I have had my car tested for about everything now and its pointing to the ECU. So has anyone had problems with there ECU and was the fix the answer

 

You don't mean the rough running? Is it only at idle?

It's (almost definitely) not going to be the PCM (ECU). Extraordinarily unlikely.... has someone led you to think it could be? Find someone else, if so, would be my reaction.

And have a look at the price of a PCM. Plus I think you'll find it would need reprogramming to work with your other modules.

 

Its not at idle its at 60 mph when you cruse if not ecu what

 

I've seen your posts about rough at idle but not at 60 when you cruise.

Long, long list of possibles but if it's OK at other speeds (or most of the time) then the PCM's well down the list. I'd hunt for a competent tech to figure it out unless you've considerably more data than rough at 60 when you cruise.

As a DIYer, I'd be trying to find all the things that cause it (and recording data streams using OBD) and all the things that don't, hoping to see a pattern.

 

totally agree about the looking for and ruling out things that cause it, but that's just what I have done and come up with the ECU as the common denomanator

as for the rouugh running, I first thought it was at about 2000 revs as that is what the revs are at 60mph but since then I find it does not miss if you hold it in lower gear and rev it up to 2000

 

jagv8 is this the thread you are referring to

www.jaguarforums.com/forum/showthread.php?t=37818

 

Thanks. Saved me hunting

If a lower gear revved to 2000 isn't rough.... it's data, which is good. Engine Load (an OBD value) is different when revving like that, as are air & fuel flow (plus RPMs etc).

I reckon you need more data. A tech would be good, too. The cost of throwing parts at it doesn't look attractive to me. I dread to think what even a used PCM and programming would cost. You don't want to find out what a new one costs!!

The 4.0 has some parts I know little about (such as AAI valve or whatever the pesky thing's called), so I don't know whether they could be involved.

 

It sounds to me like the engine is not in time?? I am suspicious since you changed the tensioners. This requires a good bit of special tools particularly to hold the cams in proper position while installing the tensioners.

Here is a picture of a guys Lincoln LS with just the smallest amount of misalignment. The car ran terrible. See if your cams are lined up again? I won't get into all the different tensioners so I hope you installed the latest and greatest version??
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