1JZ runs rich when decelerating in gear?
06-12-15, 08:53 PM
#1
1JZ runs rich when decelerating in gear?
hey guys,
just got a wideband installed in my VVTI 1JZ and i noticed that when i decelerate in gear, it runs pretty rich, like low 12s AFR in what must be open loop. during closed loop operation it is nice and stoich, like idle or cruise, and in boost it is 11-12, but when coming down a hill in gear the ECU goes to an open loop map.. anyone else notice this?
cheers
Marko
just got a wideband installed in my VVTI 1JZ and i noticed that when i decelerate in gear, it runs pretty rich, like low 12s AFR in what must be open loop. during closed loop operation it is nice and stoich, like idle or cruise, and in boost it is 11-12, but when coming down a hill in gear the ECU goes to an open loop map.. anyone else notice this?
cheers
Marko
06-12-15, 10:24 PM
#2
Pole Position
- Did you preform the "12volt fuel pump mod" ?
- what ECU are you using? any Piggyback controllers in use as well?
- what o2 sensor are you using (the narrowband one)?
- I think you should forget open/closed loop terms here, it will likely confuse the "issue" and "solution".
Injectors should more or less be shut off during Deceleration, and you should see 18:1, 19:1 even 20:1 and leaner AFRs - which obviously you know hence your question.. but there are so many possible reasons why your injectors are still firing, wiring, tuning, fuel pressure, but guessing an answer doesn't help, nor does guessing what you have done to get your sc400 to work with a 1jz vvti , with a 350 6spd.
- what ECU are you using? any Piggyback controllers in use as well?
- what o2 sensor are you using (the narrowband one)?
- I think you should forget open/closed loop terms here, it will likely confuse the "issue" and "solution".
Injectors should more or less be shut off during Deceleration, and you should see 18:1, 19:1 even 20:1 and leaner AFRs - which obviously you know hence your question.. but there are so many possible reasons why your injectors are still firing, wiring, tuning, fuel pressure, but guessing an answer doesn't help, nor does guessing what you have done to get your sc400 to work with a 1jz vvti , with a 350 6spd.
06-13-15, 08:12 AM
#3
sorry left out some important info i guess 
stock fuel pump wiring for now
stock jzx100 auto ecu, no piggyback
wideband o2 sensor feeding stock narrowband signal to ECU
thats been my experience too that under decel AFRs go lean because the fuel map is reading from the very bottom of the load table. I am ok with the injectors not shutting off on decel like newer ECUs do because it wasnt a common practice in the 90s. the jzx100 doesnt have an IDL signal on the TPS (3 wire vs 4 wire) either so that could be one thing that makes the stock ecu harder to work around it.
basically i am wondering if anyone else here with a stock jzx100 ecu has noticed this on their wideband.. might be a bit of a long shot but i suspect it might be normal.
Marko
stock fuel pump wiring for now
stock jzx100 auto ecu, no piggyback
wideband o2 sensor feeding stock narrowband signal to ECU
thats been my experience too that under decel AFRs go lean because the fuel map is reading from the very bottom of the load table. I am ok with the injectors not shutting off on decel like newer ECUs do because it wasnt a common practice in the 90s. the jzx100 doesnt have an IDL signal on the TPS (3 wire vs 4 wire) either so that could be one thing that makes the stock ecu harder to work around it.
basically i am wondering if anyone else here with a stock jzx100 ecu has noticed this on their wideband.. might be a bit of a long shot but i suspect it might be normal.
Marko
Last edited by estomax; 06-13-15 at 08:34 AM.
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