2zz down on power [SOLVED]

[inside]

I'm having some 2zz issues with low power in high revs - lift is weak and engages a bit late at around 6500 and slowly. Otherwise runs smooth through whole range, no hesitation, also no CEL light as well. Until not so long ago everything ran perfect, transition was sharp at 6200-ish. Now it seems 40-50hp is missing in the hi-cam range, e.g. 100-160km/h is 13.5s vs 9s...

We have already checked all connections, OCV/filter, cams, oil is fresh and full... lift bolts were replaced recently, <20kkm back, but will check it again.

Then I'm running out of ideas ... check MAF, check cat isn't clogged (<2 years magnaflow)...

Anyone has any other suggestion what to check, test, replace? Cheers!

[brettfield999]

What exhaust and intake setup have you got?

[inside]

What exhaust and intake setup have you got?

Intake is carbon CAI with stock MAF piece before the TB.  Exhaust has modified TS manifold, magnaflow hiflow cat and custom box... I wasn't changing anything lately, it's the setup it used to run great few months ago.

I did some more testing yesterday. Car runs nice and smooth, etc. no hesitation. In 2nd it almost seems fine, because its harder to notice as revs go by faster. But in 3rd and 4th gear pull its clear that there's no strong transition into lift. Definitely nothing happens at 6200, and during 6500-7000 the note changes gradually and it starts to pull strong by 7000, and then revs all the way to limiter.

As I recall that the transition used to be very explicit at ~6250, with torque bump and engine note clearly sensible.

[shnazzle]

wiring issues?

Doug had a similar issue I believe and it turned out to be some lift wiring that broke in the harness.

[inside]

I've just re-checked the wiring and spliced voltmeter into lift OCV wires, then went for a drive. This is what I've found:
- ECU gives 9V to the OCV according to tacho at 6100 rpm (not very accurate but close enough)
- even if I go to 7k rpm, then back off to 6k rpm (OCV is engaged constantly), I still get same "weak lift" until it starts to breath at 7k rpm

The conclusion is that problem must be mechanical, as the ecu/wiring behaves correctly.

[shnazzle]

I've just re-checked the wiring and spliced voltmeter into lift OCV wires, then went for a drive. This is what I've found:
- ECU gives 9V to the OCV according to tacho at 6100 rpm (not very accurate but close enough)
- even if I go to 7k rpm, then back off to 6k rpm (OCV is engaged constantly), I still get same "weak lift" until it starts to breath at 7k rpm

The conclusion is that problem must be mechanical, as the ecu/wiring behaves correctly.

Fry your cat?

[inside]

Fry your cat?

Maybe, idk. Haven't found any similar cases with magnaflow cats...

Today I've also tested lift ocv several times: manually powered it while idling, and engine dies instantly as it should.

Perhaps its not even lift related, but its just where the symptom is most noticeable...

[inside]

Guy at the workshop has looked into everything possible: VVT and lift solenoids, cams and rocker arms, lift bolts replaced (not broken), chain and phase... also intake, exhaust restrictions, catalyst, spark plugs and coils, cleaned MAF. Everything near perfect, he says, but no idea what is causing issues.

I've picked up the car, and the bloody thing now works! It has clear transition at exactly 6200 rpm, and engine note is different as before... also racelogic measured performance is much improved, almost at where it was last year. However, I'm a bit suspicious that it might return, even now sometimes feels it engages 100-200 revs later.. New MAF ordered, will see if this will have any impact.

[KRAMSNEHPETS]

My 2zz has just had new lift solenoid ordered today, packed up so lift not working

[inside]

My 2zz has just had new lift solenoid ordered today, packed up so lift not working

Did it fail the idle test? or what was wrong with it?

[KRAMSNEHPETS]

lift not working

[inside]

In the meantime, my 2zz is acting like at the outset, like having only half-lift.

I've just replaced MAF with new denso unit, reset ecu, and there's no change at all. 

[inside]

Having some progress!

So car returned back to sluggish, after it almost cured itself last time...  (:< >

Over the weekend I took the air filter off (as advised by workshop), and did another run. This brought the 2zz back to life even in hot summer weather, releasing 30-40 hp, with instant lift transition, etc... pure joy The air filter was of ebay carbon cai variety, pretty solid otherwise, and was cleaned last time at the workshop. Since there wasn't any specs on it, and 2zz is merely 1.8, I didn't think it will be restrictive... However after 2 years, and with hotter weather (less o2 dense air), the performance was significantly hurt.

Long story short: BMC CDA ordered. ETA end of week. I'll upload before/after datalogs once installed! 

[shnazzle]

You're at least the 5th person I've seen who has fallen for the sensitivity of the 2zz to breathing/exhaust.

I wonder why it's so damn picky.

[1979scotte]

You're at least the 5th person I've seen who has fallen for the sensitivity of the 2zz to breathing/exhaust.

I wonder why it's so damn picky.

because it makes more than 100 bhp per litre NA.

[shnazzle]

You're at least the 5th person I've seen who has fallen for the sensitivity of the 2zz to breathing/exhaust.

I wonder why it's so damn picky.

because it makes more than 100 bhp per litre NA.

Indeed. It's a very high strung little sucker.

[Dougster7]

Glad you got to the bottom of it, nothing worse than not hearing that 6200 lift kick in when it should. These engines need good airflow in and out, from filter to exhaust. I don't do many miles in my car at all (sadly don't get time for it) but notice the Apexi filter does get dirty pretty quickly considering the mileage it does. Worse so since placing behind the battery near the side vent for temp reasons. Quick blast with the air compressor every few months does the job. For being such a fiesty little engine they are very sensitive to any irregularities, that's for sure!


Sent from my iPhone using Tapatalk

[inside]

Thanks guys for all the help and suggestions! This is now officially SOLVED 

Yesterday new air filter was put in. The car is transformed, below are the results before and after... 100-160km/h goes from 13s to 8.5s 

What still baffles me still is how the previous filter (dry) degraded in performance in such a short while, as it was doing similar times a year ago (perhaps 0.5s more). Nevertheless, conclusions is definitely to keep your filters fresh!

[inside]

@shnazzle Maybe move this to maintenance/troubleshooting sub-forum? Might save someone few grey hairs

[shnazzle]

@shnazzle Maybe move this to maintenance/troubleshooting sub-forum? Might save someone few grey hairs

@inside DONE