I have gone thru everything to get rid of the flat spot but i just cant seem to figure it out.

i have a new harness for the engine, gearbox and even the electronic throttle was rewired.

i have new OVP
i have a new Air mass.

Car is always tuned up and it is powerful as it can be.

yet i have the flat spot.

any help is much needed,.....

 

What is this flat spot you speak of? My car rocks in every gear at all RPM!

 

I just read a thread about this, the OP had fixed this issue by replacing wiring and I thought it was wiring to the ETA...

 

Did you check Cam position sensor, Crank position sensor, or the over load switch in the gearbox??

 

i will be trying a new overload switch tomorrow i think and maybe also a cam position sensor. but i did disengage the cam phasing and nothing changed bar the loss of few trqs low down :P

on the star scanner everything is in good order. and cam phasing is working fine thus cam sensor should be ok. might need a new cranck sensor??? im out of ideas here. i know the harness is in good condition.

 

The m104 has an inherent flat spot at right under 4,200 rpm if that is what you are talking about. It has to do with the intake and cam settings. There is nothing wrong it is just a switch point. When you turn off the resonance flap at this point the volumetric efficiency change is huge. I did some tuning on this in n/a form with standalone and was really surprised at the change.

 

i have seriously reduced it if not taken it out. i do think there is a point at 3700 where i can feel a small dip but i have to drive more to find out. but i have solved what i was suffering which was a flat spot from 3400 till 4000 rpm, which was a huge one. turns out mu OVR was cooked. seems the electronic throttle old wires had cooked my new OVR not the car has everything new.

MAF
ALL kinds of harnesses
OVR

and i hope that once for all my car runs perfect.

 

I also hope it runs well now but don't go overboard with it and end up bending the vehicle

 

it runs gr8 and now with the new stiff spring, semi slicks and the 208 AMG55 front roll bar its a dream to drive i just need the rear bar and im done modding the susp. next mod is prolly a super charger. will be a few months before i dare make that move but im sure ill do it.

 

are the 208 AMG sway bars thicker than the C43's??

 

Yeah the c 43 has the same one as the 36 at 27mm thickness front and 16mm rear. The c 43 has stiffer front springs than the 36 and softer rear springs than the 36. The clk 55 has a 31mm front bar but I still haven't found a rear one so I have no specs on that but I expect it to be atleast 18mm at the rear.

 

Did someone say sway bars?

Before swapping the rear bar, it's usually beneficial to identify exactly what one is going after. In my case that's important because aside from not being able to drive, I have an open diff. The last couple of paragraphs at this link discuss sway bar tuning.

 

MarcusF thanks for the info I love the 911 lifting its inner front wheel Many racing cars of the 70's used to do that often. Looked real cool

 

i know marcus with a stiffer rear i might risk more inside wheel spin. thing is the bar is offered if found t usd50 which is nothing and i get to keep my original so i can test out the setups as i please. Now with the front bar in the car is really good but understeers on the tight turns as expected. im hoping the rear bar will help reduce that a little.

 

Perhaps finding a way to adjust the drop links on the sway bar would be a good way of going and fine tuning the set up depending on conditions. In my Porsche racing days, we even disconnected them when the track was wet so as to soften the suspension and avoid brutal break away.

 

I recreafted all the affected harnesses on my 1996 C36. I have a brand new OVP. I have a new MAF. New Knock sensors. New plugs, wires + coils. New Crank and CAM position sensors. New ATF fluid. Resealed vacuum, no loss. I have a short 'cool' air intake by HKS, heatshielded with lexan by me.

I DYNOed the car after all this. The flatspot is still there. It is a dip in torque right when the resonance flap switches, according to the Bentley product familiarization section.

Would make sense if the torque dip is a direct result is simply resonance charging our of phase. See below:

 

You hit the nail on the head with the resonance flap... I'm sure it has to do with the flat spot and there isn't anything you can really do about it.

 

Some reading: http://usuarios.multimania.es/cporsc...a/varioeng.htm
More reading: http://www.chrysler300club.com/uniq/.../ramtheory.htm

 

jumph4x i still have a tiny dip in my power band at just 3500rpm but before it was a huge flatspot from 3200-4000 rpm.