Hey guys! new to the forum but I've owned an sc300 with a 1jz for a little bit now and I love it. However it's developed a hesitation. Lets say you're cruising in 5th at 50mph, while in vacuum but still on the throttle slightly it runs smoothly and has no issues, but as soon as you accelerate into 0lbs it starts to hesitate and chug a little. If you accelerate thru it it does this until you hit 5lbs and it opens up and 100% of the power is back and it pulls healthy. Just wondering if anyone could point me in a direction of things to look into. I was going to do my spark plugs today but pretty much all of the coil pack screws were about to strip while trying to loosen them so I gave up on it for now, so any info on that would be helpful too ha. Any responses are much appreciated!

thanks

also motor is stock besides a front mount and it only hesitates once I've been driving it for a little bit, when it's cold/first warmed up to operating temp it pulls smoothly with no hesitation between 0-5lbs

Do you have a wideband?

1JZ ECUs have fairly notorious partial throttle spool area hesitation that's worsened by aftermarket airflow mods and downpipes. Its actually caused by a lean spike that occurs when the turbos begin to spool.

No wideband but I have been thinking about getting one. I've read about that issue online and have wondered if that was the case.

Changed out my spark plugs today and it solved the issue. She pulls smoothly thru the range now!

You seriously need a wideband sensor.....keep that engine safe and monitor your air fuel ratio

In case you havent figured out by now, the coil packs are screwed into brackets in sets of two. Each bracket can be removed by loosening the two bolts with a 10mm socket. Then you pull two coil packs on bracket off at once. And if you want to get the slightly stripped screws out, then buy an impact screwdriver at harbor freight for like $5. It did the trick for me, then I replaced the screws with allen head screws


This..

A good wideband is only $150. Its the first thing somebody with a forced induction setup should buy..

wideband and boost gauge = happy turbo

Yea, figured out that the coil packs are on brackets, saved my butt haha. Getting a wideband has only been a thought so far but you guys have pretty much convinced me ha. What position would you recommend getting the bung welded at? From what I've read online 9 or 3 o clock, but how far down from the twins?

thanks

What plugs did you use?
What did you gap them at b4 putting them in?

List of mods?

I used ngk bkr6eix-11, they're pre gapped at .044, which is a little tighter than I need to be running but I have no issues with them. Only mod is a front mount.

I used to run .28 or .32 on my 1jzgte single turbo never had a problem. But if .44 is working for you u great.

I'm on stock twins and stock boost which is probably why it runs fine. I read somewhere online that I should be running .6-.8, so I thought I'd see how .44 does and make changes from there if I had to but as of now I'll be leaving them.

I couldn't run .44 on my stock coils when pushing past 18psi on my twins or on the single.

LQ9 coils solved that problem

the stock plug gap on a tt supra is the .044, so if you can run that then great you should use that it will make the most clean power, but maybe an idle pop here and there every once in a while no big deal.
once you crank up the boost, drop it down to .032 as others have said unless you go to something like lq9, but most just gap down a little bit.