rough powerband under 4k

[ch187]

I just recently got my car/motor back together at the beginning of the month.I opted for a simple t28,z32,450cc,rom tune build. Iran it at 5psi because I'm waiting for bov/piping and ran it on compressor surge for about 3 days.

In first gear from a stop, I noticed a rough, rich powerband up to 4,000rpm. I would get some black smoke and some subtle pops. As soon as I hit 4,000, it smoothed out and pulled nice. At this point I was still running a little rich.

In second through fifth, it wouldnt smoke at all but still seemed a little rough. Again at 4,000 it would smooth out and pulled like a beast.

The engine idles great and is steady.

After 3 days of driving the turbo started showing signs of its age. Grant it, it was rebuilt in japan and sold to me via Jarco, it had excessive shaft play and sounded like rocks tumbling around in the compressor housing. Turned out being the compressor blades scraping the housing. I drove less than a mile like this before I wired the wastegate open so I wouldn't boost the rest of the way home. Of course it stops making the noise.

I've been driving it with the wastegate open for a few days total. It runs great. For not going over 0psi on my gauge, it felt better than any KA I've driven. Its a smooth, stout motor. Not running incredibly rich at all. Getting awesome economy and all.

The thing that got me is that its still a little rough. Aside the fact that the WG is wired open, its still showing the same symptoms minus the smoke. Its not as rough either, but at 4k, theres a noticable jump in acceleration.

I'm wondering if its something mechanical (maf etc.) or my tune. I've heard that ungrounded a z32 maf from the chassis will help in some cases but that sounds a little sketchy on that one.

Any advice, criticism, or help would be appreciated. You guys have helped a lot in the past. Hope I made this easy to read.

[boost_boy]

You have to be more specific when you're talking about running rough. Is it running rough as in stumbling while accelerating or do you just feel extra vibration below 4000rpm?

Dee

[ch187]

It's not stumbling. It's just a lack of power and increased vibration at this point.

[boost_boy]

It's not stumbling. It's just a lack of power and increased vibration at this point.

Well, if you're not feeding it boost, it's just going to run rich, but it will run. If you have no boost, it's going to lack in power. As I explained before, CA18DETs don't have that much power under 4000rpm with a turbo, so just imagine without. And those remapped ecus scare the piss out of me! Unless the thing was mapped on your car and on a dyno, you're playing with lady luck.

Dee

[ch187]

yeah i see what your saying. it just doesnt feel normal. never did it before i went with the new setup. the person that did the tuning tuned it to their CA. not exactly sure they did it but we'll see. i wont push it too far until i get my wideband. rebuilding the turbo and putting on my sheepdog bov and we'll see what happens. thanks dee.

[boost_boy]

Any time, bro! Just remember this, if you can't get that thing to act right, revert back to your stock set-up because rinse-down is not cool for your rings and pistons and will dilute your oil which will destroy your bearings eventually.

Dee

[ch187]

yeah it happen on my old setup. at this point if stock eccs isnt working out i'll be going MS. just thought id give nissan a chance and see if there system can handle it. i mean its not too bad. im not running that rich. im getting great gas mileage. 20+mpg