e500 sluggish performance
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2003 e500 black on black
e500 sluggish performance
-a bit of background
bought this e500 three months ago. just rolled over 140,000 miles. car seems to of been decently taken care of.
when I first got it there was gobs of low end power. regardless of what mode I was in (w or s). I could smoothly take off from a light and feel lots of instant v8 power with the slightest touch of the pedal. could put it in fourth gear and easily climb a hill like it was nothing.... you get the idea...…..
-work ive done
checked the air filters... they were old so I changed them.. avg mpg went from an average of 19 to around 23 max for a few days.
I was very careful when changing the filters by placing a fresh rag over the maf while having the filter housing off of the motor. I cleaned the filter housing and made sure it was 100 percent dry before installing the new filters and putting it back on the engine... made sure the filter housing was on the maf snug and correctly.
I replaced the spark plugs and wires as well which I talk about in the next section.
-what I noticed and what is bothering me
few days later the car would randomly dip in power. one drive cycle it would be normal with amazing power, getting about 21-23 mpg (according to the HUD)…..then sometimes it would feel sluggish and get only around 13 -15 mpg.. it would take some extra pedal to get it moving and sometimes the car will need to downshift to get the revs higher. I noticed the power dip happens around 1500-2000 rpms and then jumps back to what seems like normal power after that.
after noticing some rumbling one day I looked around the engine bay and noticed the cylinder 1 coil pack wire harness was loose. snapped it back in and viola power seemed to be restored for a short time..
decided to replace the spark plugs and spark plug wires.. all 16 of them. made sure everything was correct when ordering parts and that all the harnesses were correctly installed into each of the coils before settling it all up and calling the job done. also, did not use any anti-seize or anything on the plugs as I was informed that stuff can mess with the grounding of the plugs. just installed them directly out of the box. visually inspected them for damage or obvious incorrect gaps. although my senses told me to check the gaps regardless of the "they are gapped from the factory", I unfortunately did not have my gap measuring tool on me so I just installed them as is.
still only getting about 15 mpg... loss of low end power. before the problem would come and go but now the car just stays this way. its not absolutely annoying to drive or anything. still gets around just fine but knowing what the car is supposed to feel like, I can tell there is absolutely something im missing here.
-questions
1: any input from the wise and experienced ?
2: is star diagnostics or similar software sophisticated enough to tell exactly what is going on without the guess work and it would be worth my money to have someone scan and diagnose it for me?
3: any "resets" or something obvious to Mercedes owners that I don't know about while working on these vehicles? (this is my first one)
4. is this a common issue with an easy solution? < betting on this one
5. anyone have a bib to go along with spoon feeding me answers?
on a side note---one day I scanned it for pending codes on a hot day when it acted weird when i first got it and saw the malfunctioning accelerator pedal (sorry forgot what the actual code was but that's what it has to do with)...cleared it out. did the "throttle reset" as suggested online... hasn't come back as stored or pending since if that matters any...
bought this e500 three months ago. just rolled over 140,000 miles. car seems to of been decently taken care of.
when I first got it there was gobs of low end power. regardless of what mode I was in (w or s). I could smoothly take off from a light and feel lots of instant v8 power with the slightest touch of the pedal. could put it in fourth gear and easily climb a hill like it was nothing.... you get the idea...…..
-work ive done
checked the air filters... they were old so I changed them.. avg mpg went from an average of 19 to around 23 max for a few days.
I was very careful when changing the filters by placing a fresh rag over the maf while having the filter housing off of the motor. I cleaned the filter housing and made sure it was 100 percent dry before installing the new filters and putting it back on the engine... made sure the filter housing was on the maf snug and correctly.
I replaced the spark plugs and wires as well which I talk about in the next section.
