# getting a clean MAP signal with ITB's



## Rev Jerry (Apr 20, 2006)

Hopefully this is the last question in the long line of questions I've asked in the past few weeks.
Right now my vaccum lines are set up like so...
The fpr is getting fed vaccum from all 4 throttle bodies and has been given it's own line.
My brake booster and MAP sensor are sharing ports and are also being fed by all four throttle bodies.
So basically I have two sets of vaccum lines.
Now I have been trying to figure out a way to try and get a cleaner map signal. right now it jumps around a little at idle and part throttle. Not enough to bother me. In fact I can live with the amount it jumps around while driving normal.
However if I'm in wide open throttle my map signal jumps around A LOT. It will read a steady 82-84 kpa below 4000 rpm. Above 4000 rpm it will read anywhere from 70-87 kpa. which in turn makes the air fuels at wot jump anywhere from 12.2 to 14.9. I don't like that.
Would it be possible to get a cleaner map signal by giving the MAP sensor it's own set of vaccum ports and combining the FPR with the brake booster?
OR combining the MAP and FPR and giving the brake booster it's own ports?
Or is redoing my vaccum lines a waste of time and I should look at other ways of trying to get a cleaner signal?


_Modified by Rev Jerry at 2:50 PM 7-23-2007_


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## Rev Jerry (Apr 20, 2006)

Ah screw it. I went ahead and gave the map sensor it's own line. If it makes it worse I can always put it back.


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## barrygti (Mar 28, 2007)

I would be interested in your results as I will be setting mine up soon. Do you have pictures of your setup? Thanks


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## Geoff Rood (Apr 30, 2001)

Constructing a small vacuum manifold can help clean up the signals a bit. Imagine four equal length hoses, one from each throttle going to a small reservoir, only a few cubic inches. Run a feed off this for the MAP and see what happens. I'm not entirely sure how good this method is, but its' what i'll be doing when I get around to fitting my throttles.
Also remember, the smaller the id of the lines your'e using, the less fluctuation you will see. The downside being the smaller you go, the more delay in accurate signal you'll get.


_Modified by Geoff Rood at 3:48 AM 7-24-2007_


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## need_a_VR6 (May 19, 1999)

*Re: (Geoff Rood)*

If you can't get it under 70kpa go straight to Alpha-N and don't look back. It's nearly impossible to get a good tune on SD with only a 30kpa window.


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## WolfGTI (Jun 16, 1999)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_If you can't get it under 70kpa go straight to Alpha-N and don't look back. It's nearly impossible to get a good tune on SD with only a 30kpa window.

http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## Rev Jerry (Apr 20, 2006)

On no. At idle I'm seeing 40 kpa. If I only had a 30 kpa window your damn right I'd be using alpha-n.
THe results of the little expierence. much more response. and it did help smooth things out a little bit. I'm still having the issue but not as bad as before.


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## need_a_VR6 (May 19, 1999)

*Re: (Rev Jerry)*

That's not that bad. If it's jumpy use a mig tip as a restrictor.. ask Mendra what he used before he bagged it and went to Alpha-N


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## Rev Jerry (Apr 20, 2006)

A mig tip? As in a mig welder?


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## need_a_VR6 (May 19, 1999)

*Re: (Rev Jerry)*

Yes, they're a good restrictor and are easy to find.


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## nothing-leaves-stock (Mar 1, 2005)

*Re: (need_a_VR6)*

go alpha-N.....running on map sucked on mine...."N" is so much better, drive mine daily...


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## 2L Bunny (Aug 15, 2000)

*Re: (nothingleavesstock)*

No idea what that fancy megasquirt "alpha N" talk is. But when I was running ITB's on SDS I tried a vacuum manifold and it helped a bit. But once I went to a TPS based map it was great. Even got approaching 30 MPG on the highway, with excellent drivability.


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## dubsrphat (May 4, 2004)

*Re: (2L Bunny)*


_Quote, originally posted by *2L Bunny* »_No idea what that fancy megasquirt "alpha N" talk is.

