My X308 sometimes runs very rough at start up when the engine is cold (if you can call 30C / 85F cold...).
This morning I took a video; drop box link here: (https://www.dropbox.com/s/ddynkhtsxx...%20up.mp4?dl=0)
The car runs smooth after about 25 seconds and when the engine is warm.
Does this sound like I need to change the timing tensioners, or is it something else? The tank is fuelled with Gasohol at the moment (getting benzine here isn't always possible).
If it's the tensioners, I will need to order parts from outside Thailand so a parts list would be most welcome to me as a non mechanic...
Thanks guys!

 

Gasohol? Did search the internet and found out it is like the 95E10 we got in France, meaning there is 10% bio-ethanol in this fuel.

High performance engines do not like bio-ethanol, in fact your engine is not suitable to burn that rubbish. I can give you a complete lecture about the mapping of an ECU, to cut it short the ECU just can't handle it. What I hear is not a misfire but detonation.

Detonation kills engines, it can even blow holes in the pistons. Of course your knock-sensors should be detecting it but this is extreme and the ECU is not capable of adjusting that much detonation ( or knock if you want).

Fact is the evaporation pressure of bio-ethanol is many times higher than regular fuel, if you say the outside temps are about 30C there is a lot of pressurized vapor in the fuel system, the engine is cold and doesn't expect that. Hence, because of the compression and the highly vaporous gasses it starts to self-ignite long before it should do, slamming the piston(s) back against the direction of rotation.

Get rid of that gasohol right away and put proper fuel in it if you want your engine to last any longer than a few weeks. I do understand that it's not always available but this stuff is killing you engine.

Oh, by the way, this does not sound like there is any problem with the tensioners.

 

Check the tensioners? WELL, HELL YEAH!

 

The Jag V8 is designed to accommodate 10% ethanol. It would be nice to have 91 octane non ethanol, but many of us do not have that option.

 

I don't mean to hijack the thread, but I do have the option of 91 octane non-ethanol fuel, however, it is very, very, expensive(nearly $1.00 more than 89octane 10% ethanol per gallon) . I have been running 89 octane 10% ethanol fuel, is it a bad idea to run this engine on 87 octane with no ethanol? Would this benefit or harm my performance? It's pretty close in price to what I fill up now with.

 

W've been running on E10 here in California for years. I've run an XJ8, an XJR, XJS V12, and an XJ6 series 3 on it. They all started and ran perfectly. Your problem lies elsewhere.

 

200 million cars here in the US running on E10 right now. Funny, they all seem to start just fine.

 

Doesn't sound like a fuel issue. More so something with the timing though it wouldn't make sense that it sometimes somewhere along the lines idles out fine...

It could be something electrical, like a sensor giving false signals... Though I'm rather new to the V8-scene...

 

I would be inclined to suspect the throttle body. Have you cleaned the throat and butterfly?

Also try a hard reset. Disconnect the neg. batt. cable and touch it to the positive post for a few seconds. As long as you have the cable disconnected, clean the connections to the throttle body with electronic cleaner.

When you start the car again it will run fast, then calm down. Shifts may seem a little rough also. If all that doesn't help, try having the codes read.

 

From everything I have read the tensioner issue is more pronounced when the engine is cold, has been known for chains to jump a tooth when tensioners are ready to let go.

Listening to that clicking/knocking sound in your video I would be VERY wary of the tensioners.

This forum is the most valuable time consumer you could have access to being a Jaguar owner. Constructive knowledgable replies by experienced people who have been there and done it all well before we got bitten. Plenty written on the tensioner issue.

I have sent you a PM. We Thai Jag/Daim owners work against the odds and could help each other heaps.

 

If the cooling system needs topping up often I would suspect a leaking head gasket.
Coolant can seep into the cylinder and extinguish the 'spark' until the coolant clears.

It could also be a 'dribbling' injector leaking fuel into THAT cylinder after shutdown and flooding until it clears upon restart.

just some random thoughts.

bob gauff

 

Having emptied and refilled the tank with benzine fuel (not gasohol / ethanol mix) the car starts up properly with no more knocking / vibration and idles nice and even once again.

Thanks to everyone for your input.