rchalmers3
I speak Toyota
Hi guys, I'm hoping you can help me out. My post is a bit long, I'll put in as much as I can the first time so you guys don't have to ask as many basic questions.... or so I hope!
The vehicle is a 12/1999 4 cylinder Cal Spec 4Runner (RZN180L-GKPSKA) with an air flow sensor ahead of the catalytic converter. The car has drive-ability issues, in addition to the CEL: Pukes black sooty water out the tail pipe, loads up at low speeds and has poor mileage. The idle is stable, but a bit rougher than most 4Runners.
I have made the ordinary diagnostics: fuel delivery pressure to the filter is 50lb, no miss-fires, no exhaust leaks, no apparent exhaust restrictions, no air induction defects, no false air leaks. My little scanner (Matco Maximus 2.0) indicates proper temperature is being achieved, and the computer goes closed loop in about 20 seconds after start up.
Pertinent data points that are out of norm:
* The MAF at idle is high at 6.7-7.2 gm/s.
* The TPS is slightly low at 9.06% at idle.
* Calculated load is high: 30%.
* Injector operation is high at 6.2ms at idle.
* O2S B1 S1 is steady and fixed at .65v (=3.25v on Toyota tester)
Obviously the computer thinks the mixture is too lean, and is enriching the fuel rate to its maximum, but it's still not happy. That explains the injector timing and calculated load.
I had the opportunity to swap in a good MAF for diagnostics, but the replacement meter made no difference.
I installed a new OEM A/F sensor (part number 89467-35090) but the reading remained at the fixed, computer generated voltage listed above.
I confirmed that all 4 wires to the sensor, from the sensor plug to the computer harness plug were continuous.
I introduced air leaks and added fuel at idle. The O2 Sensor behind the converter, (B1 S2) reacted to the changes, as it also does when revving the engine. That sensor appears alive and communicating as expected. The A/F sensor did not reflect any of the dramatic changes I made in the fuel mixture.
What can the problem be? Would any of the abnormal readings be a cause instead of an effect? Have I failed to mention or measure anything?
Could it be that the computer has a single, dedicated circuit to the A/F sensor that is failed? What are the chances of that???
I look forward to your observations, suggestions and suggestions,
Rick
The vehicle is a 12/1999 4 cylinder Cal Spec 4Runner (RZN180L-GKPSKA) with an air flow sensor ahead of the catalytic converter. The car has drive-ability issues, in addition to the CEL: Pukes black sooty water out the tail pipe, loads up at low speeds and has poor mileage. The idle is stable, but a bit rougher than most 4Runners.
I have made the ordinary diagnostics: fuel delivery pressure to the filter is 50lb, no miss-fires, no exhaust leaks, no apparent exhaust restrictions, no air induction defects, no false air leaks. My little scanner (Matco Maximus 2.0) indicates proper temperature is being achieved, and the computer goes closed loop in about 20 seconds after start up.
Pertinent data points that are out of norm:
* The MAF at idle is high at 6.7-7.2 gm/s.
* The TPS is slightly low at 9.06% at idle.
* Calculated load is high: 30%.
* Injector operation is high at 6.2ms at idle.
* O2S B1 S1 is steady and fixed at .65v (=3.25v on Toyota tester)
Obviously the computer thinks the mixture is too lean, and is enriching the fuel rate to its maximum, but it's still not happy. That explains the injector timing and calculated load.
I had the opportunity to swap in a good MAF for diagnostics, but the replacement meter made no difference.
I installed a new OEM A/F sensor (part number 89467-35090) but the reading remained at the fixed, computer generated voltage listed above.
I confirmed that all 4 wires to the sensor, from the sensor plug to the computer harness plug were continuous.
I introduced air leaks and added fuel at idle. The O2 Sensor behind the converter, (B1 S2) reacted to the changes, as it also does when revving the engine. That sensor appears alive and communicating as expected. The A/F sensor did not reflect any of the dramatic changes I made in the fuel mixture.
What can the problem be? Would any of the abnormal readings be a cause instead of an effect? Have I failed to mention or measure anything?
Could it be that the computer has a single, dedicated circuit to the A/F sensor that is failed? What are the chances of that???
I look forward to your observations, suggestions and suggestions,
Rick
