Fuel Pressure Tuning Advice

[JT98CivicEX]

I have used the AEM fpr, 290cc, Cartech 2025 and GSS-342. I set the idle pressure to 31-32psi, static at 43psi. The short and long term fuel trim with the above settings are +2% (idle stft) and 0% +/- 0.8% (ltft). O2 voltage at WOT = .89-.90v. The Cartech is set to 4:1 rate gain.

The JR FMU will be a little too rich when used with the 290cc, as it's fixed at 5:1 rate gain.

[CKim]

Does anyone know if the mixture can be leaned out enough using Zip's box (map mod) to run 290cc injectors with a 5:1 rise rate? Just curious.

[JT98CivicEX]

<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor="#DDDDDD"><font size=2 face="Verdana, Helvetica, sans-serif">Originally posted by CKim:
Does anyone know if the mixture can be leaned out enough using Zip's box (map mod) to run 290cc injectors with a 5:1 rise rate? Just curious.</font></td></tr></table></td></tr></table></BLOCKQUOTE>

If you know what your stock MAP voltage reading is at atmosphere pressure, you can try setting the MAP voltage on the back of the Zip's box to a lower value than stock. You then enable the MAP mod using "MAP mod 0" and modify the setting to approx. 120-130 (positive pressure). This should tell the ECU to lean out the fuel mixture during boost.

Zip, can you confirm this?

[CROM]

Hey guys,

I will be putting in my AEM FPR and my 290cc injectors sometime in the next 3 days. I am just wondering what I should do about fuel pressures. I am going to put the Cartech in at a later date, but I want to get the 290s in and the AEM FPR. Unless it is a complete bad idea.

My question is this. What idle and static pressures should I adjust the AEM down to? And should I just keep my JR FMU adjusted to what it is at= 50 static and 60 Idle?

Will the JR FMU make me run too rich no matter how well I tune the fuel pressure with the AEM?

Thank you

[Streetwize]

By changing the 1/8NPT fittings on the JR regulator from the supplied ~3/16" ID fittings to 5/16 ID fittings and 3/8" fuel line appears to reduce the rate of rise dramatically by increasing the available flow rate through the regulator and inversely decreasing its effect on line pressure.

I just put in the 290cc/min (roughly 28lbs/hr) Prelude injectors I bought from CROM and I'm running 31 psi at idle and only about 35 static. With both the JR and the B&M rail regulator all the way out 30 is about the minimum with my 317 pump. Under full boost seems to be in the 65-ish range (calcs out to effective 34lbs/hr or enough to support 230-ish HP) at 10PSI boost which suggests the net rate of rise has been cut from the original 5:1 to around 3:1 which is right around where I was hoping for. So far, so good, but I ran out of daylight and I'll play with it some more tomorrow. Drivability feels goood, a little richer at the boost valve crossover which is what I was hoping for but it seem just a hair softer off idle and at a constant 60-65 it feels really smooth. I was trying not to have to fork out $150-200 for a Cartech, unlike most of you I haven't had too bad of results with the JR.

Wize

<font color="#a62a2a" size="1">[ March 08, 2002 09:53 PM: Message edited by: Streetwize ]</font>

<font color="#a62a2a" size="1">[ March 08, 2002 09:55 PM: Message edited by: Streetwize ]</font>