I have pretty strange idle hunting especially after engine all warm up. I took the car to my friend's shop and found out that the previous owner made a hole on the flapper inside throttle body.

I searched the forum and look like that is some kind of mod but I'm still scratching my head on why he did this mod .... what the purpose anyway other than giving me idle hunting problem.

can anyone please explain?

 

maybe the previous owner didnt know how to adjust his tps for the idling or knew that the screw in the throttle body adjusted idle. and just drilled a hole instead. im hoping not but i've never heard of this mod either! doesnt sound too reassuring.

 

Are you talking about the primary throttle plates or the double throttle plates past the the throttle body in the uim? Pics?

 

I heard of this too, but it has been a while. I don't remember the purpose of this "mod" though.

 

I had a chance to open this up again and take a picture

here it is:



let me know if anyone know what's up with the mod. should I leave it like that or replace?

thanks

 

replace the TB. That will cause a massive increase in air bypassing the throttle plates. Besides the ISC valve, the amount of air bypassing the throttle plates is normally adjusted by the air adjusting screw beneath the lower two studs. Whoever did that probably had an idle problem and didn't know how to fix it properly.

 

I'm fairly sure that's just a stock passage to the idle control

 

your TB is stock. Your idle hunting is due to other adjustment that you need to make

 

I dont see a hole in the "flapper".

 

no I was wrong about the flapper it's on the body. I wasn't around when my friend took it apart. yeah look like the guy try to fix the idle by thrilling the hole but the idle problem is still there.

so apparently this is not a useful mod. I think I'm going to replace it in a week or two to fix my idle problem.

 

once again, your TB is not modified. Look at the pic I posted showing the two stock holes that are in the TB before the butterflies.

 

yeah I see your point. The hole is bigger on mine and look like someone doing that purposely. I'm going to find a used part if it fix my idle problem, I would go for it.

 

I'm not sure what you're laughing about. I don't admit that I'm not mechanical stupid but I have a real problem and seeking for help. If you can help like others I would really appreciated otherwise don't be rude laughing

 

From what I can tell it looks stock, and stock sized. I don't think the hole is your problem. Is your idle extremely high? Or just hunts? There are lots of things that can cause hunting. Start by adjusting your TB, TPS, linkage, and dashpot correctly.

 

I'm pretty sure what they are laughing about

 

I had the 2nd gen TB in my head. That's why I thought it was messed up. I work with both types of cars and I get them screwed up in my head. The 2nd gen ISC is bolted to the primary runners and is fed directly from the airbox by an actual 5/8" hose. That's funny because I've actually done idle troubleshooting writeups...

 

I got the answer to my original question: is it a mod? and most of you said it's not. thank you for that. about my idle problem, it's not high. it's hunting when engine is hot enough. and it's not stable. most of the time it 1k rpm, when it's hunting it's 750->1k rpm. now originally I thought the hole is bigger which makes my idle unstable.

anyway thank you all. I hope I could close the thread otherwise more laughing coming... gee

 

tnn, what all is done to the car? Stock ECU? PFC?

 

stock ECU down pipe, hi flow cat and N1 cat back.

I'm getting PFC and 1300cc secondary sometime next 2 weeks or so. you were helping me on the other thread about that :-D

 

you better not drive that car until you get the PFC; you're boost is gonna be outta control!


do you still have the pre-cat on?

 

yeah I've been driving pretty easy because it's lean. I don't have boost problem because I still have my stock air box and IC.

 

tnn,

Do some simple checks for on your ground connections. You have the ones on the UIM, drivers side of the engine (near the plugs), one on the exhaust.... I've seen people forget the one on the exhaust and have the idle hunting (and I've personally done it myself as well).

BTW, is your airpump still installed and working?

 

Mahjik, thank you. I'll check the ground connections again.

The airpump is working. previous owner actually replaced new unit.

 

Check your clutch switch.

 

thanks Adam. will do. This forum is awesome, I always do appreciate all the info, help. btw I still didn't install your mod on my car yet because I don't want to do that before PFC. But I did replaced K&N filter for it.