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Missing power

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Im working a problem on a RB25DET, I have done many of these engines on my dyno so i I've got lots of comparison plots.

The engine is lacking power, generally around 70nm lower torque all across when on 1.2bar/15psi boost.

Any ideas?

Vipec v44

Batch fire semi sequential

(Tested fuel with 1 and 1/2 cycle injection with no difference)

Wasted spark

Upgraded original coils (yellow jacket)

Custom inlet and exhaust manifolds

ID1000 injectors

Bcpr7es plugs gapped to 0.6mm

No back pressure in exhaust manifold

Precision 6266 T3 in, 0.82ar turbine housing

The attached picture trends it towards a smaller 5558 turbo, and adjusted cams, other than that same setup. Note! The smaller power figures and HIGHER later-spool pressure are the trouble engine.

Look at the fuel map... Looks like that to achieve flat lambda value. What's going on?

Attached Files

Checked the following;

- Compression is ok

- timing belt correctly lined up

- timing is correct

- spark is ok, meaning no obvious blow out issues and visual spark inspection at cranking looks fine

- plugs looks fine with regards to lambda and temps

- EGT measured just aft turbo maxes at around 600celsius

- no backpressure in exhaust (-0.3 to -0.05 vs map across power band)

Camshafts are stock? What about VCT system?

Stock cams, running vct active from 1500rpm to max rpm, gives best torque on stock engine with tune. I've tried with vct off also, with even lower numbers as result.

Turbo spinns freely?

Is the timing actually doing what it is supposed to? Have you checked timing with a timing gun during a run to see if it actually hits its target?

Got good voltage?

Got a logfile from the ecu to post up? (Not just a picture but a file would be best)

Any aftermarket parts in timing mechanism? Crankshaft pulley, camshaft gear, etc...

The turbo spools and spins freely, the engine had a smaller precision 5454 turbo installed that was limited by exhaust backpressure, (+0.6bar @ 1.2.bar boost, +0.9 @ 1.35) but it was making almost the same max power as it is now with new 6266 turbo, the new turbo does generate a little more intake temp, and gain some torque & power over the previous one but the gain really only reflects the lesser backpressure, with the 6266 backpressure are negative from -0.3bar at spoolup to -0.05bar at max rpm.

System voltage is fine and steady. Remember that it is running wasted spark with 3.5ms dwell at boost, so enough time pr rev for complete dwell and cooldown, no indication of over heating coils.

However i suspect weak ignition since it was misfiring with plugs gaped to 0.8 at 1.1bar boost. They are now at 0.6, and no misfire can be felt or logged at 1.4bar, but that does of course not mean the spark is optimal..

Due to this, and the fueling issues with the second closed intake valve injection event, ive talked the owner into upgrading to a fully sequential ecu and some new coils,

But as i have multiple times before made the higher numbers on this setup as it is today i wanted to bring in the internet for a disccusion..

I have not visually observed timing and checked for drift during a run, did check with locked timing with high and low rpm in neutral without load to verify or set offset to counter any drift.

Knock response and low power gain from adding higher timing also indicates its running what i ive set the map to.

(Im using the newest Plex knock sensor system btw)

The only aftermarket part in the timing loop would be that it is running a 24/1 cas trigger disc, which is a thing i do as standard on these engines, as the original 360/6 trigger causes so much interference issues. (its far from perfect with the 24crank, 1 cam trigger either, but far better.

Try another spark plugs and coils. Last years we have a lot of chinese fakes sold here in Russia. Maybe some part reaches Norway. Just some weeks ago saw a new Denso IK24 spark plug with felt off ceramic insulator of central electrode, which blocked the gap and new melted genuine Toyota COP coil on another car.

I assume the wiring to plugs and injectors is stock and in good condition?

Also maybe there is a problem with minimum injector pulse width with rather big injectors for stock engine? Do you have a log with PW channel?

We usually reply within 12hrs (often sooner)

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