2007 Lotus 2-Eleven

Wonderful! Best of luck at blyton! Can’t wait to see this at Spa!

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What a superb set of images!


Looks fantastic and agree, the ride height makes the front wheels look lost.

Blyton Park

Blyton is my regular season opener now. Close to home, usually pretty inexpensive so no real heartache if I have to call it a day early, and nice familiar place to benchmark upgrades and test reliability.

Was attending with Brother in Law (Clio) and a friend (MG Midget with A-Series Turbo) with a few tag alongers coming along to spectate, so would be a social one too.

The morning was fantastic, different passenger hopped in for each session and the car was very quickly feeling familiar (and fast!).

The first session was very slippy, bone dry but very cold and the tyres took AGES to get up to temp. Validated by my new TPMS sensors. Once they did and pressures stabilised, the car came to life. Even with passengers in the car it was feeling on its toes, and had bags of traction. Still braking far too early, though.

Between sessions I was hiding in the trailer, desperately trying to warm up and checking the logs for any mapping tweaks that I’d need.

The mapping seemed good, as expected. Probably a tiny bit on the rich side if chasing ultimate performance, but happy to have a safety margin.

I was seeing some knock events each time the VVTLI engaged or disengaged, so put that down to valvetrain noise. I had similar noise events on the Exige but I’d configured my thresholds to be a tiny bit above it, and on the 2-Eleven it’s JUST breaching those thresholds, so slight difference of engine bay acoustics probably all it was. I can tweak the threshold to avoid this in future.

I went into it in detail on my Exige thread, but the 2ZZ in SC format is a bugger for phantom knock. It’s very difficult to tune reliable thresholds for it because the engine is just naturally noisy on the knock frequency it would make noise on. I’ve not seen a single map from a professional tuner that has attempted to remedy this, and have just left knock control either disabled entirely - or setup with an incorrect frequency. Even Lotus struggled with it, and there’s a Lotus document somewhere advising race teams to remove their knock sensor, wrap it in foam and tie it to the bulkhead somewhere…

Anyway, I’ve had a go - and I can sleep at night knowing I’ve got some knock detection/protection, but the downside is that I occasionally have to chase these phantoms.

Example here of two events, and two ‘nearly’ events.

Purple line is observed noise, green line is the threshold, brown line is VTEC engagement. You see it’s JUST touching my threshold, so triggering the knock alarm, but not actually exceeding it enough to trigger the knock protection such as pulling timing or adding fuel.

Anyway, kept on lapping - kept on enjoying it and getting quicker throughout the morning.

My intercom was disappointing. It worked fine in the first session for passenger #1, but then the passenger #2 could no longer hear the audio from my mic. I could hear the audio from my mic (it plays back to you as you speak so you know it’s working) and I could hear the audio from their mic, so it could just be a dodgy wire in their headset… or the intercom itself has broken already. Either way, annoying. Binned it off for the rest of the day.

Regular engine bay checks during the morning passed scrutiny, no leaks, weeps or any problems I could find.

Tyres started retaining a bit of temp between sessions, but had to keep the breaks short to avoid losing all my hard earned grip.

(thanks Simon for the photos)

I had an odd sudden power cut on a sharp left hander late morning. I suspected fuel surge, but I still had a decent amount of fuel left. Later found it was my DIY TC kicking in a bit too aggressively. I wound my knob back to the half way setting for the rest of the day and had no such issues.

Before we knew it, it was lunch time. Passengers all had lives to be getting on with so I looked forward to some solo laps after lunch, and really pushing on. Car felt like it had a PB lap in it, easily.

Losing the best part of 100kg is significant for any car, but in this it’s mind bending. Immediately after going out the car felt totally different. Brakes felt better, turn in felt better, mid corner grip and traction felt better…everything, except… it was slower?

It was hard to pinpoint at first… the car didn’t feel broken, wasn’t lumpy or misfiring… but it just lacked some zing in the high RPM ranges. The little shift lights progressed through at their usual romp until the final three which seemed to take an age. Hmmm.

I finished the session and eagerly checked my logs. I had made a map tweak over lunch time, just tidying up a little bit of fuelling and a DBW voltage tweak… but nothing that should have caused this.

Sure enough, I wasn’t making the expected levels of boost.

Normally I have a fairly steady level of manifold pressure going up to the redline.

In my ‘road mode’ which I used exclusively at Blyton, this should be around 140kpa (40 + atmosphere) so around 6psi of boost.

