steamdriven

Thanks @sailorbob that is also my understanding from the service manual, but I am still holding out some hope that its not an ECU fault. I think I also need to dismiss the possibility of a faulty fuel pump by testing to ensure that I am indeed getting fuel system prime at key-on ?

Hi @LotuStuart yes i've already done that. In fact that is exactly what the service manual suggests and it also comments that you might need to remove tank filler cap to hear the pump running. I thought I had heard the pump running early on in this saga (hence my concentration initially on ignition) but I am now beginning to doubt that it is in fact running- if it is running then it is v quiet ! I think the only place for me to go next is to get a guage on the fuel rail.

Update from the rabbit hole :- GT3 '98 Indeed it is now looking like fuel problem (I had not been 'fiddling' anywhere near the fuel delivery components so did not initially suspect it as the cause and I had therefore persisted down the rabbit hole of ignition, thinking I had disturbed an electrical connection somewhere). Spark is confirmed and yes plugs 'dry' . Crank Sensor and wiring ok (although the mystery still remains in my mind of why I get no RPM 'blip' on FreeScan when cranking, which is what initially encouraged me toward a possible IM /ECU problem). I've not yet done fuel pressure test (largely because I dont have equipment to hand) but I have confirmed 12v supply to in-tank fuel pump when ignition turned on, and relay/fuse intact and functional, and inertia sensor/ connections ok. I do notice however that after an initial 'flash' of 12v to the fuel pump supply on turning the ignition key, the reading falls back to zero. Is this usual (ie after energising does the pump turn off if sufficient fuel pressure is sensed , or should pump continue to get 12v ) ?

Ok, so I AM seeing Crank Sensor parameters on FreeScan under Crank. (Thanks for the tip @sailorbob as I am not very experienced in using FreeScan, but learning fast !). Car fires on 1st crank after standing for a while, but dies immediately and is simply 'dead' on subsequent cranking. I think I read somewhere that the ECU will start picking up fault codes after 8 revolutions under crank, but my current battery is beginning to die away after so much cranking so I am going to try again tomorrow with a fresh battery. (Any previously stored fault codes that may have been on the ECU when she was running ok will have been erased because I had disconnected the battery for a short time before I started getting this problem) By the way, I've now actually removed all the wrappings from my engine bay harness in the course of thoroughly re-checking all wiring, sensors and connectors. Connectors are the 'weather-pack' type and all look clean and sound. Also checked all vac lines for damage and I had already replaced the elbow connectors a while back and all are sound. Beginning to feel like a possible Ignition Module problem to me, but I would have thought I might have seen that coming earlier rather than a straight sudden failure. I still want to believe its something more simple. Any ideas on next steps ?

Thanks @sailorbob and @internets your advice is appreciated, I hope to get back into my garage this weekend and will check out your suggestions and report back.

I am of the same view @Sparky that it will inevitably be something very simple and due to something I did. I started this thread because having retraced my steps and checked and checked so many times now I am getting a bit frustrated (think Basil Fawlty) I only mention other (more esoteric) possibilities because my desperation is forcing me to those tangents, but I am not (yet) considering them as serious causes. I will keep at it and no doubt eventually post back here and confess my stupidity !

Thanks @CarBuff. I've been doing bit more research and exploration this evening :- The Crank Sensor feeds to the Direct Ignition Module and , to quote from Service Notes "pulses are received by the ignition module (located with the ignition coils) which by noting the frequency of the pulses is able to determine engine rpm, and by comparing the time interval between individual pulses can recognise the positional 'sync' pulse. The ignition module uses this information to control ignition timing during engine cranking and also sends reference signals to the ECM.........These signals inform the ECM of engine speed and position,". So from this I now suspect DIM rather than ECM but there could still be some sort of corrupted interaction between the two I guess. I want to think its something simple so will be checking the relevant connectors as you suggest as my next steps. Regards output from Crank Sensor, the service manual merely refers to "voltage pulse" and I was going off some general info I had picked up on-line:- you may well be correct about square wave DC but I dont have an oscilloscope unfortunately so had to rely on a very crude reading off my multimeter. The meter is unlikely of course to be able to handle the pulsed input so I was happy to just get any sort of reading on my lowest a/c setting of the multimeter. Perhaps I do need to look at these signals more closely. I am thrashing around a bit here and by no means an expert so any advice is welcome.

