Engine Running Lean

[SMICK4D]

Hi there if anyone can help would be much apreciated. I have a problem with my r33 gtst rb25 have been running power fc for over 12 months now. First tuned it in winter by the way everything else is standard bar power fc and boost controller & hi flow exhaust & also front mount intercooler after tuning car, car drove awesome no tune problems ran 7psi low boost & 13 psi high boost did not have any knock problems & afr was perfect. Had dynoed & produced 305hp at the wheels.

When summer came around knock level was a bit more active due to the extra hole that had been cut in air box & no cold air induction on air box due to intercooler pipe in the way & motor sucking in all the hot air under the bonnet. Coming up to christmas changed ecu,s back to standard so could run 95 octane. Due to could get for cheaper fuel through work to save money & purchased a HKS pod filter & cold air induction hose to mount pod filter outside of engine bay under guard.

After christmas fitted pod filter & refitted power fc took for drive found knock level out of control. Took to dyno to tune found engine leaning out badly had to raise fuel map severly to stop knocking on, 7 psi since then have fitted 255l/m walbro fuel pump & cleaned & flowed injectors found ok re dynoed still no good, checked fuel flow & pressure found really good.

After many many hours of wiring checks & self diagonistics check on standard ecu with no fault codes tried to run HKS pod filter with standard ecu still leaning out even when filter fitted in engine bay have changed with 3 different air flow meters still the same when crimp off return fuel line to richen up find ok since then refitted standard air box with k&n panel filter & checked afr found ok drives ok & does not lean out. However when idling & remove air filter instantly leans out put back in richens up pull back out leans out this is not right, should not matter if air filter is fitted or not. Since driving with standard air box fuel ratios dont stay consistent range from 14.5 to 11.6 on cruise would like to know if anyone would know how to fix this problem.

[Guilt-Toy]

anyone have any ideas? I am lost.

[stolen_s15]

Very odd mate! So it works ok with stock airbox? If so just keep that in.

[rob82]

Check for a tear or a hole in the intake pipe to the turbo - between the AFM and turbo. Sounds like you may be disturbing a crack in the pipe everytime your change pods.

[PLYNX]

Is the HKS pod filter a oil impregnated one ? That is one you clean after a certain amount of ks wash with a special solvent then re oil ?

[Bumblebee]

it will always hunt on cruise and idle... it'll go from rich to idle back and forth.. thats very standard and i see it every day on stock to highly modified cars

Dont worry so much unless it leans on under fullload and i mean leaner than 14:1 under full load.. that could get very dangerous

[SMICK4D]

Check for a tear or a hole in the intake pipe to the turbo - between the AFM and turbo. Sounds like you may be disturbing a crack in the pipe everytime your change pods.

hi rob i thought of that to but cant find any hole or split in turbo intake tube thanks for suggestion though

[SMICK4D]

Very odd mate! So it works ok with stock airbox? If so just keep that in.

hi nick i no it sounds wierd seeing though every second skyline getting around has some form of pod filter or after market filter i just dont under stand the reson for doing it is to mount air filter out side engine bay because lets face it any one who just bolts a pod filter on in the engine bay and thinks that there car is going to go better is kidding themselfs because we all should no the only way to make good horse power is with cold air engines do not like hot air at all thanks for reply talk later

[SMICK4D]

it will always hunt on cruise and idle... it'll go from rich to idle back and forth.. thats very standard and i see it every day on stock to highly modified cars

Dont worry so much unless it leans on under fullload and i mean leaner than 14:1 under full load.. that could get very dangerous

hi matias i would like to here more of what you have to say on this subject on the dyno with hks pod filter on had to raise numbers fairly high just to stop from leaning out on 7 psi boost as apposed to the orignal map in the pfc with standard air box and the problem is that there wont be enough numbers left when its at 13 psi boost when there was with standard air box it also seems to hunt a bit at ilde though with standard ecu and it never did that before it you can help just let me know and ill give you a contact number to call or you leave me a number i can call you on thanks heaps mate

[SMICK4D]

Is the HKS pod filter a oil impregnated one ? That is one you clean after a certain amount of ks wash with a special solvent then re oil ?

hi there yes it is and i have already washed it right out so there is no oil in it and cleaned the afm but no change thanks any way

[DECIM8]

Perhaps the stock box was sucking jack all air, the pod is sucking alot more..

Sucking more air but not giving so much fuel? try increase injector flow and see if it helps.. If it does maybe get your injectors flow tested, cleaned and reinstalled.

Just an idea, I cant work it out either