Turbo Creep.....

[vi11ain]

I've just had a Peco exhaust fitted, which sounds great and was an even better price.

However, I'm now suffering from "turbo creep" as it seems to be described here. Basically, as the revs climb, the turbo boost no longer stops at about 0.65 bar boost, but is able to climb up to about 1 bar. Fortunately the engine management cuts the fuel if it gets that high, so at least I know the ECU and the manifold pressure sensor are working ok!

I've managed to take off the turbo heat sheild and the wastegate capsule to check that the wastegate is moving freely, which is apparrently very free - no seized up wastegate then.

Finally, I have yet to check the wastegate capsule operation and the piping between that and the Boost Control Frequency Valve - not to mention the BCFV itself....

Does anyone have any pointers as to the easiest/best way to check these items? I've also read on here that some of you have enlarged the wastegate port itself - what's the likelihood that I'm going to have to do that, and is it a difficult job? Anyone got any pictures?

I'm quite happy with the power at the standard 0.65 bar boost level - I just want to be able to limit the boost.... 0.75 would be plenty, as I'd rather the engine etc lasts a good long time!

I'm hoping to make the time this weekend to try out ElanScan to see exactly what's going on, but in the meantime, any advice would be most appreciated!

Many thanks

Ben

[Doug]

there's a thread on porting the wastegate with pics--since you asked.

there's no easy, definite procedure to rid the creep that everyone follows though

[Enright]

Yes, you're not going to be able to get away with this issue. If you've got boost creep, then it's here to stay unless you either re-squish the exhaust (a bit self-defeating) or port the wastegate.

Other than siezed fasteners, the worst of which are where your new exhaust bolts to the pre-cat, and which have just been loosened anyway, it's not too bad a job. But you should still allow yourself a good long weekend, prepare for busted bolts which may need to be drilled out, and stock up on change for the swear box.

I've done it. Read from my post on 20/4 16.24 on this thread onwards.

And yes, there are pics to help too.

[vi11ain]

Ah! Well, at least I have a fairly definitive answer there!

Fortunately for me I don't have A/C on my car, so there aren't too many extra parts in the way, although I've already found it to be a bit on the cramped side in that area!

You ground your wastegate out to 21mm - I take it that you're able to keep the boost down to 0.65 bar now.... what size exhaust are you using? - mine is 2.25"

Good work on putting the pics up - that looks like it was quite a task!

Cheers

Ben

[Enright]

Ah yes, cramped is not the word. Stock up on plasters for the skinned knuckles too!

My exhaust is also 2 1/4".

If I put the standard ECU on, yes it does boost to 0.65 bar.
I use an ESM chip, so it should boost to 0.9.
It doesn't, but that's not the fault of the chip.
And most importantly, it doesn't creep.

[Monty]

1st thing i`d do would be to fit ESM everest chip the fuel cut has been raised slightly and some of the guys who fitted an aftermarket exhaust have got away with not hitting the fuel cut. its worth a try before u start ripping out the turbo

[GeoffSmith]

its worth a try before u start ripping out the turbo

It certainly is and it helped me. Although I haven't got rid of the fuel cutoff problem competely, it only occurs under extreme conditions where conditions allow - i.e. longer periods of acceleration on the motorway.

Ben, did you get the Peco with the LEC discount for £250?

Geoff

[vi11ain]

Yes, I did get the Peco exhaust for £250. Quite pleased with it, as it looks and sounds very nice - the only downside is the boost creep.

The chip upgrade is a possibility, but I seem to be able to get to the fuel cut off quite quickly once I get over about 5500 rpm, so I'm not totally convinced that it'd completely cure my problem. I'd also rather keep the max boost down to nearer the standard level, as I'd prefer the engine to last rather than have the ultimate performance.

The part I find most disappointing is that Lotus obviously went to some lengths to design the systems to limit the boost by putting on the BCFV, and added the fuel cut in case that failed, but then just put a massive dent into the exhaust (which probably spoils the fuel efficiency) when they found that the wastegate port was too small. Sounds like a bit of a bodge, to be honest!

I asked the bloke at SJ Sportscars for some advice, but he just said "put an original exhaust back on it" in a rather disparaging manner. I'd rather fix the original design flaw myself.

The only downside to porting the wastgate (apart from the obvious disassembly issues!) that I can see at the moment is that the BCFV is probably going to have to work at a higher duty cycle to maintain the lower boost values, as there will be a larger area for the exhaust gas to act upon, thus lowering the natural opening boost pressure (the manuals state that it naturally opens at 0.45 bar, IIRC). Is the BCFV able to cope with this, or does the situation I'm describing not actually occur in practice?

I didn't manage to find the time to have a go with ElanScan over the weekend, but I think I may be able to try this Saturday....

I've got a garage that I can leave the car in for weeks if necessary, so I'm going to have a go at removing the turbo over the next free weekend (whenever that might be!) and it shouldn't matter if the job over runs a bit...

ATB

Ben

[Monty]

You need to listen to the advice of the members, the BSV is controlled by the ECM and Alans Chip is no bodge. The engine can cope with more than 1lb of boost so running the car at 0.9lb will not hurt u`r engine.

Taking the turbo u risk snapping bolts and possible u`r car could be of the road for a while. So 1st i`d fit a chip.

If u didn`t want more boost why did u go for a bigger bore exhaust

Maybe in u`r case SJ`s are correct

[Elanlover]

For what its worth I say get the chip. The car will handle the boost easily and you'll love the performance gain. Its got enough safety features built in that you won't need to worry about the engine exploding. If you look at the recommended upgrades the chip AND the exhaust are right up there for performance gains. In fact, the chip comes first followed by the exhaust in my opinion.

