1j Breaking up around 5500 to 6500 RPM
 

1987 Supra 1jzgte Swap with R154.
It has been cold for the past few days here in colorado but 22 degrees yesterday and 7 degrees today. I just got the car and wanted to show a buddy a little of the power My 1jzgte has. Well for the past 2 days it has been a little choppy at high RPm but it ran fine about 3 days ago when it was around 45 to 55 degrees. I did here a small pop from the passenger side of the engine (sounded like the turbo's) but i was not under a real boost when it happened and it wasnt to loud but it was detectable. Do you guy's think i have a boost leak, bad spark plugs or should i kind of plan on it missing a little with the temp being as low as it is??
Any help i have only had the car for about a week

Depending on the sound I'd probably start with checking for boost and exhaust leaks.

Fouled spark plugs may perform worse in colder temperatures due to the richer fuel mixture.

I would start with checking those and check for any stored diagnostic codes.

I drove it yesterday and it was just fine once the car and tires warmed up. i think i was mainly hitting the max boost and spinning the tires cause of the cold. anyhow i am sure it is kind of a precursor to what will soon happen so i will keep this in mind when it happens more often.

There is no reason at all that you would hit fuel cut due to just a temperature drop or from spinning the tires.

Well it seems to be ok today! Pulls just fine but i did not go over 6200 RPM when i drove it at lunch time. Do you think it could be the Spark Plugs and an issue with gap??

Heh, if it was a 7M, I'd say you're hitting the rev limiter... but unless you're running 7M electronics... :roflwtf:

A gap issue could definitely cause such problems, but it's not something which just happens spontaneously. As I said before, a spark issue is very likely though, so checking for fouling and yes, even checking the gap is definitely at the top of the list.

No 7M stuff just a 1jz ECU for NOW! do you know anyone with a set of 440 injectors sitting around?

I've got a couple sets, but they're all top feed. :(

BOOOOOOOOOOO this man BOOOOOOOO

So i just found a small hole in the scilicone hose on the front side of my FMIC. I think this may have been the issue i was having. I can still boost to around 15 but when i got her i was around 17 consistantly. It still drives good but i think i found the issue