Only For The Cluey Ones

[Shaun_McL]

Hey Guys,

Anyone out there encountered (and solved) the following problem;-

I have a late R32 GT-R equipped with a HKS EVC 2 boost controller. I've owned it for a while now and after fitting a microtech LTX12 and tuning it makes 260rwkW on around 17psi, so it's obviously pretty healthy mechanically.

Problem is though, the power surges in 3rd or higher under moderate to heavy acceleration, annoyingly, making the car feel far slower than 460hp, when boost is controlled by the EVC (not, though, when the EVC is in 'off' [green or 'monitor'] mode, and boost at standard wastgate actuated levels). It would probably do it in 1st and 2nd gear too, but you tend to not stay in them for long when you're up it for rent.

I assume that this is caused by the solenoid in the EVC not pulsing the boost signal properly to the wastgate actuators. I do have the manual [$20 for a piss-poor copy; thanks BDS's- not] and have followed every setup/trouble shooting step;-

*Wastgate type is set correctly

*Unit has been calibrated as per instructions, twice (could it be any more tedious)

*Everything seems connected properly, as far as I can tell

*The filters to the solenoid unit are dead clean

*The unit is in the same place, but replacing, the factory solenoid (so heat shouldn't be a problem)

*Even tried setting the unit up with learning function cancelled, in 'manual' mode

I went back to BD4's and Paul had a fiddle, mentioning some stuff about base settings, offset, overboost and all that (didn't want to road test though). Anyway, I made the recomended changes and initially it seemed to work, but I, obviously, couldn't really give it any stick around Gladesville in 3rd gear. When I got out onto the freeways, I still had the same problem. None of the "Experts" seem to know or care how to fix it ("Hey, how 'bout we supply and install and SooperBoost Y2K for ya"), like most of you, I've already spent a packet on the car and would just like to solve something with out shelling out cubic dollars for once. Any help will be gratefully received.

Cheers,

Shaun.

[Sydneykid]

No AFM's, running off MAP sensor?

[Shaun_McL]

Hey SydneyKid,

Yeah the car has AFM's in place (for the cops), but they don't do anything now, since the plug'n'play LTX12 is running in a 'Throttle vs TPS' configuration.

Also, after going through calibration procedure (eg. reset) the car seems to hold more consistent boost for a little while.

[Shaun_McL]

Where's my head at. Last message should have read 'Map vs TPS' of course...'ken idiot.

I'm kinda keen to solve this- anyone interested in a good used OEM R32 GT-R gear knob in exchange for the info that solves my problem?

[Shaun_McL]

Gotta take off for a while. Hopefully come back later tonight to the forum and have some answers. Someone, somewhere hasta know....

[blind_elk]

Was the Microtech tuned for the higher boost levels?

I'm no expert, and I'll readily latch onto the latest flavour-of-the-month condition, but it sounds like compressor surge at the higher boost. Mine was doing it while tuning the Wolf yesterday, simply dial timing and / or fuel into it to cure it.

[Shaun_McL]

Yeah sure was. Mark from MRC Dyno in Castle Hill (good guy- if you need a tuner) tuned the car on standard boost and then at a higher (just under 16psi) level. He had a smooth power curve on the DynoDynamics read out when I got there, then, after we made some adjustments to the boost and re-tuned (and went through the calibration procedure on dyno), the power curve was fuzzy at the top where the boost fluctuates.

I'm pretty sure it's not compressor surge for two reasons, first, even with the EVC set to 'on' and adjusted down to near standard levels it still happens.

Secondly, not having changed the turbos in any way, their low speed airflow characteristics wouldn't have changed, and boost only gets above stock maximum once over 3500rpm.

If it helps, the only other mods that effect power are an ARC airbox with K&N filter, a set of front pipes, a hi-flow cat, and a full 3.5" exhaust. Anyone still interested in this?...

[Roy]

Problem is though, the power surges in 3rd or higher under moderate to heavy acceleration, annoyingly, making the car feel far slower than 460hp, when boost is controlled by the EVC (not, though, when the EVC is in 'off' [green or 'monitor'] mode, and boost at standard wastgate actuated levels). It would probably do it in 1st and 2nd gear too, but you tend to not stay in them for long when you're up it for rent.

So power surges means that boost is increasing / dropping. Whereabout are you taking your boost pressure sample from, and reading boost how, a gauge?

[Shaun_McL]

Boost pressure sample for EVC is tee'd into the fuel pressure vacuum line (only way to get a vacuum reading for EVC, since this connects to a section of the plenum that is behind the throttle bodies). Boost reading from EVC. Boost doesn't change much, but it is noticeable.

[Shaun_McL]

Thats 'fuel pressure REGULATOR vacuum line', of course.

[BBQ]

Try Taking your boost reading from the standard boost gauge setup instead of the fuel pressure vacuum line, As it may be loosing pressure causing the regulator to open and close giving you surging.

[Shaun_McL]

Thanks. Will try.