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Richard
Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15341
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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Jaguar xk8: Im used car dealer we have1997 xk8, it was running

Customer Question

Im used car dealer we have1997 xk8, it was running fine while we had it on the lot. Just randomly now it will start cold but wont hold idle , it will accelerate but after 2 or 3 starts it wont idle ,we thought its was the throttle body , we exchanged it for used one same problem
Submitted: 1 year ago.
Category: Jaguar
Expert:  Richard replied 1 year ago.
Hello and welcome to justanswer.com
So the engine starts but stalls out soon after starting.
Any warning lights or messages on?
Customer: replied 1 year ago.
check engine , engine malfunction, stability control
Expert:  Richard replied 1 year ago.
Ok do you have any type of scan tool we can use to read the faults.
So the engine starts but stalls out soon after starting.
Customer: replied 1 year ago.
We have codes 1st the P1229. Then P1367-68 P1797 after that all the coil codes start to pop up P0351-54-56-57.
Expert:  Richard replied 1 year ago.
Ok clear all the codes then disconnect the negative battery terminal cable for about an hour. Reconnect it and start the vehicle. See what fault returns.
Customer: replied 1 year ago.
ok this what we get P1367,P1368,P1797 NEUTRAL CIRCUIT. AFTER THAT THE COIL SP0351,354,356,357.
Starts up ok, within 5 seconds where it needs to idle the engine starts to shake and then it shuts down,
Expert:  Richard replied 1 year ago.
The P1367 and P1368 are for the ignition modules. These are the two black modules in the rear of the engine compartments secured under the cowl. It could be a coil shutting down the complete bank since they are grouped to different modules. The cylinder order is 1-4 starting from the front on the passenger side and 5-8 starting from the front on the driver side. Label each coil and we will swap them. Swap 1 to 2, 3 to 4, 5 to 6 and 7 to 8. Clear the codes and see if the codes travel to the other cylinders.
On a side note I have also seen the secondary timing chain tensioners fail causing the chains to jump. This can cause these ignition codes as well.
Customer: replied 1 year ago.
Same results moved coils- cleared codes again- crank the car- 1st codes are p1367-68 ignition spares, cranked the car again - sames codes, couple more cranks then i got P1229 - Electronic throttle control circuit. . then cranked again then same coil faults start to appear p0351 A coil , p0354 D coil, p0356 F coil, P0357 G coil
Expert:  Richard replied 1 year ago.
Ok then we may have to remove both valve covers to check the timing chains and tensioners. With the covers removed we need to rotate the engine and make sure the flats on the front of all the cams face up evenly. Let me know.
Customer: replied 1 year ago.
any way to test the coils
Expert:  Richard replied 1 year ago.
We can check to see if they are outputting spark but by swapping them since the codes did not change the coils are most likely not the problem but the modules can be bad.
Customer: replied 1 year ago.
Cam timing is fine, any fuses or relays possibilities?, it seems like its getting fuel and ignition to cold start but when the system goes to idle it does not hold idle we can sometimes hold gas pedal down and it will run at higher RPM but it shuts down like it ran out of gas. The throttle body vacuum connection doesn't seem to have any suction or very little is that any concern?
Expert:  Richard replied 1 year ago.
Try swapping those ignition modules side to side to see if the coil faults switch to other cylinders.
Customer: replied 1 year ago.
swapped modules same, can it be the fuel pump/
Expert:  Richard replied 1 year ago.
We may have more than one problem but in most cases when the fuel pump stops working it will not cause this.
Customer: replied 1 year ago.
I requested phone conversation when would you be able to call?
Expert:  Richard replied 1 year ago.
Schedule is tough the next couple of days. We may have a problem with the ECM. I will look back through the diagram and post a test.
Customer: replied 1 year ago.
any other thoughts
Expert:  Richard replied 1 year ago.
I will send over some tests.
Customer: replied 1 year ago.
Waiting for you. The website keeps asking for me to rate. I can't do that till I have solved the problem.
Thanks
Expert:  Richard replied 1 year ago.
Go to the purple/white wire at each coil and ignition module and make sure we have power with the ignition ON and make sure we have ground on the black wires on the modules. Also we should hook up a fuel pressure gauge to the rail to make sure it does not drop out.
Customer: replied 1 year ago.
Power ok , ground ok. fuel pressure with key on at 43, start drops to 39-38 engine shuts down, fuel pressure stays at 40.
new codes after try, p1228- control sleeve sensor, p1228 wastegate failed open(under pressure)
p1367,p1368
Expert:  Richard replied 1 year ago.
OK we may have a wire harness issue since the P1226 and P1228 is for the mechanical guard sensor on the throttle. Lets go right to the ECM located under the cover and ECM enclosure in the passenger rear of the engine compartment. Access the ECM to make sure all the connections are clean and secure. Locate the 16 way connector pin 13 black/yellow wire. With the ignition ON we should read about .5 volts then the voltage should increase as an assistant depresses the gas. If you do not read this then go to the sensor and check this. The sensor is the one next to the cable side of the throttle.
Customer: replied 1 year ago.
No issues here, any way to test bench the ECM and the throttle body and finally can this be a wiring loom issue?
Expert:  Richard replied 1 year ago.
If those readings are good then the throttle sensor is ok. Unfortunately there really is no bench tests for the ECM. It does sound like a harness issue.
Customer: replied 1 year ago.
It seems like something is telling ECM to stop delivering fuel to injectors after the initial cold start thats good for 30 seconds of fuel.I dont know if a temperature sensor is a possibility .
Expert:  Richard replied 1 year ago.
I do not think so as it would also store a code.
Customer: replied 1 year ago.
whats next?
Expert:  Richard replied 1 year ago.
Our diagnosis is limited without the Jag factory tool. If those throttle faults are still present and we are should that the voltage is in range at the ECM connector then the ECM may be the issue. The problem is if a new or used ECM is fitted it must be programmed for security immobilization or the vehicle will not crank.

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