WonderingRaven's build...

[wonderingraven]

Hello there,

Been a bit since I've posted here but anyways.
Trying to tame this CA18det motor I've acquired years ago.
nistune base ca18det tune with Z32 maf and DSM455cc injectors, 320LPH AEM fuel pump, T3/T4 turbo, showing between 17-20psi of boost as per gauge at idle.
External Wastegate. Forged pistons and upgraded rods. Water to Air Innercooler setup, I had an BOV and boost controller setup but removed in my current mode of troubleshooting.

All into my 1987 200sx S12.

My current issues I am having as this video the idle it's going up and down and to get it to actually rev with a response I had to change the fuel pressure between 40-50psi at idle.
My goal is to get this idle not so acting weird so I can start driving her again. I am only assuming at this point I need to up the injectors size from 450's to something around 720cc or higher.

[Izento]

You either have a air leak or your tune is off. If you're saying that you're running a base tune, I hope that's been adjusted for the injector size, otherwise the car will run very rich and stumble, just like the symptoms you're having right now.

[wonderingraven]

I did find another vacuum leak, I did adjust the nistune to the maf and injector size.

[float_6969]

That base idle fuel pressure is WAY high. It's supposed to be 2.5 Bar (36.3psi), with the engine off and the fuel pump running. If it won't run right at that fuel pressure, there's a tune issue, or a bad vacuum leak.

Also, that's A LOT of fuel pump for that setup. You could be overwhelming the return line, which causes wonky fuel pressure issues.

Also, the Z32 MAFS should ideally be paired with 550cc injectors. Nistune should be able to handle the scaling, but it doesn't always play nice.

Based on the video alone, it sounds like you have a timing issue. Have you checked the cam timing? Are the cams stock? Have you checked the ignition timing?

[wonderingraven]

cams are not stock, they are tomei something I don't recall the size but is with adjustable cam gears.

I've inherited this motor over 10 years ago, so I'm trying to dig in and figure this out. I am going to source out some 550cc and replace and re-adjust in both the fpr and in nistune. the time is spot on I can't confirm the cas when I was handed this motor I had a lot of extra parts.
but I did find one big vacuum line leak

[Izento]

CAS on CAs are known to be problematic and you can run into weird timing issues.

You probably have Tomei poncams which don't require readjustment.

Float is also correct, that's a huge fuel pump. I didn't even register that when I first read your post.

[wonderingraven]

cool thanks all, waiting for the 550cc and hopefully a replacement cas to be safe. soon as I get them all in I'll readjust the fuel pressure and go from there.

[float_6969]

If they're Tomei Poncams, they're supposed to be used with stock cams. If someone has put adjustable cams on it and they're not set to 0, that can cause issues. Also, the factory spline drive in the exhaust cam has a nasty habit of breaking off/slipping in the cam, which can cause very hard to diagnose issues as well. If you haven't checked the ignition timing, that's a good place to start as well. The directions for it are in the FSM. Ensure the base timing is correct. If you have to adjust the CAS much away from the center of the adjustment range, there's something off with the timing.

This could also just be a bad tune. Just keep working through it. You'll get there!

[wonderingraven]

Thank you, I just got the 550cc's installed just about to do some more diagnosing here this weekend. Hopefully it's just the simple things.

[Izento]

Also as a side note, yes your 450s are too small for your build. Not to say that's related to your idle whatsoever, but definitely good future-proofing to get those 550s.

[wonderingraven]

Quick update, got the 560cc, tuned it down to the 36 psi on the fpr. Throttle response is much better, but it is now acting a bit lean but that is something for the 3 day weekend to work on now.
Thanks for the help!

https://youtu.be/Cugu2wcexjY

[Izento]

Ok, so I took a look at your video. Your CAS is moved all the way to the left. Something looks off with your timing brotha. Look in the FSM to reset your timing. Your CAS is all the way advanced as far as it can get. That's probably why you're getting a lean condition.

[float_6969]

Yeah, I couldn't see it in the first video, but it's very obvious in the second video that the CAS is NOT adjusted properly. If it IS adjusted properly to get the timing right, your cam timing is off.