2006 Exige S

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Fonzey
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Yes I'm not sure what's going on with the graph for the afr (or the low down torque/bhp for that matter) but the wideband I've got built into the car now was logging realtime and they used that for tuning a anyway. I think the external clip on sensor for the Dyno software was just lobbed somewhere near the back of the car and otherwise ignored.

The wideband logs looks much less weird!

As for pulleys it's fairly well established that the mp62 can go as low as 3.0/2.9" then you're well into diminishing returns with regards to heat. OEM is something in the region of 3.25" I believe, so I still have gains to make from it before it's in the territory of short lived pub figures. Obviously a non chargecooled car will struggle earlier in this department.

Needless to say I'll be watching IATs like a hawk.
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Fonzey
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@Type116 I had 10mins so found one of the dyno runs in the logs. I don't think this is *the* run from the graph, but hard to tell as they hadn't set the clock on the datalogger until Thursday so timestamps are all over the shop :lol:

Image

In any case, seems to be robustly around the low 12.X - seems about in line with what I'd expect on a SC'd car.
ade
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Type116 wrote: Tue Aug 18, 2020 3:20 pm the fuelling looks a bit... all over, did they not give you a separate fuelling graph which displays the AFR ?

a smaller pulley will generate more heat and intake temps will skyrocket, you will have a gain to start with but wont last as soon as it gets 60+ IAT the ECU will probably start to pull timing leaving you with less than you have now. (we suffer the same situation on the VX220 circa 300bhp on 2.9" pulley is great, for 2 laps and then your sat at about 280bhp if not less.)

my advice would be to monitor the IAT see what you are getting now and try find out what IAT the ECU retards the ignition at, then you can look at using a smaller pulley.... or do what i did and fit water injection.
The intake temps don't go higher if you are running a charge cooler, I ran mine on track on really hot days, it never went more the 20 degrees over ambient, the regular intercooler however even with extra pipes is a different story.....
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andybond
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ade wrote: Tue Aug 18, 2020 8:56 pm
Type116 wrote: Tue Aug 18, 2020 3:20 pm the fuelling looks a bit... all over, did they not give you a separate fuelling graph which displays the AFR ?

a smaller pulley will generate more heat and intake temps will skyrocket, you will have a gain to start with but wont last as soon as it gets 60+ IAT the ECU will probably start to pull timing leaving you with less than you have now. (we suffer the same situation on the VX220 circa 300bhp on 2.9" pulley is great, for 2 laps and then your sat at about 280bhp if not less.)

my advice would be to monitor the IAT see what you are getting now and try find out what IAT the ECU retards the ignition at, then you can look at using a smaller pulley.... or do what i did and fit water injection.
The intake temps don't go higher if you are running a charge cooler, I ran mine on track on really hot days, it never went more the 20 degrees over ambient, the regular intercooler however even with extra pipes is a different story.....
I too run a smaller pulley and dont see temps skyrocket with a CC.
Type116
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Fonzey wrote: Tue Aug 18, 2020 7:37 pm @Type116 I had 10mins so found one of the dyno runs in the logs. I don't think this is *the* run from the graph, but hard to tell as they hadn't set the clock on the datalogger until Thursday so timestamps are all over the shop :lol:

Image

In any case, seems to be robustly around the low 12.X - seems about in line with what I'd expect on a SC'd car.
very stable on the graph the fuelling, they definitely didnt put their lambda in correctly then.
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Fonzey
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I've had an infuriating week away from the car, chomping to give it a run out! Finally got round to that this morning and unfortunately it's left me with a few gremlins to work through with the help of RRR where appropriate.

One of the issues is overshadowing the rest, and is the only one that's really worrying me. At around 7.5k RPM I gain a nasty mechanical rattle which seems to come in regardless of gear (incl. neutral) and it comes in at 7.5k RPM and if I let the revs drop it fades again once below 7.5k rpm again.

It initially manifested itself as a quick/sharp sound when gearshifting at high RPM so I intially suspected syncro or something similar, but I've since done some testing and it comes in regardless of shifting. If I hold the revs at 7.5k+ the rattle sustains, but this isn't something I want to do a lot of until I track it down.

