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supercharged 5.0 true fire 98 explorer sport

I remember you telling me James had a similar issue tuning turdle when you had it and it was something he found with the egr system, but had to do a lot of digging. Guess he never told you what he did eh?

Not quite. I had a surging idle after slowing from highway speeds while rolling. No issue while sitting still and idling. The issue was in the fuel injector -engine braking cycle ( he used a different term though)
 



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Not quite. I had a surging idle after slowing from highway speeds while rolling. No issue while sitting still and idling. The issue was in the fuel injector -engine braking cycle ( he used a different term though)

Ah, ok well that does still help
 












It does, but it's almost at the point or is at the point where it wants to stall. I know what what your thinking, big cam, lumpy idle, but don't think that's it because when in park or neutral it smooths out

No, mine did the same thing. The only way I got it to stop was at the dyno. I was told with the large cam it is hard to tune away, but it is possible. Mine is great now, but once in a while when it is on the cooler side and I grab drive after being in park, the engine dips really low to the point I think it might stall and then recovers after 1 surge.
 






Andrew, what is your idle set at in idle and drive? Im hoping you have that somewhere.

The fact that this issue was tuned out for you, I think Tim and I will try playing with the injector timing a bit at low rpm and see if this helps.
 






I am 95% sure it is around 950 - 1,100 RPM in neutral or park and 900 RPM in drive.
 






Idle RPM

Dono,
What is Tim's idle set to?
Most were set to 650 or something ridiculously slow like that.
Take it up to at least 800 in drive. If that doesn't work try a little higher.
I am not surprised that Ahodges would be around 900 in drive, Tims may have to be there also.
Make sure the TPS readings are steady.

Tim you should try to use the stock m112 plenum and throttle body with TPS, they would be a great upgrade. See if you can figure a way to hook your EGR tube to that stock cobra plenum.
 






off the top of my head i think we set the idle around 800rpm in park, and 750 in gear. its definitely no where near 1000 in park, and 900 in gear so that will be a easy change to make. mine and andys cam's are almost identical if i remember correctly. i just cant remember how his idled because its been 2 years since i have seen him.
i had also looked into getting a tps for a cobra in the fall, but on rockauto they only list one part number for them, and i dont know if its the correct one or not (that and i would have been able to use the explorer plug end, and a cobra one if i am not wrong is also in the voltage rage as a explorer).
now for the elbow...

12516233_10153422612162513_1761222743_n.jpg


i happen to have one from when i brought a m112 back for simon last time i was down at afn. see the problem, headed right into the heater plenum.
i am also looking at the thread that don posted. one thing i forgot to check (and i hope its not going to make don rip his hair out at me) was to recheck my fuel pressure at the gauge on the regulator. if i am not wrong, it should be 42lbs running at idle with the vacuum line off (trickflow rails, and fpr). if its lower then that, i hope i just didnt throw all dons hard work away with the tuning he has done to date.
 






Yea, we had idle too low. Tim upped it to (I think) 900 in gear, and 1000 in park.

Im really struggling with maf transfer function from the transition from closed loop to open loop. The numbers get strange and hard to follow.
So, Tonight we created a wot file with everything but the startup load up to 1200rpm at an a/f ratio of 11.6. I am hoping that this will give me easy numbers to set the maf transfer function with.

Tim's a champ working with me. I'm learning also, so he gets to live some pain of the learning curve.
There is still some hesitation for a moment when Tim goes wot. The a/f ratio isn't far off, so I'll be interested as we fine tune what happens here. Each a/f adjustment seems to bring better drive-ability (And loss of traction).
Tim said there was some pinging at 3500-4000 range so we pulled 3 degrees advance out (I hope I have the terminology correct here) at the wot load in that rpm range. For interest sake, this load level is at .8 in this range. I think we dropped spark to 11 (21 total). As rpm's increase from there, we are at 14 (24 total).


With both our trucks set to the multiplication factor for a 347 displacement, we are both under a max load of 1. I think we can sneak over that number a bit as we continue fine tuning,
 






The fuel pressure isn't an exact science. 40 - 42lbs is a good starting point. The higher the pressure, the less flow you will get from the pump, but better atomization, and also in theory higher fuel temps. Mine is set to 40 or 41psi.
 






Fuel pressure

Ford targets fuel pressure on most vehicles to be 39.15 (with an accurate gauge). Some were 65 psi if I recall, on mechanical returnless fuel systems.
Your returns systems on the 5.0 should be 39.15.
If you change it from there you are supposed to scale the injector high slope, low slope, and break points in the tune. Having fuel injector data precise is critical.

