Stalling when engine hot and revs lower! Xj40
#21
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Here are my photos of the throttle body etc which are on this server, so they'll enlarge without issue.
https://www.jaguarforums.com/forum/x...leanup-109079/
Larry
Last edited by Lawrence; 06-17-2017 at 08:38 PM.
#22
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Thanks guys, looks like I'm back off to the auto shop to upgrade my socket kit to one with a flex head, a little frustrating but still a great excuse to get more tools! The visual aids with the descriptiond are such a big help especially when it came to the tps etc, I definitely need to see in order to properly process haha. You're all my new favorite people
#23
#24
#25
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Thanks! Got her all re assembled and she's idling like a dream, here's hoping when I take her for a long drive later in the week to heat all the way up she doesn't start the idling issue again! I'll be very happy if this was the fix. Coolant temp sensor has been ordered as well, should be in by Tues. What a day! Couldn't have done it without all you jag folk!
#26
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Alrighty so I've taken her in to a mechanic I've been using for many years. He's done what he can so far, replaced oil filter, tested pressure and vac leaks, reset the base idle and tinkered with the throttle body / idle control, replaced some hoses just for good measure and has said no charge until I've taken it for a long drive to see if it's improved. he can't see any issues at all other than the base idle being slightly out. So tomorrow we'll go on a trip for a Yatala pie and hope it's running right. If not I'll take it back in Monday and he'll get deeper into the engine for me. I can't afford the tips this guy is worth but I am definitely sending this guy a pizza on mon. A great mechanic like that is worth twice their weight in gold.
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Don B (06-25-2017)
#27
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At an equally practical level (yep, I love pizza too) is for you to post into your local QLD Region forum to alert other members there of your trusted mechanic. Beyond anything else, the more Jags he has to work on, the more expertise and skill he gets to practice. Good for all!
I have done so my my (former) local whizz in Coffs, Denis Spagnolo.
Best wishes,
![Icon Beerchug](https://www.jaguarforums.com/forum/images/smilies/icon_beerchug.gif)
Ken
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Don B (06-25-2017)
#28
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Ok so I've heard the oil pressure sender can be a bit of a bitch. As I posted a while back, my jag runs fine when cold but when warm (after a long highway drive esp) it'll stall when I come to a stop. and then again, every time I slow down to idle. It starts up just fine and will run as long as I keep the revs up. While slowing, if I feather the throttle it will not stall as the revs are kept up. Issue I keep having is.. the oil pressure gauge starts dropping before the revs even dip below normal idle speed. it doesn't shudder, but once that gague drops to 0 ( which happens very fast once idle speed is reached) the car turns off. Is it possible for an oil pressure sender to show a fault only when warm? and if so, does it send a turn-off signal to the car when it senses the oil pressure has dropped?
I have already done the following:
checked for vac leaks
changed coolant temp sensor
cleaned Idle control valve and throttle body
cleaned MAF sensor
run injector cleaner though
NO codes have come up
oil filter has been changed
air filter is new.
Help?
I have already done the following:
checked for vac leaks
changed coolant temp sensor
cleaned Idle control valve and throttle body
cleaned MAF sensor
run injector cleaner though
NO codes have come up
oil filter has been changed
air filter is new.
Help?
#29
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#31
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Beck,
Did you also tell us in another thread that you have carefully checked the transmission fluid level while hot? If not:
Drive the car 15 or 20 minutes to heat up the trans fluid;
Park on a level surface;
Set the hand brake;
Hold the brake pedal and shift through all gear positions holding each one at least 3 seconds: P R N D 3 2 then back to P.
Leave the engine running, confirm the trans is in Park and the hand brake is set;
Open the hood, remove the transmission dipstick and wipe it clean;
Reinsert the dipstick and carefully withdraw it and check the fluid level;
The fluid level should come right to the HOT line on the dipstick.
Low transmission fluid has been associated with stalling when coming to a stop or slowing to make a turn, and Jaguar issued at least one TSB on this subject. Jaguar doesn't explain why this can happen, but my assumption is that the torque converter doesn't release properly and bogs down the engine.
A few other things that come to mind:
What is your idle speed when it settles down after startup? When you shift into Drive with your foot on the brake, what is the idle speed?
Have you changed the fuel filter?
Are the spark plugs in good condition and properly gapped?
How old are the spark plug wires?
Have you checked the fuel pump flow rate? You can disconnect the inlet hose from the bulkhead end of the fuel rail, aim it into a suitable container, crank the engine for 5 seconds, measure the quantity of petrol in the container and multiply by 12 to calculate the flow rate in liters-per-minute.
