Any scan results for ported TBs with MAF post removed? - Page 5 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 02-26-2007, 11:38 PM   #41
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Quote:
Originally Posted by big_news_1
I think many of the TBs ported by Bill W. have had some of the MAF post removed from the middle of the TB, and I would like to know what kind of scan data has been retrieved from cars using this setup.
Quote:
Originally Posted by MyLittleBlackBird
So ultimately, to have the best results, cut the post out, bore it open, smooth it up, and install a 99+ MAF and program the PCM with the new MAF tables?
What topic are you reading?

Of course I disregard all the posts about "ZM"'* TB, That'* off-topic.
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Old 02-26-2007, 11:42 PM   #42
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Dame, knock it off.

I've never cut out a MAF support except the one Gen 2 L67 TB that was junk afterwards.

If you have an issue with my work (ZM) why are you posting in this topic, and what are you basing your opinion on? I've yet to produce a part and ship it to a member that didn't perform well. Why? I keep the SCRAP here.

If you have an issue with the quality or performance of my work, I'd like to know how. I don't recall sending you any parts from here to be tested.

When I say ZM TB or LIM, you and most other members here know what it means. Disregard it if you like. It'* worked for others so far. Including ZM superchargers galore. I don't know what your issue or attitude is lately, but it doesn't belong in a topic that you have no direct experience with (this is an L36 performance topic).

This topic is BEN'* topic. We're trying to help him get what he wants out of his motor. If you'd like to bash the work I've done to prevent him from learning from my experience or lack therof, please speak from a voice of experience.

Quote:
Originally Posted by Damemorder

Of course I disregard all the posts about "ZM"'* TB, That'* off-topic.
Really? Name someone else who has tried something new on their own car, then modified other parts at their own expense and shipped them to test cars on this Forum to verify results, then shared that information with the entire Forum, at a financial LOSS for the person that did the work.

Go for it.

Back on Topic for Ben now please.
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Old 02-27-2007, 12:03 AM   #43
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I think that the ZM TB and LIM are good for a mostly stock car to mildly modded. And I like the way it is getting tested etc.
But, I do think Ben could go further with his TB. And It looks like he wouldn't have any problems tuning.
The maf support has been completely removed on L36s and S2 L67s before in conjunction with the postless 99 maf. I believe you can open it up more than the 99 TBs with the maf hump.
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Old 02-27-2007, 03:18 AM   #44
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Hey now! Easy does it, gents!

Let me clarify exactly where I was heading with this topic.

I originally thought Bill W'* throttle bodies had part of the MAF post removed, just like what Dame did a couple years ago. I wanted numbers from that type of setup, and also opinions on whether or not it worked and what improvements could be made to the method. It turns out I was wrong, and Bill isn't doing anything to the MAF post on his TBs. However, he is reporting a significant improvement in throttle response, and has had other testers corroborate his findings.

Honestly, I want numbers on BOTH setups. I want numbers on Bill'* throttle bodies, and I also want to know what can be done to effectively use a TB that has had some of the MAF post removed. I want to brainstorm ideas and compare the facts, then figure out what I should do in my application. If there is a way to use Bill'* modifications as well as cutting down the MAF post while maintaining a usable MAF signal, I want to do it. I want this engine sucking as much air as it can.
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Old 02-27-2007, 09:46 AM   #45
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The idea originally came from the Thunderbird community and was posted here back in 2004:

http://www.bonnevilleclub.com/forum/...ht=maf+support

Direct link:

http://www.mn12performance.com/mn12how-to/maf/maf.htm

Here'* the interesting part, pay close attention to Pdad'* comments in BOLD:

Quote:
Originally Posted by PontiacDad
Quote:
Originally Posted by DrJay
Quote:
Originally Posted by PontiacDad
I read the same article a few days ago DrJay. I agree the throttle body is a limiting factor and the Maf is which translates the air flow into an electrical signal. You would need a mini afc to tune the maf as the maf'* air curve is set in the pcm. By boring out the tb you throw the curve out of wack? One of the problems I've noticed here is Bonne'* eat afc calibraters, they work for a while then die? I'm not sure whats going on in the pcm to do this but suspect it maybe has something to do with the map sensor?
The MAF table won't change any and correct me if I'm wrong but the only reasons you'd want a calibrator is if you change the injectors or put a maf adjusted for different injectors in. The only issue I can see at the moment is at idle if there isn't a good flow over the wire it might be a little rough. A a/f calibrator won't change that.
Your right the maf does not change and the table is based on sensor and tb dimensions. So if you put in more air by boring it out the table is out of calibration and the engine runs lean? The pcm will correct for this as best it can via the o2 sensor but an afc will improve the a/f ratio for a quicker responce?
If the flow is strong enough you may also get DTC P0101 'maf sensor performance'
The MAF signal frequency indicates an airflow significantly more or less than a predicted value based upon the barometric pressure, the throttle position and the engine RPM.
And a little farther down:
Quote:
Originally Posted by J Wikoff
Wouldn't taking off the plate dramatically change the way the air flows over the MAF filaments? It would increase airflow over them by so much, I think you'd exceed the MAF'* capabilities to read.
Pdad and John Wikoff called it. My 93 ran so horribly lean after trying this that I had to re-install the MAF screen with two strips of tape across it top and bottom to restrict flow and preven the car from running so lean that it was throwing Check Engine lights and MAF/Lean codes. With no other 'crazy' mods at all. Simply a good CAI, exhaust, chip, and a one-step-down pulley.

