SuperCharger....Crap idle...M45
 

So I have a 97 Miata with M45...band aids...don't really know exactly what they are. Have a TDR intercooler setup.

Idle goes up and down up and down....never stalls....

If I got rid of the band aids and went with megasquirt...will this help my idle? Or am I stuck with the doing dual throttle bodies?

I don't really want to tear it apart right now and go turbo...but getting the megasquirt on there would set me up for a turbo future.

Anyone with a MSed M45 have a descent idle without dual throttle bodies?

Turbo

Do you have A/C?

I got my M45 equipped NA to idle quite well with a MegaSquirt, but it seemed to go to ---- when you turned A/C on. At a minimum it needed an idle up.

Nope don't have AC...its mostly a track car, but I do drive it to the track. The idle is mostly annoying.

Thanks for the feedback.

I've got a JRSC and MS. I just spent about 4 hours yesterday getting a nice rock solid idle. It's not the easiest task in the world to tune, but if I can figure it out, I'm sure you can too. Even if you don't really want to go turbo now, or maybe not ever, megasquirt is arguably the best upgrade you could do.

Very doable with a standalone ECU.

Sounds good, thanks.

Will be talking to you about MS vs AEM.

Thanks to all!

its the IAC not being fast enough to handle the air volume and time between the throttle plate through the SC through the IC to the engine. You can band-aide it with a dual throttle body setup, or move the TB to the stock position and run a bov (i did this and it was freaking LOUD and annoying) or take it off, sell it, buy a turbo setup and come out ahead. TDR will sell you the pipe you need for the IC for about a hundred bucks for a turbo setup.

Sometimes it idols fine...but when its hot it idles like crap.

Would move the throttle body to the stock location...but don't wanna be loud and slow.

You don't need to move the throttle body. You just need real engine management.

Such as ?

1/2 true, Even with a real management idle still sucks and is a pain to get right. Moving the TB had the best results.

I mostly agree with you Jeff. My point was just that you don't NEED to move the TB. I got mine to idle just fine with the TB on the blower. Moving it back to stock location will certainly improve things and make it easier to tune, no argument there. But with some decent tuning and megasquirt, you can get it to idle pretty well without changing anything.

What is the detriment of having two synchronized TBs? Just the added noise, weight, and cost? In my mind it is easier to leave the TB in the stock location, with stock wiring, and add a dummy to the charger for improved idle and to prevent tip in lag when using an I/C.

What is the theory behind needing a BOV, too?

the noise with a single. a dual does not create more noise.

the blowoff valve prevents compressor surge.

I jacked with moving the TB and putting a BOV on and the noise was insane. even at idle it was loud. sounded like a loud hoover. then sometimes on the highway it would catch boost and surge like crazy because there is no "wastegate" per say so it was building boost all the time even if it wasn't "using" the boost (under partial throttle). a bypass valve that recirculated into the intake stream may have helped with this, i dont know. i didnt leave it on very long.

in the end, i sold the SC, pocketed alot of money and put on a turbo. it is MUCH better and much more responsive IMO. and faster.

Just to the DTB.
It's not a bandaid, and you would still need it with a full standalone unit, as well.

The part about the IAC not being able to control a much larger volume is explained above already.
You do get a better throttle response with the DTB mod, too.

Also, if you adjust the relationship between the two throttle plates properly, you do not need a BOV.

I did it, and never looked back.

^ This.

Ok, the reason your idle sucks is because you are getting idle air from a cheap narrow ass rubber hose then trying to control it from the opposite side of the engine bay, the engine will be thinking about it long before it arrives. Thats part of why they get you to increase base fpr (along with
lack of )2 clamp for tip in lean).

See 1st pic

As you see there is not a rubber hose looking like crap, everything else just does. I have an old Link which uses a speed density setup and measures MAP sennor pressure @ stock fpr. Or after it could escape as MAPS and MAFS are way different. I shouldn't have to explain, but a turbo car with a recyrculating BOV generally has a MAF. Map doesn't care, vac leak all day. I don't have to worry about losing air. Lots of you don't either. however the flapper door (think as old school MAF) is right at the intrance of the air filter. Look at the left in previous picture and you'll see this.

See 2nd pic

Its where that long hose used to be, replaced by a TDR check valve and a autozone PCV breather. Idle is unwaveringly steady now.

For comparison I plugged the far end of the hose.

See Third Pic

Much shorter path, removal of inefficiency, better idle. Just have to run IA adjust screw a bit more open. Ignore my spelling, my post count is low. :ohnoes:

Sorry, I meant to say my windshield wiper fluid injection does fix tip in lag from IC. And adds 2 psi instead of congesting things. In fact my car feels a little too happy. Much faster and easier than moving TBs too.

Been dealing with some idle issues as well. When you removed the idle bypass hose and just installed the small air filter after the check valve, did you cap the opening in the intake elbow where it would normally connect? Thanks.