We all know what these cars are like, so I'm still a bit hopeful that it's something really silly rattling such as a heatshield or bracket, but the fact it's coming in so consistently at a certain RPM range is niggling me into thinking it's something more serious. I've ruled out the obvious stuff by going out for a drive without the undertray or diffuser attached and it still occurs. I've gone round the exhaust with a rubber mallet and there's nothing obvious there.

A few days prior to the mapping session I had the aux belt off to sort out that supercharger/alternator bracket and though tracing the source of a sound can be difficult in these cars, it does sound like it's potentially coming from the 'accessory end' of the engine, so perhaps that's a place to start. I did stick my gopro in the sidepod to see if I could see any obvious movement/shuddering of the alternator when hitting that 7.5k mark, and though I can hear the rattle on this footage - the belt/pulley doesn't look to be the cause.



Luckily(?) it's something I can replicate in neutral with the car stationary so I should be able to arrange for some stationary testing if I can rope the missus into it for an hour or so whilst I roll around on the floor with a stethoscope. As ever I welcome any suggestions of places to start!
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Fonzey
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Afternoon troubleshooting has ruled out the accessories and supercharger. I got the car up to temp on axle stands then had the missus rev it while I stuck my head in various places to see if I could pinpoint it (which I couldn't).

I then took the aux belt off and revved it up quickly and the rattle persisted so I guess I can stop wasting energy on the alternator/SC bracket etc.

When poking around the car, the rattle was inaudible from underneath the car - the other engine/exhaust noise just dominates down there - but up top you could still hear it, but it's by far the most noticeable from within the cabin.

Not really sure where to go next, missus said it sounds like it could be the exhaust but it's just impossible to pinpoint the sound down near the tailpipe. I'll go round all the brackets/hangers anyway and make sure everything is tight up.
The Hornet
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Its not the mounting from the new ECU is it ? Just thinking what would have changed on the car - and that is louder in the cabin ?
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Fonzey
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The Hornet wrote: Sat Aug 22, 2020 4:28 pm Its not the mounting from the new ECU is it ? Just thinking what would have changed on the car - and that is louder in the cabin ?
Unfortunately not, I started with anything that RRR are likely to have interfered with including undertray, bootlid and of course the ECU itself.

Tonight I've done the following:


Isolated accessories and SC
Removed cam cover for another inspection
Taken backbox and cat off for inspection

As part of that I've found two candidates but they seem very unlikely:

1) catch can bracket was just the wrong side of hand tight to the head fixings. Nipped these up but seems highly unlikely to be the cause as the catchcans are fairly rammed in anyway and suspended by the hoses etc.

2) maybe a little more feasible, I found the base of my catch can is just touching the top of the solid breather hose from the driver corner of the cam cover. Witness marks show they have indeed been making contact, probably since I raised my engine on its mounts to create clearance for the 2bular system the other month. I'll refit this tomorrow slightly higher to rule it out.

I've had a couple of separate suggestions that an exhaust leak could make a sound like this, such as a crack somewhere. Seems unlikely based on the age of the system but I can't rule anything out. I'll refit the exhaust tomorrow and pay close attention to listening out for leaks at low rpm.
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Fonzey
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Catch can and header tank proved to be dead ends, and the backbox and cat section didn't yield any nasty rattles once off the car.

I did however bolt back on the old ECU just for an experiment, an experiment that has a huge asterisk over it as the original O2 sensors are no longer connected so the car ran pretty rough and very rich under control of the Lotus ECU. I did however manage to just about rev it out to 7.5k and I couldn't hear the rattle... but then the car wasn't enjoying this experiment much so I didn't want to spend too long doing it, due to the running characteristics I'm sure any harmonics would have been different... so I have to call that test inconclusive - but still is something I've fed back to RRR.

When I had all but given up on finding something, I happened to be laid on the floor at the back of the car and noticed a very fine 'fluff' collecting inside the tailpipe. Almost a softer version of wire wool but very small quantities.

Image

Could this be early signs that the backbox is falling apart inside? I still feel it's unlikely, maybe it is an issue - but not the same issue I'm battling with. Either way I've had a kind offer of a donor box to rule it out, so hopefully get that bolted on early this week to prove it one way or the other.
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