I wrote a thread Stalling upon warm starting some time ago. The problem went away for a while but has returned and worsened.

Typically, after a normal drive and shutting down, and when the engine is still hot or warm the car refuses to start - the starter cranks but engine does not fire up. On some occasions, the engine was able to fire up after sitting and cooling off for a while - the longest wait is an hour. On another occasion we pushed start the car successfully (it is a manual).

The situation continues after installing a new crankshaft position sensor (CPS). In investigating the problem, the IDS does not detect any engine fault code. There is no engine light either. Unplugging the MAF did help successfully start the car once, but this method failed to repeat in a few following validation attempts. Further attempts so restart the car all failed, to the extent that the dash works OK but starter refused to turn. Further IDS checks returned no codes but "ECM error". Failure to return any codes despite unplugging the MAF first and the ABS Module suggested that the ECM was not working properly.

Unplugging the ECM found the two connectors badly corroded (see pictures below). This is weird as the ECM was already a replacement fitted Feb 2017 and the mechanic had wrapped it with waterproof plastic sheets. The ECM is not wet but the connectors were corroded.




I have a spare ECM which I shall install onto the car tomorrow and I hope to get the car back. Meanwhile, would hope to pick folks' brains on any other possible errors that resulted in no-start soon after shutting down the engine. We have ruled out the battery, the starter, fuses and relays, the CPS, Body Processing Module.

 

Do you get the initial 3 - 5 second fuel charge before cranking as the ECU has been warmed up and the command on signal comes from there on the same wire as the engine is rotating signal .

Push starting results are a indication that the fuel rail is charged , as the check valve is supposed to trap the charge anyway . This would point away from the fuel delivery and more to spark or injector control or quality ( warmed up ECU ? ) . Since you have 2 ECU's you can swap out to the cold spare at the point in time as the warm / installed one fails .

If you need new pins or sockets for the ECU I have that and some spares might not be a bad idea considering order time . See page 26 :

http://connectpolska.com/pdf/TEeconoseal.pdf

The large engine block ground by the starter may be compromised

 

I think you've found your problem. I'm willing to bet that it is indeed the ECU that is causing you problems.

Other than that, the only other culprit which could be the issue is the TPS at the underside of your throttle. It might be misreading the values there...not likely, but you asked. You should try to see what the ECU thinks the TPS is set at. Should be 12-13% open.

It seems like some sensor is flaking out on you. The question is whether its a sensor or the ECU trying to read the sensors through corroded contacts...

 

Keep in mind the ECU has a case ground with the rear lower bolt along with wire grounds through the connectors in swapping out that can cause problems in troubleshooting vs. just hanging on

Another heat soaked sensor would be the knock sensors throwing of the spark timing , a lessor heat soaked sensor would be the TPS but may be enough to error .

 

I'm with Vee on this. I would not be looking for anything else until the ECU pin issue is resolved and the situation reassessed.


Also, it's not clear from your OP whether this is a "No Start" issue or a "No Crank" issue. These would have very different causes and diagnosis paths.

I thought originally it was a Crank but No Start but then you said

"There is no engine light either." (which would cause a No Crank condition) and

"the dash works OK but starter refused to turn"


Can you clarify.

 

I am now out with the mechanic. Swap in another ECU but still no crank and despite forced cranking engine has no fire.

To clarify, yesterday the car cranked but did not fire up. After manipulating for a while including successful firing the car could not fire up properly without intervention. Then the car suddenly died altogether. Pulled the ECU and found it corroded. Replaced it with another just now and car is still dead.

The corroded one was mapped to disable the immobilizer. The one that just went in does not deal with the immobilizer. Am not sure if it is the immobilizer, the ECU, or other pre-existing issues. Hooked up with IDS and found error communicating with the ECU. Have checked ECU relay and connections and found nothing irregular. Will check again but seems like Rose is losing life signs again....

 

Just returned from the workshop. There was some problem with the starter cable but starter is functional otherwise. There is no ignition as there is no spark. Fuel supply is fine. Saw lots of carbon deposit in the exhaust tips, but ECU did not flag up any "fuel too rich" signals. Before the corroded ECU was removed the starter worked and engine was able to fire up through normal steps, although it took a few seconds rather than firing up instantly. IDS was able to connect to the ECU which flag the EGR failure code, but after a while the IDS reported communication problem with the ECU. My preliminary conclusions
(a) the ECU was partially working before its sudden death
(b) IDS is not able to read the replacement ECU, suggesting that power to the ECU might be compromised
(c) there are some prior temperature-related issues
Thoughts and advice?

