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Discussion Starter · #1 ·
Hit the dyno the other night with our 2006 Turbo RSX and was having some fuel issues.
When in boost the fuel pressure would rise to 40 psi but then would drop to like 20 psi after a few seconds.
We had to stop.

See it here: Turbo RSX fuel issues on Dyno

We pressure tested the Aeromotive FPR that night and it would not hold pressure so suspected it to be faulty.
I took the FPR apart but did not see anything unusual. The diaphragm was good.
Some imperfections in the seat for the diaphragm.
By hand I turned out the seat a bit with a drill bit and fine sanded the surface.
Reassembled the FPR and it seems to hold the pressure now with my air compressor at 10-15 psi
Previous test was done with hand pump at dyno.

I had emailed Aeromotive and they gave me a call to discuss.
They said if the seat was imperfect it was due to the lack of fuel pressure causing the seat to bounce. Not sure about that?
In short they believe the issue is with the fuel supply under load. Not getting enough fuel and the pressure drops.
Tuner says he believes the regulator was at fault.

Aeromotive suggested running the fuel return into a container and time the flow rate.
Anyone do this?
Any easy way to make the fuel pump run constantly on the RSX?
Is this nescessary?

Any thoughts on this issue?

Here is a description of our setup with a couple of pictures of the sending unit.

CX Racing Sidewinder manifold.
CX Racing Dual Bearing GT35R turbo. Water cooled.
Tial 38mm Wastegate
Greddy BOV
Vaccum Manifold

DeatschWerks 265 LPH fuel Pump
Aeromotive 13109 A1000-6 FPR
Radiant Fuel Rail
Russell 650133 Black Competition Fuel Filter
DeatschWerks Injectors 1000cc
Return Fuel System using stock feed as the return
Removed stock fpr and larger return jet on sending unit.
Blocked off stock feed on sending unit
Ran stock return to larger return jet. (90deg 3/8" brass barb)
New feed line from pump to rail with inline fuel filter

Hondata 4 Bar Map

KTuner Revision 1







 

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Discussion Starter · #2 ·
So today I decided to do a fuel flow test to see if there was some data I could collect. I am waiting on a new fuel sock to arrive today to perform the test again.
I connected a battery directly to the fuel pump with a battery charger on it at 13.3 Volts. I ran the pump for 1 minute at 60 psi.
Connected to two bottom pins on sending unit plug. I actually cut and spliced the wires.
Yellow with a blue stripe and black.
I ended up with 180lph. The pump is rated for 235lph at 60psi ??

Will try again with a new sock and see if it comes up.

Installed the new sock but did not make a difference in the fuel flow rate.
I am guessing there would some kind of flow rate drop going throw all the lines, fuel filter, rail, and regulator.
I suppose 180 lph is still high enough for our power goals of around 350hp.

At one point during the flow test, the system started sucking air and the fpr gauge started bouncing. I guess without the return line the cage became depleted of fuel.

I ended up removing the custom return line jet on the sending unit and connected it directly with a small piece of the submersible fuel hose.
I also drilled two 1/2" holes in the sending unit one inch from the bottom near the fuel sock to allow more fuel to flow in from the tank.
I had a suspicion that the return jet wasn't doing its job properly and the sending unit was getting low on fuel when on the dyno causing some lean issues.

We originally suspected a bad Aeromotive fpr but I have taken this thing apart and the diaphragm is good and it holds pressure fine at 20psi into the vacuum port.
The ball seat was a little rough so I cleaned it up by hand with a small drill bit.
I am certain it's not leaking and is functional?

The only other thing we wondered was if the fuel was getting too hot and possibly boiling however there is quite a bit of heat wrap there?
Maybe the return line going to the original feed was getting hot?

This site is pretty quiet and I feel like I am writing a freakin' diary here.
Nonetheless, I will post back my results from the dyno when we get things sorted.








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This is good information nonetheless if you feel as if your writing a diary. I did just enough research when putting my turbo kit together to where I didn't need to touch the fuel system though so I have no input here. I am using a DW260 (I think) and some DW 1000 injectors.

From fumbling around through the old threads, I'm pretty positive that someone said the stock rail and line would handle up to 350 maybe a little more without issue.

I haven't had the chance to get my car onto the Dyno as of yet, just a good street tune. Pushing 10psi with a turbonetics turbo kit in a k20a3, sadly. Haven't had a single issue though, which is good.
 

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Discussion Starter · #4 ·
This is good information nonetheless if you feel as if your writing a diary. I did just enough research when putting my turbo kit together to where I didn't need to touch the fuel system though so I have no input here. I am using a DW260 (I think) and some DW 1000 injectors.

From fumbling around through the old threads, I'm pretty positive that someone said the stock rail and line would handle up to 350 maybe a little more without issue.

I haven't had the chance to get my car onto the Dyno as of yet, just a good street tune. Pushing 10psi with a turbonetics turbo kit in a k20a3, sadly. Haven't had a single issue though, which is good.
When it comes to boosting, a vacuum/boost referenced fuel pressure regulator and return line are needed. As the boost raises in the manifold, the effective fuel pressure drops as the boost starts to flow the fuel down. With the regulator as the boost rises, so does the differential fuel pressure, maintaining adequate flow.
You will be running a high duty cycle on the injectors since the effective rail pressure will be 10psi short of what it should be. When going from naturally aspirated to boosted, a vacuum/boost referenced regulator with the return is critical. You run the risk of leaning it out and blowing the engine otherwise. Not a corner you want to cut.

I too had hoped not to touch the fuel setup but my tuner was not interested in tuning the car without this setup and informed me why.

I know others are running a returnless setup with low boost but.... again you run the risk of leaning out the engine.
 

