Hello All!

I've been off the forums for a while as my 1997 has been running perfectly for a long time now. I have been fortunate to be able to help some new XK8 owners in my town with the expertise I have gained from this forum. I have also suggested to them that they join as soon as possible to start their learning curve process.

Problem: About 2 weeks ago the engine started running rough and stalling every once in a while. Sometimes it would even accelerate without warning. Some time ago I did some motherboard repairs and shared the results with this forum and since the symptoms were similar I inspected the ECU but could not find any failed components. I eventually sent it out for professional inspection and repair and the job was performed quickly, replacing some components and fixing broken traces. On plugging it back in and starting the car, the symptoms have not changed.

The engine will start but quickly starts to lose RPMs and when it is almost ready to stall, it comes back to life again only to resume the dropping RPMs and eventual stall. I can keep the engine running by feathering the accelerator and even drive it around the block but it is running terribly and stalling without warning.

Up until this happened the engine was running beautifully and still does every few engine starts.

Does anyone have any thoughts? Is there an intermediate step when reinstalling a rebuilt ECU? I would check for codes but my OBD2 can't communicate.

The battery is new and fully charged. The MAS system was cleaned about 3k miles ago.

 

A repaired ECU should be plug and play. Checking for codes is the next step.

 

Thank you! I'll have to fix my OBD2 first!

 

It is my understanding that the new ECU must be married to the Security Module Via IDS in order for it to work.

Gus
www.jagrepair.com

 

Thank you Gus!
I am sorry. What you wrote is greek to me. I could guess but I am sure I would have it wrong.
How does one marry the rebuilt/repaired ECU to the Security Module via IDS?

 

If the original ECU is repaired by an outfit like ASI it's plug & play. I had the one on my 97 repaired by them. I also had the ECU from my BMW repaired by another company last year, also p&p. If you use a ECU from another car it does need to be paired.

 

Thank you, RJ237!
This was my original ECU - I sent it to Module Masters in Idaho. They replaced some components and made some trace repairs and sent it back, so I am assuming it has its original programming.

 

Yes if you repaired the original unit then it is Plug and Play if not it must be programmed to the car.
Sorry I should have made it clearer.
Gus
www.jagrepair.com

 

Could it be your MAF? Know any fellow members you could temporarily swap MAFs with? Really easy job would take only a few mins.

Another thing I would try is removing your repaired unit and ensuring all your connections are clean and tight on refit. Id bet money its something simple, like the MAF. I am sure you do not need it but here is a how to......... click me to jump to topic.

 

Thank you FrankC!
Since it is winter in the mountains, I have cleaned all the connections and reseated them to no joy but I will try cleaning the MAF. Unfortunately, I don't have access to another MAF. Thanks for your idea!

 

Thank you Gus!
I have also emailed the repair company to see what they suggest. Since the engine starts fine but then loses RPM and dies only to sometimes recover at about 200RPM, I am going to try the MAF as stated below. At least I can clean it and see what happens. I am 5 hours from any Jaguar dealer so I am on my own.
Gus, you have been a terrific help to me to keep this lovely car canyon carving and I do not have any intention of letting it sit too long!

 

FrankC,
Well, it was not the MAF but close - The breather hose retainer failed and it came loose from the intake. Reattaching it made all the demons run away and she now runs perfectly!. You were right it was something easy!

Thank you all for your assistance. For 14 dollars I've ordered a new breather hose!

Thanks again!

How do I mark this resolved?

 

Fantastic! Glad you got it sorted.

How about putting up a photo of the naughty part so if in the future anyone has this problem they know where to look?

Congratulations again.