It is correct to say that the fuel pressure should be adjusted with no vacuum to the fuel pressure regulator. I have found that the most accurate way on my truck is to do it with a jumper wire across the relay to run the pump, and have the key on but engine off. I have come to this conclusion after trying all kinds of different things to get my O2 monitors to run and pass for state inspection.
 






Ford targets fuel pressure on most vehicles to be 39.15 (with an accurate gauge). Some were 65 psi if I recall, on mechanical returnless fuel systems.
Your returns systems on the 5.0 should be 39.15.
If you change it from there you are supposed to scale the injector high slope, low slope, and break points in the tune. Having fuel injector data precise is critical.

It is correct to say that the fuel pressure should be adjusted with no vacuum to the fuel pressure regulator. I have found that the most accurate way on my truck is to do it with a jumper wire across the relay to run the pump, and have the key on but engine off. I have come to this conclusion after trying all kinds of different things to get my O2 monitors to run and pass for state inspection.

Tim, I would believe this before you believe me!
 






Tim, I would believe this before you believe me!

Agreed. It's kinda hard to argue with someone that has done way more with way less then the both of us lol
 






BTW, check out this picture from a Corral forum thread(Dart 365 - NA vs Whipple). Someone in NY has a 79 Mustang with what looks like a 94/95 front dress, and a TVS blower centered with the discharge going out the back and to an IC up front.

He(Jess) just started it so it needs some work of course. But that's an interesting way to mount the blower and include an intercooler. That could work in an Explorer, and maybe easier than my route. I love seeing new ideas.

http://s1063.photobucket.com/user/R...3-4A6F-93AE-4BBD6DBD9619_zpsalhxo5fm.jpg.html
 

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  • SN95 IC with centered blower.jpg
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ill give the guy a "A" for effort, but a not so par grade on the finish welding on that intake. thats me however. anyone that has seen the under hood of evil in person will agree i am pretty picky of how it looks.
so i just went for a dataflog run. bumping the idle up was the trick, but i think it might be a little to high (set it at 900). i am going to slowly creep it down some (park is at 1000). i will share that other findings when don has a chance to look at the log and tell me what is going on. nothing bad thankfully however.
 






I don't know what your stall is on your converter which could make a difference. It obviously takes some of the lump out of the sound but it is still aggressive. My stall is such that it really doesn't go anywhere fast until 2,000+RPMs
 






the stall is a 2600. funny you stay around 2,000 rpms, because driving the speed limit with the o/d off in town it is sitting dead on 2,000.
oh, i also forgot to mention. i checked the fpr. with the vacuum line off, its around 42, with it on, its at 39.
don did make some more adjustments for me. one was a total wash lol, but he figured it would be. he was playing around the spot when it goes lean when you first nail it. it still has a little ways to go (i think), but he's doing a bang up job. his parts came in for his motor, and he dropped them off today. he had mentioned they said it should be ready next week. if thats that case, i will be banging on his door to help put the motor together/back in.
sorry if i spoiled that news don lol
 






No problem on the parts thing. I'm not going to rush getting the motor back in. We will see how putting it back together goes.

I'm struggling with the maf transfer function on the wot runs. The maf goes from 530 counts to 800 immediately when Tim nails the throttle. I have a void of about 6 cells I'm guessing at the correction factor.
We need a nice long, steep hill to do a 3/4 throttle pull so I can fill these cells with real data.
I think were getting pretty close on the maf transfer function (other than that magic void). That makes me happy. lol.
 






Fuel Pressure Regulator

oh, i also forgot to mention. i checked the fpr. with the vacuum line off, its around 42, with it on, its at 39.

The fuel pressure regulator should regulate the pressure to 39.15 with no vacuum. With vacuum the pressure should drop 1 psi for approximately every 2 inches of vacuum. (this is because the conversion from vacuum measured in inHg to psi is approximately .49 to 1)
So if you had 20 inches of vacuum you should have 29 psi fuel pressure.

If it really only went from 42 to 39 that would mean you only have 6 inches of vacuum. Something doesn't add up with those readings.
You should fix this before any more tuning. make sure that you don't have anything hooked up to the vacuum line going to the fuel pressure regulator, like the PCV valve.
 



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Tim, Your up to bat.


:D
 






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