Running TPS based tuning is Alpha N


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## WolfGTI (Jun 16, 1999)

*Re: (2L Bunny)*


_Quote, originally posted by *2L Bunny* »_No idea what that fancy megasquirt "alpha N" talk is. But when I was running ITB's on SDS I tried a vacuum manifold and it helped a bit. But once I went to a TPS based map it was great. Even got approaching 30 MPG on the highway, with excellent drivability.

Actually Alpha-N is not Megasquirt based nomenclature. If you google Alpha-N you will find that several SEM systems refer to TPS based maps in this manner.


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## 2L Bunny (Aug 15, 2000)

*Re: (WolfGTI)*


_Quote, originally posted by *WolfGTI* »_
Actually Alpha-N is not Megasquirt based nomenclature. If you google Alpha-N you will find that several SEM systems refer to TPS based maps in this manner.

cool, why google when I can the info straight from you guys?


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## need_a_VR6 (May 19, 1999)

*Re: (2L Bunny)*

Slacker.


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## WolfGTI (Jun 16, 1999)

*Re: (WolfGTI)*

I had the fortune to examine an e46 M3 last night - it comes with ITB's from the factory - and has an air temp sensor but no MAF, I assume it also uses some sort of Alpha-N.


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## dubsrphat (May 4, 2004)

*Re: (WolfGTI)*


_Quote, originally posted by *WolfGTI* »_I had the fortune to examine an e46 M3 last night - it comes with ITB's from the factory - and has an air temp sensor but no MAF, I assume it also uses some sort of Alpha-N.

I wonder how well alpha N would do with altitude corrections


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## 2L Bunny (Aug 15, 2000)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Slacker.

Would you expect anything less?


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## WolfGTI (Jun 16, 1999)

*Re: (dubsrphat)*


_Quote, originally posted by *dubsrphat* »_
I wonder how well alpha N would do with altitude corrections

I am sure there's a map sensor involved in the e46M3 - that uses ambient pressure to lookup a table for the air density as altitude increases and then corrects the fueling. I have friends in Utah and Colorado with these cars that have zero problems driving them up in the mountains or down to sea level when in California. After all these BMW's - the e46 M3, the e39 M5, and the current generation of M cars all pass the emissions tests, and therefore have to be able to adjust fueling especially the ones tested in high altitude locations.


_Modified by WolfGTI at 2:09 PM 7-27-2007_


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## dubsrphat (May 4, 2004)

*Re: (WolfGTI)*


_Quote, originally posted by *WolfGTI* »_
I am sure there's a map sensor involved in the e46M3 - that uses ambient pressure to lookup a table for the air density as altitude increases and then corrects the fueling. I have friends in Utah and Colorado with these cars that have zero problems driving them up in the mountains or down to sea level when in California. After all these BMW's - the e46 M3, the e39 M5, and the current generation of M cars all pass the emissions tests, and therefore have to be able to adjust fueling especially the ones tested in high altitude locations.

_Modified by WolfGTI at 2:09 PM 7-27-2007_

Right, I understand they can... But what about Standalone?
can MS using the Baro Correction still use alpha-n?


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## need_a_VR6 (May 19, 1999)

*Re: (dubsrphat)*

Yes and it makes it easy. You can do constant baro on the main map sensor if you're using alpha-n.


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## dubsrphat (May 4, 2004)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Yes and it makes it easy. You can do constant baro on the main map sensor if you're using alpha-n.

Well that will make things much better for where I live. Colorado - I am in the mountains alot


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## evil-e (Aug 15, 2005)

*Re: (WolfGTI)*


_Quote, originally posted by *WolfGTI* »_I had the fortune to examine an e46 M3 last night - it comes with ITB's from the factory - and has an air temp sensor but no MAF, I assume it also uses some sort of Alpha-N.

