R33 Boosted To 9psi, Backfire & Hesitate

[R_B_Boy]

Hey,

I got a r33 rb25det auto sedan. I recently installed the ~$20 turbotech boost controller and a boost gauge and bumped it to about 9psi.

Problem is, when I plant the foot when the gauge hits about 4000rpm the car backfires a few times, hesitates, then gets the power and all seems good.

Just wondering if anyone knows why this is?

should I have t-pieced the gauge into the existing box thingy that the hose from the back of the intake manifold? does the ecu require this?

is it running too lean\rich?

and how much is a AFR gauge?

Edited February 25, 2007 by R_B_Boy

[BHDave]

Forget the dash mounted A/F gauge, unless you are spending reasonable dollars for a proper wide band type you are only guessing. For less than $100 you should put it on the dyno and see what is really happening at that point.

You will get a more stable result by removing the factory controller (which you have done).

Id suggest that the boost hit is either causing the car to richen up due to R & R or lean out due to dead fuel pump, or maybe even old coils having a cry.

As a first step though, gap your sparkplugs down to about .9mm and see if it improves.

[Strik3r]

shouldnt be getting r&r at only 9psi... all the other ones are possibilities... i'll also ask the normal 'what fuel are you using' ?. you'd be surprised how many people are using 92/95 RON fuel and wonder why as soon as they mod their car it doesnt go very good.

[tek_01]

mine didnt like anything above standard boost

pretty sure it was hitting r and r seeing as afr;s went under 10

here the post i made about it

http://www.skylinesaustralia.com/forums/in...l=my+first+dyno

so it could be that but mine didnt backfire so its more likely a spark issue im guessing

[nizmo_freek]

What spark plugs are you using?? you need to be using a heat range 6 or 7 with a gap of 0.8mm if the car has a few mods.

[R_B_Boy]

What spark plugs are you using?? you need to be using a heat range 6 or 7 with a gap of 0.8mm if the car has a few mods.

Using the iridium ones that autobarn sold me. Whatever they had in the book for the RB25DET.

[nizmo_freek]

Using the iridium ones that autobarn sold me. Whatever they had in the book for the RB25DET.

Which means they will be a factory spec spark plug, they will be a heat range 5 with a 1.1mm gap, that is fine for a standard car but not for a modified car, i had the exact same problem as you a while ago, only had a catback and decat pipe and the car felt very non responsive and would hesitate alot, i changed to ngk BCPR6ES spark plugs (these are a heat range 6 with a 0.8mm gap) and it fixed the problem straight away.