MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: JB21 on January 21, 2024, 13:18

Title: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: JB21 on January 21, 2024, 13:18
My latest post is interesting

https://www.spyderchat.com/threads/troubleshooting-2zz-crazy-high-negative-ltft-at-idle-28.162274/
Title: Re: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: M.Dub on January 28, 2024, 03:56
Did you find the problem?
Title: Re: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: JB21 on January 29, 2024, 08:39
Quote from: M.Dub on January 28, 2024, 03:56Did you find the problem?

Nope. Possible vacuum leak or MAF pipe is incorrect.
Title: Re: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: Dev on January 30, 2024, 04:29
Those guys seem to have greatly confused the issue. You have negative fuel trims. Generally it is correct that most aftermarket intakes that are 2.75 are larger than stock and do not have vanes which results in positive fuel trims due to unmetered air, not negative. Same with a vacuum leak.
What causes negative fuel trims is an air restriction, too much fuel pressure and restrictions from the exhaust. You need to look at these causes.


Title: Re: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: mr2garageswindon on January 30, 2024, 09:57
Try a new MAF just to rule it out if it hasn't been replaced recently.
Title: Re: Troubleshooting 2ZZ crazy high negative LTFT at idle (-28)
Post by: M.Dub on February 1, 2024, 12:07
Guessing you've had the same MAF pipe prior to this issue raising its head? If so I doubt it's that, maybe the MAF itself? Is the problem only at idle?