Hello All. It's been awhile as my 1997 XK8 Coupe has been running reasonably well for the last year or so. I trust you are all well and enjoying your cars.

The other day I hopped in the car and upon starting it, the car backfired and then would barely run. Foolishly, I tried to re-start it several times, with the same result. It will putter, but won't stay running.

I replaced the valve chain tensioners and related chains, guides, etc. a couple years ago - thought that's no guarantee they stayed fixed.

With my old code reader temporarily out of action (darn you IOS !), I decided to search for the obvious.

I took off the intake tube and had a look inside the throttle body. Found a fairly large plastic part - which I couldn't fish out - so shut down the repair project and attempts to start the car at that point.

Also, in looking around the car, I found plastic bits - photo attached - which I believe will match up to the bit of plastic in the throttle body.

Can anyone identify the part of the broken part?

Is the engine toast or might I luck out assuming the engine hasn't swallowed too much plastic?

Thank you.

Found on the ground near the '97 XK8. Possible match to scrap found in throttle body.

 

Take a look at this recent thread - I think that might be your answer https://www.jaguarforums.com/forum/x...1/#post2260142

 

Thank you. Upon cursory inspection of the intake tube, I found a crack, but not a missing big circular plastic piece. Really hoping I can find such a part, up or down stream - again assuming the engine hasn't swallowed the lot of it.

Will inspect further when the outside temp goes below 90.

 

A ruler or scale next to the image in your photo could help with identification.

Graham

 

Perhaps 4.5" in diameter. Origin unknown.
....It exactly matches the diameter of the throttle body. But I've never seen it before.

 

Considering how brittle 20 year old jaguar plastic is, I wouldn't be too worried about the ingestion having damaged your engine.

 

If the engine did swallow the missing bits it most likely flushed them right on out. Right into the catalytic convertor which should have all but vaporized them over time. If you get a restricted performance in the future the cats should be the first suspect.

 

I would guess that the plastic in the Throttle Body is stopping it running, or it may be jammed up in the EGR

 

Nothing in my 99 XK8 air intake looks like your photo of plastic bits.

I suspect bits from the garage is from your suspension. Diameter is about right. See pic below.




Any pictures of what’s inside the throttle body?

 

Will fish out the plastic tomorrow - or the next day considering the heat - then hit the throttle body with a shop vac. I'm curious to know just what the heck that object is.

David, I think you might be right about the suspension bit. That is a known issue in need of replacement that I hadn't yet tackled (read, was avoiding). But I'd never actually seen the part - until now.

 

I fished out the plastic bit. It's definitely from same family as the brittle plastic I found on the ground.

Also hit the intake with a shop vac.

Engine starts with a Vroom...then putters as I pump the gas madly.

My new Harbor Freight code reader says P0444, which is "EVAPP valve circuit, open circuit."

This is a new one on me. Any ideas on where I should look?

(Code reader also reads C1165, which may have something to do with the right wheel speed sensor and perhaps is why I get an occasional traction control fault code -- but I'd doubt that has to do with the way the car is running. Unless I'm missing something, I'll leave that for a rainy day.)

Thank you in advance for your help.

 

Truck Graphics,

Well the mystery deepens. Any chance of pictures of these mystery plastic bits.

Here's an excerpt a 2000 MY DTC Guide for your P0444 DTC.


If you're unfamiliar with the EVAP system, it's basically a system to recover and use fuel vapours. Looks like P0444 is a possible electrical short between the EVAP and the ECM. Most common failures I've seen on this Forum is P0445/P0446 related where the EVAP Purge Valve (behind the front left wheel well) goes bad. Also someone recently found that there's a Tank Pressure Control Valve that went bad.

An easy (emergency) way to get by/check this is to take off the fuel filler cap, stick a big screwdriver to open the internal flap and let the tank vapours disperse - some say they had to wait overnight. Safety first - No smoking or naked flames nearby - not even turning on a light switch. Then try starting the car.

