Fuel injector duty cycle/head gasket

[Kansei240sx]

Whats up guys.RB25DET in S13 as some of you may know.

Im running 370cc stock injectors ( upgrading to 550cc injectors and ECU soon ) No more SAFC.Stock turboAVC-R and SAFC2. Quest alternator running about 13.9-14.1 volts at all times unless the fans kick on, then it drops to around 13.2 volts.I've had some really odd problems the past few weeks.

When i decelerate my injector duty cycle jumps up to 100 percent on my AVC-R and the car stutters slightly. It only does this intermittently. As soon as i give it a TPS signal so slightly, it'll drop back down to like 1-5% duty cycle or so in that area.

My car falls flat on its face and runs like dog**** below 29 percent throttle and especially at low rpms. I know some of this is contributed to boost/vacuum leaks. Once it gets above 29 percent throttle the car drives normally, and pulls like it should, just with alot less power. Timing is at 15 degrees BTDCIm running a .75mm gap on NKG iridiumsZ32 MAF in 2 out 5.

Question 2. Im pulling the head on the RB25 and im going with a head gasket from Tomei most likely. Does anyone now what the RA needs to be? If the head and block surface are correct, meaning i cant slide .003" anywhere under the straight edge, would you think that is good enough to seal a metal multi-layer head gasket?

I mainly want to pull the head off to get it cleaned up and all the coolant jackets cleaned out, new idler, new tensioner, and N1 water pump, and re-do all the coolant lines and Q45 TB.

This is all i can think of off the top of my head. Let me know what you guys think.

[Darius]

DON'T PULL THE HEAD. It is like opening Pandora's Box (whoever that chick is? ). If you need to clean the cooling jackets, go get a system flush at Jiffy Lube or something. Don't pull the head for something like cleaning. I did that to be pro-active and it has been a thorn in my side ever since. Now I have a paranoia complex about it too.

How are you running the Z32 MAF as far as tuning goes? Does the SAFC allow you to modify the MAF voltage vs. air flow points? Without modification, it will cause the engine to lean out on the top end if you do not adjust the MAF scale. Doing that pretty much defeats the purpose of running a Z32 MAF except for maybe the fact that it has better resolution than the RB25.

[Kansei240sx]

SAFC allows you to modify the voltage signal in and out.

With my wideband and SAFC i have around a 11.9:1 AFR on 13 psi or so. It is usable, but not favorable.

[240z4u]

Have your machine shop check your head warpage while its there getting the busted off exhaust manifold studs extracted!

Thats what I did.

From what I have seen, a metal HG is not really needed until your making big HP. I am sticking with a stock unit and head studs.

Don't forget you have to replace your head bolts after pulling it off.

Evan

Darius is right, DON'T pull it if you don't have to! I opened pandoras box last weekend, what a mistake LOL.

[Kansei240sx]

I've already had the block stripped down to the bare head/block.

Manifold studs have been replaced etc...

Ill take your work for it.

My main concern is the injector duty cycle problem. It just strikes me as odd.

[240z4u]

I am not familiar with the apexi unit. How do you know the injectors are going 100%?

Also, a wideband would indicate wether or not you have a real problem.

Best of luck man.

Evan