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Intermittent rev surge with intermittent fault codes

3K views 22 replies 4 participants last post by  JakeSublime 
#1 ·
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.
 
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#4 ·
@mrboca
These were the codes I was getting before the alternator, ignition, maf, and o2 sensor work:

p0300
p0304
p0305
p0306
p0133
p0170
p0560
p1747 (had a hard time figuring this out, it is "EPC Solenoid Short Circuit")
@Deplore
I do know that with my vehicle, anything that is plastic is falling apart. Panels, cup holders, vacuum lines, etc. It all needs replacing.

Are all of the vacuum lines I need to replace going to be around and underneath the intake manifold? Or, should I trace every line out from the vacuum pump and replace it depending on brittleness?
 
#5 ·
Rereading your symptoms, I'm more leaning on the fuel pump and/or filter.

I'd recommend replacing the filter if it hasn't been done, sediments in it will impede fuel flow and cause symptoms you indicated because of insufficient fuel pressure.

Do you have a fuel pressure gauge?
 
#6 ·
After you clear the codes, and drive the car, when do you have the CEL come on ?During acceleration ?, deceleration ? stopping at the stop lights ?

Do you have a freeze frame capability for the P0300 ?

After you clear the codes and get a new CEL, do you always get P0300, P0304, P0305, P0306 ?
for cylinders 4,5, and 6 ? not for other cylinders ?

If so, himmm, I wonder what is common to those 3 rear cylinders ?
 
#7 ·
@Deplore,
I do not have a fuel pressure gauge but I can certainly buy one. I do know that my fuel pump doesn't sound very happy. It's external from the fuel tank, and it makes a buzzing sound. But, upon acceleration from a stop when the rev surge is taking place, it goes away. I don't have a power loss due to fuel pressure as far as I can tell. Should I get a fuel pressure gauge regardless and check the pressure?
@mrboca,
As far as I know, it won't come on while I'm driving the car. Once I park and turn the vehicle off and come back to it and start it again, it will blink the CEL and say "check engine electronics".

As far as the freeze frame capability, I do not own any type of engine reading device. What would be the best method to go about doing this? I need a laptop anyways, should I get a laptop and an OBDII to PC connector? Maybe a dedicated "live feed scanner" of some sort? If so, what should I get and where should I get it? I do know there is some type of "Mercedes Star" connector in the fuse compartment located under the hood.

Lastly, yes. I've cleared the codes twice. Once by removing the negative terminal from the battery for over an hour while I did some work on the car, another time after this when I took it to a shop and they did it for me with a scanner. Both times it seems the only codes that are appearing are the four p030x misfire codes.

I do know that each set of cylinders (123, 456) has their own semi-dedicated intake manifolds, and semi-dedicated exhaust manifolds. The exhaust manifolds join together and then once they're connected there is an o2 sensor before the cat.
 
#10 ·
@Deplore,
I do not have a fuel pressure gauge but I can certainly buy one. I do know that my fuel pump doesn't sound very happy. It's external from the fuel tank, and it makes a buzzing sound. But, upon acceleration from a stop when the rev surge is taking place, it goes away. I don't have a power loss due to fuel pressure as far as I can tell. Should I get a fuel pressure gauge regardless and check the pressure?
Well, it depends on how the car acts afterwards. You did mention earlier in this post that the car lost power...how do you know this? What reference do you have to judge the lost performance?

By the way, if you don't know the history of the service, then a new fuel filter is a cheap investment at $35. Mann or Mahl or Bosch or whatever the OEM filter is.

If you know someone who has one, borrow from them first. My initial thought was to measure the fuel pressure while the car is surging. In a healthy E320 with M104, the fuel pressure is supposed to be around 55 PSI, give or take. I know for a fact that the car will continue to run on 30 PSI and you won't notice any performance decay in day to day usage, but at top end (65+ mph) the car will lose power.

Fuel pressure regulator could be shot too, but then you'd have the surging all the time.

Could also be vacuum leak...spray starter fluid or throttle body cleaner around all vacuum hoses and see if the engine surges. If it does, replace that particular hose.
 
#9 ·
Do not yet invest in one of those MB Star C3 / C4. You will spend more time in discovering how it works and what is what than actually solving the problem. I see that as a long term tool.

For short term, I would get one of those bluetooth / wi-fi compatible OBD2 scanners that connect to your OBD2 port and communicate with your android / iphone / tablet / laptop.

