K&N box filter upgrade issue

[bimmerR75]

I may be digging my own grave here, but had an opportunity to get a new K&N box filter for half off due to some credit/coupons I had left over. Disconnected the battery initially because I thought I may have to remove the MAF cable (didn't have to) to get the box out.

NOW, I know when you disconnect the battery there is a slightly rough idle because the ECU is relearning the inputs, however with the new "free flow" filter, the idle has dropped to 1,200 RPMS, and after a few on/off cycles is now back at 1,500 - 1,600. Issue is, its still a little low when coming to a stop, then it moves back up.

Doing my due diligence here, haven't driven it more than say 5-10 miles since the install and disconnect but wanted to get ahead of this if this sounds like a issue beyond just putting the K&N in. Maybe switch back to paper? Idk, it was a good deal though!

Thoughts?

[MrBurgundy]

Well, 1.2k and 1.6k isn't a low idle. Also, filter material should not have that effect on the car's idle.

Maybe you cracked the intake boot when you were trying to fit in the new filter. Retrace the steps you took to get the filter in and out and make sure everything is okay and not broken.

When I disconnect my batt, I get a low funky idle too, for a good while. Maybe you just need to drive the car more, but please clarify your idle speed, because what you said is in fact, a high idle.

[bimmerR75]

Well, 1.2k and 1.6k isn't a low idle. Also, filter material should not have that effect on the car's idle.

Maybe you cracked the intake boot when you were trying to fit in the new filter. Retrace the steps you took to get the filter in and out and make sure everything is okay and not broken.

When I disconnect my batt, I get a low funky idle too, for a good while. Maybe you just need to drive the car more, but please clarify your idle speed, because what you said is in fact, a high idle.

Checked the intake boot this morning and it looks like there was a tiny bit of slippage off the MAF. Readjusted it so it seems to be running at 1.5 - 1.6 now (with A/C compressor on). Probably just need to drive it around a bit more. To note, also running a Dinan Chip, although have had that in the car for a year now and idle was typically running around 1.6 regularly even before I switched the air filter.

[MrBurgundy]

That's too high, it could be the tps sensor. That's the one right underneath the throttle body. Your idle should be around 750.

When that sensor goes bad, you get a high idle like that because the idle control valve is all the way open. Look up the continuity test for the throttle position sensor and check it out.



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[bimmerR75]

That's too high, it could be the tps sensor. That's the one right underneath the throttle body. Your idle should be around 750.

When that sensor goes bad, you get a high idle like that because the idle control valve is all the way open. Look up the continuity test for the throttle position sensor and check it out.



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Ok, i'm an idiot haha. It is at 750 not 1.6, its just a couple hundred rpms under the 1k mark. Just took it on a lengthy drive, turned off, restarted and it looks like I'm not having the idle issue.

None the less, going to perhaps clean the ICV at some point this week to just make a safe measure.

Thanks Mr. Burgundy, sorry for the confusion!

PS: We missed you on Sunday's drive! What happened?

[MrBurgundy]

My steering rack took a shit :c P/S fluid was POURING out

I replaced it with a re-manufactured one and it didn't even make it a year.... But I need to change my oil pan gasket anyways, so it was going to come out anyways lol

I'll be at the next one for sure though!

So, your car is all good now?

[bimmerR75]

Jeez, that sucks! It's always one thing after another with these cars haha. Not sure I'll be at the next one! Moving to PDX in a few weeks so will have to see all the folks from down here at the next E30 Picnic up in my neck of the woods.

Car is A-ok now, appreciate the advice!

[MrBurgundy]

Any time! I'll be up in washington for the next picnic, so i'll catch you there. I'll bring some chili with me lol

[jlevie]

750rpm is the correct idle when the engine is at operating temperature. An 153 DME with an M20B25 is known for idle problems. A 173 or later fixes that.