VN running very rich

[333]

Gday to all,

Im a new memember and have a question for all, as i am at a wall. the mods to my commodore are as follows (for now anyway) CAI, a resistor hooked up on the temp sensor which did a little for power, i have a resistor over the IAT sensor, smashed the cat out for better flow, these all worked fine untill i took the elbow off the manifold and machined it out dont know exact amount maybe up to 72mm from the standard 68mm although this increased horsepower (seriously it did) its now coughing when its first started then idles up, its running hell rich too, is there anyway to increase airflow as i assume that its now getting bulk fuel no air. Or is it the fact im still now using the standard throttle body 65mm. Im at my wits end. any suggestions would be greatly appreciated.

[Not_An_Abba_Fan]

Number one: Resistor, this tells the ECU to put more fuel in. Result: running rich.
Number two: Gutted cat, this affects the O2 sensor, no cat-sensor reads lean. Result: running rich.
Number three: Resistor on IAC sensor, this tries to keep it closed too much. Result: Idling rich.

Apart from being illegal, smashing the cat out really does bugger all unless you run the thing consistently above 5000 rpm. The other mods you have done all contribute to it running rich. The sensors are there to do a job, if you trick them into giving the wrong signal to the ECU, how can your engine run efficently?

[333]

Mate thats what im saying. is there a way to get more air as im getting to much fuel. yes maybe true its all illegal but 19s make a car illegal 2.

[J_D]

Your not understanding how this works. The computer regulates the amount of fuel supplied to the engine using various sensors (which you have put resistors on). Even if you could get more air into the engine the computer will just put more fuel in to compensate. You need to take the resistors off the sensors and let the computer do its job of regulating the fuel supply.

[Morton]

They're right. You can't fool the car into pumping in more gas, then try to find more air. It's the other way around... that's why we have forced induction.

[333]

Thanks for your help although fixed it today by drilling a small hole into the butterfly, seems to be running fine now. once again thanks

[vt1538]

Fixing one Fcuk up by adding another. Well done.

[Not_An_Abba_Fan]

A resistor to reduce the amount of air let in at idle, then drill a hole through the butterfly giving you the exact same result as removing said resistor......hmmmm.

[vt1538]

Should be a lot of fun when trying to coast to a stop.

[samuels]

A resistor to reduce the amount of air let in at idle, then drill a hole through the butterfly giving you the exact same result as removing said resistor......hmmmm.

LOL....guess someone will be seeing him on the side of the road,or see it on a back of a tilt a tray..

[333]

like i said thanks for your help

[samuels]

like i said thanks for your help

hey you fixed it,these kind people offered their thoughts...you deal with the consequences ...i'm sure i saw a disclaimer under all their sigs

[333]

think about it, the temp resistor is there to tell the engine its cold in return, more air/fuel ever wonderd why the air intake sound is louder when cold. The iat resistor sensor yeah may not do much but what the hell its fitted, maching out the elbow is in preperation for a bigger throttle body, do you people even know what your talking about. yeah drilling a hole in the butterfly did pickup the revs a little but its working. I put my foot down without holding on the brake and instant smoke from tyres.

[samuels]

think about it, the temp resistor is there to tell the engine its cold in return, more air/fuel ever wonderd why the air intake sound is louder when cold. The iat resistor sensor yeah may not do much but what the hell its fitted, maching out the elbow is in preperation for a bigger throttle body, do you people even know what your talking about. yeah drilling a hole in the butterfly did pickup the revs a little but its working. I put my foot down without holding on the brake and instant smoke from tyres.

well it would make sense on a carburated engine,but seeing as they don't have these kind of resisitors,makes no apperent sense,have you ever wondered yourself...now why would my intake sound so loud when cold??? think about that one!

[vt1538]

think about it, the temp resistor is there to tell the engine its cold in return, more air/fuel ever wonderd why the air intake sound is louder when cold. The iat resistor sensor yeah may not do much but what the hell its fitted, maching out the elbow is in preperation for a bigger throttle body, do you people even know what your talking about. yeah drilling a hole in the butterfly did pickup the revs a little but its working. I put my foot down without holding on the brake and instant smoke from tyres.

