Good morning all! After a week away visiting Mildura where my Z is I've finally been able to drive it after 14 years since buying it. It's been a journey so far to get it from having a dead engine to a rebuild to having it on the road a couple days ago. I'd like to run the engine in but unfortunately, I'm getting a noise that comes on when I give the throttle a decent poke that sounds like either lifter tap or possibly detonation. The noise seems to only come on during faster acceleration, it's not as present if I accelerate slowly and it can't be heard if I'm sitting at constant RPM. Since having the engine out I've changed a LOT, slightly biggers turbos, AMS exhaust manifolds, bigger SMIC's, enlarged throttle bodies, underdriven crankshaft pully, Apexi pod intake, AMS downpipes, deleted systems such as EGR, AIV.. etc. I'm trying to work out how I should progress from here, my current thinking is "Maybe, since I changed a lot, it's not getting the right air/fuel ratio under acceleration from the factory ECU map which is causing detonation under acceleration? Therefore, I should get the noise diagnosed and get some sort of base tune in the event that the noise is the result of needing a tune up". If the tuner I took the car to determined that the the noise wasn't related to needing a tune I could go down a different route (If it's diagnosed as sticker lifters for example), but I figure seeing as I changed a lot of parts a tune would be the next logically step anyway. Has anyone been through a similar process or how would you proceed given the context above? Would changing a lot of parts like this possibly result in detonation if I hadn't had the car tuned since changing them?
Bigger turbos - what are you boosting to? I mean yeah detonation is certainly possible if it's leaning out. No mention of fuel system upgrades?
I would be seriously considering something tuneable. You wont get the max use out of the mods without it. Turbos might make the same boost, but move more air. If the fuel map cant add enough fuel, you wont have a good time. See if you can get a run on a dyno or at very least a wideband O2 in the exhaust to see what the ratio is. If you are running stock injectors, you are going to max them out super quick too.
Yeah, haven't changed anything with the fuel system except for putting in new OEM injectors and a fuel filter. Haven't set the boost yet though it's got a Turbosmart Eboost Street 40. I should probably investigate that and set up a mild boost level while I run it in. Of the 90kms I've driven it since the rebuild I got it to about 3psi at the most as I haven't been driving it too hard til I work out what this noise is.
Thank you for your recommendations, I'll have to see if I can get a hold of a wideband O2. I was a bit worried about running stock injectors, though I knew if I upgraded them it'd definitely need a retune. I was hoping the factory ECU would compensate for a little extra air so long as I didn't crank the boost sky high just so I could get it running.
You should, larger turbos will have lower exhaust backpressure than the stock turbos even at lower boost. Less backpressure means an increase in volumetric efficiency so the same boost on a bigger turbo can make more power. Nistune as a minimum, link or haltech would be better.
If you have only pushed it to 3psi boost, it shouldn't be knock (detination) unless the engine is running really lean. Have you pulled the plugs and taken a look at them? This might give you some clues. Are they the plugs the correct heat range? What's the engine comp after the rebuild? Is it possible your fuel is off having had the car off the road for yonks? Are the cams setup correctly? Lots of things need to be checked and ruled out. Having said that, a tuneable ecu is a good investment to look after your new engine. I would be going for a Haltech.... so.. so easy to setup and tune
