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E300D 11-24-2013 11:59 PM

2005 E320 CDI seems underpowered
 
Good day folks

Got a 2005 E320 CDI 118k miles. It just seem sluggish and underpowered. Seems to be lacking the torque it should have.

This is my first CDI car in family. I have not driven any other CDI I6 to compare.

So its got new fuel and air filters, Clean EGR system and no check engine lights. New air intake temp sensor and new MAP sensor.

I still think the damn thing does not have the grunt it should provide. I had car scanned on MB star program and no faults found.

Would a clogged air intake make such a great difference. Would there not be some sort of fault code for it?

What about the injectors? Car starts up great and has no smoke under heavy acceleration.

Fuel milage in town is ok, not great 13l to 100km..

Thanks

Skid Row Joe 11-25-2013 12:31 AM

Quote:

Originally Posted by E300D (Post 3244586)
Good day folks

Got a 2005 E320 CDI 118k miles. It just seem sluggish and underpowered. Seems to be lacking the torque it should have.

This is my first CDI car in family. I have not driven any other CDI I6 to compare.

So its got new fuel and air filters, Clean EGR system and no check engine lights. New air intake temp sensor and new MAP sensor.

I still think the damn thing does not have the grunt it should provide. I had car scanned on MB star program and no faults found.

Would a clogged air intake make such a great difference. Would there not be some sort of fault code for it?

What about the injectors? Car starts up great and has no smoke under heavy acceleration.

Fuel milage in town is ok, not great 13l to 100km..

Thanks

Possibly........but I doubt it. I would guess that it depends on your perspective.

My CDI is like driving a leashed stallion. It always wants to pull and run like a scalded ape. Just a fraction of a steady kept push on the foot feed produces a 'kick' in each gear shift change propelling you forward.

What do the records you got with the car indicate?

KarTek 11-25-2013 12:32 AM

Those cars have so many sensors that it's hard to imagine a problem that would not be flagged by one of them.

Just speculating, I would say look at the VGT actuator and possible cat flow problems. Just a "gut" feeling, I know nothing of these...

E300D 11-25-2013 09:35 AM

Quote:

Originally Posted by KarTek (Post 3244592)
Those cars have so many sensors that it's hard to imagine a problem that would not be flagged by one of them.

Just speculating, I would say look at the VGT actuator and possible cat flow problems. Just a "gut" feeling, I know nothing of these...


I agree. Lot of sensor. We got the car with a limp mode and went from there to fix it.

We did the sensor at back of fuel rail. We had issue with the HP pump where a internal valve did not return fuel properly to fuel tank.

We replaced the MAF sensor. We also replaced the LP pump in fuel tank and fuel sender unit.

A lot of work has gone into her. Right now runs great, no codes yet low on power.

So I am coming back to the cat converter issue. While at the shop few months ago. We did disconnect the exhaust just AFT of the turbo. Thus running it without the primary or secondary Cats..

The mistake we did perhaps was the way we tested it. Only went on a short run outside of shop. Did not notice a great difference so we bolted everything right up.

Seems like I shall revisit the CAts again.

TimFreeh 11-25-2013 03:53 PM

I guess I'm a little confused but if you disconnected the exhaust system and nothing changed why would you have to re-visit the issues of the cat's being clogged?

Seems like you've already replaced a bunch of parts, was there any diagnosis done before they were replaced? If so did the replacement of the parts cure whatever issues were discovered in the diagnosis process?

I can second Skid-rows comments, my CDI comes off the line with real authority. Traction control can be activated at will with full-throttle applications on dry conditions up until around 20-30mph.

0-60 times are in the mid 6 second range and accompanied by lots of nice black smoke. If yours isn't acting like this something is amiss.

Skid Row Joe 11-25-2013 04:59 PM

Quote:

Originally Posted by TimFreeh (Post 3244836)
I guess I'm a little confused but if you disconnected the exhaust system and nothing changed why would you have to re-visit the issues of the cat's being clogged?

Seems like you've already replaced a bunch of parts, was there any diagnosis done before they were replaced? If so did the replacement of the parts cure whatever issues were discovered in the diagnosis process?

I can second Skid-rows comments, my CDI comes off the line with real authority. Traction control can be activated at will with full-throttle applications on dry conditions up until around 20-30mph.

0-60 times are in the mid 6 second range and accompanied by lots of nice black smoke. If yours isn't acting like this something is amiss.

I'm wondering why people are having stopped up cats? I didn't know these cars' cats were so short lived, or that they even ever stopped up. Or do they?

TimFreeh 11-26-2013 11:01 AM

Quote:

Originally Posted by Skid Row Joe (Post 3244880)
I'm wondering why people are having stopped up cats? I didn't know these cars' cats were so short lived, or that they even ever stopped up. Or do they?

Over the years I've only ever seen one plugged up cat, on my son-in-laws Dodge truck. It wasn't a very hard diagnosis as the truck had no power at higher revs and the cat glowed cherry red. I've made a test-bung that threads into the O2 sensor to check back pressure and it indicated something like 300 PSI of pressure at full-throttle. Typical good values are less only a couple of PSI so it wasn't a tough one. I've never seen an MB cat melt down and plug but I have seen them develop rattles when the ceramic structure inside cracks and this permits the ceramic matrix to rattle around inside the metal supporting structure.

Again its not clear to me that the converter is the problem here, if the original poster removed the exhaust system prior to the cat and nothing changed I don't see how the cat could be involved.

I do agree with the previous poster that given the level of computer management on the CDI's it seems unlikely that something could be really amiss and have nothing show up on the CE lights or SDS codes.

I'd like to know if the original poster ever did a 0-60 test and if so what were the numbers.