A genuine BAFX product is a reliable device. You can get the cheaper ones but I found them overheating for a long term use.
https://www.amazon.com/BAFX-Products-34t5-Bluetooth-Android/dp/B005NLQAHS

For the scanner program I use TorquePro app (search in google play). which runs on android. You can also download an program and run a scanner in your laptop, but s smartphone is so convenient that you keep the BAFX plugged in all the time.

TorquePro supports freezeframe, error display / lookup / clearing codes for engine related problems. You could look at the misfire information, fuel trims, O2 sensor levels, MAF output etc. etc.

Now, does your CEL blink when you drive your car ? Or, goes steady ? Or goes away ?
 
#11 ·
@mrboca,
The Bluetooth scanner you linked is the exact one you recommend I purchase? If so, I have amazon prime and I can have it here before the weekend.

Also, after I reset the CEL, it stayed off for some time, then the next day when I started my car it came back on, blinking. It blinked for roughly 15 seconds then stayed steady. Later that day it just went away. Whether it was during a drive, or after I turned the vehicle off and on again, I have no clue. I wasn't paying attention. The "check engine electronics" error that triggers the CEL comes and goes as it pleases. As far as the actual P030x codes, they may or may not, I'm not sure.

When you confirm the scanner you linked is the correct one for me to purchase, I'll order it. When it get's here, I'll throw it on my car and drive it around. At that point I'll have some harder information to work with and provide.
@Deplore,
Regarding the HP loss, it is just an assumption. It just feels like it has, possibly as rapid as over the course of the last 6 months. Though, I have not taken it to a rolling road/dyno to test it's output in kw/hp so I have no hard evidence.

The fuel filter I believe has been replaced at some point in the cars life, but I am unsure. So, I'll just get a new filter, and I'm thinking a new pump as well. I use carparts.com, it seems to have decent car parts for decent prices. I'll grab them both from there and throw them, might as well.

As far as the fuel pressure gauge goes, where should I get one and is there a specific brand you would recommend? I can't be spending too much money, but I would like to have one to diagnose problems now and in the future. So, if you could give me a link to something on amazon, or point me to an auto shop with some details, I'd greatly appreciate it.

With the fuel pressure regulator, the issue could be intermittent, couldn't it? How would I diagnose this? Can I diagnose this problem with the Bluetooth OBDII scanner @mrboca was talking about?

Lastly, I'll go ahead and grab some carb cleaner or something to spray around the vacuum hoses and see if I can pinpoint a leak. Out of curiosity, why would using something flammable in this fashion tell me if there is a vacuum leak?
 
#12 ·
Yes, it is. But, understand that it is NOT for Apple iOS. It is for an android device or windows. Once you get the device, hook it up and download TorquePro (paid version $5 I think), you will get a lot of information that will help diagnose problems. Honestly, diagnosing without a good scanner is just guessing.
 
#13 ·
About fuel pressure tester, stick with a $20 one. I use a Matco fuel pressure tester, but then again, it's $400 and I own my shop. I believe HF sells a decent one for $20ish.

Fuel Injection Pump Tester

If you want a reference, here's my old 97 E320 0-60:



Ignore the check engine light, I had codes for bad catalyst converters....turns out there was a hole the size of grapefruits in both cats. Who knew?

About the vacuum leak testing.... in an ideal situation, everything after the MAF is perfectly air tight and sealed. The reasoning is that the engine computer calculates the amount of fuel for the amount of air entering the throttle body -- and the MAF measures the quantity of the air. The computer tries to keep the air fuel ratio at 14.7:1 by injecting a proportional amount of fuel to the amount of air entering it.

Now a vacuum leak is a hole somewhere that is allowing unmetered (unregulated air, in other words) to enter the engine, and it throws off the AFR out of balance...which makes the engine surge as the computer keeps compensating for it.

Why throttle body cleaner/carb cleaner? They're flammable. When you spray, they become vapor, and if you spray them in an area with a vacuum leak (a hole in the tube, in other words), the vapor gets sucked into the engine...and the effect is the same as injecting extra fuel. The engine will rev.

In a perfectly functioning engine, you should be able to spray throttle cleaner all over the engine except the MAF (intake hose) and the engine will do nothing.

So basically if you spray cleaner and the engine does nothing, then you could conceivably rule out a vacuum leak and focus on other areas.
 
