2006 Exige S

This is where we proud owners can upload information and pictures of our pride-and-joys (their Exige that is..)
ade
Reactions:
Posts: 7363
Joined: Thu Sep 21, 2006 10:40 am
Location: Essex

Things to try from experience

Take off the undertrays completely and drive it up the road, when you take them off expect them for cracks! That makes them tizz, maybe even take off the rear panel as well?
Do you have a heatshield under the intercooler? Take it off as well
Finally, and the one that took me the longest to suss out, the point where the charge pipes inter cooler SC etc all join, undo them and make sure there is a gap that is supported by the rubber hose, IE doesn't let the two surfaces touch, OMG the noises I got from mine with that

As stated, look carefully at the exhaust, and the manifold in particular, hairline cracks in the manifold can make that kind of noise, never had it on the Exige but I have on other cars....
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Cheers Ade, all undertrays have been off the car all weekend so ruled those out.

No IC/CC heatshield

The CC pipes is a good thing to check though, I'm always careful to leave a gap (enough that I can see idle vacuum sucking the pipe in slightly) to avoid this but it's worth double checking, especially as they had all my hoses off.

Will get backbox ruled in/out tonight - if that doesn't show up anything good the manifold is coming off for a proper inspection.

RRR have been in constant communication today, they're happy enough with the logs to say that it's not about to grenade itself so I should be safe with continued testing and trial/error. They've given me a list of everything in the car that they 'touched' but I've long since ruled all that out.
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

In tonights' episode...

I first off got my donor backbox fitted, looks like an OEM 111R one - shockingly heavy and touched just about every piece of bodywork and heatshielding when in stalled... how standard cars don't rattle themselves to death I don't know...

They look very sporty though... :mrgreen:

Image

Anyway, rattle still persists - so I can cross the backbox off the hit list for now. Obviously the fluff I found in the tailpipe still needs monitoring though, could be early signs of problems - but it's not THIS problem.

I decided to push on and get the manifold off, I'd checked its nut/bolt torque a few days ago but I could at least have a good inspection for any small cracks, however unlikely with it being a month or two old.

What I found gave me a glimmer of hope, even if my ever supportive peers don't think it's likely :lolno:

Image

This is the gasket supplied by 2bular, it's different to the toyota design in that it's a single element perforated crush gasket. Lotus/Toyota use a double layer metal one which luckily I had new in box (bought before I realised 2bular came with one supplied).

It looks like it may have been blowing a bit, the gasket itself is undamaged but the soot marks extend to the edge of the gasket which suggests to me that gas is escaping somewhere. Whether it's rattling its way out at 7500rpm is probably unlikely though, but regardless something that should be fixed.

The 2bular supplied gasket also had a strange attribute in that the bore holes are oversized for the exhaust ports on the engine and the manifold bores.

Image

Image

I did notice this when first fitting the manifold but thought it best to use the 2bular supplied one because... surely it was right for the application. I'm now not too sure.

You can see on the engine side of the gasket that the gasses have been leaking into the little recess machined into the block between the 3rd and 4th chambers.

Image

There's also evidence on the mating surface of the gasses escaping.

One other thing to note, the manifold is held on with 3 bolts and 2 studs/nuts. One of the studs was only hand tight in the engine, though it's nut was on tight. Both studs got removed, cleaned up, loctited and refitted.

Again, all long shots - but a few more niggles out of the way. If nothing else I'm chewing through small problems that may have surfaced in the future anyway!
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Okidoki the manifold gasket didn't cure the issue, getting quite dejected now so took the cam cover off for another look. Still had no idea what I was looking for but decided to see if I could poke something in towards the chain guides to make sure one wasn't loose (it wasn't).

Put the car back together and pretty much gave up for the evening, then a friend messaged me commenting that my sound sounded very familar to that of a car which is failing to activate the high profile cam. If the baby cam is still active at 7000+ rpm then it gets very rattly just because it was never meant for such torture. Obviously I'm hitting the big cam on the road, as the car is pulling well and making good power - but it made me wonder if the high lift cam even activates on a stationary car. Since Saturday all I've done is test the car up on axle stands in neutral, perhaps I've been revving the nuts off of it on the baby cam only... explaining the rattle.

To add further fuel to that theory, @andybond linked me this video which sounds EXACTLY like my issue, and after speaking with the uploader it turned out he had a lift bolt/rocker issue causing his high profile cam to not activate.


So the latest theory is this:

1- The car had/has a legitimate rattle on the road, perhaps I've fixed it already through the various things I've identified/resolved or perhaps it still exists.

2- The 'testing' I've been doing in the garage has been producing a 'false' positive in that I've not been activating high lift cam and therefor I've been experiencing a high rpm rattle that ANY 2zz car would experience if the high lift cam wasn't working.

I further verified this by checking the EMU logs.

