Hey guys, im going to be boring out my throttle body for my 3400. I bought one off ebay and I was going to slap a TB spacer on it while I had it out (I know its not an outstanding mod, but I want one! ) The problem is they only make a tb spacer for the 3800. Im aware that the MAF is in a diff loc on the 3400 but is the TB a compelelty different size? Will the 3800 spacer fit? I read mr. pheonix's cardomain info on porting and polishing a TB (nice tutorial) but I was wondering where I could get a bigger tp plate once I bore it out, because I dont wanna taper the inside of mine. (Or should I taper it?)
Thanks guys
Im going to the NY Autoshow this week, lemme know if neone wants pics

 

Phoenix is the best to answer this question.

 

and here i am lol

i personally wouldnt waiste my time completely boring out the TB and droping in a new plate. yes that is the best way to get the extra flow but if you increase flow too much and dont retune the car for it you prob will end up with problems. IE runing lean and damaging the plugs, valve, pistons.[:@] i just finished reporting my upper intake manifold today and if it wasnt for my tuner i would have had to scrap them! i increase airflow to the point that the computer ran out of room to compensate! Ok back on topic...

if you over bore the TB you'll have that above issue like me. but the major gains you will get can be achieved by port matching the back of the TB that ataches to the intake manifold. these are off quite abit from factory. if you have a spare gasket and time you can even over bore both pieces to make it even larger... but i wouldnt go more the 5 mm in dia over the existing dia. Next i would focus on smoothing out the inlet to the TB... there are some square edges at the front of the TB you can smooth, and just infront of the blade you can see where it tapers down very suddenly you can prob take about 1mm off in this area to smooth the transition. after both of those move on to removing the top bar that holds the throtle blade... this is where your major flow increase will come from. and pertty much your done! just remember to clean the parts really well.


**********caution to everyone!**********
do not do any major modification to your MAF housing without a tuner to recalibrate it. polishing the surface is fine. and some can run without the screen (though i wouldnt recomend this) but any major cuting or reshaping on the maf will severily throw off the tuning of your car. as part of my report work... i did some drastic reshaping of the maf... and even with my tuner its taking a lot of work to get things normailzed again. so be warned.

ok hope this all helps.

 

so my maf is ground down, descreened and polished. Is that bad?

 

on the 3400, the maf housing is not connected to the throttle body (im sure u knew this but i jus wanted to make sure) so by me polishing it and grinding it down a little, is that a big deal? My engine doesnt knock (as far as i know) or make serious noises. It idles smooth and Im not throwing any codes, so is that ok or is there damage im doing that i dont know about. Whats the throttle blade? and why you say port matching ur talking about making inlet and outlet the same right? Is "porting" grinding stuff down or am I completly missing the point

 

http://cgi.ebay.com/ebaymotors/3-GM-...rdZ1QQtcZphoto

after panicking I decided you probably dont know what I am talking about because I am an idiot. So here is a pic of exactally what I did
http://cgi.ebay.com/ebaymotors/3-GM-...rdZ1QQtcZphoto

it says on there it wont eff up you engine, so am I ok?

 

well they are incorrect to say it wont set an engine light. it still can as just removing the screen was enough to set the light on my stock monte. as for causing problems... you cant be sure unless you have your car scaned... either by someone with a tuner or autotap or somethign that will read the sensors directly from the PCM while you drive.

that MAF is exactly what i did... the center blade is gone and everthing is smooth... only issue that might be keeping you from a light could be your engine is still drawing the same amount of air thru the TB... i would guess that if you did a high flow tb you might draw more air then the computer was prepared for and could step outside the normal tuning.

this ported MAF will be seen by the computer as if your car is runing lean. lean cause you now are leting more air thru the sensor then i expects. cause the orginal sensor was smaller inside. so as the hole grows the speed of the air thru it reduces. so the car reads a lower air speed and thinks there is less air... and its not getting any less air...its getting even more then normal for that RPM. the computer can only compensate so much for these types of errors.

so as long as nothing else is wrong with the car, and nothing else is throwing off the codes you should be ok. .... question did you unplug the battery too let the computer reset after you installed the new maf? if its runing good right now i wouldnt mess with it, but its also a possiblity that if you ever unplug the battery it might take a while for the sensor to relearn from a blank. if you have your old maf on hand i would keep it and save it for a backup.

 

I had the battery off for about 2 hours when I was trying to kill the code I got from replacing my cat (wanted it off for 15 but I forgot about it when my gf came over ). I ended up getting a obd II scanner to kill the code when that didnt work. I will be cleaning the MAF with electrical contact cleaner today because I have been seeing lackluster mpg (23 highway miles with a 3400). I was told that the descreened maf and k&n air filter could cause oil from the filter to eff up the sensor a lil. So you are suggesting that I should not mess with the throttle body until I get a tuner? I have two mafs and two TBs so would i destory the car if i tried an experiment with both a ported TB and MAF? Id drive around 50 miles to see if the ECU learned it properly and that the fuel curve wasnt messed up. The problem would be a check engine light right? So after the light came on I could just go back to the way I had it with no serious damage? Thanks a lot for the info, Im MAJOR worrier so I had a minor panic attack this morn expecting my car to blow up on the way to work 2day lol

 

To give an idea about engine problems, the engine runs fine, is peppy and doesnt stick in-between gears. I have no codes being thrown on the OBD-II scanner. It accelerates as fast as a 3400 could (I guess). So what type of problems would I see
(this is just an addition to my previous post of stuff I forgot)

 

I bought electrical contact cleaner to clean my MAF. I read many pages that says this is ok to do. Its a spray bottle and will help get rid of the oil on the sensor from the k&n filter. Could I clean my 02 sensor with this as well?
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