This is what started happening over lunch:

Made 140kpa initially, then it just tapers right down to below 120kpa at the red line, so making half the boost it should be making.

I work in IT, rule number #1 is just to reverse the last thing you did… which was the map change I made over lunch, but I immediately found a problem in the engine bay and got fixated on that all day instead.

Under vacuum whilst idling I had an intercooler hose collapsing on itself. It should have had a metal sleeve inside it to prevent this, so I whipped it off and found the problem.

A-Ha, smoking gun. Sorted. This had rotated to cause the collapse at idle, and would have been restricting boost at WOT. Love an easy fix.

…except it didn’t really fix anything. I could improve the collapsing hose but not perfect it. A bit more sleeving, or a solid 90 with straight joiners will both fix this in the long term, but the best I could do was just reduce the size of the dimple under idle.

It was a long way from blocking itself off (car would have stalled if it was) and under positive pressure it expanded back out absolutely fine… so this couldn’t be the cause of my bleeding boost, could it?

I spent all afternoon faffing around with boost pipes, checking for leaks and restrictions… couldn’t find anything amiss other than this joiner.

The car still drove pretty well, obviously it was slower- but it didn’t feel broken. I weighed up the idea of just driving it anyway, but I’d never forgive myself if I went on to cause terminal damage by ignoring a clear issue, so I called it a day. I never did do a solo session at proper speed, but it was a shakedown run - so no need to sulk.

At time of typing I’m a little confused, but I have a couple of theories:

  1. Perhaps my lunchtime map tweak did something unexpected. I’ve retrospectively looked at logs, and my throttle traces are all what I’d expect to see. I am however seeing some inconsistencies in throttle pedal sensor voltage. Sometimes 100% throttle is 3.5v, sometimes it’s 3.7v. My tweak at lunch time was to change this so that I was always seeing 100% pedal, and the logs suggest I achieved that… but I shouldn’t have needed to do it, and perhaps something else is going on.

  2. There’s a mechanical/physical restriction somewhere. I’ve had all the intake off and can’t find anything amiss other than this collapsing elbow. I will of course fix/replace that, but as I said - I can’t see how this is causing a restriction when the system is positively charged. Only other thing I can think of is an exhaust issue, maybe the cat has collapsed. I’ve known this once before on a friends Exige and it happened during a dyno session. Manifold pressure went down and power stopped climbing at around 6k RPM. I struggled to understand how a restriction in the exhaust side could reduce manifold pressure rather than increase it, and I still struggle with that now… but I’ve seen it happen, so I know it’s possible.

  3. SC belt slipping. Having an aftermarket pulley on a non-AC car means there aren’t many documented sources for correct belt size. I made a best guess based on info I could find, and I went for the larger side of tolerance. Perhaps I should try the next size down.

My IT brain can’t rule out #1. I’ve checked the logs, my very last WOT pull before lunch made full boost. I tweaked map over lunch. First WOT pull of the afternoon and it was losing boost. That’s too black and white to ignore.

Really wish I reverted it in the afternoon, but discovering that boost pipe just distracted me. Oh, and I ran over my own USB cable so I couldn’t upload a map tweak anyway :rofl:

Anyway, I didn’t sulk too much. I’ll fix the boost pipe elbow, probably take the cat off and give it a shake, and will revert my map tweak. Probably all one step at a time so I know what the fix was, if I fix it.

I do appreciate any suggestions though.

This ended up being my last few decent laps of the day, just before lunch.

Still need to work on external mic positioning, not happy with how much wind noise I’m picking up. Working on it!

Enjoyable day despite the afternoon. Brother in Law took me out in his Clio (one of the new ones with flappy paddles) and it was ace, really didn’t expect it to do what it did. Very capable car, I’ve never tracked a FWD car myself but this made me want to.


100% agree with you here - revert the map to rule out the last change. However the trace of the manifold pressure could suggest otherwise. Its doesnt appear spikey in its nature, more a gradual fade then off the cliff. I would expect the nature of the variable voltage to cause flutuations not a gradual then sudden manfold pressure which is crucially ( in my mind ) towards the higher end of the RPM scale where I would expect a belt to slip the most due to rotational speed.

I am rather dissapointed I didnt log my belt slipping or we could have compared.