#14 ·
@Deplore,
Okay, I'll grab that pressure tester tomorrow.

In regards to the 0-60, my 97 E320 definitely doesn't accelerate that quickly. I assume the fuel injectors play a large part in this, would you agree? They haven't been changed or cleaned since the car was built.

Thanks for the info on the vacuum leak, that makes sense. Although, I thought you were referring to vacuum line leakage.

Lastly, I plan on doing a few modifications under the hood. I want to do things like upgrade to fuel injectors with a larger orifice size, upgrade my throttle body to a larger diameter, either rewrite or upgrade the ECU for some increased performance. What specifications do I need to pay attention to when choosing new fuel injectors? I assume injectors are universal, given they are the proper diameter and depth.

Once I get a new vehicle and I'm not solely dependent on this one, I plan on installing a small turbocharger as well. I'd like some more experience with welding, fabrication, and engine understanding. I've done some extensive research on the subject, and I'm confident I can do the upgrade without blowing up my engine. But, I digress, that won't be for a while, it's just a pipe dream at this point. Lol!
@mrboca,
I would never, ever use an iOS/Mac device. So, we're in the clear in that aspect. Then, I'll purchase TorpuePro and stop guessing, as you say. Haha!
@Everyone,
Thankyou for your help, I greatly appreciate it. I tried doing this on my own, but it's gotten too expensive and irritating. So, time to talk to the professionals. :nerd
 
#15 ·
If the car was subjected to dirty gas and the filter is bad, then yes thats possible. But leave that for last resort.

Vacuum leak is any sort of crack in vacuum tubes, or PCV hoses, or any sort of hose/tube whose function is to maintain the internal atmosphere pressure from outside influence. If the intake hose is cracked and lets air in, that's a vacuum leak. If the intake manifold gasket is damaged and lets air in, that's another vacuum leak.

Bigger fuel injector doesn't help much here, the ECU in these cars are very difficult to tune -- in fact, I don't know of anybody outside of Poland and Holland who can do it. In fact, the only modifications to the M104 engine I'm aware of is the turbo exhaust manifold sold by turbobandit....and even then it'll get expensive in a hurry.

Cheapest performance option I've found is to drop in a C36 AMG engine in. I plan to do that some day when I buy another 97 E320.
 
#16 ·
@mrboca
@Deplore

Alright, I have the pressure gauge and OBDII reader. I threw the reader on my car last night and monitored the live feed data while I was driving. Here are the min/max of the live gauges (don't mind the messenger head, I didn't think to remove it from the screen) :

https://drive.google.com/file/d/0B9ncFDxuwlOSYlhPa2RtQzQwUkE/view?usp=sharing

Note the vacuum gauge. It went into the positive side. Is this bad? The vacuum dropped and went positive the harder I pressed the accelerator.

Next, look at these 02 sensor readings:

1: https://drive.google.com/open?id=0B9ncFDxuwlOScWZncHV0dkhWbms
2: https://drive.google.com/open?id=0B9ncFDxuwlOSWExvU05TY1ZnOW8
3: https://drive.google.com/open?id=0B9ncFDxuwlOSMktNX0phVWd2ODg
4: https://drive.google.com/open?id=0B9ncFDxuwlOSYXdBaWROMVZKSmc

I just replaced this sensor, is it possible the ECU isn't reading it properly? Or maybe the sensor isn't 'sensing' properly?

Next, last night when I got my car from my dad's house, it was flashing the CEL saying check engine electronics. I put the reader on and the same p030x codes came up. I cleared them and restarted the car. Within a minute or two they came back. I drove the car home (roughly a 30 min drive) and when I got to my house I was checking the readings and things, cycled my car on and off and to my surprise.. The codes had gone away. No more CEL. They really do come and go as they please.

Also, my father told me when he was driving my car, he saw a new code come up. It flashed the CEL and read "TL Traction". What is this?

Furthermore, I may have forgotten to mention, the reason why I replaced my alternator was because it was putting out <12v to 16v intermittently. Could the over volting have damaged a controller or computer of some sort?

Lastly, here are some "Vehicle Test Results", that for whatever reason didn't complete(?) :

1: https://drive.google.com/open?id=0B9ncFDxuwlOSQ3N6MEQyTWNtdUU
2: https://drive.google.com/open?id=0B9ncFDxuwlOSWXZYZjcyNU8wM2s

Also note, when I say the CEL "flashed", I literally mean it was flashing, not just a steady 'on'. Just for future reference.
 
