Samw124

Hi 55 enthusiasts

I have recently done a lot of mechanical work on my 2003 E55.
I've now got 8an fuel feeding a central entry fuel rail, returning to tank via a fuel regulator.

I have previous a RaceIQ tune, only modification is long tube headers, then larger heat exchanger.

I have an AFR guage and a digital fuel pressure guage to monitor these two things.
Now Ive been adjusting the fuel pressure at idle,I have the vacuum hose attached to the vacuum port on the supercharger near the throttle body.

I have afr 14 to 15 at idle, about 12 to 14 on deceleration, for example slowing down to come to a stop.
But upon gentle acceleration the afr is not getting richer as it should, it I staying in 14.5 to 16 territory.

I have been in touch with oe tuning who advised me to get a a.data logger to record all vital data so I can get a new tune

My questions
which data logger can I use for decent cost
Fuel pressure is at 66 psi with vacuum attached. It is 76 psi without vacuum attached. Am i in a good spot to start data logging or should I change fuel pressure?

I have never tuned or messed with this stuff before. Only repair my cars, no engine modifications - so I'm learning.
👍😎

SICAMG

Very slow accel your fine. Your O2 sensors are doing the work and even if you put 90psi to the injectors the O-2's will correct it to be where the ECU want's to be happy.
I run a vacuum line but with a one way check valve. Meaning it will only allow boost pressure in, not vacuum. I also have an adjustable bleed valve to control boost pressure in the regulator
I run 65psi at idle and normal driving and than under boost it will hold at around 65-68psi. So with 17lb's of boost , the engine is seeing about 50psi due to injector seeing boost on opposite side.
Leave vacuum off the regulator and only run boost. Our ECU's only know a steady fuel pressure when driving and constant changing vacuum signals and fuel pressure is making the ECU constantly fighting to keep the injector signals correct due to fluctuating fuel pressure.
Your 14.5-15 zone is perfect for a nice clean running engine so no worry's with that.

Samw124

Merry Christmas firstly
👍👍

Ok then thank you for teaching me something new SICAMG.
One way vacuum.

I have a Fuelab pressure regulator, the small one that goes up to 90psi. To make it fit in a nice area and also be adjustable.

I am hopeful of getting a tune file from OE Tuning who are in Santa Ana, Soutjer California. I am confident in their service because they did a tune for my R320 CDI and its perfect. The owner also seems to understand 55k tuning very well.

OE Tuning want me to do proper data logging and I do not know which item to buy to get that info. Or do I simply have to get a dyno tune?

I've found an AEM AQ1 data logger, still researching if this would provide the info needed to get a custom tune.

Samw124

So I have a further question
right now I dont have one way vacuum to the fuel presure regulator. Is it more hurtful to leave this vacuum connected, or should I disconnect it and monitor afr ?

I've just done quite a bit if work on my engine, basically almost replaced every pulley item, ps air con, crank , water pump idlers, tensioner, alternator.
also resurfaced cylinder heads, replaced valve stem seals, replaced timing cover and ll gaskets and o rings. Timing chain, oil pump chain and all guide rails and O ring on oil pickup tube.

Then by
crazy coincidence the car started running crazy rich in the 9 AFR range and check engine came up, starting both front precat o2 sensors were faulty. I have long tune headers but anyway the first o2 sensors in the exhaust system. So I replace both of these and the rich condition went away.

Yes I am amazed that both were faulty at the same time, although with differing error codes. My car hadn't been driven since Nov 2019 so maybe just sitting there and the fact that they are from 2003 made them go.

this is going to hopefully be my daily driver, that's why I've been replacing a lot of items that affect reliability.

SICAMG

DO NOT run with out any boost reference....you mush have this to increase pressure under boost.Leave the line on for now until you get the vacuum valve.

Samw124

Ok understood

Thank you and I'll update once things are working as normal

Samw124

Just an update on this return system for anyone who wants to know the conclusion.

Even after adding the one way vacuum valve the car ran ok, still lean, always in the 14s and 15s on 50% acceleration. Idling was also similar.

Then once again it decided to go down to the 9s when I was in a busy road. Loads of smoke and hesitation. I said enough is enough. So I removed the return setup. I got these AN caps that simply screw on and seal any open fuel hose from AN fittings.

The psi was mid 60s with the return setup and the car never ran well. Now back to normal with 80 to 82 psi fuel pressure.

I know a dyno tune and proper datae logging would have sorted it. But maybe for a later date if I decide to have a lot more boost.

Thanks
Sam

SICAMG

Very strange you had that issue with a lower fuel pressure as well.

Samw124

Yes indeed.
I replaced both the o2 sensors and it seemed to run better but not like before.
then the sudden low 9s Afr problem happened again.
I smoke tested the car myself very patiently and there are no air leaks.
So I decided to be happy with a central feed fuel rail and looped with a section in the loop for my fuel pressure monitor ((aem digital guage).
I capped off the return line at the rank with a 6an cap and blew out all the fuel out of the return line with an air tool.

I can easily have a return line in the future if I have a good opportunity to do a dyno tune and access to a knowledgeable person. Never tuned anything before. I can repair and replace things. But no tuning knowledge or tools.
Thank you!