The E46 M3 has a MAF built into the airbox. The air temp. sensor is integrated into the MAF on a stock car. Dinan and others have you un-pin the intake air temp sensors from the MAF and run new wires directly from the ECU down into the brake duct on the drivers side and mount a dedicated temp. sensor. This is done when you install a Dinan cold air and throttle bodies/software. I installed a Dinan stage I supercharger setup on an M3 a year or two ago at work and it got rid of the MAF altogether. The air plenum that goes from the airbox/MAF to the throttles has the velocity stacks built into it on the inside. It's funny that this has come up now, but a little over a week ago, I cut up an M3 air plenum to rob the velocity stacks out of it! We've had the plenum sitting around for close to 2 years in storage from installing an Active Autowerks Stage II supercharger kit which uses a welded aluminum plenum. I went to parts and asked how much the retail price was on that M3 plenum and it is $704.00







!!! I've got the most exspensive velocity stacks ever sittting in the bottom drawer of my toolbox at work right now !


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## xr4tic (Dec 10, 2001)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Yes and it makes it easy. You can do constant baro on the main map sensor if you're using alpha-n.

You can if you use pure Alpha-N. There are some people that use Hybrid Alpha-N (like me), which still uses the MAP, plus use the MAP for the timing table instead of TPS.
With MS Extra you can add a 2nd MAP sensor for constant baro correction, I think the only limitation is it has to be the same as the main MAP - you cant use a 1bar for baro, with a 2.5 bar main


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## WolfGTI (Jun 16, 1999)

*Re: (evil-e)*


_Quote, originally posted by *evil-e* »_
The E46 M3 has a MAF built into the airbox. The air temp. sensor is integrated into the MAF on a stock car. Dinan and others have you un-pin the intake air temp sensors from the MAF and run new wires directly from the ECU down into the brake duct on the drivers side and mount a dedicated temp. sensor. This is done when you install a Dinan cold air and throttle bodies/software. I installed a Dinan stage I supercharger setup on an M3 a year or two ago at work and it got rid of the MAF altogether. The air plenum that goes from the airbox/MAF to the throttles has the velocity stacks built into it on the inside. It's funny that this has come up now, but a little over a week ago, I cut up an M3 air plenum to rob the velocity stacks out of it! We've had the plenum sitting around for close to 2 years in storage from installing an Active Autowerks Stage II supercharger kit which uses a welded aluminum plenum. I went to parts and asked how much the retail price was on that M3 plenum and it is $704.00







!!! I've got the most exspensive velocity stacks ever sittting in the bottom drawer of my toolbox at work right now !









The e46 M3 I was looking at did not have a MAF in the after market air box it did have the temp sensor in there.


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## urogolf (Dec 10, 2000)

quick side note,
i was running map only (1 off each tb) on my itbs for a while and was having a bog if i lifted throttle and got back on too quickly.. switched accel and decel to tps and thats all gone... 
i got +-30 mpg on the drive to waterfest and on the way back too
i was very happy with the results
OT mendra i saw your car at chillis for the first time and i must say its friggin amazing http://****************.com/smile/emthup.gif 
i was lookin around for you but never found you


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## WolfGTI (Jun 16, 1999)

*Re: (urogolf)*

Thanks for the compliment - I sent you an IM regarding what you said.


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## evil-e (Aug 15, 2005)

*Re: (WolfGTI)*


_Quote, originally posted by *WolfGTI* »_
The e46 M3 I was looking at did not have a MAF in the after market air box it did have the temp sensor in there.

No worries, just letting people know the scoop... Found some pics on my computer of the install.
The three wires capped off are the MAF wires and the two that have been extended are the temp sensor wires.








And I haven't seen your car in person, but the pics and the videos/sound clips of the ITB's are sweet http://****************.com/smile/emthup.gif .


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## Rev Jerry (Apr 20, 2006)

Wow this thread went a little off track!
Just a little update. Still using SD for tuning and I'm currently seeing 33 mpg. I beat up a stock 1999 e36 m3 last night. I need to get some dyno time and get the timing table set up. Then post some numbers.


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