[Spadwaller]

I did a spark plug change on my friends AMG 1997 E420. Later during the week he noticed that the power was erratic after he put his foot on the gas sometimes. I tested it out and it happened to me on the freeway going about 70ish I put my foot on the accelerator then released my foot and then I press on the gas again and 0 acceleration for about 2-3 seconds after that I get TOO much power I have to let off the gas. It has also happend at stop lights. I'm waiting at a RED light, GREEN, I press the gas and nothing,2-3 seconds later I'm over reving. I dont know if the spark plugs job has anything to do with this problem but it seems to be getting worse. Any ideas??

Thanks,

The Waller

 

[raymond-]

i'm not sure the cause....though i'm scratching my head over your friend's E420 "AMG"

 

[Spadwaller]

i'm not sure the cause....though i'm scratching my head over your friend's E420 "AMG"

I'll clarify its a 1997 e420 Sport it also has 350,000 miles on it. After some googling is it possible the fuel filter is to blame?

 

[yeldogt]

Before I started installing new parts - I would look over what was done.

When working on older cars -- especially with that kind of miles - the age of components can be a problem -- wire and wire insulation especially - vacuum hoses. All that stuff that has not been moved in a long time

I have had similar symptoms with a failing coil -- not bad enough to throw a code.

 

[Plutoe]

First off,-----------You need to ask youself-----WHY sparkplugs.

Keep asking that type of questions, but please don't go near a tool any tool untill you have an answer!!

 

[Spadwaller]

First off,-----------You need to ask youself-----WHY sparkplugs.

Keep asking that type of questions, but please don't go near a tool any tool untill you have an answer!!

Ok, Why spark plugs? All I can figure is that whatever is going on it feels like theres bad gas in the tank. I checked the plugs and re-tighten them again. I get no codes either. I didnt come into contact with anything but the engine cover either. The vaccum hoses that go through the center of the intake manifold seem to been brittle and in need of replace however they look intact I noticed that when I pump chevron 91 into the tank the car seemed to run better IMHO. Any one see anything similar to this before??

 

[tirona]

what type of plugs did you use (non-resistor, resistor, copper, platinum, iridium, gold...)? i know for a fact m104 is very picky when it comes to spark plugs with only copper non-resistors, and also spark plug connectors need to be changed every time the plugs are changed. maybe it's same deal for m119, and if so you need bosch f8dc4 or equivalent plug. you might have to change the spark plug connectors too. hopefully m119 owners will chime in.
also wouldn't hurt to change the fuel filter, it's a $15 part anyways.

 

[Kajtek1]

Doesn't sound like any spark plug related problem I have ever hear about.
Those engines are computer controlled, so that would be computer to blame with no codes. Maybe Pedal Position Sensor is sticking?

 

[Spadwaller]

Would these symptoms be cause by a either a failing fuel filter or a bad oxygen sensor??

 

[Kajtek1]

One thing I learned about those cars is that there is no simple answer to anything.
It is not like on old cars, where sticky gas linkage was easy to spot.
What I get from your description -the computer is acting up on something. Since computer operates on who know how many sensors and programs -with no codes to scan we can only try by error, or wait till a code will show up.

 

[n42w88]

TOO much power

There's no such thing as too much power, only too little traction and too much traffic in front of you.

If you have a scan tool, one that can view the live data while the car is being driven, that would probably be revealing. Even if the engine light is not on yet, a misfire could set a pending code that might give you some idea where to look.

Usually a clogged fuel filter is not an intermittent fault - once the engine becomes starved for fuel the power doesn't come back until you let off the throttle. This sounds like some kind of ignition fault, or loose wiring.

I would check over the ignition wiring, look for cracked wires, etc.

 

[Patch's]

I might add that the coils maybe week! They have a cycle the temperature will effect week coils you should measure resistance on the coils and ign. wires. Anything suspect in vacuum leakage should be attended to regardless of there contribution to the present problem, any failing part you skip over will likely grow boots.
patch's

 

[Kobus]

Not sure if that model already had an electronic throttle position sensor (TPS), but if it does, that could also be typical symptoms of a failing TPS. You push down on the pedal, nothing happens for 2 or 3 seconds, and then it suddenly accelerates like a scalded cat. The TPS has 2 circuits and if the readings doesn't correspond, the ECU take some time to decide which is correct and then act. It can also make you seem as if you are a learner driver with a manual stick - all jerky in your driving.

On my SLK it did not set a CEL, but it was reported by CarSoft, and will of course be picked up by STAR. Most probably it will NOT be picked up by an ordinary OBD2 scanner.

 

[Spadwaller]

Final report...

It seems when I was fiddling around checking for broken/brittle little plastic hoses I disconnected the MAF connector and had not twisted the connector in completely. I tightened the connector all the way and so far so good been a week more or less.

 

[tonysmallz]

Final report...

It seems when I was fiddling around checking for broken/brittle little plastic hoses I disconnected the MAF connector and had not twisted the connector in completely. I tightened the connector all the way and so far so good been a week more or less.

as soon as i saw this thread MAF poped straight into my head.. mine failed after i took the battery off, i refitted the battery only to be greeted by no power i couldn't even get past 40mph..

 

[yeldogt]

Great -- cheap fix. I do wonder why this did not give you a code?