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Greg, Shop Owner
Category: UK Car
Satisfied Customers: 7120
Experience:  17 years Shop Owner /Technician. 27 years experience,
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Have a J type jag with 44000 miles on the clock... problems

Customer Question

Customer: ***** *****... have a J type jag with 44000 miles on the clock... problems with misfire at around 2000 rpm that goes away of increase revs. Also when cold car runs fine, but when normal running temperature soon stops and have to start again. All coil packs replaced including all sensors, but the problem still remains suggesting either running too lean or problem with cAT
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Submitted: 1 year ago.
Category: UK Car
Expert:  Greg replied 1 year ago.

Hi .

Is the check engine light ON when the engine is running .

Was at anytime the system checked for codes .

Rgds Greg

Customer: replied 1 year ago.
No check light on right now, but just did a diagnostic and here are the codes
PO420 Cat System below threshold Bank 1
PO174 System too lean Bank 2
PO305 Cylinder 5 misfire
Customer: replied 1 year ago.
Diagnostic tool AutoLink AL319 also suggest Fuel Sys01 Fault
Expert:  Greg replied 1 year ago.

First do a fuel pressure test .

And do a compression test .

When was the last engine tune up


Customer: replied 1 year ago.
Greg, it came from the garage like this after replacing sensors etc. costing me nearly £450. I'm just going to take it back to them as my information suggestsPO 420 - Oxygen (O2) sensor not working correctly
Damaged or leaking exhaust (pipe, manifold, catalytic converter)
Damaged catalytic converterPO305 - Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issuesPO174 - Suspect HO2S on Bank 2This is just too much for me to go through, but thanks anyway for trying.
Customer: replied 1 year ago.
I've just called the garage and given them an earful. It is going back into tomorrow. Please take your £3.00 and let me have a return on the balance.Thank you.
Expert:  Greg replied 1 year ago.

Hi ,

Looking at these code a bad injector on number 5 could cause these codes ,

A fuel pressure leak down test should be done talk to the shop that did the last repairs .

this will confirm a bad injector ,and a back pressure test done on the exhaust to check and see if the cat has slight blockage

not letting it operate as should and giving the 2nd sensor the same reading as the first ..

A few test are going to be done to see what is causing this ,

Rgds Greg