Strange hesitation low rpm modded E55K
03-02-2018, 08:25 AM
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2004 E55
Strange hesitation low rpm modded E55K
hi,
ever since ive owned my E55 Which is bout a year I’ve noticed a slight hesitation/flatspot when accelerating moderately, kind of as you would in traffic or off the lights when driving normally. I’d say around 1500rpm and mainly felt in 1st gear. it’s very noticeable with the exhaust note, it sounds like the cars taking a dump, only way to explain it.
When you get up it however she’s still a rocket and runs 12.0 all day long. No sign of the flatspot.
I have done plugs and air filters but not the fuel filter. It has 130000km/80000miles.
From what I’m aware the previous owner had done stainless headers, full exhaust retaining rear AMG muffler, 18psi pulley, bigger cooler, pump and tune
Dont think anything has been done to fuel system.
Im thinking maybe change the fuel filter and see or at least check fuel pressure.
If if not I’ll put it on the dyno and figure what’s going on with the tune. Is it true some workshops lock the ECU so you can’t tamper with their tune?
thanks in advance from down under
ever since ive owned my E55 Which is bout a year I’ve noticed a slight hesitation/flatspot when accelerating moderately, kind of as you would in traffic or off the lights when driving normally. I’d say around 1500rpm and mainly felt in 1st gear. it’s very noticeable with the exhaust note, it sounds like the cars taking a dump, only way to explain it.
When you get up it however she’s still a rocket and runs 12.0 all day long. No sign of the flatspot.
I have done plugs and air filters but not the fuel filter. It has 130000km/80000miles.
From what I’m aware the previous owner had done stainless headers, full exhaust retaining rear AMG muffler, 18psi pulley, bigger cooler, pump and tune
Dont think anything has been done to fuel system.
Im thinking maybe change the fuel filter and see or at least check fuel pressure.
If if not I’ll put it on the dyno and figure what’s going on with the tune. Is it true some workshops lock the ECU so you can’t tamper with their tune?
thanks in advance from down under
03-02-2018, 11:13 AM
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'99 and '05 E55 AMG
Urk! If that's the original fuel filter you're running on borrowed time and should be on the side of the road any week now. Lots of posts on this. Look for "W211 E55 fuel pump relay and fuse maintenance" and "fuel pump adapter cable" under advanced search. And there are several variations of the fuel filters and pumps and not all are compatible. The latest fuel filter and fuel pumps require adapter cables for each to work with the stock electrical harness. Search and read!
Fuel pressure should be about 80 psi.
Example here:
https://mbworld.org/forums/w211-amg/...ml#post7284407
Posting your location would also help as there are different part numbers for the filter depending upon which region of the world in which you are located. EDIT: I just figured out from where you are. Different part numbers in Australia but the info about the relay still applies.
Fuel pressure should be about 80 psi.
Example here:
https://mbworld.org/forums/w211-amg/...ml#post7284407
Posting your location would also help as there are different part numbers for the filter depending upon which region of the world in which you are located. EDIT: I just figured out from where you are. Different part numbers in Australia but the info about the relay still applies.
Last edited by bbirdwell; 03-02-2018 at 11:19 AM.
03-02-2018, 01:36 PM
#3
My guess is a hiccup at SC pulley engagement. My car got one when I put a eurocharged tune on it. (Had a smaller SC pulley already I had been driving around with stock tune and no hiccup).
I asked them to fix it when I had the tune adjusted for headers, but no luck. Been thinking about getting a Tony Leshaw tune. Every one seems to love his customer service.
I asked them to fix it when I had the tune adjusted for headers, but no luck. Been thinking about getting a Tony Leshaw tune. Every one seems to love his customer service.
03-03-2018, 08:00 PM
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'06 E55, '05 C55
I have a similar flat spot/ hesitation in that RPM range. No idea if my fuel filters were ever replaced (at 99K now) and I am extremely confused on what is actually needed to do the filter swap.
When I look at the new fuel system part numbers I find these as the most up to date:
211-470-00-00 Fuel Delivery Module (dual pumps)
211-470-64-94 Tank Inner Module (actually filter/regulator)
211-471-05-79 Fuel Sender Seal x 2
211-440-05-07 Cable Harness adapter for filter/regulator
211-540-07-00 adapter cable to fuel pumps
But I also see confusion about the new dual pumps providing too little pressure? No fuel smell either so maybe my pumps were replaced before, and I just do know about it. There have been posts about testing the amp draw on the pumps, but never saw a write up on how to test that, but that would defiantly help.
I too have a EC tune and pulley, but had the hesitation before the tune and pulley as well. My car is a US spec '06.
When I look at the new fuel system part numbers I find these as the most up to date:
211-470-00-00 Fuel Delivery Module (dual pumps)
211-470-64-94 Tank Inner Module (actually filter/regulator)
211-471-05-79 Fuel Sender Seal x 2
211-440-05-07 Cable Harness adapter for filter/regulator
211-540-07-00 adapter cable to fuel pumps
But I also see confusion about the new dual pumps providing too little pressure? No fuel smell either so maybe my pumps were replaced before, and I just do know about it. There have been posts about testing the amp draw on the pumps, but never saw a write up on how to test that, but that would defiantly help.
I too have a EC tune and pulley, but had the hesitation before the tune and pulley as well. My car is a US spec '06.
