engine power loss

[joboo]

my 95 C36 has a problem with the engine that is starting to happen more & more. About 2 years ago it did the same thing and the dealer just replaced the plugs abd all was good til now its back. Anyone know of this? When I step on the gas hard the car will not take off as it should, it stumbles and then goes as if it were running on 2 cylinders. When I come to a stop it idles very noisy and seems like it may stall and the whole car shakes. But when I turn off the car and restart it will be fine for a while.???Please help...Thanks

[rollinrealbig]

check your ignition system.

Ive had the same thing - my car would just shake like my wheels where about to fall off and it was just a bad plug in cyl. 4

try replacing all of them, and check to see if theres oil around them.

[Sulaco]

Everyone on this forum who reads this will say the same thing:

The car has been kicked into limp mode. Whenever it detects cylinder misfires and such it will turn off whatever cylinder(s) were having trouble. The problem can be with any part of the ignition system: plug, plug wire, coil, coil connector. However, your car is a pre-update model. That means it came with a very poorly designed wiring harness made of biodegradable insulation. If it's the factory original harness you can be pretty sure your problems start there. I'm going through the EXACT same symptoms as you on my 94 C280. I recently replaced the wiring harness which fixed most of the problem, but it's still got a slight misfire somewhere. But all my coils and plugwires are factory original and I'm slowly replacing them all until I get the problem nailed.

Unfortunately there's no real way to diagnose this problem without spending tons of cash. Even if you locate what cylinder is causing the trouble (if your check engine light comes on, go to autozone and have them pull the codes for you. You'll get a code like P030X where the X is the cylinder misfiring) you could go through alot of trouble and still not fix it. If the cylinder is an odd number, it could be the plug. If it's not the plug, it could be the plug wire, if not the plug wire it could be the coil (because each coil controls 2 cylinders). If it's not the coil it is almost certainly the wiring harness. That part alone is $600 and about 2 or 3 hours installation (if you want to do it yourself. it's not that hard).

[jnenad16]

you need a tune up. spark plugs, wires, coil ends, fuel filter need to be changed. you might also want to check out your vacuums, there might be a leak.

EDIT: sulaco is right about the harness, too.

nenad

[Sulaco]

I just realized that nenad is the only guy on this forum you can really count on to deliver exactly what you need to hear. I should just give up! :)

Edit: nenad, I also wanted to ask you something: I know I've got some vacuum troubles somewhere inside my car (center vents don't work, rear right door won't unlock). Where do I go to check for leaks? Where are all the valves and boxes? What about under the engine? Which ones should he be worried about?

[jnenad16]

Originally posted by Sulaco
I just realized that nenad is the only guy on this forum you can really count on to deliver exactly what you need to hear. I should just give up! :) :cool:

nenad

[BongC36]

Hi, were you able to fix the misfiring problem?

my 95 C36 is having the same symptoms now. Replaced plugs, fuel & air filters, wiring harness and coil suppressors to no avail.

Car pulls hard, stumbles and accelerates in 'stages' instead of smoothly, then the ECU turns off cylinders 1 & 6

Regards

[jnenad16]

Originally posted by BongC36
Hi, were you able to fix the misfiring problem?

my 95 C36 is having the same symptoms now. Replaced plugs, fuel & air filters, wiring harness and coil suppressors to no avail.

Car pulls hard, stumbles and accelerates in 'stages' instead of smoothly, then the ECU turns off cylinders 1 & 6

Regards check if your coils are connected, the connectors that supply the power to the coils can easily slip off, and cyl 1 and 6 are fired by the same coil, so I would definitely start there.

nenad

[BongC36]

Yes the coils are connectes properly. The misfire in intermittent. What are the symptoms of a failing MAS?

[jnolte]

Originally posted by BongC36
Yes the coils are connectes properly. The misfire in intermittent. What are the symptoms of a failing MAS?

it could be MAS. Sounds like wire harness but u replaced it.

[jnenad16]

if it was the MAS, the idle bounce up and down, and the misfire would be rampant across all cylinders, not just 1 and 6. I still think its ignition problem. did you check your ignition cables for arcs in the dark?

nenad

[BongC36]

Thanks for the reply. Yes I did check for arcing in the dark, but none detected.

We replaced the MAS ($$$!!) but the intermittent misfire is still there. I am posting the diagnostic printout in a new thread

[FreeStyler]

I have the EXACT same problem except with a twist. First off I have a 1998 c230, and the reading I got on the OBDII was misfire in cylinder two. I have replaced all sparkplugs, replaced the valve cover gasket and rubber boots around the plugs and still no luck. Funny thing is that my car only shakes after three things.

1. Sharp turns or regular turns. After I come out of the apex of a turn boom limp mode. My car never dies, just shakes wildly. I am getting really frustrated however, because I am tired of restarting my car after EVERY damn turn.

2. Everytime I put the pedal to the metal my car goes into limp mode. Especially when I am trying to catch up speed getting onto a freeway. This really F****** ticks me off. I have to pull over on the freeway and restart my car and its works fine. Really damn annoying.

3. While in park if i turn my wheels either left or right all the way till the steering wheel locks, my car shakes however with this shake it stops as soon as i turn the steering wheel back and I dont have to restart my car.

Looks like I am taking this car to the shop soon but I want to try some more things myself before i do that.