So after doing a few routine bits and pieces on my 1998 GT3 it decided not to fire-up for me. Cranks but no spark, fuel pump heard to run ok so I've ruled out fuel problem for now.. Concerned that I had disturbed something, but I have visually gone over everything and can see nothing obvious. The sudden failure may just be coincidental. No Fault Codes on FreeScan but interestingly no RPM reading during crank so I suspected Crank Sensor. However, after bench testing the sensor, and checking sensor wiring back to the Ignition Module, I can get c. 2 volts a/c at the ignition module, so it must be something between the Ignition Module and the ECM ? When I exposed the ECM Module to see if anything obvious I found one of the mounting bolts to have dislodged itself, leaving the module loose, so wondering whether it has had some vibration damage going on ? Any ideas anyone ?

I am going to start a new thread, as it looks like - in my case - the ECU is not picking up the crank sensor output

Thanks for the question @Sparky - answer is that I did notice that the red insulation boot on the starter motor +ve connection post was falling apart so I disconnected and fitted a nice new silicone one, also the spade connection on the starter motor for the red/white wire that triggers starter to engage was very loose and I had been suffering intermittent failure of the starter to engage, so I disconnected and crimped that up for a better connection. That is about it. I was pleased that the starter was firing up but not so pleased that the engine stopped firing. !

Update on my post above:- I've taken crank sensor to the bench and tested with multimeter (it gives me small a/c current and internal ohms resistance is intact) Also I've tested wiring back to coil assembly and that is ok too (got good earth on the ground wire and the +ve wire is intact and there is no short to earth.). So what the hell ? Why is FreeScan not reading revs when cranking. Also I forgot to say - I have no fault codes showing on FreeScan.

Excuse me jumping-in on this thread but this similar problem has just arisen on my '98 GT3 and so I found your advice above really useful. Genius advice guys- thanks to you I hooked-up Freescan and there is no RPM reading on cranking, so I am guessing crank sensor/wiring as suggested by @Escape I think I must have disturbed something when I had a 'tidy-up' of the wiring when I removed the air intake hose that crosses the flywheel housing right next to the crank sensor (don't fix anything unless its broken, right !). So how do I now test whether I need a new sensor or whether I've 'simply' disturbed the wiring somehow ? (I've already tried disconnect/connect at the sensor and everything is visually clean and sound)

Thanks @agentdr8 - I knew someone would come good on this. You are correct in that it does fit in the wheel arch enclosure. I could not figure why I had one of these , rather than two which I'd have expected if it was in both wheel arches, but - as you've discovered, it is an asymmetric 'tech pack' fitment because it is designed to provide some protection/sound deadening for the sub-woofer. By the way- like @Cdm2018 - I also took the opportunity of having the rear cabin trim removed of beefing-up the sound deadening around the sub itself. Thanks again to all who took the trouble to respond.

Thanks @agentdr8 , you are correct that it is the same type of foam, and I thought it was from the rear wheel arches too, but I cannot orientate it to see where it fits ! Its a very particular shape. I am probably just being thick !- I was never any good at those childhood shape puzzles ! I will keep trying.

Having spent the past few months stripping down the whole rear end, and the cabin, including engine removal for various jobs and up-grades, I am now re-assembling. (EVORA LE 2010) You know what happens sometimes when stripping out - you tell yourself "I will remember where this goes" only to feel utterly foolish at re-assembly by thinking "where the hell did this bit come from" So, help please - LOL anybody recognise where this bit of foam insert is from ? ☹️ ian