Some questions about tuning

[carlukepeugeot]

Hi folks,

I know there have been alot of tuning threads, but I have read them all (that I can find) and still have some questions. Have a ph2 Dturbo on a lucas pump and top mount intercooler. I recently fitted a mumby MBC and did some pump tweaking and boost fettling. Basically I have adjusted the main fuel screw by turning clockwise about 90 Degrees, and I have messed around with the MBC to find that I must be fuel limited to about 16psi on full boost.

The car was much quicker after the tune compared to what it was - i had the standard 12-13psi before hand. Some things confuse me though, alot of guides I saw saw maximum adjustment on the fuel screw should be around 40 degrees, though many others where people have done '1 turn' or '1 1/2 turns' etc. Are the 40 degrees suggestions wrong?  If I did 40 Degrees the car would only be a little quicker than stock and even at 90 Degrees, its not *that* fast nor is the boost *that* high. If 40 Degrees was really the max you should do then I would have expected the boost on full chat to be way up at 24 psi or so, but as I say I am at a seemingly fuel limited 16 psi after 90 Degrees.

Also, the boost compensator. Most seem to say it does nothing, however on my car it does alot. It makes a large difference to spool up and if I wind it in much then the car lags alot. Any reason why I am seeing a significant effect from the compensator setting?  The thing that confuses me about this is that most say that you can reduce off boost smoke by adjusting the compensator. This confuses me since it's job is to add more fuel while on boost is it not?  

Also wondering how people have found their MPG to be affected by tuning. Pre tuning I got around 46 mpg fairly consistently. Post tuning, I think I am at about 43mpg if I am careful, but only high 30's if I use the extra power (not even ragging around alot, just say 50% of the time nursing the throttle, 50% driving quickly but not flat out). 

Just wondering if I am doing something wrong...

Cheers
Craig

[Doseph]

I would say get a Bosch pump but out of interest, I asked a good friend that used to be on here all the time and answered these kind of questions. His answer below:

The more you turn the more fuel it will use. By the sounds of how far you've turned the fuel up, I would bet it's smoking. smoking is wasted fuel.
What turbo have you got and what is it boosting at?

You could probably more out of it with more economy.

---

With the MPG thing, I drive a 205 with a XUD, standard k14 turbo (wastegate adjusted) and Bosch pump (wound up and with some mods).
I got 45mpg last time checked and this was a few hundred mile trip from east to west with slightly spirited driving.

[carlukepeugeot]

Hi thanks alot for that. No smoke at all. Like I said it's only fuelling enough with the 90 Degrees turn, to make 16 psi peak (flat out in 3rd / 5th) with the MBC set so that it's not opening, i.e. I am fuel limited at 16psi.

[Doseph]

Crank up the fuel until it starts smoking on boost and then back it off a tad?
16psi is pretty low. i think i run between 20-24 with a clean filter on WOT.
Maybe try a new fuel filter too? for veg i used to use a audi tt filter which plugs straight into 8mm lines.