#17 ·
The first screen shot does not really say much as the car was not running (rpm= 0). You need to get the car running, and fully warmed up. What it does show is the coolant temp is almost 97 degrees C which is somewhat on the high side ( which can happen when the engine is turned off and the coolant is not circulating).

You need to get a snapshot of "emission readiness since DTC " display when the car is running and fully warmed up. This gives a lot of information.

Also you need to search and put it on the screen the "raw data display" which shows the MAF, O2 sensor readings, fuel trim info, intake temp, coolant temp etc. again when the engine is running, and fully warmed up.

Assuming the O2 sensor pics are for the same sensor, it seems to respond fine to the flip-flops, but the mixture detected is a bit on the lean side. It is therefore more important to read the long and short term fuel trims.

The codes you read without CEL probably are pending codes (if in green display). For them to become a current code (red display), they need to repeat in two consecutive drive cycles. If you keep clearing the pending codes, you will not get a CEL.

When you mention "TL traction" and flashing, was it the triangle flashing or the CEL ? what was the actual error code if any ?

Within certain limits, the modules have over voltage and under voltage protection built in. If the problem is detected the modules simply shut off.

You need to explain the problem a bit more clearer. You start the car from cold, it starts and runs fine. It idles smooth when warmed up. You drive the car for some time maybe highway driving at certain speeds, and when you stop at the stop lights it goes "wah wah wah", idle rpm goes up and down. Does it do it all the time ? sometimes ? when the engine is not fully warmed up ? after city driving (stop and go) or after a long stretch of highway driving ? After the rpm fluctuation, at the stop, does it do the same when you stop again ? or is it intermittent ?

Post the readings above and answer the questions so the area of troubleshooting can be narrowed down.
 
#18 ·
Unless you're getting specific codes for O2 sensors, those readings means nothing. O2 sensor reading will be all over the area...hell, I can make a perfectly functioning O2 sensor look faulty on the graph by playing with the gas pedal. Plus the graph doesn't have the values (where is the voltage for O2 sensor?) so it means nothing.

Vacuum gauge is fine.

If you're still getting the misfire codes for the same cylinders, pull up the spark plugs and coils and inspect them. Swap them to another spark plug/coil that doesn't have the codes and drive again. See if the codes stay on the same cylinder or move to the new cylinder.

Vehicle test results also means nothing here...this is meant for Ford and GM vehicles that have their own test results.
 
#19 ·
My 104 motor had an intermittent surging idle, took me ages to track down. Turned out to be a sticking purge (MOT) valve, causing a vacuum leak (connects between the inlet and charcoal canister) New valve sorted it.

Dead easy to check, kicking myself I hadn't checked it earlier.
 
#20 ·
Should be easy to check. Just apply power to the purge control valve to open (to simulate ECU activation), and if you get the same errors (P030x misfire), then that is the problem. More than often you get EVAP errors (pending or current P044X or P045X series). when the system detects the problem. After the engine is warmed up, if you re-start the engine, the purge valve should start ticking.
 
#21 ·
Try sucking though it to see if it holds vacuum, mine was intermittent so sometimes it would sometimes it wouldn't. It worked electrically so the only code it through was for a the Lambda.

I don't think they use 12v so a 6v battery will be enough to get it ticking. To check my purge valve was the problem, I just plugged the vacuum lines and ran it for week before ordering the new one.

:grin
 
#22 ·
The curious thing is the OP has misfire codes only on the upper 3 cylinders. I do not see how a bad purge valve can cause this. The way the secondary air injection (US only) is tested is when the car is decelerating just momentarily start the pump and observe the O2 sensor jump. I assume the the EVAP system purge valve is checked in a similar way (or unlikely, using the MAP sensor as in the EGR testing). So when you plug the purge lines towards the engine, and the canister, I would think you would see one of EVAP related codes. It is free to try :)
 
#23 ·
I have solved the rev surging issue.

It turns out that after replacing the fuel injectors, the problem has subsided. The car has been operating with the new injectors for 2-3 months and not a single time has the problem returned.

I do have to say that I did change the fuel filter, fuel pump, and fuel pressure regulator along with the injectors as to ensure proper fuel flow to the injectors. As a side note, I have noticed a slight power increase as well, though this could just be wishful thinking. :grin

Thanks for the help everyone.
 
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