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I know my tuner has told me I was 39% duty cycle with the setup I've got, I don't know if that's high or not. AFRs are consistent throughout the rpm range as well. I keep a constant eye on it. I don't race it or anything as it continues to be my daily driver. Just wanted boost on tap for fun.

If it blows, it blows. I've got another engine on the stand ready to go in anyhow. I hope you get your issue figured out. I would like to know for the future when I plan to run high boost.
 

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Past Driver’s Ed
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I wouldn't drill the 2 1/2" holes into the fuel pump housing. The housing needs to stay intact to provide a steady supply of fuel to the pump under conditions when the fuel tank is low and you are braking or making turns. I have force induction running on E85 with a return fuel system and haven't had any issues for 6+ years. I will look for my notes and pictures if you would like. In the meantime if you're interested check out my showcase for a list of my mods.
 

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Discussion Starter · #7 ·
I wouldn't drill the 2 1/2" holes into the fuel pump housing. The housing needs to stay intact to provide a steady supply of fuel to the pump under conditions when the fuel tank is low and you are braking or making turns. I have force induction running on E85 with a return fuel system and haven't had any issues for 6+ years. I will look for my notes and pictures if you would like. In the meantime if you're interested check out my showcase for a list of my mods.
Yeah, I didn't want to hack up this sending unit at all. I did read a few posts to not drill holes. One owner told me to cut the bottom out of the cage as he did, but this wasn't something I wanted to do. I did put the holes an inch up from the bottom to still allow the return fuel to pool in the bottom of the cage.
As we were having some kind of fuel issues whether it be because of the FPR or the return fuel jet I modified on the cage or other, I am not certain what was going on. I had to change something before the next dyno run. With the 2 holes, I was able to run a good fuel flow test without the return. If the holes prove to be problematic in the future I will just swap in another cage.
I will post back again next week after our next dyno run with some results.

I have been wondering about the base fuel pressure to be used.
I was reading the tech specs on our DeatschWerks Injectors 1000cc. The dead-time values provided are for 51psi (3.5bar) delta/base fuel pressure.
I wonder what base fule pressure we should be using.
I think we were at 37psi base pressure before. Then was told to set it at 43.5psi.
But should we be at 51psi?
Does it matter? I am not sure.
 

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Past Driver’s Ed
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Yes, I have my fuel pressure set 50 psi. That pressure works well for both 93 octane and E85 tunes using 1000cc injectors. Also, I increased the diameter of vortex jet port located were the return fuel line meets the pump housing. Purpose of the jet is to use the return fuel to draw more fuel from the tank to amplify the volume of fuel returning to the pump housing. Be carful when drilling the hole bigger because its pretty fragile plastic.
 

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Discussion Starter · #9 ·
We hit the Dyno again last night and this time we had some success. Fuel pressure held steady and would rise properly with boost.
I had set the base fuel pressure to 51psi. We didn't have any issues this time around with the FPR.
I can't say for sure exactly what caused our issues the first time on the dyno.
Certainly with the FPR not able to hold boost/vacuum was not good.
Could have been the top hat on the FPR was not tight or the fuel return on the sending unit was not doing its job or maybe both?
We ran out of time last night as it was getting late so we will have to do one more round to finish things off and see what kind of power we will get.

Here is a video of a pull on the Dyno.

During the dyno tuning under heavy load that sidewinder manifold was glowing red hot. Wow. I did not think it would get that hot.
No wonder we need to heat wrap everything so well.

I will post back with some final power results after the next dyno tune.
 

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Discussion Starter · #10 ·
We hit the Dyno again last night and this time we had some success. Fuel pressure held steady and would rise properly with boost.
I had set the base fuel pressure to 51psi. We didn't have any issues this time around with the FPR.
I can't say for sure exactly what caused our issues the first time on the dyno.
Certainly with the FPR not able to hold boost/vacuum was not good.
Could have been the top hat on the FPR was not tight or the fuel return on the sending unit was not doing its job or maybe both?
We ran out of time last night as it was getting late so we will have to do one more round to finish things off and see what kind of power we will get.

Here is a video of a pull on the Dyno.

During the dyno tuning under heavy load that sidewinder manifold was glowing red hot. Wow. I did not think it would get that hot.
No wonder we need to heat wrap everything so well.

I will post back with some final power results after the next dyno tune.
 

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Discussion Starter · #11 ·
We ended up blowing out the exhaust manifold gasket that came with the cxracing kit.
Not sure if the manifold came loose or the gasket failed and then the manifold came loose.
But needless to say the manifold was loose.
Probably a good idea to re-torque these after a few heat cycles.
We purchased an OEM gasket and is much better quality.
Dual layer stainless steel gasket.
 

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Discussion Starter · #12 ·
We had hit the dyno again to finish the tune.
At 12 psi we were at 350 whp and this was our goal.
Still some issues with the tune though.
The knock sensor is getting triggered during a pull.
I don't like this and need to get it sorted.
We sent the tuner some data logs and hope to get things tweaked a bit better.

The car pulls hard now though...Fun !!
Need to set up boost by gear too cause 1st and 2nd gear is crazy now.....
In 2nd gear when boost hits she just breaks free...

Cheers
 

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Discussion Starter · #14 ·
We sent a couple of data logs back to our tuner to refine the tune and setup boost by gear. With the new tune, 1st and 2nd gear boost are set at the wastegate spring (about 7psi).
As well we are no longer having any issues with the knock sensor and things seem to be pretty decent now.
 

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Past Driver’s Ed
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You may want ask your tuner about this. My tuner Vitaliy Mikitchenko (VitTuned) would not touch my car unless I had a real wideband on the car. He believed the car was effectively untunable with a factory primary O2 sensor, which is not accurate in boost. I wired my sensor directly to the KPro4 ECU as the primary sensor.
 
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