Fitting the cat isn’t going to solve it, plenty of people run without cats (including me) and have no issue.
The good news is that you’re running out of things to check! Other things that spring to mind are fuel pump, injectors and IACV, but they would be unlikley to cause a very specific rev limit at varying loads. ECU? Again, unlikley, but could rule it out…
Cleaning the CPS made no difference, will have a peak at the flywheel later, although from the service history it had a new clutch 1000 miles ago, and no evidence of a new flywheel being fitted so I expect to see the standard one there.
I’m wondering if it could be fuel related as this issue only seems to take place during WOT…
I think this a key thing to clarify before you look at the next steps; does it only happen only under WOT or does it happen at 50% throttle too?
I would have thought that smaller throttle openings wouldn’t have given the same specific rev limit. However, if it’s WOT then you definitely need to check the rail pressure to identify if it’s pump or FPR.
Sorry, let me clarify. The 5.5k limit once initiated happens at all positions of throttle.
What im talking about is before the 5.5k limit is imposed the car will at some point and usually in 3rd gear and so far only ever during WOT impose a limit at 6.2k ish. After this the limit is then 5.5k
I’m yet to find the 5.5k limit come in without revving past 5.5k to just over 6 first.
So what I’m wondering is do I actually have an issue where the car is doing something wrong at 6.2k?
Checked the VSS again, as I wanted to wire brush the spigot on the hub. Noticed a small mark on it…(I’d have changed the sensor by now but it’s seized in the ally block)
Ah right - gotcha.
It doesn’t sound like the speed sensor, since that is just one limit.
If you’ve got no restrictions on the intake, none in the exhaust, have tried plugs, leads and coil, checked the crank signal, then I’d probably be checking fuel system next. Might be worth dropping a question in the WhatsApp group and asking Jerome as he’s done it recently.
Had a peek at the flywheel, looks like a standard unit?
Thanks for the tip on the access hatch - unusually simple 
Sorry if you said before that the rev limit only kicks in after you have been at high revs, I missed that, is it always or sometimes?
It could be spark or fuel. As you have changed the plugs leads and coils it’s not them.
It could be a clogged fuel filter, worth changing anyway. Faulty injector (check the look clean, they can be tested), or even the fuel pressure regulator or fuel pump.
Can you feel a misfire at higher rpm? If you hold 6500-7000 rpm does it stumble?
The 5.5k limit only occurs after the car has hit a slightly higher rev limit at around 6.2k, this isn’t a misfire it’s like a rev limiter. I’d say this happens 50% of the time I drive the car past 6000rpm.
I’ll have a go at holding high rpm and see if I notice any sort of misfire. I’m yet to notice one.
Fuel filter is new but I’ll do it again now the cars been used.
When you say clean the injectors do you mean remove them entirely?
Thanks again for the suggestions!
I’ve never had to test injectors. I think the Exige has different injectors to a normal Elise, white ? Yes pull them out, check the nozzle looks clean. I’d carefully put each one on a glass bottle arranged so they can be seen, then crank the engine. It will not start but you should see a nice spray pattern from each injector. There are companies who can test and clean injectors.
If the injectors are good I’d check the fuel rail pressure, I’m not sure how you would do that whilst driving and doing 6k rpm.
Elise parts sell injectors, pressure test kits and fuel pumps. Changing the pump is a tank out job. If you have fitted a new filter I doubt it’s that.
I once spent months trying to fix a misfire on an s1 Elise. Turned out the relay unit was pulling the ecu power too early on shutdown, leaving the idle air value in unexpected places.
Took your advice and the guidance given from Jerome was to test fuel pressure at the inlet to the fuel pump.
I got 3.9bar, which Jerome believes to be too low (6-7bar is what he has).
Has anyone else done this test to see what pressure they have?
Fuel pressure after the pump should be around 3-3.5 bar. 6-7 is waay too high.
I’m not sure of the fuel pump outlet pressure, but I’d imagine it is above 3 bar since that’s what the regulator can supply.
How did you check pressure, and did you think about checking the flow? Might be a better indication, as the pressure is just restriction to flow, and if the injectors aren’t firing, it might be building up pressure, but not providing enough flow when driving. I think Jerome might have done that too.
I just connected to the input on the fuel filter feed.
Jerome had the same fault as me but only 2 bar which is an issue so I’m inclined to say the feed at my fuel filter being just under 4 bar is enough so will see what’s coming out the other end of the fuel rail, and then test injectors.
Whether injectors are firing or not, the regulator should keep it sensible, that’s what it does, unless very broken. Unless you fancy driving at plus 7k with fuel pressure gear attached, it’s always something I’ve shied away from.
Double the pressure is terrifying. Could get very exciting!
Sounds like where we would test it. 2 bar isn’t great, but 7 bar sounds beyond the limits of the pump/regulator. I’m not sure I’d want to put 7 bar through the OE plastic hose or even if a standard pump could support that.
Regulator should be open below the set pressure, and then start to close off above the set pressure. The pump doesn’t produce pressure, just flow; the injectors firing robs some of that flow, and so if the pump is struggling, it would be possible to have ok pressure against a dead-head but reduced pressure at higher rpm, which the regulator can’t do anything about since it’s fully open. I’m not saying this is definitely the case in this instance, just pointing out that fuel flow is the important thing here.
If testing injectors, just send them off for a clean/test unless you have access to a proper rig. I’m with JDS here on testing pressure at full load unless it uses proper connections, the last thing you want to do is set fire to the car!
Thanks guy’s so I’ll park the idea that my fuel pump needs replacing for now.
Will testing fuel pressure after the FPR rule anything out?
I’m happy to send injectors away but Is there any logic for how a clogged injector would cause the fault I’m experiencing?
Fuel pressure after the FPR should be 0.
I really don’t think that that is your issue, as you have you look to have to have good pressure. Unless you are using the same gauge as Jerome??
Testing/cleaning your injectors is no bad start but not sure that it’a a fix.
The Exige ECU is really grumpy. It picks up on loads of little things, to stop the back of the car setting itself on fire. There was a big download to help with misfires.
5500 was a rev limit imposed to save ‘thermal events’
So this weekend I bit the bullet and dropped my tank. After lots of horror stories of tanks being riddled with rust or the remains of very old fuel I thought given the history of this car (laid up for almost 10yrs!) there was a good chance the tank would need checking.
The job wasn’t half as bad as I was expecting.
And the tank was in far better condition than expected, I’ve not flushed it out properly yet but this was all I’ve been met with so far.
Plan will be to check if this tank can be refurbished and then refit with a new pump.
I admire your determination!
I had a misfire on an s1 Elise, took me about 2 years to find it. Trivial in the end. It was not the same as your issue.
Thanks I had to do something, this has also allowed me to check the loom for any obvious damage…none found.
Perhaps a new fuel pump will solve the issue but I’m not getting too enthusiastic about it…