Checking the fuel pressure on an XJ40 requires appropriate adapter fittings for the gauge, so it's not really feasible for the average DIYer. But it would be worth pulling the vacuum line from the fuel pressure regulator (FPR) to check for signs of wet fuel, indicating failure of the diaphragm, which not only means the FPR is no longer holding proper fuel pressure in the rail, but raw, unmetered fuel is being inhaled into the intake manifold, leading to rich running.
Is the EGR valve operating properly? You can test it with a hand vacuum pump. Have you cleaned the EGR port on the underside of the intake manifold behind the throttle body? If your car has a carbon canister, the purge valve hose also connects to this port.
If your car is equipped with a carbon canister, the purge valve could be stuck open (which creates a vacuum leak for the engine) or there might be a problem with the pressure control valve (Rochester valve). Do you notice a "whooshing" sound of air being sucked into the fuel tank when you remove the filler cap?
Have you checked the distributor cap, rotor and distributor shaft for signs of arcing or damage? You might also see if the shaft has any sideward play, indicating a worn bushing.
That's all I can think of right now - it's late and my brain is tired, so for any of the above that makes no sense at all, I apologize in advance.
Oh, and since you already have a thread on stalling, and since Larry has correctly pointed out that the oil pressure sender has nothing to do with your stalling issue (other than reacting as the engine rpm fall during a stall), we should probably combine this thread with your other one so we can see what has been discussed previously to refresh our memories. I may do that tomorrow but I'm too tired right now.
EDIT: I have merged the threads.
Cheers,
Don
Did you also tell us in another thread that you have carefully checked the transmission fluid level while hot? If not:
Drive the car 15 or 20 minutes to heat up the trans fluid;
Park on a level surface;
Set the hand brake;
Hold the brake pedal and shift through all gear positions holding each one at least 3 seconds: P R N D 3 2 then back to P.
Leave the engine running, confirm the trans is in Park and the hand brake is set;
Open the hood, remove the transmission dipstick and wipe it clean;
Reinsert the dipstick and carefully withdraw it and check the fluid level;
The fluid level should come right to the HOT line on the dipstick.
Low transmission fluid has been associated with stalling when coming to a stop or slowing to make a turn, and Jaguar issued at least one TSB on this subject. Jaguar doesn't explain why this can happen, but my assumption is that the torque converter doesn't release properly and bogs down the engine.
A few other things that come to mind:
What is your idle speed when it settles down after startup? When you shift into Drive with your foot on the brake, what is the idle speed?
Have you changed the fuel filter?
Are the spark plugs in good condition and properly gapped?
How old are the spark plug wires?
Have you checked the fuel pump flow rate? You can disconnect the inlet hose from the bulkhead end of the fuel rail, aim it into a suitable container, crank the engine for 5 seconds, measure the quantity of petrol in the container and multiply by 12 to calculate the flow rate in liters-per-minute.
Checking the fuel pressure on an XJ40 requires appropriate adapter fittings for the gauge, so it's not really feasible for the average DIYer. But it would be worth pulling the vacuum line from the fuel pressure regulator (FPR) to check for signs of wet fuel, indicating failure of the diaphragm, which not only means the FPR is no longer holding proper fuel pressure in the rail, but raw, unmetered fuel is being inhaled into the intake manifold, leading to rich running.
Is the EGR valve operating properly? You can test it with a hand vacuum pump. Have you cleaned the EGR port on the underside of the intake manifold behind the throttle body? If your car has a carbon canister, the purge valve hose also connects to this port.
If your car is equipped with a carbon canister, the purge valve could be stuck open (which creates a vacuum leak for the engine) or there might be a problem with the pressure control valve (Rochester valve). Do you notice a "whooshing" sound of air being sucked into the fuel tank when you remove the filler cap?
Have you checked the distributor cap, rotor and distributor shaft for signs of arcing or damage? You might also see if the shaft has any sideward play, indicating a worn bushing.
That's all I can think of right now - it's late and my brain is tired, so for any of the above that makes no sense at all, I apologize in advance.
Oh, and since you already have a thread on stalling, and since Larry has correctly pointed out that the oil pressure sender has nothing to do with your stalling issue (other than reacting as the engine rpm fall during a stall), we should probably combine this thread with your other one so we can see what has been discussed previously to refresh our memories. I may do that tomorrow but I'm too tired right now.
EDIT: I have merged the threads.
Cheers,
Don
Last edited by Don B; 07-24-2017 at 09:53 AM.
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#32