25 replies to this topic

[Muda]

Ya know, when the Hawk comes off the lake it can do a lot of strange things. But I had a 1.6 for 4 years and it had a wide band in it for all of those years. And when it gets hot I've got to lean it out and when it gets cold I've got to richen it up. Wasn't till last season when I put in the fuel pressure regulator that I got to do it that way but it's the same game.

Why do you think they set up the stock computers so pig rich? It's so you don't do damage in lean conditions, i.e. cold weather. My street/track Cooper S used to pick up 20 hp in the Winter, or was it lost it in the Summer.

[Funracer]

the answer to your question is if you turn the allen screw clockwise it will raise the fuel pressure, and like wise if you screw it out it will lower the fuel pressure.

This is correct. Usiing the KISS rule easy way to remember is "Lefty leaner, Righty richer".

[Tom Sager]

Colder air = more oxygen per unit volume, requires more fuel. If you don't add fuel you will be LEANER than you were when it was warmer. Warmer air, you run richer.
Unless it's different on this coast.

This is true except that the air flow meter and ECU (at least on a '94/'95 and a '99/'00) compensates for the cooler air temp and in our case over compensates. In other words, the engine management system richens the mixture more than desired as outside air temp drops so we have to reduce FP to get back to the best A/F. Without a restrictor plate the engine management system might compensate better than it does for weather changes.

[Muda]

OK then, put in a wide band and adjust to taste.

[Tom Sager]

So lets say you dyno at 70 degrees, if you get to the track and it is 45 degrees, odds are you will be running rich...leaner if it is 100 degrees out...correct? So in theory, if you dyno on a really cold day and a month later run the car on a really hot day(maybe 60 degree swing)could you run lean enough to hurt the car?

I don't think it would be lean enough to hurt our cars if done for a session or two. I don't think temperature is the only factor. I've made notes on FP settings for a given temp and then had different A/F results at another event at the same temp and FP. Other variables are humidity, barometric pressure, altitude and of course the fuel itself. Drag racers are a good resource on getting coached up on this.

[Jim Drago]

I run a wideban and log it to traqmate.. Then look after the session and make adjustments if necessary.

Jim