1j Breaking up around 5500 to 6500 RPM

TripleC · 12-03-2009, 03:50 PM

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

cre · 12-03-2009, 11:11 PM

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.

TripleC · 12-04-2009, 02:45 PM

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.

cre · 12-04-2009, 08:29 PM

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

TripleC · 12-04-2009, 08:55 PM

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??

cre · 12-04-2009, 09:24 PM

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

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.

12-03-2009, 03:50 PM	#1
TripleC 3" Exhaust Join Date: Nov 2009 Location: Fort Collins, CO Posts: 103	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

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12-03-2009, 11:11 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	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.

12-04-2009, 02:45 PM	#3
TripleC 3" Exhaust Join Date: Nov 2009 Location: Fort Collins, CO Posts: 103	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.

12-04-2009, 08:29 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	There is no reason at all that you would hit fuel cut due to just a temperature drop or from spinning the tires.

12-04-2009, 08:55 PM	#5
TripleC 3" Exhaust Join Date: Nov 2009 Location: Fort Collins, CO Posts: 103	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??

12-04-2009, 09:24 PM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Heh, if it was a 7M, I'd say you're hitting the rev limiter... but unless you're running 7M electronics... 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.