 

Did you inspect and clean the ECU connectors? If the pins on the ECU were corroded then the connector will be also.

Are you getting Check Engine Light now when key turned to Pos II ?


If possible I think it would be better to try and clean/repair the old ECU pins. A replacement ECU with a diferent spec is introducing another set of unknowns in to the problem.

 

Checked and cleaned. All dash lights look in order including engine light and they all go out except hand brake after a while when attempting to start the car - which is normal. Seems like we are chasing electric gremlins that is possibly preventing the old and new ECU from functioning properly. I am sure the old ECU is dead, as it does not return after cleaning. The pins are very fragile and one almost fell off when we tried to blow dry the oxidation. The high suspects are hard-to-reach relays, ground points and harness connectors. Before all these happened we were trying to fix the oil leak from the O-ring between the partition plate and the manual gearbox. Car was working fine after a test drive until we stopped the car and tried to restart in 10 minutes. The difficult-to-start syndromes took place far earlier and when it happened it was always after a momentary off and when engine was hot or warm. If started successfully car worked normal until another shut down and re-start. Cold start was always in order. However, Rose is now in coma again. Would try to see if the trunk-to-cabin harness is again the culprit. The plastic buckle broke a year ago and the harness connector has been held together and tightened by plastic tie traps. Nevertheless, would also need to hunt down on the no-start when hot or warm problem.

 

 

I never could find find a part number for that connector as it is the same as the RS3 connector that was damaged on mine . True the trunk / cabin connector will prevent the car from starting . I cut out my RS3 connector and replaced all the wires pins with environmental splices .

The same connector is behind the glove box as a source of a part

As a least intrusive try the Greem / Black wire can be bypassed around the trunk connector and get you going

I already have a connector pin map for this

On the ECU connectors the sockets are as important as the pins . Do you need part numbers ?

 

Both ECUs were specially written by Andy to go with the auto-to-manual conversion. As Rose fell into coma the first time before adopting Andy's first ECU, and the immobilizer was the primary suspect (no proof) at the time, Andy wrote me another that bypassed the immobilizer. I somehow believed that it wasn't the immobilizer the first time Rose went to deep sleep a few years ago. It was a rusty and badly corroded ECU (I had another thread on this forum). My question is, now that Rose is in similar situation, how do we know if the immobilizer is the problem and how to reset it? There were some previous threads but I never saw a solution. One way to eliminate the possibility is to seek help from Andy to reproduce another ECU that neutralizes the immobilizer, so other investigation and fixes may proceed. Another question is, if it is not the immobilizer, what else could have caused the car refusing to start when engine was still hot or warm? This is a very trying moment for my mechanic, and is very discouraging having moved on that far since the last recovery.

 

Yes, but I would need to know where to get hold of them as I hope the first ECU only had surface corrosion and could be reused by replacing the connectors.

If it were the immobilizer, should not IDS still be able to communicate with the new ECU? It now says "communication error", so I believe some electrical faults are preventing the new ECU from taking command.

 

 

https://www.3waycomponents.co.uk/36-...-Connector-Kit

https://www.ebay.co.uk/itm/36-Way-Fe...-/131070500549


Page 41 pin connector C507-26 is labeled immobilization but is labeled 35 as fuel inhibit on Jaguar wiring guide

http://www.gomog.com/allmorgan/GEMS/GEMSbyPoole.pdf V8 version

The socket release tool is a 2 pronged pitch fork and saw it once . But in practice you have a new backshell to install the new sockets and the sockets can be soldiered on instead of the special crimping tool . Don't forget to put the green seals on the wires and scoot them back along the wires before installing the sockets . To insert them in the backshell use a very pointed device to push them in as it is a rear release .

The gap that allows water in is under the wiper area long plastic trough and is held on by plastic screws so be careful .