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Yeah the logs let me see the following:

TPS Voltage
TPS % (a product of the voltage depending on how it’s scaled, so 3.5V = 100% TPS, for example)
DBW % (what actually happens at the TB)

So I can see clearly that my DBW was still opening to the correct level after lunch, regardless of my changes to the TPS scaling. If my map tweak did cause an issue, it’s some sort of bug/glitch that the logs aren’t displaying properly. If the logs are to be believed (see no reason why they shouldn’t be), then I was getting 60% TB before lunch, and was getting 60% TB after lunch, (My road map is 60% DBW to cap power).

Perhaps in hindsight I should have given race mode a quick pull too, to see if that changed anything.

All stuff I can test in the near future… once the gritters have moved on :upside_down_face:

Mini update

Took the catalyst off to see if anything was amiss in there, looks good to me.

Bit of a relieve, because these HJS cats are not cheap… especially when they’ve been ceramic coated three times over!

In the meantime Pro Alloy sent me some bits of pipe for me to play with.

Needed a bit of trimming, but I’ve now got hose joiners that are practically solid.

Done an idle test, and no more collapsing. I’d love to go do a road test to see if I’m now boosting properly, but … well, snow.

I’ve got an 1873mm belt sat waiting to go, it’s 7mm shorter than the current one but I’m reluctant to stick it up despite the downtime because I want to know what the specific issue is/was.

My test plan is to therefor take the car out as it is, do some pulls and see if I’m boosting properly again. If not, I’ll have the laptop with me and can revert my ECU config whilst on the test run and try again. If that still doesn’t work, I can come home and swap the belt.

If the belt swap doesn’t sort it either… well, I’ve not thought that far ahead yet. One way or another, I will eventually swap the belts - because the current one seems on the slacker side of tolerance anyway.

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Good luck with it and very nice work matching your crocs to the car :grin:

Sexy and Sporty you mean?

Yup, that’s what I meant to say :grin:

I think I just threw up a little…

Good idea using some Alu elbow to minimise the crushing under vac

Boost problem solved, it’s both a relief and an annoyance to report that it was my lunch time map/DBW tweak that fecked something up.

I just took the car out, did some pulls and noted the exact same boost ramp down towards the limiter. Pulled over and reran the DBW wizard, this spends about 5 mins modulating the DBW automatically, measuring response times, voltages, etc - and then it sets all of your DBW parameters for you.

I went back out, and was hitting full boost every time.

I’m annoyed at myself for not reverting at Blyton, but I was so distracted by the boost hoses I left my logical troubleshooting at the door. I’m also annoyed that I cannot explain why the changes I made, caused a problem. I’m staring at the two pulls in the logs now and DBW activity is identical, so whatever I did - it’s not something I can see in the logs.

Oh well, lesson learned. The DBW config created by the wizard is not perfect (I’m only getting 97-98% TPS when the throttle is pinned). This is what I tried to fix on the day, but I’ll just live with that. My Dyno science showed that there’s zero power loss by being a few % short of full throttle… it just annoys me when I look at graphs.

Think I’ll still put the shorter SC belt on, this one is a bit on the slack side. But happy days, onto the next trackday with not much of a job list.


Hoping to get some road mileage in now that it’s hopefully stopped snowing, so thought I’d retrieve my road wheels/tyres out of the trailer and get them cleaned up.

The Gtechniq C5 on the trackday wheels (shadow chrome ones) is still holding up brilliantly, they clean up a treat. The Satin black wheels which came on the 2-Eleven less so.

Got them best I could, then slapped some poorboys sealant on to give me half a chance for the rest of the year.

Track wheels can wait patiently for a few weeks…

Popped out for a chilly blast up to the North Yorks owners club meet, nothing too much to report - car did what it was supposed to do.

I did test a new external mic position though, and I think I’ve finally got something that will stop clipping and collecting wind noise on track.

Back in the lab, I finally figured out what my DBW mistake was at Blyton. As a reminder, I was seeing a max of 97% TPS in the logs from the morning session so I tweaked the voltage down a bit so that 100% throttle = the voltage I was seeing in the logs.

After that, the car was dropping boost at high RPM and was generally more sluggish. My mistake was that I changed the voltage for the TB opening potentiometer, not the pedal one… this explains why the pedal and TB were both still reporting 100% to the ECU, but I’d altered the definition of what 100% is. Idiot.

Oh well, glad I’ve fixed it - and it’s allowed me to change the proper value and I’m now seeing 100% TPS in the logs again, so all has ended well.