M35 Rough idle

[conan7772]

So still in the process of elimination to restore the super smooth idle and engine rev I had pre AMPerformance intake and new 7 range plugs.

Idle is more like a rumble and and rev is a tad rough compared to before, but it bothers me a lot and sucks on long drives.

Also noticed an decline in fuel consumption.

I've changed coils packs for nothing so it's not those.

Could be a bad plug, or maybe just the difference between the factory 6 and iridium 7.

The last thing could be the absence of the resonator on the intake.

I remember Dale retained his and just fabricated a better flowing bottom half.

I'm thinking of mating a factory top half to the AMPerformance intake to see if it fixes this.

Any thoughts ?

cheers

 

[OZZYR32]

This is what mine is doing and I have the standard type plugs in and still the standard intake. I have checked several times for a vac leak and changed the hoses and all the sensors to no avail. I have now ordered a couple of new coil plug stems to change over as it seems to be a miss on the drivers side bank. It runs fine when I drop it down a gear and have the revs above 3000rpm but misses and hesitates between 2000 and 3000.

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[conan7772]

yep , your problem sounds like coils.

mine doesn't miss, it's constant.

 

[joshm35]

Yours sounds like afm. Its almost like one of the pins is dirty/not making full contact inside the plug. Assuming this happened after ypu installed the intake and afm was plug was unpluged?.

What about 02 sensor.

[conan7772]

hmm don't think so, no codes for that.

I'llgive the AFM a clean and clean the plug a bit.

The engine just doesn't sound or feel right.

Like the harmonics are out

 

I'll try fitting a resonator to the AMP intake by welding a pipe onto it to connect it

[YangLIU]

3 hours ago, conan7772 said:

hmm don't think so, no codes for that.

I'llgive the AFM a clean and clean the plug a bit.

The engine just doesn't sound or feel right.

Like the harmonics are out

 

I'll try fitting a resonator to the AMP intake by welding a pipe onto it to connect it

from my experience, i'd say some AFM issue may not trigger the dash CEL.

when you totally blow the AFM, then there is CEL, but for intermittent AFM problem, there may not have CEL

Edited July 14, 2016 by YangLIU

[joshm35]

Check the voltage going to the AFM.

[Daleo]

Given the sealing arrangement used by the AM Performance intake between the two sections; bet my life that the miss is unmetered air getting in through the slip joint.

It's a silly idea, and unless it was an o-rings joint; it will always leak a little, if not a lot.

[joshm35]

Given the sealing arrangement used by the AM Performance intake between the two sections; bet my life that the miss is unmetered air getting in through the slip joint.

It's a silly idea, and unless it was an o-rings joint; it will always leak a little, if not a lot.

Never had any issues when i had it on mine....

Air flow is feeling very restricted as of late

[conan7772]

Quote

the smoke test did show leaks in the join, Jez siliconed the two halves together, so should be 99% better.

I'll try the resonator install, easy weld on a piece of pipe , just need a resonator now.

I swear this car went harder before I started modding it, down low anyway.

Might even be a blown head gasket, got oil pissing down on to the turbo now too.

 

 

Edited July 17, 2016 by conan7772
more info

[joshm35]

Oil down turbo side is cam cover gasket

[BoostdR]

What are the short and long term fuel trims doing? 

[conan7772]

?/ Don't know mate, I didn't tune it.

Anyway it's not tune related, nor can any tuning fix it.

After fitting new plugs and the intake, which was a mistake, should have only done one then tested, car vibrates on idle and up to around 2500 rpm.

I noticed it instantly and exhaust is louder.

Thought maybe a bad coil.

I've seen a few vids on resonator removal on other cars with massive negative effects.

Strange exhaust tones and loss of power.

Can't find any evidence of improvement.

One article which was quite in depth mentioned intake resonators as crucial to that specific engine design.

Anyway, the engine was way smoother before, so I'm trying hard to restore that.

Apart from that it goes pretty hard, high rpm in low gear manual mode is insane.

If it aint the resonator then I'll try new plugs again, maybe go back to stock 6 spec standard.

If that doesn't fix it I might try drinking way more alcohol.

 

[YangLIU]

Why you don't switch back to stock lower intake pipe from AM performance to try? Maybe you wanna sell AM one after change back

[conan7772]

Do you think it might be the extra airflow causing  ?

Could try a quieter muffler, my exhaust is 113 db atm

[Daleo]

Are you 100% sure that the gasket is in place, and the intake is sealed against the comp cover? The gasket is tricky to get in the right spot; and can swing down on the stud. 

What about the sealing face of the intake itself; definitely flat?

It has the hallmarks of an unmetered air leak.

[BoostdR]

You can check your fuel trims with hobDrive. If you want the app I have a discount code.

[anthonyrs4]

??

[Spear17]

my car just did the same thing when i was driving it stalled on me and lost power, the after 6 tries of cranking, she started up again, i gave her a couple revs to make sure she was running smooth, then when i started driving halfway to my girl's house the car was lugging again at 60km/h. Any idea if this is similar to your guy's cars problems? Any idea what the problem is?

Edited May 17, 2018 by Spear17

[Equilibrise]

That sounds like afm or unmetered air (intake leak)