Rb20det Misfire Off Boost?

[cogs]

hey guys, my R32 misfires (I think thats what it is?). When the engines cold and I'm slowly accelerating it sometimes has shit all power then suddenly it gets full power and takes off like its hitting boost or something (its not though). This is under 3k revs. Seems to be kinda random, but is around 2000-2500 revs that it happens i think. You can be driving along too (when its cold), holding throttle steady and drone suddenly increases and it loses power.

I have no idea where to start looking?

It's an Rb20DET, FMIC, 16psi. The ignition amplifier (I think its called, the thing that usually sits on top of engine near the firewall, little black box thing) is just hangind loosely (not bolted to anything) as coil-pack cover has been removed. There looked to be a bit of moisture around coil-packs so I sprayed WD40 and cleaned up a bit around them but it hasn't made any difference. I havent tested the coil-packs or taken them out to have a look at them or anything. Haven't checked plugs or anything yet either. Car is currently running very rich due to the way its tuned (Adj. fuel pressure regulator) runs about 50-60psi fuel pressure on idle and possibly has bigger injectors. Has standard computer. Atmospheric BOV. Bigger fuel pump (Walbro 500hp i think). Bigger turbo (custom Vg30). Pod filter. That's all I can think of.

Not sure what other info is needed to diagnose but I just think it's odd as I searched and most misfire probs were at higher revs?? This only happens when car is cold and at low revs.

Any help would be greatly appreciated! Thanks.

[TTT]

I’ve had 2 rb20’s, they both do it.

Ask around and you will find that they ALL do it.

Something about the cold start and how rich it runs till warm or something.

Doesn’t seem like there is a fix for it.

Best way to describe the problem is like something is holding it back then just releases it.

All around the 3000rpm range while engine is cold.

I got around it by driving and shifting at 2500rpm till temp gauge is half way..

Which ends up being about 5 minutes of driving.

[cogs]

thanks for the info mate, much appreciated!

[heyhey!]

is this meant to be a joke???

[Haysey]

why would it be a joke?

pretty serious joke if it was?!

wtf

[Ronin]

Yep my 32 does the same thing, its just the way they are when cold.

[Rolls]

All of mine have done it as well, one misfired badly when it was doing it, the other just has a very slight drop in power.

[Guest tosboost2]

mine does it every time the engine is cold so i just put the turbo timer on for 7 minutes have a smoke then drive. waste of fuel but i hate the feeling of it. feels like the car is retarted, so to save myself i only get in it when its hot;)

[_x_FiReStOrM_x_]

I've got a stock rb20det, and that does it too... as others have mentioned, probably nothing to worry about.

Edited June 19, 2007 by _x_FiReStOrM_x_

[SuAvE-1]

well, rather than accepting the problem... our cars at some stage did not have this problem.

I have similar mods to you and have only recently copped this problem. It was mainly noticeable with the change of the turbo. I did/do have problems with my coolant and water temp sensors and adjustable FPR.

50-60 PSI is fine at 6000rpm's plus. It is designed to handle the 16PSI boost you're running. We have standard computers. That fuel pressure means we totally richen out our lower rpms (anything less than 5k). We get surges cutting in and out because we are seriously running wayy too rich. I plan on cutting back my boost until I can afford to get some sort of fuel computer. This way I can run lower fuel pressure and make the car more daily driveable.

I get this problem all the time, especially cruising around 3100rpm on the freeway, warm or cold. I think that might have something to do with my coolant sensors.

aside/ I would have thought the ecu would just open the injectors for less time given the increased fuel pressure however this doesn't seem to be the case. the ECU generally runs the same regardless of how much fuel pressure is in and can't seem to recognise an over rich condition.

Hope this helps you. try cutting back boost and running a lower fuel pressure.

[Rolls]

People with standard everything just an exhaust/boost increase get this problem as well though.

[Rekin]

not really related to the topic, but i hope that you arent running 16psi on stock rb20 turbo...

Saw a rb20 turbo go pop due to running 15psi on the weekend.

13psi~ is the max safe you should run at

All r32's have same problem as you described, as mentioned its due to the ecu.

I heard that switching off engine and turning back on will bypass the sluggish start, but never tested

[Proximity Motorsport]

no R32s ive seen have done thiss? Including mine which hadnt started in over a month and we started it, idled for few mins then drove off still slightly cold. Kept it under 3000rpm and nothing felt odd.

[Kinks]

I had a redtop RB20 that did this, it's definitely something to do with the cold start because a few times i was holding the throttle steady, and it was struggling a bit (almost like it was running lean and retarded or something) and then like a light switch it came good and i started accelerating because cold start had finished and it went back to its normal map.

resetting the ECU seemed to help marginally but not really.

my theory was coolant temp sensor or something was buggered, so it was getting wacky cold start enrich values. but I never bothered diagnosing it further.

[BenA31]

yeah my ceffy with rb20det does this when cold and so did my previous R32, if left to idle for a few mins prior to driving it doesn't appear to happen or if it does its minimal. I'd be agreeing with it being more a issue with the water temp sensor i just haven't got around to replacing it yet.

Edited July 25, 2007 by skypy12

[slydn 32]

My RB20 was struggling for power when cold untill i had my computer re-mapped now it doesn't feel like there is something holding it back. The guy who tuned it did say it was running really lean before he tuched it, not sure if this had anything to do with it.