TMAllison 11-26-2013 01:27 PM

Is the trans set to winter or summer? May be as simple as being set to winter and reducing available torque.

JimFreeh 11-26-2013 01:35 PM

I had the trap oxidiser plug up in my 87 300TD.

This was the replacement one that was included in the entire exhaust replacement recall of years ago.

Symptoms were low power and lots of black smoke.

I dropped the exhaust aft of the turbo, and it was clear almost immediately that the exhaust was plugged. Car obviously ran much better with the detached exhaust. It was noticable even running down the driveway (300').

A simple tool made from a piece of rebar sharpened like a flat blade screwdriver made short work of the plugged matrix w/o any outward signs of tampering.

Jim

E300D 11-26-2013 02:39 PM

We did replace a whole bunch of parts after a full diagnostics of the CDI

We had fuel pressure issues that threw the car into limp mode as well as noise LP pump.

What I also need to mention is that the P.O run the car for approx 50K miles on Biodiesel...

So what happened was that he got the limp mode and dealer assumed the whole car fuel system is dirty and needs to be replaced. I took a chance on the car and bought it.

The fuel pressure problem went away after we swapped out the fuel pressure sensor at back of the fuel rail.

The noise fuel pump aka lift pump aka low pressure pump was replaced with a new one along with a fuel sender unit.

Additionally the HP pump was replaced due to a stuck internal fuel return valve.

MAF was also replaced since we did not get any readings from it.

So right now the car runs good. No codes and and engine runs smooth. However the issue of low power remains.

Why I think I should revising the CAT is because we disconnected at the turbo but did not really drive the car at a good speed to notice a difference. Sure the turbo was spooling up louder and I did notice the electronic VNT actuator move as it should.

So I think I shall go back, unplug the CAT and go for a boot in the car.

Another suspect I have is a blocked intake manifold. However when I pulled out EGR valve it was clean as a whistle.

Now back to the point where PO used Biodiesel in the car: The car had already approx 30-40K miles when he started using biodiesel.

I do not have sufficient knowledge of biodiesel but I know MB allows only something like a 20% blend with petrol diesel. Well from what I gathered the PO run B100 or 100% biodiesel.

From what I understand biodiesel burns clean and acts as a detergent, cleaning out crap and such from the engine. In theory, is there a possibility where a whole bunch of gunk and crap from the combustion process clogged up one of the cats over the last 60K miles?

I have not done any 0 to 60 times. The car seems fine but lacks that responsiveness.

I have switched bet Winter and Summer mode but not big difference in response.

If I hold the car against brakes and let turbo spool up it takes off, but I am unable to activate traction control. Also there is very little black some if any when I floor it.

Thanks guys,

Skippy 11-26-2013 06:20 PM

13l/100km=18 mpg (US). That's worse than my 300D. Something is wrong, but I'm not sure what. I'm having trouble thinking of a powertrain problem that would create those symptoms without throwing a code. Have you checked for dragging brakes?

TMAllison 11-26-2013 08:15 PM

Quote:

Originally Posted by Skippy (Post 3245363)
13l/100km=18 mpg (US). That's worse than my 300D. Something is wrong, but I'm not sure what. I'm having trouble thinking of a powertrain problem that would create those symptoms without throwing a code. Have you checked for dragging brakes?

Its a lil low but in the realm of possibilities if you only drive in town and are VERY heavy footed......I'd probably look at the Cats too, although maybe there's a SBC brake failure going on? Worth questioning.

For reference, my 09 (OM642) gets ~25mpg in town lugging around at 1100-1200 rpm. Highway at 80mph it gets 38mpg; guessing at 65mph it would get in the low 40's. It does get up and roar whenever you put your foot down hard and challenge the traction control as another poster mentioned.

The Bio use concerns me, may be inj or pump issues still unresolved. I believe B5 is the max bio limit.

Randy 11-27-2013 10:23 PM

Gosh, my 2005 will fly; I try to stay off it because I don't like the smoke, but it will fly. It has 130K. I just made a trip out of state one day, averaged 40.7 mpg according to the on-board. I typically get circa 35 around town here (rural area).
BioDiesel? Uhoh...no telling what it could be. Injectors clogged? Turbo wheel dirty? Are you certain the trans is shifting into high gear? Is a brake caliper sticking/dragging?

E300D 11-27-2013 11:05 PM

thanks for all the replies. I am too scratching my head..

I think brakes are OK. I did several tests where I put car in N and it was moving without any binding on brakes. Unless the SBC system engages somehow during driving and impedes the wheels.

I bought diesel injector tester kit Lhttp://www.princessauto.com/pal/en/Testers/Fuel-Injection-Test-Kit/8504748.p

We will test the injectors in upcoming days.

Would it be safe to assume that the car would throw codes at me if CATs are blocked?

E300D 04-22-2014 09:36 PM

Update:

Had car at MB dealer and checked for all updates on software on ECU and Tranny..No changes after software reflash to latest.

Checked injectors and flow test them.

Checked Y values on High Press Pump


Cleaned out intake manifold from carbon build up. Wasnt bad at all, mild build up no blockage.

Replaced MAP sensor and air temp sensor on boost pipe leading into intake manifold of engine

Replaced MAF sensor at air intake filter with Bosch unit

Checked exhaust for blockage, nothing found,

The E320 CDI drives fine with no codes but still lacks that power it should have out it.

I am out of ideas of what to check next.:(

Is there a sensor that I might be missing, perhaps its giving wrong values to ECU?

I have absolutely no codes at all. Nothing stored. No limp mode. Revs to redline but aint got that punch it should.

Runs smooth, no black smoke,

I am about to give up. A car of this caliber with a whack load of sensors and nothing is showing up...

What am I missing?>


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