Supercharger issues on 1999 xkr
 

Hi all, I've been working through the issues on my 1999 xkr which had been stood for 8 year's prior to me owning it. It's had a service , plugs etc and yesterday I replaced the maf which was also shot.
Hoping for great things I took her out this morning. She stalled twice going into roundabouts which had happened previously. This happened early in the trip but not after a bit of a run. Feeling more confident i went on the motorway and pub my foot down on the slip road.
The supercharger kicked in , all but reluctantly and with a few non jaguar like shakes and rattles. After his I could accelerate upto the speed limit okish , but if I floored it nothing happens. It just seems to bog out and stay at the speed im going at. I havent cleaned the butterfly in the throttle body yet.
Any suggestions or thoughts please. No codes either..? Many thanks in advance

Definitely sounds like fuel pump(s) and / or fuel filter issues..


sitting for any length of time will kill these old
fuel pumps.

Z

Both the pumps have been replaced as has the fuel filter.

it would be helpful to mention that in first post.

Z

Yes, sorry.

no worries. I’ve been more opaque on many occasions.

No codes are being recorded ?

a supercharger not putting out boost is usually just poor performance, without any other signature issues.

a car that’s been sitting for a very long time often has a variety of problems all linked to gasoline age. Even a new fuel filter can become contaminated rather quickly.

On the fuel delivery side, I’m suspecting some problem(s) with the gas flow or pressure.

Ignition wise, I’d suspect wiring damage from age, elements, or carnitas.

Anything more you can post about condition of car, performance anomalies, and parts replaced would help.

photo(s) are pure gas, not ethanol blend, that merely sat too long, the inside of the gas tank was even worse.

https://cimg1.ibsrv.net/gimg/www.jag...9e24a8d72.jpeg

https://cimg2.ibsrv.net/gimg/www.jag...7d458b5fe.jpeg




Z

I'm not sure what you mean by the "supercharger kicked in" - the supercharger is running all the time, it doesn't have a separate clutch for example and you could take the belt off and see if it makes any difference if you thought there was a problem with it.

What are the state of the tensioners on the car? Are they the original or have they been changed? If they are original you need to change at least the secondaries before doing anything else.

Have you tried adding a bottle of injector cleaner to a tank of fuel? Maybe an injector is blocked.

You can also check the live data on your OBD tool and see if that gives you any clues as to what is going on - fuel trims, MAF value, accelerator position etc.

As dibbit states the SC does not 'kick-in' but the bypass valve could malfunction and remain open.

Hi gents, thanks for your assistance. I've took the car out today and will try to explain things better. Please excuse my ignorance. I think i may have included the supercharger inadvertently.
The problem occurs when you accelerate. Press on the gas and it reacts in different ways. The worst episode today was on the motorway, and after pressing the accelerator going up a slight hill it just seemed to fade away. Worst sympton after putting your foot down is surging as if it's on kangaroo juice. You turn the key off and start her up again and all is well until you put you foot down . If you coax her along on the motorway, speed increases steadily but it did start missing a little about 80mph.

May be the throttle body? Is yours the AJ26 (vacuum actuator TB) or AJ27 (electronic TB)?

Hi, it's the aj27. I cleaned it yesterday before I went out. Tickover seemed to be spot on it's under acceleration that it flops.

Hopefully this link will work. This is what was happening as I accelerate up the slip road. Not the best video but I had other issues.https://photos.app.goo.gl/u9SipFWsShSjaWjy9

It could also be the MAF, wondering about the inlet amount of air. On diesel cars, it's easy to test simply unplugging the connector, if the engine runs better without it, it's obviously bad. But the Denso electronic of our cars may be different, I don't know if it worked the same. Need to wait advice from other members..

Hi, thanks for the reply. I've replaced the maf. I did the unplugging it and the engine kept running with the old one. I also had codes coming up for the maf. Replaced the maf with a used one and the engine cut out when I unplugged it as I believe it's supposed too. Also I've no codes.

The engine should run ok without the MAF plugged in, but you should get a fault immediately and a code. The computer uses a default map.

You might want to double check what happens and as I said above, look at the live data.

hi dibbit, ive took your advise and been and had another go. I unplugged the replacement maf and the engine stumbled briefly and then continued to run. I swapped the maf for the original and repeated the process. Same result, it stumbled briefly and continued to run. You are correct, I can't believe they lied on YouTube lol. As far as live data goes I have the following info, rpm745,shrt ft1 -6.3% long ft1 11.7% shrt ft2-7% long ft2 12.5%. Maf7.22g/s tp3.1%. I previously had a misfire showing on cylinder 5. The plug ceramic was cracked so I changed all the plugs. Didn't change any coils. Also added a bottle of injector cleaner and changed the filter. I have another fuel filter on the way following zray advise. Don't know if this rules anything in or out? Still no codes either.

What kind of fuel injector cleaner did you use, and how many ounces was it?

Not sure on the injector cleaner or weight, I didn't think to pay attention as I was too busy chuntering about the price.
Not sure if this is relevant but ive just read that the gearbox dipstick tube can affect vacuum if not sealed properly. I noticed yesterday after my drive the cap was not seated properly after i replaced the gearbox oil recently. The new locking tab had gone in incorrectly and the cap was not tight. I replaced it with a spare tab and heard it click home nicely. Don't suppose that could have been my issue could it?

Those trims show you may have an air leak. Do they drop near zero if you rev to (say) 2500 when parked?

Air leaks can cause stalls, of course.

That sure sounds like my old '59 Chevy with the weak fuel pump. Surging and bucking when you got onto the throttle, was fine if you accelerated slowly. :D

I know you replaced the pumps, but have you measured your fuel pressure since then?