Engine running lean

[firdausasri]

Hi Guys,

I've just send my Polo for dyno yesterday after installing custom FMIC, intercooler and open pod filter. Guess what, the engine is running lean i.e. 1:14 @ 3-4.5k rpm, 1:13.5 @ 4.5k-6.5k. This is after I had installed custom intercooler, open pod filter and downpipe.

The increase of power & torque is very substantial this time around and I'm very sure it's not happy dyno because there's one Mk5 Golf GTI chipped running on the same sort of power that day:


Following are list of my mods on the engine (the rest are stock) so far:

1. Unitronic Stg1+ reflash
2. VF Engineer DV (relocated) (pictures)
3. K&N open pod with heatshield (pictures)
4. Mitsubishi Lancer Evo 3 intercooler with all new custom piping (pictures)
5. ECS Stg1 Clutch Kit
6. Custom 2.5" catless downpipe (pictures)

I'm seeking your advice on how I can fix this issue. Should I get 3.5bar fuel regulator, bigger injectors, bigger fuel pump? Or just another custom remap would do? Appreciate your help very much. Thanks in advance

[firdausasri]

On top of this, will it be compatible to put in these:-

1. APR Fuel Pump for Mk4 1.8T (URL)
2. 4 bar FPR for Mk1 TT 225 (URL
3. Genesis 380cc injectors (URL

[Spec83]

I am having a lean running problem at the moment too... any information in relation to the APR fuel pump would be great

[firdausasri]

I am having a lean running problem at the moment too... any information in relation to the APR fuel pump would be great

So I'm not alone then
How lean you're running mate? I'm thinking of installing 3.5bar FPR and perhaps 380cc injectors. APR Fuel Pump is the last resort hopefully. But these are only hunch to solve the problem....

[Plautos]

If I´m reading the graf right, the engine is runing lean over the max boost range.

So, you should try a 4bar fpr... I think it will solve your problem..

So I'm not alone then
How lean you're running mate? I'm thinking of installing 3.5bar FPR and perhaps 380cc injectors. APR Fuel Pump is the last resort hopefully. But these are only hunch to solve the problem....

[Spec83]

I am the same, running 0.94 a/f from idle right into the main load part of the curve causing all sorts of detonation problems... Have checked all the hardware I can with vcds and it all checks out so I dont know what else to do!!

I was thinking the next step could be FPR and/or fuel pump

[firdausasri]

Plautos,

Thanks for the ideas, I'll try to fit in 3.5 or 4 bar FPR.

Spec83,

My friend having the same problem too, changing 380cc injectors doesn't solve the problem. FPR and fuel pump is the way to go. So to the fuel filter.

[insanekiwi]

Try the fuel pressure regulator first - this basically makes the fuel injectors to work harder to bring up the injector rate from 280cc (I think it was factory) up to 310-320cc. This will be the cheapest way to approach things first.

[firdausasri]

I was about to install Turbosmart FPR unfortunately it didn't comes with fuel rail adapter. Got to wait again...

[firdausasri]

Hi Guys,

I finally solved this issue by installing 4 bar FPR and clean up the injectors. Stock injectors tested having 300cc or so is not enough to push for 210-220whp on 80% duty cycle. Next phase of upgrade would definitely be 380cc injectors and custom remap.