36lb or stock LS1 injectors? HC is high...

[evren]

Hi guys;

I've installed 36lb Bosch injectors to my car, and on the emissions it is horrible.

The HC level is around 2000ppm!

I have a cam (223/227@114 LC 0.592” lift use a valve spring with a lift of 0.600’) and full headers + high flow cat and no catalyzer.

I've used the ASA 2000/2002 corvette injector sizings and also tried some other resources, and even tried a stock tune with idle parameters, and cannot seem to get around it.

Is it really big for an LS1 5.7 with above additions to it?

should I use the stock injector sizing? would the stock duty cycle will be high or not?

any inputs are appreciated...

Thanks
Evren

[mr.prick]

Are you using these?
Bosch_0280155868_36 lb_injectors.txt (http://forum.efilive.com/attachment.php?attachmentid=9079&d=1285514630)

http://i235.photobucket.com/albums/ee259/whitespar/Bosch_0280155868.gif

[evren]

yep. but no luck... :(

I bought them from here: http://www.speedinc.com/cont.cfm?cid=C0000845

[evren]

to be more precise:

the stock I had was: Bosch 0280155931

current 36lb: Bosch 0280155811

[mr.prick]

I believe the 0280155811 is similar to the 0280155868 :nixweiss:

[evren]

interestingly it is 0280155868 (as on the injectors that I've removed today) and I've tested with the old stock, the values are the same... looks like something is wrong other than my injectors or settings...

Friend of mine has exactly the same setup (headers, not cats, 36lb, cam etc...) and can pass the HC tests...

so I'm thinking either Fuel Pressure Regulator? or MAF (not sure if having a maf sensor will really correct the huge gap.)

the nominal HC level is 800 PPM and mine is around 2000ppm :(

any ideas guys?

[joecar]

Do you have any logs showing front O2 sensor voltages (HO2Sx1)...?

[evren]

here is the log attached. showing O2 are switching fine at idle.

tune wise I'm on CL tune and I've a similar tune with a friend of mine, and he has no prb. only diff we have is the MAF sensor, which I don't have for the moment.

And I don't think MAF will make that much of difference in HC emissions reading, I mean the gap of emissions values are almost double or triple so something other than this can be wrong.

thanks to all again...!

[joecar]

The log shows that it's trimming (regardless of injectors or MAF)... so I don't see the cause.

Does your friend have cats...?


... full headers + high flow cat and no catalyzer.
...You have hiflow cats but their catalyst has long since been "worn" off...?

[evren]

he doesn't have cats and I don't. he had a similar tune to mine, and no MAF either.

I'm also suspicious of something different that might cause, is the fuel regulator.

I've installed the Walbro 255 sometime back, but I recon that it was the high pressure version. maybe that is causing fuel regulator not to control excessive fuel at idle? since what ever I've changed on the tune, AFR, timing, stock tables, VE, didn't made much sense.

so I just bought a fuel pressure regulator with the gauge on it, so will try and see the exact pressure and adjust it if needed.

other than this I cannot assume any other problems... if you have any other advices pls share.

thanks for the help.

Evren

[joecar]

If rail pressure is higher than what the IFR table was programmed for, then the injectors will flow more than what the PCM expects...

but, in Closed Loop trimming brings the the fueling to stoichiometric which means HC should be lower than what you see...

so, I'm confused, lol.

[evren]

could it be overflowing/floating? regardless of what is commanded, maybe the regular is not doing his job properly.

I just bought a fuel pressure regulator with gauge on it, so will give a try tomorrow. The rail pressure should be @ 58 psi right?

[joecar]

If the injectors were leaking, the trims would peg negative and a DTC would set.

Yes, stock rail pressure is 58 psi.

Post some more logs showing driving at 35-45 mph in 3rd (automatic) or 4th (manual) gear.

[evren]

I've got this sometime back, but should contain a similar data of cruising. Let me know if it is useful?

[5.7ute]

Can you log IBPW at idle to ensure you are not pegging a minimum limit?

[evren]

I've done that as some point, and here is the log.

Thanks

[5.7ute]

I cant get much from that log sorry as there is no real pids logged to get a reference from. Something like your 02 log with IBPW instead of IAC position would be better. Also it might be worth you reading this link I just found. http://www.ratwell.com/mirror/interro/techgas.html

[evren]

Ok, today I've managed to install my Fuel Pressure Gauge, and below are the details. do you think I'm fine with that? if not what else might be affecting my HC level (rich fuel) where my LTFT is around -4

I've even tried to change the AFR via DVT to 17-19 but nothing has happened. I'm still thinking that the fuel regulator could be an issue? any ideas guys? stuck with this emissions test really :(

At Idle:
http://i708.photobucket.com/albums/ww85/evrenaker/FGP_Idle.jpg

Ignition On - Engine Off
http://i708.photobucket.com/albums/ww85/evrenaker/FGP_ignition_on-engineoff.jpg

[joecar]

Does your FPR have a manifold reference hose (i.e. is it a return style FPR)...?

[joecar]

What car do you have...?

[evren]

it doesn't have a return style. I've got a Holden VZ SS (5.7 LS1 - 2005 model, where the TB is electronically controlled)

as I know the FPR is in tank along with the walbro unit. The unit I've got is Walbro 255 ltr/hr high pressure version.

[joecar]

You have a 10 psi variation in rail pressure... I'm not familiar with the Holden fuel pump, does the PCM vary the fuel pump voltage to get pressure changes...?

If not, and if no manifold reference, then the 10 psi pressure difference is a problem since the PCM can't account for the changes in IFR due to that change.

[evren]

I'm planing to put back the stock fuel pump 194ltr/hr - so you think it is necessary to put a fuel pump larger than the stock one? I mean at what whp should I replace it?

I've been advised to put 255 walbro but looks like that could be my issue pushing to much at idle and cannot be controlled...

[evren]

also to confirm, is this the right kit for my car? http://www.lingenfelter.com/mm5/merchant.mvc?Screen=PROD&Store_Code=LPE&Product_Code=L710660504&Category_Code=C75

[swingtan]

Just a couple of points on all this....


In CL mode, the trims will keep the final AFR around stoich. which yours are doing. Regardless of fuel pressure issues, the final AFR is being controlled by the NB O2's.
Your LTFT's are pulling up to 10% though, which indicates the commanded fueling is way too rich.
RE: the fuel pressures, the VZ will "prime" the fuel system with a 2 second cycle of the fuel pump, then turn off the pump if the engine is not started. Was the image posted when the pump was running or after it had been powered off? You may want to check the pressure with the pump on to see if it's different.
Your idle spark control is working pretty hard. Large changes in the spark timing will impact exhaust mixtures and that includes the HC levels.


So, some things that may help....


Tune the VE table and then, if using one, tune the MAF. Get the idle mixtures as close as possible to "correct" so the trims are not working so hard.
All cammed cars want to "lope" to some degree. Attempting to "correct: this llope can cause other issues so I find it better to just let the lope occur and have minimal corrections. If you look at your log, your engine idle speed varies by about +/- 50RPM, so you would have minimal corrections in this range. Outside of this range is where you want corrections to come in. So it may be an idea to ranp the idle spark corrections in slower at the beginning.
You may find that altering injection timing will help with emissions. If you make your INJ timing when hot, closer to the values used when cold, then you may find the emissions are a lot better.


Simon