spegru
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| posted on 30/4/25 at 12:40 PM |
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Mine is an early AJ30 from '99 so that could be relevant to observations.
I've just taken out my VVT solenoids for a look. No sign of filters though
To be honest they look very clean
However I had a play around with their operation.
It is complicated by the fact that they are meant to be controlled via PWM even though it is said that on these earlier engines there are only two VVT
positions
So I experimented with a simple 12v supply since 100% PWM basically means 12v on. I can imagine that current draw may be increased without PWM but I
measured the actual current draw as, 1.2 amps so I am not concerned - after all this is a valve and so quite a heavy duty item.
I tested by blowing into the end and what I discovered is that in the normal un-powered state the valve is open.
When powered, the valve is closed. Both valves were the same. Voltage polarity also did not matter
I'm not sure whether the normal state at idle should be open or closed - but if it should be closed, *then it was wrong when I was testing
previously* as it is not even connected.
Is this the reason for my rattle? Was I confusing the noise with something else?
I don't know but I will certainly be experimenting with this next time the engine runs. And I shan't be bothering with PWM.
Seems to me that the VVT was meant to be multi variable and hence PWM control - but in practice it was only ever set up to use 0 or 100% so why bother
with PWM at all?
On the other hand with after market ECU it might be possible, even with these earlier engines to achieve multi level VVT using PWM to alter the
degree of valve oil leakage and hence alter cam timing to varying degrees
[Edited on 30/4/25 by spegru]
Check out Invader Garage on Youtube
https://www.youtube.com/channel/UC3C55qk-tbKc0WjmxGqFoXg
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Partofthechaos
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| posted on 2/5/25 at 09:29 AM |
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I know this is the V8 rather than the V6, but it may well show some useful aspects of Jag chain stretch. Tom Lenthall was confident that this needed
doing, despite it looking fine, they also look at the oil pump chain. Does the AJ30 have one of those?
https://youtu.be/Atg6irkZWq0?si=v2UM9g9stgdNn4fl
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spegru
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| posted on 23/7/25 at 07:33 PM |
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Thanks for that link Mr Chaos. Not seen that channel before.
Actually I'm not sure whether the AJ30 V6 is related to the V8 at all. I know that Jaguar have a V6/V8 family that is, but perhaps not this
one
(actually I was surprised to see FoMoCo (Ford) stamped somewhere inside the Cam cover of that V8 as I thought Jaguar had gone their own way after the
AJ30 - so I'm not sure)
Anyway back to the AJ30.
When I had it out again recently (for a gearbox issue) I did take off the cam covers to have a look at the timing chains, which seemed fine.
However, after getting it all back together again, yesterday I made a breakthrough:
It is running semi ok on a ME360 ECU from Motorsport electronics and actually the tapping noise wasn't very audible with the bonnet down.
With the bonnet up I was listening to the tapping noise trying to work out where it was coming from and simultaneously noticed that it seemed to be
coming from the middle of the cam covers area - and that the fuel pipe was pulsing in time to the tapping.
Bingo! The tapping noise is the fuel injectors I thought!
So I went to the ECU and checked whether I could change from batch injection to sequential injection - and still get it to run (I had given up on
that when I was having trouble with a previous stage)
It ran and the tapping noise was gone!
(I suppose that six little taps, spread out, are not so noticeable as 6 all going at once)
Check out Invader Garage on Youtube
https://www.youtube.com/channel/UC3C55qk-tbKc0WjmxGqFoXg
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spegru
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| posted on 23/7/25 at 07:38 PM |
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by the way it seems from AJ30 docs that the VVT valve is indeed open by default - and that that switches the VVT off.
The valve closes and that switches VVT on.
Weird but that fits the test I did. So that likely means at initial start up and/or after a long time of disuse VVT is likely on, until oil pressure
comes up to switch it off.
However VVT was certainly nothing to do with the tapping noise (see previous post)
Check out Invader Garage on Youtube
https://www.youtube.com/channel/UC3C55qk-tbKc0WjmxGqFoXg
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