4JB1 Fueling Adjustment

[flatlander07]

After the EGR block off, front mounted intercooler, 14 psi boost, and 2.5 inch exhaust, particularly with the flapper deal omitted...is it possible to adjust the fueling with an exhaust pyrometer?? I'm a fan of post turbo for saftey of running a probe thru the impeller.
What should it run stock, and after mods, for max economy, least unburnt fuel, but not melt the metal parts??

[wbski007]

I don't know my pyrometer readings pryor to turning up my fuel and boost, I have my fuel screw turned in one full turn and my boost is running at 14 psi, my egt is running at 600 degrees F just going down the road, up to 800F pulling hills and when I'm pulling my camper it has gone as high as 900F on steep hills, you can safely go to 1100F all day and even 1200F for short periods as aluminum doesn't start to melt untill 1300F, I have my probe right in the exhaust manifold, putting the probe after the turbo is a good idea, but I don't know if it will give a lower reading there or not? The idea is a good one tho, as I never thought about the probe coming off a distroying the turbo, some food for thought, hope this helps.

[flatlander07]

Wayne,

Yea, the purists say ahead of turbo. I have a 2002 Dodge 3/4 Ton with HO 24V Cummins, and if you read enough, like on turbodieselregister.com, you can get a temp. drop across turbo general rule of thumb.

Your's sounds very good. Kinda low EGT's, maybe could run a little leaner, but just on the conservative side...AND with available WFO if needed in an emergency, at high power output.

Anyway, this is interesting. So how is your mileage?? Did you do all them mods I mentioned. What's your results on them, power and economy??

Jeff

[pig75]

The less fuel you give a diesel the cooler the exhaust temps are.
You can not run a diesel too lean. Opposite to a petrol engine

[wbski007]

Not pulling the camper I get around 30 MPG, pulling the camper I get 21 MPG which I think is great as I do carry alot of extra weight when traveling, such as 90 gals of fuel and lots of tools, camper weighs around 1600 lbs loaded, so my little 4 cyl has its work cut out for it, I did all the mods myself, for what it is, it does a great job pulling all that weight, no complaints here, I love my Isuzu.

[flatlander07]

Holy Cow,

And I recall, you have the 2.5 Liter. Not to belabor the inquiry, but how many R's can you continously do at high speeds feeling comfortable that you won't (as they say in Nascar) suffer from weak oil pan???

I'm trying to spin 2750 all day long??? Is that going to crash the mpg??

Also, did you advance the injection pump timing too with your mods...I thought I saw that as one of the things to do.

That is interesting about lean lowering EGT's. But I'm struggling to optimize mpg. And I've heard more power means more mpg...even if its more fuel.

Jeff

[geeves]

The Mus are doing 3000 at 100kph in standard trim the bighorn 2400 due to the longer diff. Both see around 8l/100km to 8.5l/100km. Max torque is in this range so this is where the engine should be most efficient. Dont worry about reliability They run the same engine in trucks at 3500 plus all day every day. Mine sees the rev limiter at 4200 just about every time it goes out

[wbski007]

At 65MPH I'm turning 2800 RPM, and doing that all day long is no problem, when I had my 2.2 I was turning around 3500 RPM to keep it at 65 but that was because it was a 4 speed and I used to do the all day long also and I put alot of miles on that little motor and it didn't seem to bother it one bit. I didn't touch the timing at all on my 2.5, just fuel, boost and bigger exhaust.