Not that no, the test and times recorded are simply a way for me to usefully compare engine response, as I still have a noticeable hesitation issue, where the engine will briefly stumble before revving. As a result, the engine can seem more sluggish than it actually is, or can lead to blaming the poor old 4 speed auto for lack of response. Ive taken readings from the mass air flow sensor and they seem reasonable, 1.3v at idle and 2.85v with a large dose of throttle, so perhaps its not responding quickly enough, leading to a lean condition, therefore, stumbling. When the MAF is unplugged and the ECU is forced to use hardcoded values, the hesitation disappears completely. Il try to stick together a video to show the differences more clearly.

 

Black / Light Green wire on the MAF ties into the EVAP valve as well as the power for the injectors . Could the Evap valve be be shorting causing lose of power to the injectors and MAF ? Is is plausible to remove the EVAP connector and see a difference ?

 

Has now changed. When coming to a stop, the engine will miss, possibly just the once, and then its fine. If I stay in D, it may occur again in the next minute or so but its not very consistent. So im assuming that the underlying condition is getting worse, as I have only added andy's bracket in the meantime. Ive also ran some injector cleaner though to no avail. I may purchase a single "made in japan" coil and try it in each cylinder, to rule out a coil problem.

 

*Update*

Was commuting this morning, car was missing more frequently, and then there was a very short cutout at 60mph, enough to trigger the check engine light briefly, but car continued to drive until I got to my destination. When I returned to drive the car back home, started the car and the engine was stumbling then surging then stumbling etc. Put in drive and it was ok, but there were obvious hesitations and flatspots. finally about a mile down the road it cut out and wouldnt start. when it did it took all of a few seconds to cutout again, so I decided not to chance it as I was in a decent place to breakdown as it where.

Ive already ordered a new CPS as that last time I started it, there were no revs during cranking. Its at 106k miles now so if its the original CPS its definitely overdue. Anyone else think its likely to be CPS?

 

CPS and coils are the most common causes of X300's engine weird behaviour, and 90% of the time it is the CPS (LHE1640AA) which is a cheap fix for about GBP33.

 

Yeah ive got one coming today. I did replace the MAF on the day it broke down, with a "new" one from global car parts, but I doubt its that as it drove better when I installed it, the unusual behaviour only started later.

 

New crankshaft position sensor cured the problem, these things really do fail just like that. Warning sign seemed to be very infrequent misfires when in drive, usually only noticeable when stationary. The CPS that was removed is Lucas stamped, no date but looks old and the wire/rubber is very rigid.

Did notice though that the idle occasionally dipped too low for my liking when coming to a stop, drop from ~600 to 500rpm etc, others have attributed this to low ATF fluid level. Mine was on the first mark for the hatched "hot" section so Il add another 250ml of Redline D4 and recheck. If not il look at the IACV.

 

Glad that a new CPS fixed it. Many fellas have learned to have a spare one, even a used one, in the trunk.

I recently adjusted my idling using the Jaguar IDS. It now idles beautifully at 750 rpm at operation temperature. Yours is pretty low if it is just around 600 before dipping to 500.

 

How do you do this in the IDS? Do you need exhaust reading to adjust the idle? I have an iDS and have not figured out how to do this.

thanks.

 

Find "Vehicle Configuration" under the top menu, then select "Set-up and Configuration" where you will find "Throttle Pot Adaption Test" and "Oxygen Sensor Orientation Test". Suggest you do the O2 sensors test first even though you have not replaced them. Then conduct the "Throttle Pot Adaption Test", during which IDS will guide your through including warming up the engine. You will notice the engine idle speed going up and down before leveling off by itself - which will be your new idle matching the prevailing ECU, TPS, O2 sensors, etc.

 

Where did you source your IDS other then a jaguar shop ?

 

I got the VCM kit a few months ago from forum Moderator Cambo. See his earlier thread "Original VCM Diagnostic Interfaces" in the Classified Section. He runs a Jaguar performance centre in Australia, and has a very strong network with software specialists, auto electricians and engineers.

 

Have noticed something recently. Car rolls forward fine in drive, but in reverse, on basically flat ground it will stumble with little to no throttle input, sounds like a IACV issue no? Im basing that on the other issues im having, which is a rubbish idle in park and somewhat in drive.

 

The transmission connector sending the signal back to Transmission and or Engine ECUs corrupted as you command R position . Suggest clean connector on left side of transmission , don't have to jack up car .

 

Bit more info now im monitoring it. When selecting Reverse, revs drop to 500-550rpm, Drive sits at 650-700Rpm normally. Will try your suggestion Lady P as shes going on a ramp this week I think anyway.

 

Am about to get a set of used injectors, thought id look at the purge valve first. Pulled hose off at the valve side, sealed the tube with an Allen key and started engine, no measurable improvement. Its getting booked in for a scan soon, these cars are hard to diagnose without such equipment in my opinion.

 

The injector pulse time or duration is at it's shortest in the park position , idle , and or maybe reverse position as the ECU senses this through maybe the transmission connector or the TPS or other means say the ECU sensing from the shift gate switches by way of the TCU . Unresponsive or binding injectors is the term often used . The cleaning method I used like in the video just used straight hose with hose clamps for 2 injectors at a time with a hole drilled in the middle for the glued in red tube . The connectors on the trunk compartment lights are the same as used in the engine so they can be barrowed

 

Little sidetrack, since I ignored the first instance but now its happened twice so..

Cruising at 70mph, had been for several minutes, trans randomly shifts down to 3rd, then 2 seconds later shifts back into 4th. I dont think it started accelerating when it changed to third, was just as if id moved the stick to 3 then back to D.

Only thing ive done recently is auto fluid swap, so could this be the redline working some crud loose in the valveblock? Also saw a suggestion that it was a bad TPS or an engine misfiring under load.

 

The old fluid logic boards on the ZF4HP22 transmissions on the sport model vs.the electrical solenoid controlled ZF4HP24 then maybe yes .

 

It's the 4.0, so the electronic transmission