think my coils have passed their sell by date, or would there be another cause?
 

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1995 C220
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Im not sure how to do it but there should be a way to test the input wires to the coils and see if the coil is getting the signal to fire. I think there is also a way to ohm the coil to see if it is good.
 

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1996 C280 W202
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Discussion Starter #15
Im not sure how to do it but there should be a way to test the input wires to the coils and see if the coil is getting the signal to fire. I think there is also a way to ohm the coil to see if it is good.
Just to update I bit the bullet and had it towed to my mechanic, he plugged in his diagnostic and it stated there was an implausible signal from the crank sensor and a message about timing being out in relation to the trigger ring...what does a M104 crank sensor use to determine crank position? I’ve seen people mention three “teeth” on the flywheel, I can’t see any mention of a reluctor ring.

He claims there is now spark but it backfires through the intake, obviously the computer doesn’t know when to fire correctly. He will assess on Monday and let me know. I will update when I find out so that if others encounter this they can possibly get an answer as some of threads seem to end without conclusion.
 

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1995 C220
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I think the crank sensor picks up the signal from a magnetic tooth on the flywheel( or 3 if the people you mentioned are correct). If that didnt fix it, now you have to hope one of the teeth didnt break off the flywheel. Not sure why they would unless something got in there. Spark is a good sign though; perhaps it has just jumped time now.
 

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1996 C280 W202
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Discussion Starter #17
I think the crank sensor picks up the signal from a magnetic tooth on the flywheel( or 3 if the people you mentioned are correct). If that didnt fix it, now you have to hope one of the teeth didnt break off the flywheel. Not sure why they would unless something got in there. Spark is a good sign though; perhaps it has just jumped time now.
Thank you for all the advice so far, really appreciate it.

The mechanic now claims the timing chain snapped, I don’t know how this was determined, I am going to pop in tomorrow and see for myself, the engine only has 193000km (~120k miles) which is not a lot in my opinion.

I never heard any noise when trying to start the car (I have experienced the noise of a chain going first-hand, I worked at a mechanic for a year) I am unaware if M104’s are interference engines or not, but it did not occur while running so “if” it has snapped I am hopeful that there would be no major damage.

Am I right in thinking that he should still inspect the flywheel even if the chain is snapped, I know it would cause a no start, but the codes still pointed to the flywheel timing.
 

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1996 C280 W202
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Discussion Starter #19
Well, the code for the flywheel timing could be there because the chain snapped to begin with.
Seems so, popped in to the mechanic today and he said the chain jumped teeth, but did not in fact, snap, somehow that got lost in translation over the phone previously, he says it jumped 4 teeth on the camshaft, maybe tensioner failure or chain stretch. He has ordered a new tensioner and chain from MB so at least it’s oem parts going in.

He agrees about the flywheel timing issue being linked to the jumped chain. He also said he tested for compression and it was still present on all 6 cylinders, so that bodes well for the valves I hope...
 

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Thats great news; it means you dont have a bent valve. Sounds like he is on the right track, and you dodged a bullet.
 
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