My Interesting problem...

[Quick Nick]

I have been running my car for about 3 months with this issue now and thought I would report.



Since I got my Tong Hybrid back from Turbo Dynamics where it was further hybridised (is that a word?) on stock ecu with fcd, mbc and rrfpr, it was rolling roaded where the engineer told me it is running lean at anything less than 4 BAR fuel pressure. This is for low boost about 7-8psi.

This seemed a little high (understatement) to me and I was getting probably about 15mpg so it was ludicrous. I since turned down the fuel pressure slightly to about 3.8BAR as I know the fuel pump (stock) and even the injectors wont last long at that level.

For about 2-3 months I have been driving around, not ragging it butdriving normally, and getting about 180 town driven miles out of a tank. This seems to be just over 20mpg and so clearly isnt right.

I know the only solution is to get it completely mapped with a new ECU but this is not an option at the moment. I am about to order an uprated fuel pump as this has been on the to do list for a while, but will the uprated pump will help bring down the required fuel pressure or will it simply run the same amount of fuel at 4 BAR but not be as near to its limits as the stock fuel pump?

In short, is my stock fuel pump knackered and that is why the required pressure is so high to get the right amount of fuel in? Or is it simply a crazy turbo that needs that amoun of fuel? I cant imagine it is the latter..

 

[ktl]

it wont be the turbo mate, so your maybe right in that sense. its worth sticking a new upgraded fuel pump if in later you do want to run more boost.

go from there thought but 4bar of fuel is alot, running 1 bar on a ct9 and at 3.1bar of fuel was overfueling my car.

 

[danb87]

i had mine an around 2.7 bar of fuel at a bar on my ct9, an that was after it was setup on the dyno an that was runnin rich too be safe.so id say 4 bar is slightly too much aswell.

since fitting my hybrid ive had mine at 3.2 bar, an after a wide band test thing, it was ruunin 11s which i was told is good. (dont wuote me on this tho im not an expert of the fueling)

 

[turbo head]

Get something like a HKS afr and get it set up by someone with the fpr and fcd and uprated fuel pump. if you keep going as you are i cant see your engin lasting too long imo

 

[Stu-]

Sounds like whats happening is that is over fueling everywhere except at full boost/high revs.

How have you got your rrfpr set up? Stock reg still in place the rrfpr plumbed on the return to the tank?

 

[TurboDave]

I'd get a second opinion on the AFR's as a stock ecu, fpr, pump and injectors wont have an issue fueling a hybrid in what ever guise at 7-8psi.

 

[Stu-]

Totally agree - wideband check would be the best thing to do.

If the rrfpr is in place of the stock reg then it will be a big cause of the problem. If its plumbed after the stock reg then things should be fine as it will only increase the fuel as the boost rises.

 

[TurboDave]

Totally agree - wideband check would be the best thing to do.

If the rrfpr is in place of the stock reg then it will be a big cause of the problem. If its plumbed after the stock reg then things should be fine as it will only increase the fuel as the boost rises.

Having a RRFPR wont cause the problem if it has replaced the standard FPR, the base fuel pressure is set and then it raises in line with the inlet manifold pressure.

 

[Stu-]

Understand what your saying but it depends really on the reg. As this setup is with a stock ecu the difference in pressure ramp ratio between a stock reg and the aftermarket reg could be causing over fueling for low/mid revs/load. By using a stock reg as well as a rrfpr then you have the best of both worlds - normal driving and fuel usage off boost and then the benefit of additional pressure when the boost comes on. With the base pressure set so high there will definitly be overfueling which will be causing both bad fuel usage and robbing of power.

Given an aftermarket ecu then there should be no problems with running a rrfpr reg only.

 

[Stulet-GTT]

I would uprate the fuel pump then turn down the fuel pressure, im not fully sure but i have read on hear an seen alot that people only run the fuel pressure at about 2.7bar...

I would take the car to somewhere else aswell, maybe someone with abit more knowledge about the turbo side of cars an get it re-set up again...

 

[TurboDave]

Understand what your saying but it depends really on the reg. As this setup is with a stock ecu the difference in pressure ramp ratio between a stock reg and the aftermarket reg could be causing over fueling for low/mid revs/load. By using a stock reg as well as a rrfpr then you have the best of both worlds - normal driving and fuel usage off boost and then the benefit of additional pressure when the boost comes on. With the base pressure set so high there will definitly be overfueling which will be causing both bad fuel usage and robbing of power.

Given an aftermarket ecu then there should be no problems with running a rrfpr reg only.

Thats not true buddy, if the standard reg is in place regulating the fuel before it gets to the uprated fuel reg then how is it going to ever see any more fuel to raise the pressure with?

I have never ever heard of anybody running a standard and aftermarket FPR together it defeats the point.

 

[Quick Nick]

OK, the standard FPR has made way for the adjustable one. I have never heard of anyone running both, realistically I didnt know that was ever done. Interesting that nobody else has really had this issue, I had the car on the rollers with an excellent tuner, highly reputable and when it went in the AFR at 2.5 BAR was 18 and didnt get down to 11 until 4BAR fuel pressure.

It makes sense that it would be running rich off boost throughout, as rrfpr are a very simple and crude way of upping the fuel pressure, but I still cant understand why everyone else runs a good afr at 3 BAR fuel pressure with the same mods.

I was hoping that fitting a walbro fuel pump or similar would allow me to turn down the fuel pressure, I was thinking perhaps it needed turning up so high because the pump was knackered and therefore not returning much more fuel despite whacking up the pressure. If this is the case then simply fitting an uprated pump may help the problem.

Thinking outside the box I also have a massive front mounted air filter which will be bringing in loads of air, and this may simply be too much air coming in compared with the amount of fuel delivered. You think this is feasible and getting a smaller air intake would help? In theory it would run richer with a smaller intake.

 

[sx_turbo]

you cant run the stock fpr and an uprated fpr, the stock one will cancel out the adjustable

 

[TurboDave]

Size of the air filter will make no difference as the amount of air entering your engine depends on how much your turbos compressor can flow.

Have you ever had your injectors sent away and cleaned or tried another set?

 

[Quick Nick]

Size of the air filter will make no difference as the amount of air entering your engine depends on how much your turbos compressor can flow.

Have you ever had your injectors sent away and cleaned or tried another set?

Thx Dave. Havent had my injectors sent away but they looked tip-top when they were out the engine a few months ago, so i doubt it would be that. I keep coming back round to the stock fuel pump.

In theory at the same pressures would stock and uprated pumps offer the same amount of fuel or would uprated offer more at the same pressure? If its the latter, then I am hoping the new pump will allow me to turn down the pressure, although also in theory this may not help my fuel consumption but may help the engine life-span.