John_Worthington
Senior Member
Offline
Hi fellas,
I am still trying to diagnose and repair a cold start issue on my '98 XJ8 VDP. After start up the engine slows to a high idle of about 850 rpm and I get a light 'clack, clack, clack' sound and the idle sounds like I'm misfiring. I have found that a slight increase in RPMs 'clears' this issue and then the engine idles smoothly. As I press the accelerator down I hear a single 'click' and then the idle smoothes out. It's like something is freeing up or engaging and allowing proper aspiration.
This symptom has been going on for a year now and I originally thought I was getting timing chain noise and changed out the entire primary and secondary components. The timing is intact and the overall visual condition of the cams is excellent. I have also replaced all the plugs and checked over all harnesses, coils, vacuum lines and hoses for irregularities. The noise was there before, during and now after all my tinkering. The only code I have for OBDII is P1000 which I believe is a system check cycle not cleared since I last disconnected the battery. I do not get any MIL illumination.
I am now thinking it might be a hydraulic lifter/ valve train issue, or maybe low oil pressure from a bad pump, gummed pickup screen or faulty sender as the root cause. I had the car in to re-pack a wheel bearing the other day at a local garage and asked if they could manually check the oil pressure for me but to no avail. Before I start digging deeper (and making a great big mess) does anyone have any advice or familiarity with this symptom?
Yours humbly,
John W
I am still trying to diagnose and repair a cold start issue on my '98 XJ8 VDP. After start up the engine slows to a high idle of about 850 rpm and I get a light 'clack, clack, clack' sound and the idle sounds like I'm misfiring. I have found that a slight increase in RPMs 'clears' this issue and then the engine idles smoothly. As I press the accelerator down I hear a single 'click' and then the idle smoothes out. It's like something is freeing up or engaging and allowing proper aspiration.
This symptom has been going on for a year now and I originally thought I was getting timing chain noise and changed out the entire primary and secondary components. The timing is intact and the overall visual condition of the cams is excellent. I have also replaced all the plugs and checked over all harnesses, coils, vacuum lines and hoses for irregularities. The noise was there before, during and now after all my tinkering. The only code I have for OBDII is P1000 which I believe is a system check cycle not cleared since I last disconnected the battery. I do not get any MIL illumination.
I am now thinking it might be a hydraulic lifter/ valve train issue, or maybe low oil pressure from a bad pump, gummed pickup screen or faulty sender as the root cause. I had the car in to re-pack a wheel bearing the other day at a local garage and asked if they could manually check the oil pressure for me but to no avail. Before I start digging deeper (and making a great big mess) does anyone have any advice or familiarity with this symptom?
Yours humbly,
John W