# 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v



## H2Zero (Apr 25, 2003)

Dear All,
I have just recently completed the above conversion to my 16v. It runs on MS. I feel the car is very sluggish even more so then before the conversion. I have 272 degree cams and I am looking for those who have done similiar conversion to share knowledge.... cheers


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

What was the exact setup before the conversion? Have you checked the cam timing to make sure it's on? Synced the igniton timing? Have the a/f tuned in pretty decently? WOT spark timing?


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## H2Zero (Apr 25, 2003)

P&P, balanced, 81.5mm pistons and a customed equal length exhaust manifold....


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## buttbump (Jul 27, 2007)

*Re: (H2Zero)*

What ECU are you running? Give more SPECS, and I will see if I can help you!
Off Idle the biggest, dies then picks up as RPM goes up?
Pictures of your Conversion?
Bump


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## Fast929 (Nov 13, 2004)

*Re: (buttbump)*

Comp ratio would be beneficial as well.
Stock?


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## ValveCoverGasket (Mar 20, 2002)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Have you checked the cam timing to make sure it's on? 

both cam to cam and overall timing, definitely check both

the next place id look is the overall state of the tune...


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (ValveCoverGasket)*

thanks for replying I will check all the above.


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

I am runnign MS, tried tuning yesterday but due to rain did not accomplish much. Anyway the car runs nice at high revs but on low revs (normal town driving) the car stutters and may even die. 
May have the mechanic look at the cam set-up this weekend so can anyone advice if I need to change the gasket should I open the rocker cover to set the cams?.... thanks.


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## oilpangasket (Dec 5, 2007)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

if you are running megasquirt and spark with itbs and a big cam like that then do yourself a favor and use Alpha-N. If you are running it off the MAP and using speed density you will have a very poor map signal and it will run like ish. Alpha-N goes off the throttle position sensor (if you dont have a 16v tb that has one then get one)


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (oilpangasket)*

its running on Alpha-N. starts ok, driving slow a bit challenging, loves WOT.


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

Tune the fuel map in then play with accel, you can set the timing to something like 28-30 across the board so you don't have that to worry about.


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Tune the fuel map in then play with accel, you can set the timing to something like 28-30 across the board so you don't have that to worry about. 

what timing r u referring too? Yes now I have to feather the accel now and then but I notice when the car is warm it felt as if it was going to stall, what should I look out for? Of course I didn't not wait to find out if it really stalled ..... any ideas


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

Sorry, ignition timing. Raise the idle if you feel like it's going to stall, get it closer to in tune, and then lower it again. Warm idle afr's on a 16v like to be about 12.8-13:1 on most engines and richer as the cams get larger.


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (need_a_VR6)*

got some runnig issues.... car was runnig ok TUE but on WED after being stuck in traffic for about 1/2 hr the car began to bog when I accelerate not allowing me to go above 3500rpm. On idel it feels like its running on 3 cyclinder and the rev shows 900rpm against the normal of 1200rpm.
I changed the plugs and it started but now it does not want to idle, pls can anyone offer advice.
Thank you.


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm opening tappered to 42mm throttle plate conversion to a 16v (H2Zero)*

Do a compression test first, then check each plug for spark, then pull the fuel rail and make sure all the injectors are firing an even amount.


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm conversion to a 16v (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Do a compression test first, then check each plug for spark, then pull the fuel rail and make sure all the injectors are firing an even amount.

thanks for the reply. The situation was caused by a lose air temp sensor socket.... thats done and I did some more tuning and its easier to drive or take off slowly during traffic but on the run and when the revs drop to about 2000rpm the car stutters but when i throttle it, it GOES.....







I can smell gas waiting at traffic but I guess thats the trade off for Alpha-N tuning.
Friends are suggesting I change to iridium plugs but as the plugs get flou so often is there any solution to this? When I changed from platinum to normal plugs (because I fould the platinum) I notice the difference so if I can go Iridium it could onle get better right? VW suggest we use hot plugs should we change to cold plugs now with my set up?


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm conversion to a 16v (H2Zero)*

Sounds like you're way rich, you using a wideband for tuning? If so, you sure it's calibrated and MT is configured for your controller type?


