mark kibort

Greg, you are in the same boat.. if you dont likek what im offering, ignore it. My fire backs are when ive been attacked.. Ill never attack first.
go look at the thread.... ive only tried to help here. Brendan posted the insults first starting with the offensive fat guy in the wheelchair picture, which has no place here in my opinion. But you missed that?? that appropriate? that's contributing? whats wrong with you greg?
BTW: i just read all the posts over the last 4 pages and the only one being inappropriate and having a personal attack is BC brendan and you. my posts to him were responses. my interactions with AO , Ken, and others are strictly technical without any personal comments

PorKen

Unless he changed it, the MAF is set lean of center at 300 ohms. He could probably dial up the CO to make idle and cruise happy but even with the additional effect the CO screw is programmed to have on WOT with the S3.S300s chips it would still be on the lean side.

Getting there! Would be good to record the fuel pressure on the road. I don't put much stock in the effectiveness of the driveway dyno.

BTW, if you haven't already, you should adjust the MAF to 382 ohms to eliminate a variable.


Would be lean. With the S4 FPR it is in the low 12's at WOT with the stock chip which is about what the stock chip and S3 FPR will do at higher rpms (in hot weather).

Cosmo Kramer

Yes but it's only mustering up mid 40 psi right now under load. If the S3 regulator gives constant 36-38 psi he should be bang on at high 12's-13.

Still, there HAS to be a reason why this car can't give 55 psi under load with the S4 fpr. Just have to find it.

mark kibort

why dont you put much stock in the driveway dyno.. you can actually simulate WOT in almost any RPM, like brake dyno. ive done it at 3k, 4k, and 5K rpm to test things. it works great. you are at WOT, and holding it there for a few seconds..whats not to like?

so you think at 50psi at 11:1 and 12:1 , he can put the S3 regulator in and he will be lean? 50psi to 38psi?? I think both of us would agree that most likely, he will be in the high 12s or 13.5 to 1 ,which is the stock spec. I might be wrong, but i don think a 10psi change will do that much here.
it would be an interesting test. also to see if the sytem goes to 38psi based on the new 38psi fuel regulator. if it does, then it points to the S4 regulator as being odd, or some other restrictions that the S4 doesnt have to make the S3 run at 50psi vs the rated 55psi.

mark kibort

bingo! however he is really at 45 now from what he said. if he was 40psi, thats the same as S3 for all practical purposes. the video showed 45psi at WOT and he said he now is seeing higher pressures , right ?
in my experience, ive taken the 84 from 13:5 to 12:5 with changing the fuel pressure to 52psi. (max of the regulators) I think that was only about a 10psi change. i havent seen much of a difference with the stroker going from 50psi to 40psi, but it might be drowning from the beginning anyway.

as you say, the curious part is why he isnt getting 55psi. the filter cant cause that, because if it did , you would see big fuel pressure drops at the higher rpm. plus, there would be no change at idle. he has static fuel pressure of 55psi... so why does it go down 10psi when running and no vacuum?

PorKen

Actual WOT fuel pressure is unknown after the fuel filter change. Only that idle is 45 psi with vacuum.

S3 FPR is rated at 36 ±3 psi (hot_33-39_cold).


Because...that's what 20" hg of vacuum does, independent of your 'observations'.

1 psi = 2" hg

(Also factor fuel temp and outside air pressure.)

GregBBRD

Has AO measured the fuel pressure with the vacuum line disconnect, after the new filter got installed?

That would be the data I'd be looking for, before worrying about too much more.

Like Ken says, the "vacuum" fuel pressure of 45 PSI is in the ballpark.

GregBBRD

The angle of the C/V joints tearing the boots?

mark kibort

good point..... but i havent seen a problem... but will have to check that angle out. i guess it depends on shock droop.
thanks!

mark kibort

hopefully, we will get a WOT fuel pressure reading shortly. I dont think it will change much, but we will see.

now, as far as vacuum on the Fuel regulator, just because you have 17" Hg (not 20"Hg ) doesnt mean that effects the fuel pressure in the same way. I showed you pictures of the Sunx meter on the vacuum line showing 17psi vacuum. then i showed the fuel pressure change without vacuum attached. its 4psi. look no further than AOs video when he revs to WOT, vacuum goes to near 0, and the pressure change is only 4psi.
help me understand what you are thinking.

the video clearly shows WOT pressurue of about 43-44psi max and off and idle with vacuum is around 40psi. notice off throttle it falls further, but thats because the vacuum willl spike at near 25-27" HG off throttle from moderate rpm. still only about 6-7psi diff at that vacuum.

Hilton

Its not perfect with the stock chip, because he's not running the stock fuel pressure. The stock chip with stock fuel pressure would be lean too.

And yes, adjusting the MAF pot can make a pretty big difference to the mixtures - Ken's point just above about setting the potentiometer in the MAF to the mid-point of 382ohms is a good start. Right now at AO's 300ohms, the ECU is reducing the fuelling because its been "calibrated" to an overperforming MAF.

The ideal would be to adjust the MAF signal input using the pot and about $3 worth of bits (crocodile clips, LED, 750ohm resistor, bit of wire), but centering the pot as a start would certainly help.

Only?

john gill

the ignore list simplifies the posts dramatically

mark kibort

we dont know what the fuel ratios would be with the stock fuel regultor, because what we DO know is that he is rich and actually very rich with the stock chip and the S4 regulator. remember, he was testing at 45psi pressure. if stock is near 38psi, then thats only 7psi difference. not enough in my experience to make a radical change in AFR's.

i was under the impression that the MAF adjustments are really more for part throttle operation

it will be interesting to see if the changes he saw with fuel pressure after the filter was changed, changes his AFRs. my guess is that they wont.

and as far as your "only ? " post..... yes, Ken was pointing to a direct relation of manikld pressure and fuel pressure reduction and that is not the case. its not 10 psi drop of fuel pressure with the vacuum attached... its more like 5 and for good reason.

PorKen

Any news?

AO

Nope. I've been traveling for work the past couple weeks. Where I left it last, I had installed a permanent WBO2, and the stock LH chip. WOT AFRs were in the mid 11s, so it's safe.

The only things I have not touched are the injectors and the front fuel damper. The damper is the only thing I can reasonably think of that would be a bottleneck as the fuel comes in through that and then distributes to the fuel rails from there.

I probably won't do anything further this year unless I can get my hands on a spare damper (cheaply).

I'm on a waitlist for a track day this Thursday, but then it will likely be going away for the long winter nap.