Hi guys,

So, here's the story...

XK8 - P Reg (97)

After having the gearbox rebuilt I haven't used the car too much. Found after a while that the fuel consumption wasn't very good. Certainly not unto my usual figures. Not sure if they are related - but thought I would throw that in. This is the only job on the car that has not been done by a Jag independent.

Spent the last couple of days stripping out the driver's side blower and fixing that. All back together again now.

Thought I would investigate the fuel issue. Posted on here about it running rich, and was told to check the fuel trims.

Read them yesterday and they are high. LTFT 14.5% and STFT 19.5%, both banks. Was informed on the other thread that I should have a fault code on the ECU - checked again and no fault codes.

While I was idling the engine there was an intermittent click - like a relay, but quite loud and this was accompanied by a jump in revs and Mass Air flow data. The MAF data jumped from 4.5 to 8 then gradually settled back to 4.5. Never noticed this before it always idled very smoothly.

Today, decided to check again for fault codes and read the data again. Started the car, connected to the ECU, it stalled. Restarted, idled for a bit and then stalled. No change in Fuel trims and no change in fault codes - none.

Had a poke about the engine bay and pulled out the MAF to have a look - it's the old style one, so a complete unit between air box and pipe and expensive to replace!

Checked for cracks in the pipes, leaks etc - couldn't see anything - haven't investigated further (yet).

Put it back together and decided to reset the ECU, disconnected the battery etc. and then took it for a drive. Seemed all ok and the fuel consumption got to a reasonable figure for a short drive with a mix of dual carriageway and some A roads. Mostly normal driving and a few little foot down moments.

Got back, quite pleased with the fuel consumption figures etc. So decided to read the fuel trims again to see where I was at. Here is where it gets weird...

Plugged the reader in to the car and connected. It stalled. Restarted it, same again. Unplugged the reader and restarted, seemed ok, but 30 secs later, stalled again and said Battery not charging. Subsequent restarts have said the same thing.

Here are my questions:

1. Do I have an issue with the fault code reader? It's a cheap Chinese thing from Ebay and an iPhone app.
2. Have I caused a fault on the ECU?
3. I don't have the best battery in the world on the car, could this be the issue? I've had it on a trickle charger for the last couple of days.
4. Does the alternator really need replacing, or could this just be the battery has totally failed?
5. Can I replace the MAF housing for a later type and run the later type (cheaper) MAF sensor?
6. Someone suggested that the gearbox people might have swapped over the connections for the up stream and down stream O2 sensors - how would I check this? Does someone have pictures of where they are plugged in and which is which???

7. What's the best way to go looking for leaks in the intake? I have heard about testing with smoke, but I have no idea how to do this or what kit is needed. I do have a DJ style smoke machine, would this work if fed into the intake?


Sorry for all the questions, just trying to get my baby back to tip top shape and don't have money to take it to the nice Jag people at the moment. I have done a lot of work on cars over the years, so I am fairly savvy with most stuff when I know what to do and where to look...

Many thanks for any input here.

 

What's the voltage across the battery terminals with the engine not running and with it running?

 

hey all,

this brings forward a question...mine is an '05 xkr and, as well, i am wanting to buy a scanner that can read/reset ALL the functions of my cat..ecm, tcm, body moduals...etc, to include the ability to upload the latest zf6HP26 update and reset the adaptive relearn. Q: what/who's do i buy for my cat ?..where ?..so as not to have the same problem MattArnold is having ? The scanner i have is setting off the check engine lite as well....

many thx to all the veterans that make this forum so great !

max & XKRFACE

 

It isn't polite to hijack a thread when you could easily open your own. MattArnold is trying to resolve air leaks, but also having OBD problems. Your issue is looking for software that does everything. I think IDS/SDS would be the best choice.

 

Matt, your scanner may not be using ISO 9141 protocol. There are many inexpensive scanners, but not all will interface with a '97. Somewhere on the forum there's a list of tools that members have used and approved, but I don't recall where.

Your smoke machine will probably work, worth a try.

 

I did check the protocol - and yes I believe it is using that. I can't check now as the battery is removed waiting on the new one that I treated it to. Can't hurt, right?

 

It's very low. While checking it I noticed with the engine off the fuel pump relay is clicking on and off a lot. So I'm guessing the battery is dead now. I have ordered a replacement as I didn't think it was great anyway and it can't hurt.

thanks,

 

Btw - where would I feed the smoke? it doesn't seem to be happy to run with the air cleaner box open, and would this be done while it's running or engine off?

