Here's my issue. I'm running HRC stage 2 with an intake walbro fuel pump (not using the inline accell fuel pump) and the HRC fuel pressure regulator (cartech). I have the base fuel pressure set at 45-50psi. With a spare set of RC Engineering fuel injectors that are rated at 275cc/min, i get to about 9psi of boost until i go to a lean condition (read: no fuel). I dont have any leaks within the fuel system whatsoever, and my fuel pressure gauge reading at around 9psi is always 100-110psi (which is what hrc says 10psi of boost should have). Whats the deal? Am i running out of fuel? The stage 2 from HRC is supposed to run fine with stock injectors and the same fuel pressure readings mentioned above, but even then i run out of fuel when running bigger injectors...

I'm leaning towards that the walbro pump i have isnt flowing enough =/

Below are two links to pics of my spark plugs. They look fine to me, no lean conditions on the plugs, no detonation. Beware the pics are kinda large (450k or so). They are cylinder #1 through #4 from left to right on first pic, and right to left on second pic.





Thanks for any info. Ah the beauty of tuning a turbo'ed N/A car =)

_________________
Vinnie Lima
aka Kiku
http://www.asog.net
kiku@asog.net
AIM: Kiku888

1997 Chrysler Sebring "Silver XTC"
I4 420a w/ HRC Stage 2 w/ FMIC
Crower Rods/10:1 JE Pistons/Lots of other stuff
Proud member of the ASOG BoOsT jUnKiE crew

what happens if you keep on the gas when you go to this lean condition, mine does this and it goes lean for a second and then it gets rich right after then it is fine i think it is the fpr working outta sync with the ecu, but i'm not certain.
lates
james

i remember when we first installed the HRC kit on daves car and were heading home frmo miami it did the same thing. went lean for a second then slammed over to rich. but this was also at 6-7psi

uh....funny, cause that's the same thing that happens to me, but today for some strange reason, while i was racing a gaymaro it stayed at lean for a while, (like 15 seconds) I was scared and let go...usually it stays at lean for like 3-5 seconds and than it Slams over to the rich side.....if somebody knows, hook us up man, I'm also running the intank walbro.

i think its cause it takes a second for the extra fuel to kick in... or the walbro to power up?!

When it goes lean are you losing power or is the air/fuel just saying your lean? You said your still at 100-110 fuel pressure so im leaning towards the o2 sensor. What does it do under normal driving conditions and even idle? Also, what is your vacuum when idle?? It should be between 15-17 according to Chilton's. If your not losing power when it goes lean then I dont think your really running lean, I ask because mine did the same thing with my fuel pressure what it should be and everything but the car would run lean and lose all power. It ended up being my plugs, not that they were bad, but that the gap was too large.

If you are using 275's, you can probably lower your fuel pressure at full boost a little bit to ease up the load on the fuel pump. The 110 is the pressure needed on the stock injectors to force them to flow enough fuel.Try turning your fuel pressure to 80-85psi for 9lbs on 275's. Do you have an EGT? That could help confirm this by getting an idea what your temps look like.

I took it out for a spin this morning and i could then really verify my fuel pressure at certain boost levels. It is getting up to 100 or so psi of pressure.

My idle vaccum is at around 17 vac or so.

What you guys are saying that it goes lean for a second or two then slams into rich is exactly what is happening. But while it is at lean, and i keep my gas pedal to the floor, it would before seem like i have no power on my stock injectors, but now with the 275's the car will sputter like i'm extra rich.

My egt's at 9-10psi is around 1350-1400...my egts are not much higher than when i was N/A =/ At idle, it is at 800*, at cruising at lower speeds it is at 100-1200, and hitting it hard it gets upwards to 1450 (which is the highest its been).

But is the momentary "lean" on the A/F meter normal when the 5-10psi boost kicks in? Its like the fuel pump or fpr is "delayed" in opening fuel =/

How about the plugs? They got some soot on it a bit which seems like i'm running rich...no signs of detonation/lean conditions whatsoever =/

Are you using any sort of fuel cut defenser?

If so, check your voltage at WOT. Remember, the ecu sends a voltage message to the injector that corresponds with what's going on in the map sensor. If that sensor is receiving an inordinately low reading, the ecu may think you need less fuel than you're actually getting.

You need either the S-AFC ("sensor chk." screen) or wired up multimeter to check the map sensor readins at WOT.

what readings are supposed to be normal at wot?and which of the 3 is the map sensor in the volt check menu?

4.7, 4.8, 4.9v..

In the afc's sensor check, there's only three voltages, and one of them is labeled thr (throttle) - the other two are MAP and RPM. RPM has very small voltages, while the MAP works on a 1-5v scale. Easy to figure out which is which while you're looking at it.

It should not go past 4.79v on the 420a's...

I'll check that out, thanks for the pointer.

i think that is for 96 and on about the voltages. i don't seem to have a problem on my 95 and I do not have a fuel cut defenser installed. correct me if i am wrong.
lates
james

The map sensor and fuel injector voltages still apply, but if you don't have a FCD, you have no worries about voltage alterations to your injectors.

Anyone who has an ecu and fuel injection has to deal with sensor voltages just as much as mechanical problems anymore. It's not enough to be mechanically saavy anymore, but you have to have some electronic expertise as well.

Sorry forgot to answer your question....i do have the HRC fuel cut defencer...

It seems that with the 270cc/min rc engineering injectors and lower FPR base and WOT fuel pressure (set at 35psi and 80-90psi) i can hit 10psi with no lean problems.

I'm still tuning so i'll let you guys know...

I'm not sure of the other people, but sometimes my power doesn't kick in until it goes to rich from lean.......

yeah i guess this is a normal behavior....i was just worried that i was out of fuel at higher psi levels...but couldnt trace any lean condition on the plugs!

Others may have alluded to this, but the Walbro 255lph hi-press cannot safely support enough fuel for 9 psi of boost at 110 psi fuel pressure. You absolutely needed to lower the fuel pressure. RC engineering has a formula that will help you figure out what pressure to run with those injectors: http://www.rceng.com/technical.htm#WORKSHEET
By my calcs, 84 psi and 275s will give you 360 cc/min fuel at 100% duty cycle (same as stock injectors as 110 psi fuel). Remember that the actual pressure across the injector is fuel pressure - manifold pressure. That should bring the fuel pressure into a range that the walbro can handle better. In fact, if you have the hi-pressure model GSS341/342, you will have a good margin of safety. Here is the Walbro pump chart. BTW, I'm making a comprehensive set of VFAQs on choosing fuel system components (be done in a week or so).
http://www.houstonhardware.com/~cbehnken/

Corbin

'95 ESI-T
HRC+FMIC+ETC...

Thanks a bunch man. My problems seem to have gone away after i tuned my base pressure to 35psi at idle and +-85psi at WOT/10psi boost...