Hi winthatt,
The oscilloscope signal seems to be ok from a pattern prospective assuming the VHPD reluctor ring pattern is the same as the VVC one.
I would appreciate a picture of the stock Exige S1 fly wheel reluctor ring if anyone has one? After tripping over my old one several times during its replacement I lost my sense of humour and threw it out.
I don’t believe that the ECU takes the wheel speed sensor into consideration on starting, it provides a standard signal for all sensors which are not expected to provide a valid signal during engine cranking, i.e. speed sensors, O2 sensor etc.
Changing the flywheel is a last resort, a major job, I removed the engine to do the original replacement and it’s in excess of £350 to purchase.
Out of interest, does your rev counter do anything when you crank the engine over? From memory is should do something when cranking, will check a car at work tomorrow.
If it should do, and your doesn’t, it points towards the CPS/trigger ring again.
Hi JDS,
Yes the loss of connectivity is annoying, I even tried it with a NOCO GB50 booster attached to the battery without success.
The fuel pump primes the fuel rail once the ignition is turned on.
A positive voltage is also present at the fuel injectors, a good bright light suggesting a good voltage.
You are correct with the fuse, Fuse box B fuse B4 15 amp, which is working on my Exige.
Coil pack pin Number 2 has 12 volts when the engine ignition is turned on, once again a good bright light suggesting a good voltage.
I include a better picture of the CPS, if it goes in the housing any further it will go past the teeth of the reluctor ring and the plastic housing will be in danger of touching the teeth.
With the ignition turned on the rev counter needle after a short delay dips down below 0 rpm about 5mm hovers and returns back to 0 rpm.
What happens to the rev counter when you crank the engine? Let the rev counter do it’s reset thing and wait until it’s back at zero before cranking. If you’re seeing 190 rpm or so on the scope, you should see the same on the rev counter. Will check tomorrow if that’s the case with an Exige we have at work.
With the CPS, you have a spare to play with. It depends really on where the strongest signal for the magnetic ‘insert correct word here!’ is? At the tip of the sensor probe, or inside the plastic housing where all the windings are?
I would start by plugging a noid light into an injector and cranking to see if there was anything happening. If not, I’d be removing the boss from the sensor, make sure the sensor doesn’t hit the teeth on the flywheel by hand, then get someone to crank the engine over while moving the sensor in and out, while you watch the noid light. If it lights up, you at least know you are on the right path.
At this point you are only trying rule something in or out. It doesn’t have to be the permanent solution if you do get a result.
Good Evening Alec - Fight the good fight 
- sorry to hear 
- Yes of course , ay time . please txt me and we can meet up same place - and sort day & time - Yours Dave
Hi Dave,
Thanks for the moral support and offer to meet up to loan your ECU. I’ll keep in touch.
Not ready to give up yet, but I am running out of ideas. Just one idea left to try later today.
I hope lotus technical support will help, or JDS can shed some light when he takes a look at the Exige at his works.
Sorry, I didn’t get a chance yesterday, but checked today.
Ignition on, let the needles do there reset thing, crank engine with the injectors disconnected and after 2-3 seconds rev counter goes to around the 200 rpm point.
If yours doesn’t do this it’s pointing at CPS/trigger ring to me.
Has the engine ever run with the EP flywheel fitted?
Hi JDS,
Thanks for checking your Exige starting process.
The flywheel is part of the Exedy clutch and flywheel kit, no it’s never been run since it was fitted.
I am resistant to removing the flywheel until it is absolutely proven to be the issue. I don’t want to remove the engine & gearbox again. It wasn’t fun the first time. But I will try another CPS and compare the test results with the other two sensors, clutching at straws.
I’m about to check the reluctor ring position on the flywheel, which is my final check before waiting for Lotus Technical to get back to me.
Failing someone giving me the correct Vpp from the CPS or at the ECU connector I may as my last resort before giving up, consider changing the ECU for an Emerald K6 ECU with wiring loom conversion, as I understand the CPS trigger voltage is adjustable. Confirmation yet to be received.
If this fails it’s going to be spare parts.
Thanks again.
For the 2 minutes it would take to file off the boss on the sensor, refit, check that it doesn’t hit the flywheel and see what happens when you crank it over, I’d giving that a try.
JDS = Voice of experience
Just to make it clear, you’re suggesting I file the boss which incidentally the CPS has a mounting face all around the sensor, so presumably that as well in order to move the sensor further into the bell housing.
If it moves any further part of the metal end of the sensor, which as I understand it is the extension of the magnetic field will move beyond the teeth. I include pictures to illustrate.
Yep, that’s the part. I think we managed to remove the boss part with a file, and carefully mounted the sensor in a lathe , then again used a file and slowly turned the lathe - by hand!!
I’d take a picture, but don’t think it would help too much. As said before it sorted a 4k rev limit issue with an EP flywheel, but haven’t driven it on the road yet, but now revs cleanly to 7ish in the workshop, with no loss of signal on the live data screen.