03-03-2018, 10:28 PM
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'99 and '05 E55 AMG
Any way you can place an Air/Fuel meter on the car? I found that flat spots (from my days of tuning aftermarket ECU's in forced induction Miatas) were usually caused by a lean condition. Lean feels like a "bog" as when pressing the throttle the engine just seems to lose power (hope that makes sense). Alternatively, it could be going pig rich but that is unlikely as it only occurs for a short interval of a few hundred rpm if I read your post correctly.
03-04-2018, 01:14 AM
#6
Sorry guys, is it common for a clogged filter or fuel system issue to begin to affect normal driving before WOT driving? As the OP described accelerating "as you would in traffic or off a light" I doubt this is an under boost issue, I would guess that if your fuel system was at the point that closed loop driving was getting lean enough to cause noticeable issues, the first time you went WOT(open loop) you would probably melt something.
Bbirdwell's got much more experience with the platform with me so pls correct me if I'm wrong, however I would not go chasing down fuel system components just yet. I still think it would be better to look towards SC clutch engagement or tune issue.
I would take off the SC belt for a day or two and and see if the hiccup is gone before you start spending money on anything. (the recommendation for a wideband is always good though, regardless of the situation
)
Bbirdwell's got much more experience with the platform with me so pls correct me if I'm wrong, however I would not go chasing down fuel system components just yet. I still think it would be better to look towards SC clutch engagement or tune issue.
I would take off the SC belt for a day or two and and see if the hiccup is gone before you start spending money on anything. (the recommendation for a wideband is always good though, regardless of the situation
)
03-06-2018, 03:42 PM
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Hey thanks for all the replies.
The SC clutch engagement issue sounded like a possibility but after watching the tach more closely during the flat spot it happens at much lower rpm than usual engagement which is around 2000rpm if I’m correct? It actually is felt a bit lower in the Rev range that I originally thought. More like 1200rpm which would probably rule out the SC pulley engagement.
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
The SC clutch engagement issue sounded like a possibility but after watching the tach more closely during the flat spot it happens at much lower rpm than usual engagement which is around 2000rpm if I’m correct? It actually is felt a bit lower in the Rev range that I originally thought. More like 1200rpm which would probably rule out the SC pulley engagement.
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
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03-06-2018, 03:59 PM
#8
Hey thanks for all the replies.
The SC clutch engagement issue sounded like a possibility but after watching the tach more closely during the flat spot it happens at much lower rpm than usual engagement which is around 2000rpm if I’m correct? It actually is felt a bit lower in the Rev range that I originally thought. More like 1200rpm which would probably rule out the SC pulley engagement.
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
The SC clutch engagement issue sounded like a possibility but after watching the tach more closely during the flat spot it happens at much lower rpm than usual engagement which is around 2000rpm if I’m correct? It actually is felt a bit lower in the Rev range that I originally thought. More like 1200rpm which would probably rule out the SC pulley engagement.
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
03-06-2018, 05:12 PM
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Hey thanks for all the replies.
<snip>
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
<snip>
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
<snip>
Would a clogged filter cause this hesitation at low rpm though but no other symptoms when on WOT? Do the fuel pumps run on a duty cycle I.e. low duty at low rpm and a sudden surge of fuel required during initial acceleration but can not supply adequate fuel and feeling almost like a lean misfire? But on WOT pump is fully activated and providing full pressure adequately?
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
<snip>
Im kinda thinking along the path of getting it on the dyno to see what the AF is and what else is going on with the ECU in regards to timing, boost, SC engagement etc but this may be futile if my ECU has been locked by some tuning house in the states (I’m in oz) does anyone know if this is the case?
I would guess something to do with the tune. It's easy to tune for big horsepower at WOT but a PITA to get all RPM and MAP ranges to work well with timing, target air/fuel mixture, volumetric efficiency, mixture enrichment depending upon coolant temp, air temp, throttle position rate-of-change, etc, etc, ad infinitum. Changing the intake or exhaust will have an effect that must be accounted for. Heck, pulling the Helmholtz resonator off an NA Miata intake has a discernible effect on the torque at particular rpm ranges. I don't even want to begin to consider the complexity of the Mercedes sensors that provide input to the engine control unit.
Best bet is to record data from as many sensors as you can and look for the one or two that look different as you go through the RPM range in question while comparing it to another RPM range where all works well; Be easier if you can do so by recording data at several different MAP levels across the RPM range (i.e. 70 kPa, 90 kPa, 110 kPa, etc). RPM, throttle position, air/fuel mixture, mixture feedback loop, O2 sensor data, MAP blips, etc. It's a process. Just display your data and step back and forth the RPM range in question. You may be able to quickly narrow it down to a few areas of interest and, if it does appear to be something in the tune, e.g. air/fuel goes lean over a 200 rpm range, you should be able to discuss it with the person who programmed that tune and have it modified for your car.
Best of luck and keep posting what you find.
Last edited by bbirdwell; 03-06-2018 at 05:18 PM.
03-06-2018, 07:28 PM
#10
I have a feeling its got its got something to do with the tune, when you guys mention you have a Eurocharged tune or whatever, is this done live on a dyno and adjusted for your particular setup or you send off the ecu and tell em what mods you have and they do a bit of guess work to get it to work for your car?
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
I have been told that some of these places actually lock your Ecu after doing the tune so it can’t be tampered with.
The SC clutch engagement issue sounded like a possibility but after watching the tach more closely during the flat spot it happens at much lower rpm than usual engagement which is around 2000rpm if I’m correct? It actually is felt a bit lower in the Rev range that I originally thought. More like 1200rpm which would probably rule out the SC pulley engagement.
