The truck has been running poor for a time. Its a '91 FJ80 3FE. We had the exhaust replaced from the headers back to the muffler (had rusted out, nothing to weld to) not long after purchasing it (1 month, low kilometer use). The exhaust replacement should be a carbon copy minus removing the cat, 2 inch pipes then collecting into 2.5 pipe to a flow master muffler to exit
Not long after (2 months or so with some kilometers done) the truck developed a rough idle (400/500rpm) when it came up to operating temperature, and has a dead spot in the rev range of ~1800rpm-~2300rpm (particularly noticeable going up an incline). No code was present. So by the research I did, we got rid of the EGR system (no replacements parts in New Zealand). Didn't resolve the symptoms.
Next I noticed a massive vacuum under the fuel cap, so researched again, we bypassed the carbon canister. Didn't resolve the problem.
Next completed a vacuum test with engine starter and via proper smoke tester. No vacuum leak found. We did test by spraying engine starter directly into the intake which would lift, and smooth out the idle out (lean air fuel ratio I guess).
Current day, have had the fault code of 21 (oxygen sensor signal/heater signal) come up. I am surmising that the (or both) O2 sensor(s) are effecting the air/fuel ratio (leaning it out I guess). So ordered and received two Denso (alleged OEM from what I read) O2 Sensors from RockAuto couple days back.
Before I fit them, I want to air these theories out.
Removing and refitting the O2 sensors for the exhaust repair disturbed them, to the point of an intermittent fault that the ECU didn't initially recognise until now.
or
are the O2 sensors crossed over from original - is the O2 sensor reading the wrong pipe. I have done what I can to confirm that O2 sensors are connected right but for my sake I would like this ruled out by some assistance please (the 3FE is very uncommon in NZ).
Currently the O2 sensor that reads 1, 2, 3 cylinders is connected to the harness running down the wheel guard (R/H pipe in the picture). And the 4, 5, 6 cylinders are connected to the harness running down the firewall (L/H pipe) in the photo. Clarification would be great.
Thanks,
Ryan
Not long after (2 months or so with some kilometers done) the truck developed a rough idle (400/500rpm) when it came up to operating temperature, and has a dead spot in the rev range of ~1800rpm-~2300rpm (particularly noticeable going up an incline). No code was present. So by the research I did, we got rid of the EGR system (no replacements parts in New Zealand). Didn't resolve the symptoms.
Next I noticed a massive vacuum under the fuel cap, so researched again, we bypassed the carbon canister. Didn't resolve the problem.
Next completed a vacuum test with engine starter and via proper smoke tester. No vacuum leak found. We did test by spraying engine starter directly into the intake which would lift, and smooth out the idle out (lean air fuel ratio I guess).
Current day, have had the fault code of 21 (oxygen sensor signal/heater signal) come up. I am surmising that the (or both) O2 sensor(s) are effecting the air/fuel ratio (leaning it out I guess). So ordered and received two Denso (alleged OEM from what I read) O2 Sensors from RockAuto couple days back.
Before I fit them, I want to air these theories out.
Removing and refitting the O2 sensors for the exhaust repair disturbed them, to the point of an intermittent fault that the ECU didn't initially recognise until now.
or
are the O2 sensors crossed over from original - is the O2 sensor reading the wrong pipe. I have done what I can to confirm that O2 sensors are connected right but for my sake I would like this ruled out by some assistance please (the 3FE is very uncommon in NZ).
Currently the O2 sensor that reads 1, 2, 3 cylinders is connected to the harness running down the wheel guard (R/H pipe in the picture). And the 4, 5, 6 cylinders are connected to the harness running down the firewall (L/H pipe) in the photo. Clarification would be great.
Thanks,
Ryan
