Has anybody played around with camshaft timing on the 4.0L EF engine?
If the camshaft and auxilary shaft are either advanced or retarded, do you get fault signals to the eecv that cause any problems with normal running of the engine?
Will the engine know when to fire each cylinder at the right time still?
I beleive the crank trigger is the primary source of ignition timing, but the auxilary shaft is a double check, so what effect does that have on overall ignition timing?
Thanks Guys.
Glenn
You should find that there'll be no drama just adjusting the cam timing - the only impact it'll have (apart from the obvious changes to power and behaviour) will be with regard to slightly altering the vacuum readings the ECU will see at idle (this will theoretically be right thru the range but shouldn't make much noticeable impact except at idle), where making the cam timing late might cause ragged idle due to lowering the vacuum.
There'll be no need to alter the aux shaft timing - just moving the cam timing will be all you need to do - I can vouch that moving the std cam gear timing by one tooth in either direction from correct timing won't cause valves to hit, but I don't know about any more than one tooth. Best way to do it is with an adjustable cam gear - but again I can't say how far you could go before having valves hit - presumably the adjustment slots are of a size that won't allow it to go too far as long as the centre position is std timing - but I don't know for sure.
One tooth = just over 4 degrees.
Advancing your cam timing should make the bottom end stronger with consequential loss of top end and vice versa. My own experience has been with both std and EDXR6 cams in an ED engine - and I found that the top end gain vs bottom end loss with later timing is proportionally better than the other way round.
The method for altering timing on std cam gear is to relieve the chain tensioner load (you'll need to search or get a manual for that procedure) then "walk" the chain across the teeth on the gear in the correct direction for the desired result. Make sure to mark your starting point so you don't accidentally go too far. Then you need to release the tensioner again of course.
With an adjustable gear you don't need to mess with the tensioner at all (except to fit it in the first place of course).
Yhe i got an adjustable crank gear which has 9 keyways. Staright up , +8 to -8 degrees. But you also have to move the aux gear the same or it won tline up at all. That aux gear drives the CMP sensor which is the camshaft position sensor.
Ah HA you say?
So thats why i was interested to know if it will have an impact on the ignition timing.
??? - Oh, I think I see where you're comming from. It's easy to overestimate the complexity of how the EEC5 operates - you're making the error of figuring that the ECU tracks the precise position of the cam - which it doesn't.
That CMP sensor is not a precise cam position sensor - it simply provides the ECU with a cue as to when #1 piston is comming up to TDC on compression (the crank sensor just tells it when the piston is on TDC, not which stroke it's on) - so when you shift the cam around you don't have to worry about making sure that CMP sensor follows it - it will still be giving the ECU what it needs.
All you need to do to change the cam timing with an adjustable gear is loosen the adjustment bolts/screws on the cam gear, then carefully move the big bolt head in the centre in the direction you want to change the cam timing - ie. this will rotate the cam slightly either in the direction of rotation of the engine (advanced) or opposite to rotation direction (retarded).
As far as ignition timing goes, I'm pretty sure the EF timing is run by the ECU from it's precise reading of engine TDC - which it does get from the crank position sensor. Hmmm - with that in mind I'd guess it's not possible to actually change the base timing on an EF. The only other possiblility is that the CMP sensor is involved in setting timing - if that's the case then it's still not directly linked to or affected by where the camshaft is and will still provide the ECU with a suitable feedback for working out which stroke #1 is on even if it's moved around somewhat.
Yeh sounds OK i guess. Figure this ok, Lets say i have an old timing chain that is so streached that is throws the cam out by 4 degrees RETARDED. This will also throw the auxilary sprocket out by the same amount. So the CMP sensor will know that at TDC on the power stroke the camshaft is lagging behind the crank by 4 degrees. Still dont know if it will alter the ignition timing hey?
Nope - nothing to worry about there beyond the actual mechanical implications of the stretched chain - which itself is no drama as long as it's not whipping or rattling and doesn't break.
The thing to remember is that the CMP Sensor DOES NOT READ THE EXACT POSITION OF THE CAMSHAFT - the signal it gives out is only used to determine what stroke the piston is on in #1 cylinder - it's an approximate indication of where the cam is at - not it's precise position - and the interest in that is purely because that's how the ECU figure's out what stroke the piston is on.
As a mater of fact, from what I understand, because the EDIS setup fires two cylinders at once, the CMP signal isn't even referenced for ignition - the TDC crank position signal is all that's used for that (and other signals such as rpm and TPS etc.) The real reason for the CMP is for injector timing.
Here's an extract from the workshop manual that will probably make it clearer:
"The actual adjustment of the CMP sensor is not critical as it's purpose is only to identify which part of the cycle cylinder 1 is in. The CMP rising edge must occur between 5 degrees BTDC (cylinder 1) and 45 degrees ATDC (cylinder 1)".
Actually, from that I guess that if the aux shaft and therefore the CMP sensor get moved somehow out of that 5 BTDC to 45 ATDC range then there would be issues with fuel timing - in which case it'd probably run like total crap - but if yours is only 4 degrees ATDC then you've still got 41 degrees left before it'd show a problem (the chain couldn't even physically stretch that far) - and as I've explained, changing the cam timing itself will have no effect on the CMP or ignition timing, so you'll be apples for tweaking the cam back to where it should be on the adjustable gear :-)
EDFUTURA! You seem to know what you're talking about, and yes it makes sense about the CMP, even if i retard the cam by 4 degrees it's still within it's range for the injector timing.
This is the million dollar question.....
How far will the EECV go until it goes into a tail spin.
I have another mod with the intake manifold air temp sensor which I'll talk about later.
Cheers EDFUTURA.
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Camshaft & Auxilary shaft timing
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