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Injectors - What the heck - baffling myself here


LittleBlueGT

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I know those two bolts, but when I took them off it was still attached internally to the damper (circled in red).

 

At that point you just pull it IIRC (I may be wrong). There is a nipple with an o-ring that may sit tight inside.

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At that point you just pull it IIRC (I may be wrong). There is a nipple with an o-ring that may sit tight inside.

 

I will report back when I break something and my car is completely undriveable. All because of new injectors.:spin:

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LittleBlueGT, just curious what did you wind up with for latencies for the 650cc in RomRaider terms? Yours are red top right?

 

 

They are red-top, and I did end up with significantly higher then OEM or what DW says we need for latencies. I am not 100% convinced I am right though.

 

I compared 2.5 MAFv at 2500 and at 5500 rpm, then did the same thing at 2.7, and 2.8 volts.

 

I then adjusted latency so that I hit target AFR for both rpm slots. Car drove great (normal non-boosted driving) til FPR went south.

 

I am going to look through RR and see if anything else impacts fuel targets at different rpms, to see why my latencies have to be soo high. My DW850s also had to be fairly high in the latency department.

 

I will update my thread once I have some decent data:

 

http://www.legacygt.com/forums/showthread.php?t=119811

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Littleblue,

Just got back from Cobb Plano tuning my car yesterday. I think I have Fuel Pressure problems or something with my AVO pump. Ill try to give you a call later today, wanted to let you know how things went as well.

I was having problems on E85 hitting 100% duty cycle on the 850 injectors at peak power output, yet two STI's that went after me were only hitting 80 percent.

 

I put down 350whp and 373wtq on E85.

A couple of Stage 2 STI's with the vf39 put down. 334whp and 400wtq

 

That was on a Mustang Dyno as well.

 

I think Calvin thought I could have put out some more but with the injector duty cycle at peak power maxing out we didnt want to push it.

 

We both thought that it was either the fuel pump or the regulator not putting out the needed pressure.

 

By the way Calvin a 10 year subaru tech said himself the regulator system on the legacy is weird, totally different than the sti. He said it could be converted to the STI style which is much more straight forward. I cant remember the details about it though.

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^^05

 

went back to "normal" FPR system in 07 or 08

 

 

I swapped FPR's when I went topfeed

 

Details on cost of that, install issues, and what FPR is used?

 

Did it just hook right into the fuel supply and return on the firewall?

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I took the TGV's and fuel rails (including fpr) off a 07+ Spec.B

 

I don't remember what I paid.

 

At the firewall you have Fuel Supply, Fuel Return, and Evap line.

 

ALL Subaru's have the same three connections at the firewall, so any swap should work.

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Some LGTs (including my 05) have the FPR mounted near the strut tower, in an assembly with the two pulse dampers. Others have the FPR integrated with the hard lines that go between the intake manifold runners.

 

Seems like the FPR location could be pretty much independent of the side-feed vs top-feed question. If you buy a few feet of fuel injection hose and some clamps you can remove those hard lines. I ditched them when I moved my FPR to make room for a blow-through-MAF charge-pipe.

 

The only catch might be if those hard lines I mentioned are different for the top-feed rail setup, but my guess is it still won't matter.

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Since a handful of the 04-06 STI guys converted their sidefeed series rails to parallel with 5/16" barbed tees and 5/16" fuel line (except for the one incoming 3/8" line and stuck a FPR in the mix, they showed there is really very little to it. Just need the little FPR adapter plate thingy off ebay, and a non pain-in-the-butt FPR setup.
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Since a handful of the 04-06 STI guys converted their sidefeed series rails to parallel with 5/16" barbed tees and 5/16" fuel line (except for the one incoming 3/8" line and stuck a FPR in the mix, they showed there is really very little to it. Just need the little FPR adapter plate thingy off ebay, and a non pain-in-the-butt FPR setup.

 

You think there is any advantage to do ing that with my set-up?

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Even though my injectors seem to work great, car does not hold fuel pressure over an extended period of time. AFRs are good, even on boost at 90% IDC. But overnight the car takes a few extra cranks to start. It never used to do this, even when the car sat for over 30 days!

