40 replies to this topic

[Simon]

Hi all, I have a 4g93t in a Satria Gti whic i recently took it on the dyno to check on why the car isn't producing any power past 4.5k rpm.

Car produced 120fwk on 13psi at 4.5k rpm then the power curve flat lines. I couldn't get the dyno graph as the printer ran out of ink but the car was running extremely rich.

So far I'm thinking that it could be the 02 sensor (4 wire), AFM (gsr), ecu (jap gsr)?????

Your thoughts and advice would be greatly appreciated.

[EVL20T]

How rich, what were the a/r reading?

[Simon]

Can't remember exactly what the tuner said but it was pretty bad. Line hardly showed up on the dyno.

[nwr31]

do you know what ecu it has? i had a mines ecu & it was stupid rich (around 10)

[GSR]

O2 sensor wont fix your afr at wot..
As mentioned above what ecu are you running? Standard ecus are mapped fairly rich, especially in the top end.

attached are fuel maps found in standard cc gsr (4g93t) ecu

Edited by GSR, 05 July 2011 - 02:31 PM.

[EVL20T]

He says its running jap gsr ecu

I know my evo ecu ran mega rich around 9.8 standard lol

Being a jap car I would assume the 1.8 turbo ecu being very similar

What fuel pump u running?

[GSR]

are you still running standard turbo? and what are you using to control the boost?

if you still have a standard 13g td04l and a bleed valve to control your boost,
then you're most likely making 13psi fairly low at the rev range and it drops dramatically
as it reaches the redline (probably back to 9psi) and thats why your power flatens out after 4500
and feels like its not making any power.

dyno graph would really help to eliminate the above possibility.

[nwr31]

i took all those ?????? to mean he wasnt sure

[EVL20T]

Maybe he isn't lol

[Smutt]

What Fuel Pressure Regulator are you using? a rising rate 1 to 1? or higher?

You might have one that is too high.

What pressure is your idling fuel pressure set too.. this might be too high as well as the above..

[Simon]

Car is not fitted with an aftermarket fuel reg.

[GSR]

Its good that you'll replace your O2 sensor if yours is not working or its old and lazy because that will fix your fuel economy but unfortunately it wont fix your rich afr problem at full throttle.
ECU looks at O2 sensor only when in closed loop mode and to be in closed loop mode certain criterias are to be met such as amount of airflow and position of your throttle.
Those criteries are set quite low because closed loop mode is intended to be used for light engine loads (idle, cruise) and as soon as the ecu see anything above those set values it puts its self in open loop mode.
For example as soon as you put your foot down (like you do when you perform power run on a dyno) ecu is no longer in closed loop mode and disregards O2 sensor.

What colour are your injectors?

Edited by GSR, 06 July 2011 - 03:33 AM.

[Simon]

Standard turbo is still being used. The parts listed in brackets are the current parts on the car. Duel stage boost controller is being used but the same problem occurs on low boost which is set at 9psi.

Turbo is spooling without any issues and it doesn't seem to be loosing boost from any leaks which iv heard is another reason from running rich.

I also called RPW and spoke to David and first thing he said was 02 sensor. Iv bought on and have it ready to be installed tomorrow but wanted to see what you guys thought as well.

This is the first time the car is doing this as with the previouse owner, it was on the dyno and made 130fwk on standard boost.

Injectors are the factory GSR yellow - 390cc and the car has been fitted with a walbro intank fuel pump.

Edited by Simon, 06 July 2011 - 04:29 AM.

[GSR]

Im assuming you say yellow because the original white has turned into light yellowish colour due to its age however if its a proper/strong yellow yellow like in the picture attached then you have 510cc injectors and that is the cause of your rich air fuel ratio.

Edited by GSR, 06 July 2011 - 04:35 AM.

[Simon]

Im assuming you say yellow because the original white has turned into light yellowish colour due to its age however if its a proper/strong yellow yellow like in the picture attached then you have 510cc injectors and that is the cause of your rich air fuel ratio.

Nope, not that yellow. I have spoken to the original owner and he confirmed they are the standard GSR injectors. When the problem was seen on the dyno, the injector size was the first thing i questioned.

[EVL20T]

Its just the stock maps from the ECU chipe your stock ecu or get an aftermarket ecu and be done with it

[GSR]

I also believe you dont actually have a problem and rich afr is purely because the standard ecu is mapped that way.

Heres a dyno graph I have found of a standard cc gsr with exhaust and bleed valve, power was also droping badly after 5k.

Attached Thumbnails

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[BMGTZ]

I am thinking that walbro has a bit much grunt for the standard fuel reg. I have used the walbro in a few cars and over time seen the standard reg slowly fail.

try another reg if you can borrow one....or get a sard reg.

[nwr31]

I also believe you dont actually have a problem and rich afr is purely because the standard ecu is mapped that way.

Heres a dyno graph I have found of a standard cc gsr with exhaust and bleed valve, power was also droping badly after 5k.

that graph is not much use tho, cause it doesnt show afr's - just a shockingly bad boost curve which is whats probably causing the power drop in the top end in his case.

[GSR]

Its not that shocking, its a very common boost behaviour and power output by an engine thats equipped with relatively small turbo and a bleed valve.

Anyhow, heres another example shows afr and boost. Notice how the power reaches almost its maximum around 4800rpm and stays pretty flat up to almost 6000 and starts droping over 6k. Air fuel ratio is kept around 12:1.

http://www.rpw.com.a...turbo&Itemid=40

Yes the boost is a little unstable, but I bet you if the boost was reached to 12psi earlier and stayed flat to as long as it can the power would also reach to around 160hp earlier and would just stay flat in the same way and it would probably start droping even earlier.

I would still love to see his dyno graph as I dont think there is a major problem with his car from the information we've collected so far

Edited by GSR, 06 July 2011 - 09:01 AM.