 

No joy...No more plastic bits found...It's not my daily driver so it's been static the last month or two...But either I'll fix it or it's going into the shop...Usually I sleep on my Jag issues and come up with a solution, but drawing a blank.

 

That's because there is no issue with your Jag at the moment. It's actually upgrading itself. It's in the first phase of weight reduction: lose useless old plastics. Phase 2 will be rust of the wheel arches and floor boards.

 

If it sits much longer, you may be right. I can't do anything about the crackly plastic, but would hate to add lightness with rust!

My new theory is that the plastic in the intake is just a red herring, and not related to the plot - why won't the car run right?

Other pieces of the plot:

1) I had been messing around with the taillights and have a bunch of wires from the boot fusebox and lamp control module in an un-tie wrapped condition, if not disorganized. Perhaps I jostled something in the fusebox.

2) The car was very low on fuel when last started successfully. I added fuel when it wouldn't run right. Also - last night - I depressed the fuel rail port after the engine had been sputtering. Got some fuel, but not a spurt, though pressure could have bled off by that time.
A.Perhaps I burned out the fuel pump (replaced last year)?
B. Or perhaps the hose from the fuel pump blew off the pump. ?
C. Perhaps there is a connector from the fusebox - or in the trunk - from a power source to the fuel pump that has become dislodged. The fuel tank mounted connector is fine....

Haven't listened for fuel pump sounds yet, but have checked fuses and relays relating to the fuel pump in a cursory fashion. Perhaps that should be revisited.

 

Check the fuel pressure with a smart phone connected to the vehicle PCM via the OBD port using a Bluetooth interface.

Fuel pressure with the ignition in the ON position, without engaging the starter, should be around 3 bar.

 

Does the '97 have a fuel pressure sensor? Last time I used my Harbor Freight gauge which is leaky, but works of a sort.

(Not to change the thread of my thread...but I bought the code reader and earlier the fuel pressure gauge because my Apple phone wouldn't talk to my old ELM 327 device..However, I just bought a Microsoft Surface to replace my old Surface, so would love to avoid the leaky and dangerous fuel spray if I can get a reading...)

I will report back on my findings.

 

I do not believe the '97 has a fuel pressure sensor.

One bit of good news is that in the '97 the purge valve is accessible in the engine compartment, next to the coolant tank.

It sounds like you have a fuel pressure gauge already, so I'd definitely go ahead and give that a shot to get questions about fuel pressure out of the way. Check the pressure when you turn the key to on, without starting, to make sure the pump is priming right, and then watch the pressure with the car trying to get running.

Also, pull the vacuum line off the fuel pressure regulator to see if you smell gas. I understand that's an easy quick check to see if the pressure regulator has gone bad. If you smell gas, then it's bad. If you don't smell gas it may or may not be bad.

 

1) Problem solved.
2) It really was a (brittle) plastic car killer causing the problem
3) I've lost my vision - or at least my mechanical awareness - in my not quite old age.

Earlier today, I arranged to take the car to the shop because I was thoroughly baffled with my problem.

Then later in the day, a young fellow who I know to be a crackerjack mechanic dropped by my (truck wrapping) shop on unrelated business. I asked him to have a look and...
"There's your problem."

The front side of the intake manifold had completely blown out. Because the void was the same blackness as the rest of the manifold, I couldn't see it, though I could have stuck my beefy arm in it! However, there was one "tooth" of plastic left that my young friend spied.

I'm guessing the "panel" was attached in some sort of plastic welding process that couldn't withstand a backfire. Now, why it backfired, I have no idea, but the intake manifold shouldn't blow itself apart. It''s naturally aspirated, not supercharged.

This is the first time I've read of such a part failure. Has it happened to anyone else?

Hopefully this is the end of the story.

 

It is possible for a backfire to occur if the valve timing is incorrect. Have the primary and secondary timing chains, guides and tensioners been replaced with the latest versions?