Actually there are a few on this forum that know what there talking about. You obviously know very little about efi engine management otherwise you wouldnt have done what you did.
For starters that so called resistor trick only works until until the engine works out whats going on & trims back the fuel.
Your next big fix will fcuk up the way the IAC stepper motor controls idle speed & will cause many drivability issues.
If you want more air in the engine get a bigger cam, some head work & a good exhaust. Once you can use all the air that the intake can flow then make the other mods ie bigger or bored out throttle body etc.

[333]

I didnt mean to p*ss people off all i wanted was advice it was only since machining the elbow out it was getting to much fuel, this is why i asked the question most who replied were pushing the fact it was the sensors (which i did take on board and thanked u for) as it had been running the resistors quiet well untill i refitted the elbow. process of elimination. i needed the car on the road as quick as possible hence drilling the hole.

[PaRaDoX]

Number one: Resistor, this tells the ECU to put more fuel in. Result: running rich.
Number two: Gutted cat, this affects the O2 sensor, no cat-sensor reads lean. Result: running rich.
Number three: Resistor on IAC sensor, this tries to keep it closed too much. Result: Idling rich.

Apart from being illegal, smashing the cat out really does bugger all unless you run the thing consistently above 5000 rpm. The other mods you have done all contribute to it running rich. The sensors are there to do a job, if you trick them into giving the wrong signal to the ECU, how can your engine run efficently?

agreed..........

i bet it still runs 16s tho :P

[vt1538]

Going back to the original problem. If the car only used excessive fuel after you machined the elbow you have stuffed up there somewhere. There is more than likely a vaccuum leak causing the computer to add more fuel.
Drilling the throttle body should only make this worse as idle vaccuum will still be down. Remove the elbow & check all your seals etc for damage.

[333]

true may run 16s may not but you gotta start somewhere how do you think a turbo was invented some dude spent his time listeing to people like you who knocked him for trying to force more air fuel into his engine, now after getting it right the same people who spent there days knocking him pay him thousands of dollars enough said.

[333]

And Vt1538 it was a vacum hose slipped down behind the engine, fitted it back on running heaps better and idled down a bit although still has a hole in the butterfly. thanks for your insight much appreciated

[Not_An_Abba_Fan]

true may run 16s may not but you gotta start somewhere how do you think a turbo was invented some dude spent his time listeing to people like you who knocked him for trying to force more air fuel into his engine, now after getting it right the same people who spent there days knocking him pay him thousands of dollars enough said.

Turbo's were actually developed for aeroplanes because the air density at altitudes wasn't enough to keep the engine running. A turbo was invented to force more air into the engine so it had enough power to keep it higher in the air. The next logical step was to bolt one on a motor vehicle to boost it's power.

[AirStrike]

This thread is too funny......'hey all I have installed some performance $15 resistors off this power seller on ebay and now my car wont run correctly'

[333]

mate its got nothing to do with the sensors as for where i got the idea it was in a reputal magazine you all might be familiar with, its running fine now, it was a vacum hose, and as for the turbo invented for planes, you are all missing the point, its the people who think of new ways to find power (granted maybe thousands of people who have done it all b4) that you people pay including me money too.
think,
cams
heads
throttle bodies
custom tuning
boreing the block out
ect
do you actually think these things just worked. trial and error boys and girls.

[AirStrike]

mate its got nothing to do with the sensors as for where i got the idea it was in a reputal magazine you all might be familiar with, its running fine now, it was a vacum hose, and as for the turbo invented for planes, you are all missing the point, its the people who think of new ways to find power (granted maybe thousands of people who have done it all b4) that you people pay including me money too.
think,
cams
heads
throttle bodies
custom tuning
boreing the block out
ect
do you actually think these things just worked. trial and error boys and girls.

Are you listening to yourself mate? People pay hundreds of dollars to get there cars tuned to get optimum AFR's ect, but you can do it with a resistor, please.

[333]

Mate i aint talking about resistors. its got nothing to do with resistors, granted ive fitted them many people on this site probaly have to. did i say i could tune a car by fitting a 2 dollar resistor no. fools rush in where angles fear to tread, sometimes the fool comes out on top, sometimes not. am i saying to everyone on this site to rush out and do this mod/trick no. but when it comes to running another slightly modified Vn i might have an edge i might not.