intermittent exhaust smoke + P1646 , Repair log w/pics
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intermittent exhaust smoke + P1646 , Repair log w/pics
I purchased a 2003 STR with 126k miles. After a 100 mile drive home with no smoke issues i got off the freeway. I noticed alot of smoke coming out of the exhaust only on a few occasions. The problem was hard to repeat. It intermittently happens a few sec after accelerating from a dead stop and accelerating after a sharp turn.
I've decided to do a tune up and pcv valve.
After removing parts I noticed the AF was crushed and not sealing and long over due for a change, deposits on the spark plugs, and 10000 miles since the last oil change when they used 20w-50. Vacuum tube to PCV full of oil.
I decided to do a compression check while the plugs were out. I pulled the ign and Fuel inj fuses from the engine compartment fuse box.
The compression numbers from the driver side bank 180,180,190,170 and right bank 190,185,190,180.
I've decided to do a tune up and pcv valve.
After removing parts I noticed the AF was crushed and not sealing and long over due for a change, deposits on the spark plugs, and 10000 miles since the last oil change when they used 20w-50. Vacuum tube to PCV full of oil.
I decided to do a compression check while the plugs were out. I pulled the ign and Fuel inj fuses from the engine compartment fuse box.
The compression numbers from the driver side bank 180,180,190,170 and right bank 190,185,190,180.
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Aha. The upstream O2s will (should) NOT fluctuate. They are the wide-band type (aka linear aka AFR). Older (*), lower-tech cars use the kind that fluctuate.
The downstreams are that type but should not fluctuate other than very rarely as they're cat monitors (and also fine trim adjust).
Do not put in the wrong kind!!! (Probably don't change them, depending on how they're working.)
If you like, blip the throttle and see what the O2s do. Should respond very fast. Generally, they seem to last well but in case a jag tech chimes in - just go with what they say
(*) all the S-Types up to 2002.5MY (2003MY USA) use the older type O2s. Makes it tougher to get fuelling and emissions as exact. From 2002.5MY all moved to the more expensive, better, widebands for the upstream O2s.
The downstreams are that type but should not fluctuate other than very rarely as they're cat monitors (and also fine trim adjust).
Do not put in the wrong kind!!! (Probably don't change them, depending on how they're working.)
If you like, blip the throttle and see what the O2s do. Should respond very fast. Generally, they seem to last well but in case a jag tech chimes in - just go with what they say
(*) all the S-Types up to 2002.5MY (2003MY USA) use the older type O2s. Makes it tougher to get fuelling and emissions as exact. From 2002.5MY all moved to the more expensive, better, widebands for the upstream O2s.
Last edited by JagV8; 01-08-2012 at 10:44 AM.
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03Xtype (01-08-2012)
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After installing the bank 1 upstream O2 sensor the P1646 code has not came back on, I have not noticed any smoke out of the exhaust yet after a few short drives. I have been getting some detonation under load with more then 1/4 throttle, I'm not sure if this was pre existing or not. The detonation has diminished by about 70% after octane boost and some extra gas. I'm hoping after all the monitors are complete that maybe the detonation will be gone? Any other suggestions would be appreciated.
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If you check it's working, it may then be worth disconnecting the battery for 5 mins to clear the KAM (keep alive memory). That will clear out learned values - on the basis it may have some bad ones due to a bad sensor (if it was bad).
Read JTIS / codes PDF first 10 or so pages about "drive cycle" if you want to help it relearn.
Read JTIS / codes PDF first 10 or so pages about "drive cycle" if you want to help it relearn.
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