Cooke, Brian (68 Bronco)

[nvrstuk]

Is there any way to get the engine rpms to drop quicker when the throttle is released? For street driving it's not an issue. Off road a split second of "unintended" rpm takes you into rock or dropping off a ledge when you were inching into it under power but now need to stop in a few inches. Makes a real difference.

[nvrstuk]

Here we go...

Immediately after the throttle hit the floor the AFR went to 15.4 and seemed to sit there for a couple seconds. Came down to 15 and 14.0 after several hundred feet of travel.

Got down into 13's after that. Wish I could video the tach and AFR at the same time. Maybe I could tape the phone to my forehead. lol

Have a good Sunday

[nvrstuk]

Better attach the datalog...

Didn't hit rev limiter so no .50 caliber lean pop... that was nice. :)

[decipha]

I reduced dashpot but without a vss or nds to know when the vehicle is moving or in gear its going to increase the chances of stalling at times. LMK if she gives you any trouble.

The backfire isn't a lean pop it's a misfire from cutting cylinders. Lean pops happen in the intake. Backfires happen in the exhaust.

This should make her happier. Load this in and shoot me back another driving around.

At 56 degrees when you cold started her the isc was maxed. When you put it in gear and it dropped down to around 700 thats the aboslute most the iac can give her. I would imagine its probably ok for another 20 degrees or so. If its below freezing out she will probably struggle to idle for the first 20 seconds or so and if you toss her in gear without letting her warm up for a minute or two she will probably conk out. I have no idea how to get an iac to flow more other than maybe finding a bigger design iac. You might want to check and see if you can remote mount an iac from an 99-04 mustang as they use larger lines. It may be possible to drive two iac valves as well wired in parallel. I'm not sure how much juice the ecu can deliver or if it will hurt the circuit but may be worth considering. You do have an actual motorcraft iac and not a standard products correct? How old is the valve itself?

[nvrstuk]

AFR's when I mashed the throttle were in the 13's. Seemed to get to 14 somewhere in there but I couldn't see what rpm.

I lost the first datalog after start up when the laptop slid and uplugged.

I did two WOT tests on this datalog. Hope that helps some.

I will let it get cold and do a cold start up in 35 deg tonight. So far no issues with cold starts. 7 deg next Tuesday so that would be a great test. :)

[decipha]

Yeah it leaned out from some old kam's saved in there. I wrote some code to min clip the kamrf's to prevent negative fuel trims for safety. Been wanting to do it for years and it just took me about 5 minutes to write lol.

I reduced the dashpot a smidgen as well to help her crawl more.

imaf corr
775 1.03
750 1.035
700 5
650 3
600 .98
550 .97
525 0
475 .96
450 0
375 .98

Load this in and shoot me back another.

let me know how she's running overall as well. Any better than the old tune that was on her?

[nvrstuk]

I just started driving her around this am. Getting a feel for how it runs. Seems to "pull" much more evenly if that's a thing. Power down in the lower band is much stronger and smoother. Didn't have that before. I'll run it harder tomorrow after I load this latest tune.

I'm liking what you've done so far. Much more responsive than what was there. AFR #'s are night and day different than before. I was getting very worried about washing cylinder walls with the tune I had.

[nvrstuk]

Went well. Mashing the throttle I am now at about 10.4 (maybe a little more) but instantly goes up to the mid 13's and seems to stay there.

I datalogged this warm up and first WOT. Then I data logged another decent acceleration then I did a WOT in 1st gear.

Attached both this data logs

[decipha]

Excellent. She looks great and the new code works perfectly.

This should have her more stable on tip in.

[nvrstuk]

Here's one long tune with 2 different WOT logs.

I have been driving the Bronco most of the day so it wasn't cold when I started but it was up to temp when I data logged.

First log hit 15 AFR the split second I hit WOT but was in the lower 13's within a split second. Ran fine

Can't tell ya much more. Definitely a hesitation at 4500 (or close). You mentioned that it could be the converter but I don't see how without shifting and applying full throttle the entire log? I don't understand how it can change unless the pressure in the trans is actually changing somehow??

Thanks