Lumpy idle after TC cam chain tensioner replacement

[SimonD]

I've just replaced the cam chain tensioner on my 43k mile 2010 TC and am struggling with a rough idle.
My immediate thought was an unseated cable but it all looks ok to me.
I used a Motorworks replacement tensioner which seem to put an awful lot more pressure on the chain than the oe one. I've seen posts on-line suggesting that this can cause cam timing issues but it seems unlikely to me.
I'll probably re-install the original and see if the problem goes away but does anyone have any experience of this?

 

[botus]

check the valve timing - should have double checked that before start up ?

 

[Posh Pete]

Check cables leading to injector butterflies. Are they seated properly?

 

[SimonD]

I've checked the cable seating. I'm not sure I understand how valve timing can be affected by a tensioner change.

 

[Santa-2512]

I've checked the cable seating. I'm not sure I understand how valve timing can be affected by a tensioner change.

Start by asking yourself some questions

1 ) Why did you change the current tensioner ?

2) do you know what a cam chain is / how it works ?

if the answer is / was it was rattling, may draw you to the conclusion that the current chain or tensioner was very worn ?

The chain keeps the timing of the valves set to open / close at the correct time the pistons come to the compression period at the top of the bore

Move it one tooth, you may get a stumble or misfire, at worst its a bent valve or holed piston

 

[SimonD]

1. It was rattling
2. Yes, I have rebuilt several car/motorcycle engines in the past

It still doesn't explain why a cam chain would jump a tooth while unbolting an old cam chain tensioner and bolting in a new one without turning the engine.

 

[Smiffypr]

1. It was rattling
2. Yes, I have rebuilt several car/motorcycle engines in the past

It still doesn't explain why a cam chain would jump a tooth while unbolting an old cam chain tensioner and bolting in a new one without turning the engine.

If you didn't ensure that there were no valves open (e.g. TDC compression), the valve springs can move the camshaft.

 

[Santa-2512]

1. It was rattling
2. Yes, I have rebuilt several car/motorcycle engines in the past

It still doesn't explain why a cam chain would jump a tooth while unbolting an old cam chain tensioner and bolting in a new one without turning the engine.

???

Its a tensioner , it keeps the chain under tension to prevent it jumping / slipping teeth

If its stretched that far, and you take the tension off, you may have pushed / pulled the chain over a tooth when you replaced it, or as you said it was very tight to fit,


Have you put the old one back and has the lumpy idle gone away ?

Happy to accept i'm wrong , some of the resident experts may offer anothther diagnosis ,

 

[Slipperyeel]

Just an outside idea, could the throttle cables in the Bowden box be misbehaving/come unseated?

 

[SimonD]

OK, thanks for that I see what you mean now.
I was also concerned about the cables inside the box.
Anyway, I pushed and pulled all the cables and reseated the plugs before trying it this morning - the idle was still lumpy.
Popped down to the garage when I got home this evening and it started up as smooth as ever!
Will finish the service over the weekend and give it a decent run.
Thanks all.