Turbo 300 Update

[Emerald 74 4X4]

So I got my exhaust system installed and was able take the truck for a good drive to get it tuned up a little. Was able to get it to cruise ok with only a barely noticeable lean miss from time to time (almost seems like a timing problem more than a fuel problem). The initial acceleration is good, but then it tends to lean out when the MAP nears 15 to 0 inches Hg under load. Seems to want to run lean a lot and can hear pre-detonation under heavier loads.

Then my computer battery died and that was the end of tuning for the day.

I'm not sure how the ignition curve I have setup is doing well or not or if it is making it run leaner. I have not been able to make full on boost pressure yet as I'm trying to tune the under 100 kpa areas first. I do notice that the MAP reaches zero more quickly for only having 3/4 throttle though.

 

[Emerald 74 4X4]

I just thought about something this morning...

I originally was going to run 58 psi fuel pressure, but I had some problems with initial startup when I first was getting things started and idling about a month or so ago. I dropped the fuel pressure down to 45 (along with the ECM programming of course) to see if it did anything. It didn't but I never bothered to change it back yet.

This weekend, I noticed that after the engine has been sitting off when hot for a few minutes, upon startup it idles rough until I rev it up a little bit. Do you think the lower fuel pressure is causing the rough startup and lean miss under load when hot due to vaporization in the fuel rail. The 58 psi increase would take care of that if it is the case. I may have to try that and see what happens next weekend. I also need to get a new brake booster. (leaking when applied causing high idle and no brakes!)

 

[StrangeRanger]

45 PSI vs. 58 PSI will reduce your fuel throughput to 88% of what you intended. That could definitely create some lean conditions.

 

[Emerald 74 4X4]

Yes, if I didn't change the ECM programming to suit the pressure drop. Now that I think about it, I better make sure I did. Im almost completely positive I did because it is the base fuel calculation dependent upon injector flow @ X pressure and is the most important calculation to make the engine run even ideally let alone perfectly optimal. But I'm wondering about the low pressure more in regards to the heating of the fuel in the rail and vaporization causing inadequate fuel delivery and lean conditions.

 

[StrangeRanger]

Well, that is allegedly why Ford went to the effort of using a different FPR and smaller injectors rather than the same 19# injectors @ 39 PSI that they use in nearly everything else.

 

[Emerald 74 4X4]

Indeed...I'll have to try it out and see if I get a different result.

 

[Emerald 74 4X4]

Well I found out that I did indeed have too low of fuel pressure. The original gauge that I used must have been inaccurate causing my fuel pressure to be somewhere between 30 and 35 instead of the 40 to 45 that the gauge had measured.

So after using a gauge from my workplace that is trustworthy (and finding out the low pressure), I adjusted it to 58 to 60 psi and adjusted my primary fuel calculation.

Then I had to basically start all over and tune everything up to where I had it last weekend. I was able to get it to idle ok (still wants to hunt at idle and I'm not sure why yet) and I got the highway driving including moderate inclines dialed in to about 14 to 15 air fuel ratio. It definitely rides on the richer side from 13 to 14 when hitting an incline, but stays almost stoichiometric. It may have to go a bit richer for a little more initial torque for heavier loads though.

The inclines (at 60 to 65 mph) hardly affected the manifold pressure, or the throttle position which is a good indication that it will do well for towing.

Has anyone has any problems with "behind the seat" fuel tanks sucking air around corners? I feel like when I turned corners, it would start to slightly stumble and run lean, then smooth out. It was at a 1/4 tank plus, and then when I filled it up, I hit the highway, so i was not able to test it.

Anyways, now that I have it my my house I can work on it on my own schedule without driving 40 miles each way every weekend. Should see some good progress.