It doesn’t need to be your permanent solution - ours may not be yet! - but hopefully if it shows an engine speed/injectors/coil working by moving the sensor, then it confirms what the issue is.
OK will give it a go, then take a screen shot with the scope to compare signals.
Actually, thinking about it, have you checked the basics? Not wishing to insult you here!!
Is the rear earth strap attached to the chassis with the spreading washer in the correct position? Have seen a couple that weren’t after engine/gearbox changes, causing poor or non starting.
We also had one that had the normal symptoms of a flat battery, jump pack on, car started. Charged battery, cleaned and tightened terminals, optimate did it’s save, charge, maintain sequence, then it would crank over great, but wouldn’t start until jack pack back on, then away in a couple of turns of the starter. Despite same cranking speeds. New battery, same size and capacity, everything back to working perfectly.
Apologies for the delay in my reply, the battery was getting a little tired, so I charged it overnight.
I found a picture of an Exige owner’s flywheel some time back, can’t remember where but the important bit is that the reluctor ring pattern matches mine, & so does TDC. Guess that I can remove the flywheel off my list of culprits, with great relief.
Tried your CPS suggestion, removed the boss on one side, it’s moved in about 2mm and the air gap is about 0.85mm. Alas although the Vpp from the CPS increased to 6.28Vpp, and to 0.88Vpp at the CPU connector, the engine still does not start.
I note your earth strap comment. No insult taken. Any port in a storm. Whilst removing the engine I found the chassis rear earth point bolt securing the earth straps to be corroded in the reeve nut, it spun the reeve nut whilst attempting to remove it. I had to remove both, replacing them with a bolt and lock nut (half thickness to allow the stepped washer to fit over the top and mate on the chassis).
I have clamped a jump starter cable directly from the battery negative to the rear earth point, it made no difference, so guess the rear earth point is good.
The battery was purchased in September 2021, a Yuasa YBX5063 12V 52Ah 520CCA, a lot bigger in all specifications than the standard fit. It’s been maintained since then by an Oxford Optimate 12v conditioner and checked with a TOPDON BT100 battery tester. The terminals posts are like new.
The battery is at 12.8 volts, the battery earth post is connected directly via a jump cable to the rear earth point, the NOCO 1500A jump starter is connected to the battery as additional support.
According to the Oscilloscope the time for one revolution is 300 mili seconds, which is 200 rpm, a slight improvement from 192 rpm, still no sign of fuel, spark or starting.
No OBD codes recorded live or pending. Still no reply from Lotus technical.
Good news on the earth point.
Still not totally convinced that the flywheel is off the list, but will give it a stay of execution for a while yet!
Are you getting anything on the dash when cranking?
‘The battery is at 12.8 volts, the battery earth post is connected directly via a jump cable to the rear earth point, the NOCO 1500A jump starter is connected to the battery as additional support’ Have you tried the jump cable directly to the gearbox casing and the jump starter to the starter motor, gearbox casing? This rules out the earth strap, chassis, main power feed and other connections.
Are the earth ring terminals connected at the head by the dipstick?
Yes, there is better dashboard response.
Initially, when the ignition was turned on only the tachometer needle would move down past the zero, hover for a second or two and go back to zero. Now when ignition is switched on, both tachometer and speedometer needles go below zero hover for a second or two and return to zero. The tachometer needle moves to 200 rpm when cranking.
Not sure why the better response, so will see what happens at the clocks when cranking without the NOCO, if ok will remove the earth strap and crank. It may give an idea if there’s a battery or earth issue.
I’ll charge both the car battery and the NOCO up overnight and try the NOCO directly on the gearbox and starter motor tomorrow.
Yes both earth ring are connected to the head by the oil dipstick. I have continuity between batteries –ve post and rear earth point, also between batteries –ve post and the head earth rings/head.
I’m not sure where the earth goes once it leaves the battery –ve post, thought it went straight to the rear earth point. The electrical drawings a little vague, is there a front earth point? If so I haven’t found it, not sure where it would be located. The front is too packed to follow the cable with an endoscope.
I’m also tempted to replace the 47K ohm resistor with a new one, with the intention of improving the 0.84v signal at the ECU connector.
The rev counter moving sounds promising.
Have you tried to see if there is now an earth trigger at the coils and injectors under cranking?
The front earth is behind the battery on the passenger side, with a similar set up to the rear, with a rivnut, bolts and spacer set up. They tend to give less issues than the rear, as unless you have lost the foam blocks behind the front top wishbone rear mount, it stays pretty dry and corrosion free.
Absolutely.
Yes tried the Noid light in No 1 fuel injector, nothing. Fuel pump not running during cranking either, guess the relay is still not being energised.
Not seen the foam blocks, have replaced all the wishbone bushes and ball joints. Think I’ll investigate the front earth point. If for no other reason than peace of mind.
The foam blocks should be behind the front top wishbone, rear arm. To stop the road rubbish ending up in the battery/heater box area.
Very weird that you have engine speed on the dash, but no fuel pump, injector feed.
Will have a thinky!
Where are you based, as really intrigued as to a solution!