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm conversion to a 16v (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Sounds like you're way rich, you using a wideband for tuning? If so, you sure it's calibrated and MT is configured for your controller type?

did not use the wide band, will do that soon. By the way whats a MT?
need_a_VR6 Ignore the above Q i saw your responce in another thread... cheers


_Modified by H2Zero at 1:42 AM 5-14-2008_


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## need_a_VR6 (May 19, 1999)

*Re: 4A-GE ITB's 45mm conversion to a 16v (H2Zero)*

Not using a wideband it's pretty tough to dial in quickly. You can enable the O2 correction and watch the % correct at low loads and try to dial the VE table in manually, or log and tweak it.


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## mxman (Jul 31, 2003)

*Re: 4A-GE ITB's 45mm conversion to a 16v (need_a_VR6)*

for a strong idle, more ignition advance will raise your vacuum, vacuum is measure in megatune or MT by kilopascals or KPA in megatune... by the way, low numbers are more vacuum and higher numbers are less vacuum. 25-35 is good for a stock engine for your car it's probably 60kpa or more. There should be a barometer, you can also goto "realtime display" in tuning or something and watch the gauges...
Anyways, some situations where you want to build vacuum....
1> 1st start of the day when the engine block is not heat soaked....
this is when the engine usually makes the worst vacuum and runs the worst... 
2> during warmup of the engine any time the coolant is below 160 degrees farenheit or F ... if you're in celcius thats like 80c?
3> idle, more vacuum at idle means the engine has a better seal and is probably inherantly making more torque..
remember guys, our friend here is apparently in malaysia so acronyms may not help him...
Most ITB cars make only 60kpa of vaccuum which is not much vacuum... another situation where they don't make a lot of vacuum is when it's got cams, unfortunately your car has big cams and itb's so it will make very poor vacuum.
Alpha n has nothing really to do with the quality of your idle so much. Your ignition advance table was 6 degrees advance when it was stock at idle. (at around 800 or 900 degrees.) You will now need more like 20-30 degrees of advance to make sure it idles properly.
One thing to remember, when the car is warming up, too much advance slows down how fast the engine heats up to operating temperature. I run my megasquirtted car in -30c -40c temperatures in winter so I want it to warm up very fast. If you give your car a lot of extra advance it will take a while to warm up. It sounds like you are driving it as a daily driver to work or something. 
I had the most vacuum with my stock car at 25 degrees i believe at idle fully warmed up to 160f or 180f. 
As far as fuel goes, when you get your wideband you're going to want to be around 13:1 air fuel ratio. Usually this makes the most engine torque at idle and most vacuum. You may want to wait to tune the idle air fuel ratio until you buy a wideband oxygen sensor setup like the innovate lc-1 or AEM Uego. 
A lot of advance makes the engine transition very fast around idle and can cause the engine to stall. So if you' are decelerating it may try and stall when you are coming to say ...a stop sign or something.
Hopefully this helps , I'll check in later!


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm conversion to a 16v (mxman)*

thanks for the help .... will try it out. Oh yes its my daily driver. If I understand you correctly I should advance the distributor slightly right? My car only idles louzy when cold... its GREAT when warm.

By the way can anyone advice me what throttle did you use for the conversion, I am currently using one from a toyota van which is not good as it catches on the return.


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## secondgen (Jan 9, 2004)

*Re: 4A-GE ITB's 45mm conversion to a 16v (H2Zero)*


_Quote, originally posted by *H2Zero* »_thanks for the help .... will try it out. Oh yes its my daily driver. If I understand you correctly I should advance the distributor slightly right? My car only idles louzy when cold... its GREAT when warm.

By the way can anyone advice me what throttle did you use for the conversion, I am currently using one from a toyota van which is not good as it catches on the return.

No, advance the timing in megatune. You should never have to move your distributor after the initial set-up and sync.


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## H2Zero (Apr 25, 2003)

*Re: 4A-GE ITB's 45mm conversion to a 16v (secondgen)*

dear all. I have dynoed my car at 154bhp and 130ft [email protected] The figures to me are lowish especially the torque, can anyone give me any pointers as what I have done wrong. For info the piping size of my exhaust is 2". Thanks.
Just a re-cap, 2.0L conversion with 9A crank, P&P, 272 degree can with ITBs.


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