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Intermittent rev surge with intermittent fault codes
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JakeSublime
Novice
Feb 12, 2017, 9:30 AM
Post #1 of 11
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Intermittent rev surge with intermittent fault codes
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Hello everyone, I've been having a problem with my vehicle recently. I just purchased it about 6 months ago and she was fine for about 3 months after date of purchase. Here are my cars details:
1997 Mercedes Benz
E320
I 3.2l
103.6k miles
When I place my car in drive and drive around, it is usually alright. Every once in a while (maybe once a day, per 4 hours of driving) when I approach a stoplight and stop, my tachometer will bounce between 250 and 1000 rpm. The bounce is so bad, it sounds like my car wants to die at the low side of the surge. It will surge roughly 1.5-2 times per second over the course of 10+ seconds creating this "wahh wahh wahh wahh wahh" until I either accelerate from the light, double foot the pedals to manually increase the fuel flow, or it solves itself (which I can't remember if it does).
When this problem started taking place, I would get a "check engine electronics" message. I began using process of elimination to replace parts that would cause this. Here is everything I've done in order of least to most recent:
tuneup (air filter, oil, oil filter)
front brake pads
trans tuneup (trans fluid, filter, pan gasket)
o2 sensor (upflow before cat)
maf sensor
spark plugs, cables, and coils (when doing this I accidentally broke then replaced a vacuum line)
alternator and fan belt
After replacing all of this, I still get the "check engine electronics" message on my dash HUD, and 4 intermittent fault codes that come and go, even after a clear:
p0300 - Random/multiple cylinder(s) -misfire detected
p0304 - Cylinder 4 -misfire detected
p0305 - Cylinder 5 -misfire detected
p0306 - Cylinder 6 -misfire detected
The things that still need looking at are my starter (it sometimes makes a buzzing/grinding noise upon starting), fuel injectors (I have a loss of hp from factory spec. Also on startup the car will start to turn over and shut off, then I have to remove the key and start the car again which takes a second then it will start). The fuel pump, which is external to the fuel tank, makes a semi-loud buzzing noise. I'm not sure if that's normal or if it's failing.
Then there are random aesthetic things that need to be addressed, but those are for AFTER the car runs like a top.
That's all the info I can think of needing at this time. Feel free to ask whatever you need, and also thanks in advance.
(This post was edited by JakeSublime on Feb 12, 2017, 9:35 AM)
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kev2
Veteran
Feb 12, 2017, 9:58 AM
Post #2 of 11
(3342 views)
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Re: Intermittent rev surge with intermittent fault codes
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Do you have a scanner with ability to see live data... process of elimination AKA shot gunning gets expensive fast esp with MB parts.
the misfire issue is either a ignition, injection or mechanical problem (compression vacuum).
That idle bouncing would generate codes other than P030x -
Suggest - A professional scan that would show data such as ECT, FT's, and o2 sensor voltages allowing a tech to ID suspect systems.
"I have a loss of hp from factory spec" how do you come to this conclusion - anyway she's 10yrs old... some wear is expected.
Being 10years old even a GM vehicle would have issues at that age.
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JakeSublime
Novice
Feb 12, 2017, 10:21 AM
Post #3 of 11
(3336 views)
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Re: Intermittent rev surge with intermittent fault codes
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She is actually 20 years old haha. And, I only assume. I've driven a fair amount of vehicles in my lifespan with ranging hp ratings. My vehicle, with a stock 223hp, definitely does not feel like it has 223hp. But, I want to put a lot of work into this car and make it run and look perfect again.
Regardless, I do not have a live feed scanner, but I would be more then willing to purchase one. How much do they run?
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 12, 2017, 11:42 AM
Post #4 of 11
(3327 views)
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Re: Intermittent rev surge with intermittent fault codes
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Regardless, I do not have a live feed scanner, but I would be more then willing to purchase one. How much do they run?
LOL........................ Anywhere from $4,000 to $50,000, depending how good a one you buy.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Feb 12, 2017, 11:43 AM)
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JakeSublime
Novice
Feb 12, 2017, 8:50 PM
Post #5 of 11
(3306 views)
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Re: Intermittent rev surge with intermittent fault codes
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@Hammer Time
What is the device specifically called that I would use to perform this task?
(This post was edited by JakeSublime on Feb 12, 2017, 9:04 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 12, 2017, 9:00 PM
Post #6 of 11
(3300 views)
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Re: Intermittent rev surge with intermittent fault codes
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An enhanced scan tool with bidirectional capability and European software.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 12, 2017, 10:15 PM
Post #7 of 11
(3290 views)
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Re: Intermittent rev surge with intermittent fault codes
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@ JakeSublime : Pretty much the answer is a dealer and a charge just for the diagnosis. It's one of the exotic brands of vehicle that's on it's own cost wise. Expect 3X the cost for anything, maybe more,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Feb 13, 2017, 10:18 AM
Post #8 of 11
(3283 views)
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Re: Intermittent rev surge with intermittent fault codes
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Interesting that you have misfires on 4,5,6 cylinders. Those cylinders are on the same bank and share the same O2 sensor. Maybe there is a fault with the upstream bank 2 sensor causing it to stick lean or rich and cause the engine to surge. Scan tool or monitoring O2 sensor voltage would be techniques to use to see if there is an O2 sensor issue going on.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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JakeSublime
Novice
Feb 13, 2017, 4:22 PM
Post #9 of 11
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Re: Intermittent rev surge with intermittent fault codes
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@Discretesignals,
Agreed, it's only coming up with those cylinders misfiring. But, there is only one upstream o2 sensor.
There are 2 exhaust manifolds, one from cylinders 1 2 3 and one from cylinders 4 5 6. They both join and then there is a sensor on the exhaust pipe just before the cat. I know this because in order to change that o2 sensor I had to drop my whole exhaust from engine to tailpipe. 
I was told on another forum with the same post that this may be caused by a vacuum leak. Thoughts?
(This post was edited by JakeSublime on Feb 13, 2017, 4:45 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Feb 13, 2017, 5:15 PM
Post #10 of 11
(3249 views)
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Re: Intermittent rev surge with intermittent fault codes
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It's possible a vacuum leak could cause surging, but usually vacuum leaks don't come and go sporadically. Sometimes vacuum leaks can be temperature related because of the contraction and expansion of gaskets. Someone is going to need to analyze some scan data while the issue is going on to see if that gives any direction.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Feb 13, 2017, 5:15 PM)
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JakeSublime
Novice
Feb 14, 2017, 1:20 PM
Post #11 of 11
(3227 views)
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Re: Intermittent rev surge with intermittent fault codes
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Well, I found some decent Bluetooth obdII devices that can allegedly broadcast live data from the vehicle's control units to my phone, or laptop. So, what I'm going to do is see if I cant use the freeze-frame function for when the CEL comes on and hope that gets me somewhere.
When the device comes in I'll update this forum post with my findings.
In the meantime, I'll look for vacuum leaks.
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