 

Engine off. My prefernce is to feed into the intake tube where the mafs housing connects, using rags to seal it. Open the throttle body butterfly and use a piece of wood to keep it from closing. Inspect the accordion folds of the intake tube carefully, it's one of the most common problem areas.

 

Smoke machine is run with engine off. An idea is to use the vacuum line to the fuel pressure regulator. It would fill the intake with smoke leaving all the usual parts in place. Smoke needs to be a some (low) pressure to displace the air already there and show up through the leaks. Double check there is smoke in the crank case too, by pulling the dip stick.

Battery is by far your first priority. I would say re-assess with a new battery. Bosch AGM comes highly recommended, but I suppose any proper battery will do.

This clicking and jump in idle speed makes me think throttle body, which is a known problem area for the early cars, but there are usually codes.

 

+1 fmertz. I just found this link:

OBDII Code Scanners ** Member Approved ** - Jaguar Forums - Jaguar Enthusiasts Forum

 

+1
Replace the battery (or at least have it load-tested and fully charged) if there is any doubt about its condition before condemning anything. It's a root cause of all manner of electronics bad behaviour.

I also use a cheap clone ELM reader with the Torque Android app and have had no issues, although others have reported spurious problems with the adaptor plugged in.

I imagine that the click (or more so a 'clack') you hear will be the A/C compressor clutch engaging. This has a transient effect on the engine revs, and is accompanied by the fans switching on which has a more pronounced short-term effect on the engine revs (certainly on my car) due to their heavy startup power draw making the alternator work hard temporarily. Turn the A/C off to confirm.

The HO2S connectors are mounted on the top of the transmission underneath the throttle body. I'll try to find a pic. for you or grab one from my car and post back.

Your fuel trims are out of whack, but you're getting great advice from the folks here who have been through this and will guide you to the solution.
Take a look at this thread of H2OBoy's a while back that will give you some insight into trims:
https://www.jaguarforums.com/forum/g...17/#post300258

Good luck!

 

Hi Matt,
Here are the two HO2S connectors on my '98. I imagine that they won't have moved much from 97. RHS and LHS are looking forward from the rear. Check that the wiring leads to the sensor on the same side of the car as its connector.

RHS:



LHS:

 

Many thanks for that.
I shall have another look when the battery turns up. I’m hoping it will arrive tomorrow.

I’ve been studying up on these sensors and the fuel trims, plus trying to find leaks. Hopefully I will get to the bottom of this.

Tested the ODB connector on my Porsche and that has no issues monitoring data, so I’m hoping it will be the same when I get the Jag started again.

 

Right - SOLVED the weird issues with the ECU.

Today the new battery arrived and was duly fitted to the car. The ECU was reset - hard reset.

Started the car - tick over fine, then started to run rough and all over the place. Checked the fault codes, all random errors. Clear codes, engine runs fine, then more fault codes engine running rough. Check codes, more of them, different codes, not all one bank etc etc.

Bit the bullet, pulled the ECU from the car, opened it and repaired it - INTERNAL ECU FAULT.

Back in the car, starts fine, ticks over fine, runs fine - no fault codes.

Now back to the fuel trims....

!please join me on that thread for more help please!

 

Good catch:- common issue on the 97

 

Many thanks for all your help on this one, it's been most valuable and welcome.

Matt.

 

So what was the internal fault you found, and how did you fix it?

 

Having a read through here and other forums some people had complained about early ECUs going wrong, one guy on here had tried replacing some components, so these were the first to check. Opening up the unit and a good first visual inspection lead me to find little wrong. A multimeter and some probing revealed some strange results around the electrolytic capacitors, even in circuit some were reading much lower than expected. So, I lifted one out of circuit to measure and sure enough it was zero reading. I took it out completely and found that it had leaked - which they are known for. There was some damage on the circuit board due to this, but that checked out ok and no broken tracks, so I sealed that, put a new one in and moved on. By the time I found the 2nd one that read suspect, all the electrolytic caps got replaced. I am sure there are other things that can go wrong with these, but that would require a lot more diagnostic kit or info. A circuit diagram would have been awesome, but of course Jag don't release that info!

By the way, this is some careful and delicate work with a small electronics soldering iron...so proceed with caution....

There are internet services that you can send it off to for inspection and repair... might be worth checking if you need to.

Hope that helps.
Matt.