need help detonation through intake maniflod

[jdmnewf]

i'll provide some back ground info.

i have an rb26dett fresh rebuild top and bottom swapped into my r32 gtst. running r43 n1 turbos, r34 o2 sensors, oem rb26 r32 ecu, rb20 ingitor and coil wiring, all remaining sensors and wiring are rb26 out of an r32. i also had to hard wire the drop resistor in the injector wiring.

here is what happen when i started the engine. had to feather the throttle to keep it running, engine was pinging back through the intake manifold. did a leak down test and compression test. Both numbers not great but engine only ran for a couple seconds nothing got to seal. removed cylinder head everything looks good nothing came into contact. filled cyclinder head with fluid to if valves were not sealed, nothing leaked back through.

looking for any suggestions, or if anyone ran into this before. i know it sounds like timing, but before i stripped the engine we removed the belt retimed it cranked it over twice and the samething happened.

[rolyaT]

Possibly a intake valve not sealing correctly. Only way det could happen in the plenum, if that's what it is. But start up shat idle is usually a boost leak or your iacv valve. Plus iacv is right below manifold so possibly your hearing something with that. Just guessing though cause I haven't heard the noise.

[Skym]

Using parts from different engines sounds like cause of trouble.

Feathering throttle (opening throttle bodies) sounds like engine is running too rich for some reason. I would check fueling side of engine and check for aftermarket injectors (or wiring to and from injectors, ECU).

Usually o2 sensors are not looked at by ECU after cold startup, but try unplugging o2 sensors and see if engine starts and runs smooth.

R32 ECU needs R32 o2 sensors, R33 ECU needs R33 o2 sensors (when Nismo swap stock ECU from R32 to R33 they change o2 sensors from R32 to R33 to suit). I would think R34 ECU needs R34 o2 sensors. R32 RB26 ECU, R34 o2 sensors doesn't sound right.

Then I would check signals RB20DET ignitor (or swap with genuine R32 GTR).

Another is check oil thickness, as too thick oil can make engine struggle to idle.

[JeeBus]

ignitors are the same^^

Check cam/crank timing and CAS timing when you have the motor back together.

Sounds to me like timing was off.

[jdmnewf]

it sound like a metal on metal sound. checked cams for clearence before taking apart. all good. tried a different cas sensor. ran the same. it smells like it is running pig rich. injectors are rb26 oem ones out of know good engine. any suggestions for testing the iacv valve while engine is apart?

[Skym]

Injectors can leak and cause idle problems and the fact it came from intake manifold side points towards them.

Also just wanted to eliminate incompatible parts, wiring as a cause (now or later on).

I agree, CAS could be part of it if cam timing is out.

but before i stripped the engine we removed the belt retimed it cranked it over twice and the samething happened.

Thinking about what you have just done to engine (rebuild), if you skimmed head, block the cam timing, CAS probably will be out.

Here's a how to on degreeing your cams -

http://www.camshaftshop.com/the-sole-purpose-of-degreeing-your-cam.php

[jdmnewf]

i did resurface the head and block

[cory]

I don't think it has anything to do with the timing. When we had it running it idled quietly but really rich and it made this ping noise about every 10 secs. Seems to loud to be timing but I could be wrong. It didn't sound anything like the det that you get on boost. The engine has only be running for about a total of 5 mins or less

[Skym]

5 minutes is probably enough to reach coolant temp where ECU looks at o2 sensors. I think every 10 sec is when o2 sensors switch from rich to lean and lean to rich (check in engine manual, as time in seconds is mentioned there). Sometimes ECU + o2 sensor can do that with intake manifold flange leak if bad enough (rpm needle would go up and down), but also the incompatible o2 sensors could be a cause.

[jdmnewf]

i don't think it was running for 5 minutes. after a few pings we would turn it off.

[cory]

My bad it only ran for about 30 secs at a time. Not enough to warm at all

[my3awds]

Rebuilt with factory specs or different crank/cams? What exactly is the numbers accross the 6 cylinders? Are you consistently low on all or is it random cylinders? Not sure on RB26's since I'm new to them (but not to import builds) but could you possibly have the camshafts swapped around (in for ex, ex for in)?

[cory]

Crank and camshaft all stock. Machine shop said to have it all in spec.... Not possible to mix up the cams one has a the Cas on it

[jdmnewf]

tested injector resistance last night 3 are perfect and 3 have no resistance. possible 3 injectors stuck open?

[jdmnewf]

have 3 injectors replaced. misfire almost gone completely. car is reving high and racing. When it starts racing up and down is when the misfire occurs. throttle positioning sensor is in spec, timing is on. when i adjust the acc valve there is no change. Unplugged it and car runs the same. any suggestions. new r32 o2 sensors on the way.