On the road, you can see the 'VTEC' activation in red:

Image

On the axle stands, despite similar RPM - no vtec:

Image

So obvious next steps are to get the car back together and do a road test to see if any of my tinkering has actually solved the original fault or not. Perhaps this is all just a desperate clutch at some hope, or maybe I've just wasted 30 hours of garage time for no reason :lol:
User avatar
andybond
Site Admin
Reactions:
Posts: 1213
Joined: Thu Aug 30, 2018 9:16 am
Contact:

Its all a learning curve!
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Looking at the graph posted above has made me wonder how the Lotus ECU handles deactivation of 'lift'. Should it shut down as soon as the throttle is released or should it remain active until RPM falls below the threshold again? As you can see from the sharp fall-off on the graph above, it looks like it shuts off immediately but I'm not sure/convinced the Lotus ECU works in the same way? @matt447 do you have some logs to compare?
User avatar
matt447
Reactions:
Posts: 122
Joined: Mon Apr 13, 2020 7:13 pm

Hi mate - I don't have any logs of this at the moment to compare with you, but I read a thing a while ago when debugging my lift issue (which was down to the bolts disappearing) and I'm fairly certain one of the inputs to the lift equation was a minimum speed... The car needs to be physically moving. You can obviously tell your EMU Black to just use the 2nd cam at stationary if you need to :)
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Cheers Matt, yeah I took a look - turns out I was wrong, it's not minimum speed preventing lift but it's actually the MAP sensor reading. For anything under 50 kpa the high lift cam will not engage.

So when the car is generating no load, ie on axle stands or when cruising in neutral - there's no boost = no VTEC yo.

In short, the following parameters must be met for the EMU to activate high lift:

- 4900rpm
- 50kPa
- Minimum of 50% throttle position sensor
- 0km/h minimum speed (so irrelevant)

If I watch my GoPro footage back of when I last drove the car, it's fairly clear that at load the rattle is inaudible UNTIL I shift into the next gear where you hear a really short/sharp rasp of the rattle on shift (almost as if a syncro is knackered :lol: ). Alternatively if I rev it out and then just release the gas (no gear change) the rattle comes in off-throttle and tails off as the revs drop below 7.5k (such as in the alternator-PoV video)
If my theory about all of this is correct, then that makes sense - as when I shift, I take my foot off the gas and so TPS drops to 0%, lift then disengages and for a short second the low cam comes into play at 7000+ rpm or whatever I shift at. As soon as I shift into gear and get back on the gas, the rattle goes away because I'm now back on the high lift cam...

The EMU has parameters to say "Meet X on the way up the rev range, but allow for an additional Y when coming back down". So what I could do is potentially keep the 50% TPS requirement in place (I guess this helps smooth things out when just cruising at the NSL or whatever rather than the cam jerking in and out) but I could tell it to keep the cam engaged all the way down to 0% TPS when coming down through the range. The 4900rpm requirement would still remain, but under 4900rpm the car doesn't rattle on low lift cam.

I'm trying to find information on how the Lotus ECU works, and whether it's normal for a 2ZZ low lift cam to rattle so much at 7.5k and above. I've had at least two people now (plus a YT video) tell me that my sound is representative of a 2ZZ running without a high lift cam at high RPM so that's supportive of the theory, but it's probably fair to say that RRR (and other EMU vendors) have done a fair few 2ZZ's now on this ECU, and from what I can see from the base map settings the VTEC crossover parameters are fairly standard.... so why hasn't anyone else noticed this if the low cam rattle is normal?!

I'm trying not to get carried away with thinking I've fixed it, but can't test till later today when I can get the car back together. :roll:
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Fonzey wrote: Wed Aug 26, 2020 7:47 am but it's probably fair to say that RRR (and other EMU vendors) have done a fair few 2ZZ's now on this ECU, and from what I can see from the base map settings the VTEC crossover parameters are fairly standard.... so why hasn't anyone else noticed this if the low cam rattle is normal?!
I just downloaded the 2ZZ base maps from ECUMaster for a look.

On the Cable throttle base map, the 50% TPS requirement still exists BUT they allow for 50% less than that on the 'run down' which is exactly what I proposed doing.

On the DBW base map (which my map is based upon) the 50% TPS requirement exists but they only allow for 20% less than that on 'run down'.

So basically for a cable car, VTEC will stay enabled during gear changes at high RPM but on a DBW car, VTEC drops - and I think that's my rattle. Maybe :|
User avatar
Fonzey
Reactions:
Posts: 811
Joined: Tue Nov 27, 2018 12:17 am

Problem Solved :mrgreen: Well, I think so.

Went out for a drive at lunch, rattle still present but as per my recollection of the weekend you couldn't hear it rattle whilst going up the revs, only when decelerating or changing gear.

Checked logs and you can see a VTEC drop out just as MAP and TPS drops for the shift:

Image

I pulled over and got the laptop out, made two changes to the 'deactivation' criteria for VTEC which would essentially ignore TPS and MAP values when coming off-cam and did another pull.

Image

As you can see, MAP and TPS still falls during shift but VTEC critically remains engaged.... and the best part, no sign of any rattle. :clap:

I'm pretty damn chuffed to have come to this conclusion and fix, but obviously I have questions...

1) Is it indeed normal for a 2zz on low-lobe at high RPM? I guess it doesn't really matter in the long run, as it should never normally happen but would still be nice to know.
2) Did RRR forget to configure this, or do they configure all 2ZZ ECU's like this? I'd guess not, as surely somebody else would have complained of rattles by now. Perhaps ECUMaster released a new version of the base map that they used for my car and I'm the first person to notice it? Who knows.
3) How/Why wasn't this noticed on the dyno? Perhaps in a noisy dyno cell with det cans on it's hard to hear, to be fair.
4) Have I actually fixed it, or have I just covered up another problem by configuring VTEC in this way?

Needless to say, I'll do my best to find the answers to that - but for now I'm a happy camper.

Big thanks to @lotuslee and @andybond for the constant flow of suggestions since the weekend, also I've been talking to Jonny @ Performance Autocare who was prepared to shuffle stuff around and have a poke around my car for me at the weekend, he's also been suggesting and recommending stuff at all hours. Great support :thumbup:
Post Reply