 

Car held pressure (I don't know how much pressure, but enough to start instantly) after fuel pump install, after flow balanced OEM injector install (done w/ TGV deletes) after DW850s, and now after the whole 650s and FPR headaches it doesn't.

 

I don't have the means to test 43.5, or 60+ psi. But I did take apart my fuel lines again today (connections at intake manifold) and used my air compressor to put in 25 psi to the whole FPR assembly, then I clamped the line, and held it for 3 mins. No loss in pressure at all. I then did the same thing on the other side (fuel rails, injectors, etc....) and same thing. No loss in pressure for about 3 mins. I then got tired of holding it.

 

Any ideas as to what is happening to the fuel after a few hours of sitting, if I cannot find any source of pressure leak?

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I wanted to find the answer to this as well. I never got confirmation whether the car was supposed to hold the pressure overnight in the first place.
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I wanted to find the answer to this as well. I never got confirmation whether the car was supposed to hold the pressure overnight in the first place.

 

Rao knows, he is just with-holding.

 

Does your car start almost instantly after being left overnight?

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There must be a check valve in the line after the pump, or built into it. Is it possible this is leaking back.

 

There is a valve in the pump assembly that holds pressure.

 

The thing is it held pressure for 3 mins today, it worked flawlessly for the past 2.5 years. And I never touched it since.:spin:

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Rao knows, he is just with-holding.

 

Yeah, but instead he is willingly contributing his oil knowledge to oil and completely non-oil related discussions alike.

 

Does your car start almost instantly after being left overnight?

 

Pretty much. But I think it takes 3-4 hours for the pressure to go to zero. I've not checked in a while, but can do it. Trivial with the gauge I had installed permanently, just need to remove the fuel pump fuse before turning ignition on.

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Yeah, but instead he is willingly contributing his oil knowledge to oil and completely non-oil related discussions alike.

 

 

 

Pretty much. But I think it takes 3-4 hours for the pressure to go to zero. I've not checked in a while, but can do it. Trivial with the gauge I had installed permanently, just need to remove the fuel pump fuse before turning ignition on.

 

The thing is, mine takes an extra few secs to start, definitely noticeable.

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You think there is any advantage to doing that with my set-up?

 

I think the factory per-cylinder injector tables compensate for any side-effects of the factory (series) routing - at least when used with the factory injectors. So, I think it's optimistic to switch to parallel fuel plumbing and expect consistent AFRs in all cylinders in all conditions. Then again, the funny behavior we both saw with larger injectors indicates that it's optimistic to expect consistent AFRs anyway. :)

 

Next summer I plan to install 4-channel EGT, and compare EGT in each cylinder before and after a change to parallel fuel routing, and tweak the per-cylinder tables to match. I suspect that the funny behavior we both saw with larger injectors might be a side-effect of the series routing and/or might be solvable with per-injector tables, but I won't be messing with either of those things until I can measure the results.

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I think the factory per-cylinder injector tables compensate for any side-effects of the factory (series) routing - at least when used with the factory injectors. So, I think it's optimistic to switch to parallel fuel plumbing and expect consistent AFRs in all cylinders in all conditions. Then again, the funny behavior we both saw with larger injectors indicates that it's optimistic to expect consistent AFRs anyway. :)

 

Next summer I plan to install 4-channel EGT, and compare EGT in each cylinder before and after a change to parallel fuel routing, and tweak the per-cylinder tables to match. I suspect that the funny behavior we both saw with larger injectors might be a side-effect of the series routing and/or might be solvable with per-injector tables, but I won't be messing with either of those things until I can measure the results.

 

Sounds like a plan.

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Just let the gauges sweep before you start, that gives the fuel pump enough time to get the pressure back up.

 

I tried that, no difference.

 

So, I went out and logged the fuel pump duty. It does not turn on until the car is started or being started.:confused: At least fuel pump duty cycle shows nothing in RR logger (you know either 33, 66 or 100%).

 

The only possibly explanation I have for that is that I changed injectors w/o disconnecting battery. Why that would matter, I don't know, but it is the only thing I can think of.

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