Note that Damemorder'* before and after data was never posted. I have no idea if his car truly ran good with it or not. Seat of the pants just doesn't cut it in this case, and I don't recall ever seeing or hearing of any scan data. My conclusions:


Quote:
I know I need to make some more warm and hot runs to fully diagnose it, and the ported TB may still be an issue. Keep in mind 20 minutes after leaving for CA, I threw a CEL and pulled a code for "Exhaust O2 Lean Condition" and pulled over to reinstall my MAF screen. It made enough difference to prevent it from happening again on the trip (this is with the Walbro fuel pump, but only 50 miles of runtime on it).
Quote:
Ohhh....let me be the first to reply that I had massive KR (valid knock, I heard it) on the way home.

WTF?
Quote:
Originally Posted by willwren
Back to the stock TB for me. I'll still be way ahead of the game with all the other porting. I think I'll machine the throttle shaft on the stocker first, and countersink the screws. But I'll leave the MAF support intact other than alot of polishing.
Quote:
Originally Posted by willwren
Well......my plans are to machine a flat on the spare I have (so I have a flat face on each side of the throttle shaft) and countersink the 2 screws. That'* probably good for perhaps 2-5% more flow. Then POLISH the full TB bore, but no porting or MAF support removal.

All rough edges cleaned up, polished, and less restriction going around the throttle plate and shaft should show a potential 5% increase in flow capability. Rather than the extremes I have now.

That'* where I'd start if I were you, and that'* where I'm going with mine. You'll almost certainly need a vertical Endmill for that modification. There'* no way a dremel or die-grinder will do it cleanly.
This is when I first tested it on the Zilla. With a stock 92/93 TB. Then after the Gen3 swap, I did it again with more good results. After that, I did test TB'* for BillBoost37, jr's3800, and Harofreak00 (not delivered yet, but will be later this week). Bonnememn will also be getting an L27 TB at the same time as Andrew.

My suggestion is not to take too much of that MAF support out at all, as it ran my MAF sensor out of range at the top end, and disrupted airflow so horribly that the MAF sensor couldn't get a good read. It ran slightly better with the MAF screen installed, which is what clued me in to the turbulence at low-mid throttle angles, but still ran me horribly lean at the top end.

You're obviously welcome to give it a try, as you can tune your PCM now for different MAF tables if you need to (assuming you don't outflow the capability of your MAF sensor) but you can't tune out turbulence in your TB.

And as a last bit of advice, don't follow the advice in the topic or article that states to leave the backing plate off the sampling tube. That plate is there for a reason. It reduces the rate of flow through the tube by a calibrated amount in order for the sensor to get an accurate read. My car simply wouldn't run at anything above idle with the plate off. So I modified it and reinstalled it.

Here is the link to my old topic:
http://www.bonnevilleclub.com/forum/...ht=maf+support
REMEMBER: This gave me VERY poor results. I don't suggest this to anyone, and I don't do it any more myself. If you want to, you take on the risk. I just want to clearly state that again, since I'm linking to the topics that show how to do it.

And in that topic:
Quote:
Originally Posted by Foghorn
Nice work Bill...as usual

I'm thinking though that you're going to need an AFC to tune that. I have no experience with the Series I TBs, but the the 97 Series II TB has a similar pedastal for the MAF and for those that removed it found themselves to be quite lean. I've seen people running AFCs at 103 to 104% with this kind of mod.

On the other hand...what a teeny tiny TB you have there :P :P

Cheers,
Foghorn called it too. But my TB is a wee bit bigger now, too.

Results were horrible. Running an AFC as high as Foghorn states is pretty far out there. An AFC isn't a mod. It'* a temporary bandaid at best. So for that reason an a half dozen others, this mod sucked.
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Old 02-27-2007, 11:33 AM   #46
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Never hurts to be more clear.
Just to be sure any/everyone knows what I mean when I suggest removing the maf...
I definitely don't mean taking it out and leaving the stock maf in there. That maf was designed to meter air with that post in there.
The 99+ TB and mafs are a whole other animal. The maf just sits in there out in the open. While there is no post, there is a trapezoidal hump to ramp up air torward the maf.
I grinded down the hump in my 99+ L67 TB and streamlined it from the entrance. This obviously dosen't direct air over the maf as much as stock but it certianly isn't more turbulent.
Here is a pic of what I did to the maf area with the 99 maf installed and here is a comparison from to my stock 95 TB with the post.
And as I was saying before, I was able to get consistent and correct fuel trims after tuning.

If you were to remove the post, drill the maf hole larger, and install the postless maf into the TB, you are more than likely to have to build up epoxy/material at the base of the maf to make it flush with the bottom. Just make sure everything has a smooth transition.
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Old 02-27-2007, 01:42 PM   #47
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That is an EXCELLENT summary of our TB knowledge so far. Thank you Bill and Mike!

I feel that either Bill or Mike'* methods could work fine for me at this point. I have the luxury of Thomas' tuning software and wideband O2 at my disposal, so I'm not worried about getting the A/F dialed in. I just need to talk to Doug and see which direction he wants to go with this mod. I certainly agree that a MAF post modification is bad news unless you have the ability to custom tune your A/F ratio, or an AFC at the very least.

Again, thank you for the great recap of the entire TB saga, Bill. It was an interesting read and good reminder why people generally don't pursue the MAF modification.
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