S-type with strange engine performance
#21
#22
Thanks everyone for your answers. The source of hissing turned out to be the PCV pipe. It's especially audible at idle. I blew this hose with a smoke generator towards the motor, there are no leaks. I noticed that it sucks on the oil filler cap at idle, there is a decent vacuum in the crankcase. I suspect that pcv is out of order.
Last edited by Alexander UA; 03-19-2023 at 04:39 AM.
#23
Thanks everyone for your answers. The source of hissing turned out to be the PCV pipe. It's especially audible at idle. I blew this hose with a smoke generator towards the motor, there are no leaks. I noticed that it sucks on the oil filler cap at idle, there is a decent vacuum in the crankcase. I suspect that pcv is out of order.
#24
The PCV system on the V6 is a bit different than most vehicles, and is open at idle. On most other vehicles, it's is closed at idle. I found the PCV valve clogged on my '02 V6 and it caused some issues. Details here, see post #21:
https://www.jaguarforums.com/forum/s...rly-v6-264531/
Is your PCV valve located at the back of the engine, or under the intake plenum? I think it functions the same regardless of position.
https://www.jaguarforums.com/forum/s...rly-v6-264531/
Is your PCV valve located at the back of the engine, or under the intake plenum? I think it functions the same regardless of position.
#25
This is the point that no smoke leaks were noticed, everything is hermetically sealed.
#26
The PCV system on the V6 is a bit different than most vehicles, and is open at idle. On most other vehicles, it's is closed at idle. I found the PCV valve clogged on my '02 V6 and it caused some issues. Details here, see post #21:
https://www.jaguarforums.com/forum/s...rly-v6-264531/
Is your PCV valve located at the back of the engine, or under the intake plenum? I think it functions the same regardless of position.
https://www.jaguarforums.com/forum/s...rly-v6-264531/
Is your PCV valve located at the back of the engine, or under the intake plenum? I think it functions the same regardless of position.
If I understood correctly from your topic, then the crankcase ventilation is designed in such a way that the air after the air filter is sucked through a large branch (pipes in the valve covers) into the crankcase, and then, together with crankcase gases, enters the intake manifold behind the throttle valve.
Last edited by Alexander UA; 03-19-2023 at 04:54 PM.
#27
I am willing to stake your reputation on it.
I did a lot of headscratching on this very subject a few months ago. I played with a brand new PCV valve to confirm how the system works. I’m not a climate change researcher and was not trying to reach a predetermined conclusion.
And yes indeed, this PCV system works opposite of most other vehicles. The PCV valve in this case is basically just a check valve to prevent reverse flow, such as with a backfire. Under normal conditions, it is always open.
See post #25 at the previous link to see how I tested this theory.
In my case, it didn’t immediately fix everything (still had a bad coil at the time) but it definitely improved an erratic idle.
Buy a new valve and play with it yourself to see.
Your smoke test? It’s great for finding external leaks. But if your PCV valve is clogged, a smoke test won’t find that. My PCV valve was maybe 90% clogged. It would still let some smoke through when I tested if air could get through. Some did, but not enough for normal engine operation.
Definitely check out your PCV system and replace the valve if needed. Carefully check the lines, too. I found mine in poor condition. If cracked, unmetered air will be drawn into the induction system and possibly set some codes. Just be aware a clogged PCV valve may only be part of the equation and other faults may still be active.
I did a lot of headscratching on this very subject a few months ago. I played with a brand new PCV valve to confirm how the system works. I’m not a climate change researcher and was not trying to reach a predetermined conclusion.
And yes indeed, this PCV system works opposite of most other vehicles. The PCV valve in this case is basically just a check valve to prevent reverse flow, such as with a backfire. Under normal conditions, it is always open.
See post #25 at the previous link to see how I tested this theory.
In my case, it didn’t immediately fix everything (still had a bad coil at the time) but it definitely improved an erratic idle.
Buy a new valve and play with it yourself to see.
Your smoke test? It’s great for finding external leaks. But if your PCV valve is clogged, a smoke test won’t find that. My PCV valve was maybe 90% clogged. It would still let some smoke through when I tested if air could get through. Some did, but not enough for normal engine operation.
Definitely check out your PCV system and replace the valve if needed. Carefully check the lines, too. I found mine in poor condition. If cracked, unmetered air will be drawn into the induction system and possibly set some codes. Just be aware a clogged PCV valve may only be part of the equation and other faults may still be active.
The following users liked this post:
JagV8 (03-20-2023)
#28
it expects unmetered air from the crankcase at all times, valve is always open. this is the same way the v8 does it with but with an oil separator valve instead of mesh inside the valve cover
get the propane and watch how your fuel trims react. smoke test is not reliable
get the propane and watch how your fuel trims react. smoke test is not reliable
Last edited by xalty; 03-19-2023 at 07:05 PM.
The following users liked this post:
JagV8 (03-20-2023)
#29
Respectfully submitted
#30
Equally, it's fairly easy to miss a leak using such as propane - because you may fail to spray in the right place or may somehow not be looking at the trims just at the moment they change (it happens).
Whatever you do, don't assume you'll hear a leak, though. Occasionally you will but it's usually a BIG (from the car's viewpoint) leak.
#31
I may have missed something but you need to focus on what codes the car is throwing?
Keep reading and then erasing ALL codes. The two you posted are O2 sensor codes so your looking in the right place.
Please post JUST the code itself. The many pictures are very confusing trying to find all the code numbers.
Note you show numerous U and B codes. The U codes are network related which means wiring problems or more likely weak or bad battery? How old is the battery? Any chance you can swap a new one in to test?
B codes are body codes which should NOT have anything to do with the engine running badly?
When you did the smoke test was ALL of the plastic intake ducting in place? This is a very likely place for a crack or hole in the plastic to create an unmetered air leak. This will cause exactly the problems your having?
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Keep reading and then erasing ALL codes. The two you posted are O2 sensor codes so your looking in the right place.
Please post JUST the code itself. The many pictures are very confusing trying to find all the code numbers.
Note you show numerous U and B codes. The U codes are network related which means wiring problems or more likely weak or bad battery? How old is the battery? Any chance you can swap a new one in to test?
B codes are body codes which should NOT have anything to do with the engine running badly?
When you did the smoke test was ALL of the plastic intake ducting in place? This is a very likely place for a crack or hole in the plastic to create an unmetered air leak. This will cause exactly the problems your having?
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#32
#33
#34
yes it was me. I had a leak at the exhaust round flange above the converter
#36
Fix the exhaust leak and your problem may disappear.😃
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