scotty305

iTrader: (2)

Interesting that the problem wasn't fixed by the fuel pulsation dampener. Can you make the engine run well if you add a 'spike' in the fuel map at a certain RPM, or does the problem move around at different throttle position or gear? I think I might see the O2 Short Term Fuel Trim doing odd things in one of your logs, it looked to me like the O2 trim may have been removing fuel at lower RPM and causing the problem as opposed to fixing it. Can you post a datalog screenshot showing these channels?

RPM
Throttle Position
Manifold Pressure
Fuel Pressure
Injector Output1 Injection Time (ms)
O2 Control Bank 1 Short Term fuel trim
Wideband O2 1


If you're comfortable adjusting ECU settings, it would be helpful to see a log of the same conditions with the O2 feedback disabled also.

AlexG13B

iTrader: (7)

yea it seems to drive ok. although I can almost feel at times when it does it. almost like a slike hesitation.
seems to be just rpm dependent. wil do it when driving or neutral. it has the spike in map now, prob about 15% more fuel.
i dont know if we try o2 disabled. ill ask the tuner. he is stumped as well right now and ive spent so much money and effort that im running out of ideas and patience haha

il get that log for you today or tomorrow.

AlexG13B

iTrader: (7)

this one doesnt look too bad. I remeber the base fuel being in the 90s%. I need to verify with tuner that no other setting has been changed
in this last log it shows 70s for base fuel

scotty305

iTrader: (2)

I agree that doesn't look too bad. I'm not a Haltech expert and I don't consider myself a tuner, I'm just someone who has tuned a few cars over the past 10-15 years. If that were my car I might disable O2 feedback and then drive the car slowly through those RPM that seem unhappy. I would try to drive those RPM in second and third gear, and when I got to the bad spot I would use left-foot-braking to change throttle position and see if the problem is still there at higher load. Obviously be careful at higher loads, 15 AFR at 10% throttle is no big deal but 15 AFR at 50% throttle is not safe for very long. You might just need to adjust a few cells in the map to compensate for intake / exhaust runners that aren't matched to each other. The flow in the intake runners isn't smooth like a shop-vac, there are pulses as the intake ports open and close. And those pulses sort of bounce back and forth like waves, which can make resonances and anti-resonances at different RPM and/or load. There's a phenomenon called 'fuel standoff' which happens when those pulse resonances and anti-resonances line up in a way that pushes some of the fuel backwards out of a carburetor at certain RPM. It would be harder to see this on a fuel-injected car, since the injectors aren't mounted near the throttle.

It's hard to prove what's happening until you make a change that fixes it, unfortunately. You might be getting unlucky in terms of the fuel injector behavior, assuming you've had the same injectors the whole time. Those flow charts from Injector Dynamics are nice, but note they only show data as low as 3.0ms and your datalog shows the primary injectors operating in the 1.5ms - 2.0ms range which is off the low end of their charts.

Rotamad

had my car on the dyno lean spot is gone at 2500rpm! now we have the same issue at 6000rpm. we are currently at 350hp at 5000rpm. ive currently got loom out for the tuners to go thru and check it. they are starting to wonder if its the fuel rails because the injector sits offset to the rail. ive not heard nothing bad about ffe rails and they have been helpful when ive contacted them

Rotamad

Hi buddy how did you get on? I got my car sorted! Not a 100% sure what caused the issue but I changed the following. Added id750 fuel filter, radium rails plus dampeners, went to 2x walbro 460 pumps!, cut 80mm out of vac line to fpr!! And this worked! Car behaved nicely! Just a couple small issues to sort but we know what’s causing them

AlexG13B

iTrader: (7)

that's awesome! mine still has it, I have the walbros and that fuel filter already. wonder if changing my fuel rails and shortening vac hose to regulator will help

which dampners are you using and how long is vac hose to fpr?

Rotamad

I changed my fuel rails from full function engineering to radium! The radium rails have ports on both rails for pulse dampeners that radium sell! They are also vac referenced !That’s on jc manifold! Just check the others have it! Also was told that vac line to fpr needs to be short as possible it can actually give a fake or weak signal! I cut out about 80mm out of it! Do you have braided or rubber fuel hoses?

AlexG13B

iTrader: (7)

braided nylon hoses in engine bay, stock metal lines under and some rubber from. filter to stock lines
my vac hose goes from the port on LIM to the front of UIM where regulator bolts to

Rotamad

Try replacing the hoses with rubber in the engine bay! I had rubber originally and went braided! That’s how I found the problem at 2.5k. I fixed that with the pulse dampener. The fuel rails have the thread for fittings go past the injector hole! We thought there might be a chance that the fuel going into injector hole might be disturbed with the threaded hole! Not 100% sure! But it was one or all of the as mentioned above that fixed the issue

Rotamad

By the looks radium 13brew also have port for pulse dampener! Also radium rails at a an8 bore rather than an6 the ffe ones!

AlexG13B

iTrader: (7)

o wow interesting. I did install a radium dampner before the primary fuel rail and that didn't really fix it.

Rotamad

Originally I had mine before primary rail on a tee the 90deg! That definitely fixed my low lean spot! But I gained one at 6700rpm! I’m guessing it was the fuel filter! Where is your filter located? Mine is in boot

AlexG13B

iTrader: (7)

on rear frame by diff

Rotamad

That should be fine! Keep us posted! Keen to see you get it going👍