-what I noticed and what is bothering me
few days later the car would randomly dip in power. one drive cycle it would be normal with amazing power, getting about 21-23 mpg (according to the HUD)…..then sometimes it would feel sluggish and get only around 13 -15 mpg.. it would take some extra pedal to get it moving and sometimes the car will need to downshift to get the revs higher. I noticed the power dip happens around 1500-2000 rpms and then jumps back to what seems like normal power after that.
after noticing some rumbling one day I looked around the engine bay and noticed the cylinder 1 coil pack wire harness was loose. snapped it back in and viola power seemed to be restored for a short time..
decided to replace the spark plugs and spark plug wires.. all 16 of them. made sure everything was correct when ordering parts and that all the harnesses were correctly installed into each of the coils before settling it all up and calling the job done. also, did not use any anti-seize or anything on the plugs as I was informed that stuff can mess with the grounding of the plugs. just installed them directly out of the box. visually inspected them for damage or obvious incorrect gaps. although my senses told me to check the gaps regardless of the "they are gapped from the factory", I unfortunately did not have my gap measuring tool on me so I just installed them as is.
still only getting about 15 mpg... loss of low end power. before the problem would come and go but now the car just stays this way. its not absolutely annoying to drive or anything. still gets around just fine but knowing what the car is supposed to feel like, I can tell there is absolutely something im missing here.
-questions
1: any input from the wise and experienced ?
2: is star diagnostics or similar software sophisticated enough to tell exactly what is going on without the guess work and it would be worth my money to have someone scan and diagnose it for me?
3: any "resets" or something obvious to Mercedes owners that I don't know about while working on these vehicles? (this is my first one)
4. is this a common issue with an easy solution? < betting on this one
5. anyone have a bib to go along with spoon feeding me answers?
on a side note---one day I scanned it for pending codes on a hot day when it acted weird when i first got it and saw the malfunctioning accelerator pedal (sorry forgot what the actual code was but that's what it has to do with)...cleared it out. did the "throttle reset" as suggested online... hasn't come back as stored or pending since if that matters any...
Last edited by couchpotato203; Aug 30, 2018 at 07:05 PM.
Thread Starter
Newbie
Joined: Aug 2018
Posts: 2
Likes: 0
2003 e500 black on black
welp…
decided to check out my egr valve. thing was as clean as could be. I replaced the vacuum hose on it for preventative sake and decided to look around for other questionable hoses. only one that looked bad was the one connecting the two secondary air pumps.
I noticed cylinder 1s coil harness plug has the retaining clip snapped off so you can just pull up on it and it will pop off. it seemed to be snug in there but after pushing it down a little more it seemed to have the ever so slightest room to go down a bit more.
after reattaching the air box, I noticed the passenger side intake tube can possibly hit the side/top of the connector of you're not careful.
my theory is that with the air box off, I had made sure the connector was in all the way but upon re assembly, I was knocking the clip out ever so slightly. enough to not make the coil miss-fire bad but enough to mess it up a bit.
I carefully inserted the intake tube making sure not to disturb the electrical connector and drove for 44 miles. half city stop and go, other half long flat highway consistent driving. cars hitting 20mpg and the powerband down low has greatly improved. still not 100 percent smooth but id say 85-90 percent which is good enough for me.
decided to check out my egr valve. thing was as clean as could be. I replaced the vacuum hose on it for preventative sake and decided to look around for other questionable hoses. only one that looked bad was the one connecting the two secondary air pumps.
I noticed cylinder 1s coil harness plug has the retaining clip snapped off so you can just pull up on it and it will pop off. it seemed to be snug in there but after pushing it down a little more it seemed to have the ever so slightest room to go down a bit more.
after reattaching the air box, I noticed the passenger side intake tube can possibly hit the side/top of the connector of you're not careful.
my theory is that with the air box off, I had made sure the connector was in all the way but upon re assembly, I was knocking the clip out ever so slightly. enough to not make the coil miss-fire bad but enough to mess it up a bit.
I carefully inserted the intake tube making sure not to disturb the electrical connector and drove for 44 miles. half city stop and go, other half long flat highway consistent driving. cars hitting 20mpg and the powerband down low has greatly improved. still not 100 percent smooth but id say 85-90 percent which is good enough for me.