AS for the ECU case connector I would recommend a low temp liquid soldier and a heat gun method


Editing

 

Let me distill the info more clearly so folks do not blame it entirely on the ECU.

(1) Prior to the ECU failure, I had been experiencing a deteriorating problem of "no-start, engine-hot" issue, i.e. the engine cranks but does not fire up until it cools down for a while.

(2) While trying to investigate problem (1), the starter also failed to turn. Checked and found starter cable compromised; starter turned properly upon bypass but engine did not start - checked and found no spark. Scanned the car with VCM/IDS but it failed to communicate with the ECU. Checked the ECU and found the connectors corroded. ECU cleaned but starter had no response.

(3) When swapping in a used, good ECU, still no crank; VCM/IDS showed "communication error" with ECU. Relays and Fuses are checked in order. Now investigating power supply to the ECU.

(4) In validating the functionality of the corroded and replacement ECUs, I pointed out that the replacement ECU does not take care of the immobilizer. Both ECU were written by Andy, but the corroded one was able to bypass security, so the starter, fuel pump and ignition should work without waiting for "permission" from the security module, i.e. the car will not be immobilized.

On problem (1), I have searched extensively on the web and found a discussion with the problem solved. See "Starting problem when engine is HOT!" in Team-BHP.com. Briefly, it says the problem lies in the starter brushes which would play up when engine is hot. The problem has nothing to do with the battery. The other possibility discussed was "vapour lock" - read the interesting story of "The Pontiac that was allergic to Vanilla ice-cream".

I am still not sure whether the original cause of the "no-start, engine-hot" problem was the starter bushes or the vapour lock, but priority now is to validate functionality of the replacement ECU. Is the engine immobilized? Can the replacement ECU reset the immobilizer in the normal way or must it be reprogrammed as the previous one to bypass security, but why can't the VCM/IDS at least be able to communicate with the new ECU. Have to ask the mechanic to verify if there is power supply to the ECU. If there is, then the replacement ECU is the prime suspect. A lesser possibility is that the VCM/IDS is faulty and is not reading the car properly.

Am perplexed with Rose's erratic path to recovery. Thought she rehabilitated progressively well..... Oh dear!

 

Without dragging you all over the car , have you checked the ignition switch for the ground that enables the starter relay to close . My switch is variable and not fully and firmly closed in the start position .

I had corrosion on the switch connector at pin 5 which is the fixed bolted ground path for the switch .

If you get the starter relay to close or click have you considered hitting the starter motor at the time of event with something and maybe get the brushes to make better contact .

Thanks , Parker , The Jaguar Whisper

 

I just found out that there was in fact a "Jaguar TSB "Poor Hot Start" about the hot start problem. I am still not sure if the Tank Pressure Control Valve or known by others as Fuel Vapour Pressure Control Valve [CBC7714] is the cause of Rose's no-start problem.

 

The X300 has 2 types of fuel systems in the linked diagram below on page 60 . One way to know is if you have 1 or 2 large square evaporative canisters being one on the left in front of the rear axle and the second on the right in front of the rear axle . You don't have to jack the car up to see this . With the 1 canister system you don't have certain fuel system valves . Mine has only 1 canister .

http://www.jagrepair.com/images/Trai...20-%202000.pdf

Back to something easy to check since you mentioned no starter rotation is the ignition switch which you just need to take the 3 screws off the bottom of the steering column to get to . Without putting a meter on it you can visually look at the condition of the connector as I found corrosion on mine and cleaned up . If you pull up on the connector it comes off its mount so you have it in free space to easier play with .You are looking for a solid switch electrical closing from pin 1 to 5 as you have the key in the start position . And ensure you have a good ground on the socket side of the connector at pin 5 . As you play with the switch on the other pins more then one pin at a time closes to the pin 5 so it can be confusing but in this case you are looking at pin 1 to 5 . Note that the Red / White wire goes to the BPM and the transmission rotary switch before it gets to the starter relay . With the rotary switch I believe you will get a agreement light in the P on the shift column but yours is different . Your modification issue ?

Did you ever get the starter relay to click during your no start event

Below is a Word file from someone else I can't open myself that may have some information for you :

 

Back to the fuel tank . The pic below is on the normally aspirated engine as it refers to a on - board vapor recovery system and is not on the S/C engine wiring guide