My 96 vdp has a miss that is not present all the time. She will idle smoothly for a few seconds then stumble for a few more . If I rev it up a little bit the motor seems to smooth out but as soon as it is idleing again the miss returns. I have replaced the ECU LNA1410VE/102 with an LNA1410vd/102 as jaguar no longer sells the original and it took 14 months to find the one I have. Also have replaced 3 coils,4 O2 sensors,the throttle position sensor,cleaned the crank pos. sensor,put in new spark plugs,checked compression,checked fuel pressure,on both side of the regulater.When it is running at idle the revs climb and drop buy about 200 revs,like a blown head gasket but I have 210 psi in all 6 cyls. I am at the end of my rope here folks. Should I just jump or what?? I don't have any electronic code readers or the skill to know what it would mean anyway. I'm an old school grease monkey and don't get electronics. Please help me if you can.Thx...Jamie

 

Doug will probably be along shortly.

However, in the meantime, how about system grounds, and vacuum leaks?

 

Jamie:
Considering what you have changed, I believe your next step is a new CKPS.

 

I agree with Ross.

Since you have replaced the TPS, I have read here that it requires "orientating" to the ECU. The threads I have read that mention that, talk of "idle fluctuations, and idle stumble", mmmmm.

Mine is a 3.2ltr, yours will be a 4ltr, and I have replaced my TPS and nothing was required, but I believe the TPS is different for the smaller engine????, and does not require this added work, dunno really, mine simply attached into place (2 small screws) and worked fine, maybe I was lucky haha.

Also the infamous "black goo" inside the throttle body can cause idle issues, but I reckon you would have cleaned that with the TPS replacement??.

 

In a perfect situation, the TPS replacement would not require the calibration. Many report changing them with none required, At least for me, though, it was the magic elixer.