scan tool data question

[High Arctic Si]

are all those number + and not minus?
the a/t car ,the colder transmission, the ATF IS COLDER and on an A/T that oil pump uses lots of energy just in park. (newer cars have 2 speed pump and uses less energy) and 9 speeds on newer cars... (a 195F thermostat can help here) keep in mind the engine coolant heats the tranny to
/

id bet that front 02 sensor is original and long over due for a swap.? 100k miles it's at design limits, less with wild additives in the tank.

use penetrating oil over and over (@ O2) as the engine (header-collector) cools down and it may come off more easy, use a pro grade o2 socket (split side) for maximum purchase force to hex end.
IF the the 02 is old , and biased as many are , if old, the LTFT is skewed. (id replace it , just the front sensor, for max fuel pay back) id get a bosch PnP


The ECU reads the 02 and calculates fuel trim. and 14 is not super bad, this is only a slight lean-ness corrected. +14, added to -14 = 0 (algebraic addition)
id look at how fast the 02 swings, good ones swing about 6 times a second, old ones go slow. 1 times? (graph mode)

watch for cracks in the main air pipe.and flex fittings, or the broken mount to said pipe, and if cracked, and sucking air. (no leaks from Throttle body to MAF.
Is the engine holding closed loop at idle (1st check) then 2nd, is it CL at light flat, steady cruise?
a dirty MAF will under report air flow, (causing lean run) , but is corrected and the results are in CL are larger + xx LTFT (corrected by the CL trim)
Under reported air (MAF) causes under fuel injected. which is lean, the 02 senses this wrong state and the ECU corrects it and LTFT will be too high (PLUS side) and corrected.
The problem with air leaks, is when not in closed loop. (WOT or accelerating fast)
Dirty Maf:
clean the maf from a far distance, do not blast the fragile element too close.... its a $1000 part at SUZ, stay 1 foot far as you spray, spray , wait 1min, repeat 3 times. to clean it.

most EFI engines run a tad rich (day1) , due to MAF being rich by a tad say 5% then the LTFT goes -5% to correct this.

NOT Closed loop: modes...
then when you go open loop or wide open throttle the CL features shuts down and the MAF rules the roost. (injects, based on it)
at WOT you do not want a lean state. It needs to be a tad rich WOT. The MAF does that.

Some newer cars learn the MAF trends and attempt to correct it, even WOT.
it's best to have a clean system, that is fresh 02 (B1S1) and clean MAF and no air leaks
for all modes of the ECU to work good and no leanness in transitions, in speed.

Recap points:
1: a fresh 02 (front)
2: no exhaust cracks near that 02.
3: no air leaks in the induction path: maf to intake valves (same for injector cushions)
4: MAF clean.

A: closed loop at idle and light flat cruise.
B: check engine light off running. no p0300.

Ok, so when i looked at your OBDII full scan page, I noticed that you were getting something like -3 for LTFT. Then I found another recent thread somewhere else and someone has a 1996 X90 and they also reported +14.8 for LTFT .

Jus t trying to figure what a good standard is. I have the new O2 sensor in hand just goot take my time and get the old one off.

Car is running in closed loop,
Check engine light is off, most of the time. Trouble have pooped up the odd time, cylinder one misfire, and a random misfire after i pulled off the air intake and changed the plugs. Cleared it and it hasnt come back, yet.
Car is running well but seems to be using a lot of fuel. (lots of idle time though)[/u]
Plugs were really white/off white and not looking so good. little lean i guess. not expert plug reader but they looked as if they had been hot, #1 cylinder showed no sign of flooding or lack of combustion.

Thanks for the advice


Si

---

are all those number + and not minus?
the a/t car ,the colder transmission, the ATF IS COLDER and on an A/T that oil pump uses lots of energy just in park. (newer cars have 2 speed pump and uses less energy) and 9 speeds on newer cars... (a 195F thermostat can help here) keep in mind the engine coolant heats the tranny to
/

id bet that front 02 sensor is original and long over due for a swap.? 100k miles it's at design limits, less with wild additives in the tank.

use penetrating oil over and over (@ O2) as the engine (header-collector) cools down and it may come off more easy, use a pro grade o2 socket (split side) for maximum purchase force to hex end.
IF the the 02 is old , and biased as many are , if old, the LTFT is skewed. (id replace it , just the front sensor, for max fuel pay back) id get a bosch PnP


The ECU reads the 02 and calculates fuel trim. and 14 is not super bad, this is only a slight lean-ness corrected. +14, added to -14 = 0 (algebraic addition)
id look at how fast the 02 swings, good ones swing about 6 times a second, old ones go slow. 1 times? (graph mode)

watch for cracks in the main air pipe.and flex fittings, or the broken mount to said pipe, and if cracked, and sucking air. (no leaks from Throttle body to MAF.
Is the engine holding closed loop at idle (1st check) then 2nd, is it CL at light flat, steady cruise?
a dirty MAF will under report air flow, (causing lean run) , but is corrected and the results are in CL are larger + xx LTFT (corrected by the CL trim)
Under reported air (MAF) causes under fuel injected. which is lean, the 02 senses this wrong state and the ECU corrects it and LTFT will be too high (PLUS side) and corrected.
The problem with air leaks, is when not in closed loop. (WOT or accelerating fast)
Dirty Maf:
clean the maf from a far distance, do not blast the fragile element too close.... its a $1000 part at SUZ, stay 1 foot far as you spray, spray , wait 1min, repeat 3 times. to clean it.

most EFI engines run a tad rich (day1) , due to MAF being rich by a tad say 5% then the LTFT goes -5% to correct this.

NOT Closed loop: modes...
then when you go open loop or wide open throttle the CL features shuts down and the MAF rules the roost. (injects, based on it)
at WOT you do not want a lean state. It needs to be a tad rich WOT. The MAF does that.

Some newer cars learn the MAF trends and attempt to correct it, even WOT.
it's best to have a clean system, that is fresh 02 (B1S1) and clean MAF and no air leaks
for all modes of the ECU to work good and no leanness in transitions, in speed.

Recap points:
1: a fresh 02 (front)
2: no exhaust cracks near that 02.
3: no air leaks in the induction path: maf to intake valves (same for injector cushions)
4: MAF clean.

A: closed loop at idle and light flat cruise.
B: check engine light off running. no p0300.

Ok, so when i looked at your OBDII full scan page, I noticed that you were getting something like -3 for LTFT. Then I found another recent thread somewhere else and someone has a 1996 X90 and they also reported +14.8 for LTFT .

Jus t trying to figure what a good standard is. I have the new O2 sensor in hand just goot take my time and get the old one off.

Car is running in closed loop,
Check engine light is off, most of the time. Trouble have pooped up the odd time, cylinder one misfire, and a random misfire after i pulled off the air intake and changed the plugs. Cleared it and it hasnt come back, yet.
Car is running well but seems to be using a lot of fuel. (lots of idle time though)[/u]
Plugs were really white/off white and not looking so good. little lean i guess. not expert plug reader but they looked as if they had been hot, #1 cylinder showed no sign of flooding or lack of combustion.

Thanks for the advice


Si

still cant figure out these colours[/color]