Might need some new brakes though............

[GeoffSmith]

Ben,

Glad you benefitted from the LEC/Peco deal.

I understand your nervousness but tend to agree with the above - try an Everest first. I had a nasty experience with my S2 when the wastegate stuck - it was only because I experienced massive overboost without fuel cutoff that I found out that I had a MBC and Superchip "upgrade" fitted. Alan (ESM) was kind enough to check out the code and found that the chip merely inhibited the fuel cutoff safety feature - all for ~£300. Needless to say, they ended up in the bin (except Dico had the MBC but that's another story) and I went back to a stock PROM. By the time I suffered boost creep and fuel cutoff regularly after fitting the Peco, I was convinced that Alan really does know what he is doing and would not jeapordise our, or his own, cars. I therefore tried the Everest and gained the benefits of having more power available if I choose to use it. The chip does NOT give shed loads of massive boost (such as I was getting with the stuck wastegate) but is very controllable by the throttle position - if you don't want full boost, you don't push your foot to the floor, it's as simple as that.

Hope this has been of use to you - personally I would recommend trying the Everest before attacking the wastegate. Elanlover does make a good point about the brakes though.

Geoff

[GeoffSmith]

With reference to the above, it was interesting that Matt Neal (BTCC) has a Supersh1t logo on the front of his helmet.

[GeoffSmith]

The part I find most disappointing is that Lotus obviously went to some lengths to design the systems to limit the boost by putting on the BCFV, and added the fuel cut in case that failed, but then just put a massive dent into the exhaust (which probably spoils the fuel efficiency) when they found that the wastegate port was too small. Sounds like a bit of a bodge, to be honest!

I think you might be a bit harsh there! Whatever the reason for the squish, it is not very long compared to the length of the exhaust and I don't believe it adds a significant restriction. Don't forget that the stock exhaust is 2" whereas the Peco is 2¼" which does make a significant difference in the differential pressure that the wastegate has to control.

[Enright]

No, I have to agree with Vi11ian on that score.
To remove the possiblity of boost creep by twatting the exhaust rather than specifying a larger wastegate does seem a bit Heath Robinson to me too.
It may not be so bad for us 15 years later, but imagine all the dis-satisfied customers who tried uprating their exhausts, only to turn the car into a dog and cost them a shedload more money.
I bet there were some red faces back in the day. In fact I heard that quite a few main dealers refused to fit sports exhausts due to all the customer complaints they received.
After all, if you spent many hundreds on a new exhaust and it made the performance worse, you'd naturally blame the component that you'd just fitted wouldn't you? And it would take a lot of explaining to calm someone down from that position.

[vi11ain]

You need to listen to the advice of the members, the BSV is controlled by the ECM and Alans Chip is no bodge. The engine can cope with more than 1lb of boost so running the car at 0.9lb will not hurt u'r engine.

Taking the turbo u risk snapping bolts and possible u'r car could be of the road for a while. So 1st i'd fit a chip.

If u didn't want more boost why did u go for a bigger bore exhaust

Maybe in u'r case SJ's are correct

I think you misunderstood me a little there - I wasn't referring to the chip as a bodge - just the engineering done by Lotus with the exhaust/turbo installation. The chip does sound like a good quality upgrade and I'm kind of tempted, but I'd like the wastegate to be able to cope with the extra gas flow with my slightly modified setup first.

I had two reasons for changing the exhaust - firstly I was informed by the garage at the last service that the rear silencer box and the middle section would need replacing (that would make the second replacement of each of those since I bought the car) and secondly I wanted it to sound just a little more like a sports car, to be honest! I was quoted £350 for the standard - rust prone - parts, so £250 for the Peco sounded like a great deal.

I'm not scared of taking the turbo off - I just wanted to be sure that was the correct next step to take to properly cure the creep. I'm not going to be able to start on this for at least a couple of weeks anyway, so I'm going to give the relevant nuts and bolts a few soaks with WD40 before then. I don't drive to work and I can happily cope without the car for a couple of weeks or more.

Hell, I might even buy one of the chips - any of you tried the Kilimanjaro, or is it much better to go for the Everest?

Thanks for all your advice!

Ben

[vi11ain]

For what its worth I say get the chip. The car will handle the boost easily and you'll love the performance gain. Its got enough safety features built in that you won't need to worry about the engine exploding. If you look at the recommended upgrades the chip AND the exhaust are right up there for performance gains. In fact, the chip comes first followed by the exhaust in my opinion.

Might need some new brakes though............

I know what you mean about the brakes! I have fitted the EBC discs and greenstuff pads, which made quite an improvement, but they still could be a bit sharper, if you ask me!

Single pot calipers on sliders aren't the best arrangement, by any means!

Cheers

Ben

[Elanlover]

vi11ain, with regard to your various comments on bost, exhausts and the turbo I think you (and all of us) should keep in mind that cars aren't built (at least not Lotus cars) but slapping components together that "may" work together. They pick specific parts to tune the car to a specific performance range. At the time the Elan was built the Esprit was the big horse in the stall and I'm sure they weren't interested in having the 2 cars compete with each other. The Elan delivers the performance it was designed to yeild with the stock parts chosen.

I doubt Lotus engineered the car with all possible future enhancements in mind 15 years down the road. Sure, we can complain that adding all this stuff sometimes has the opposite effect (worse performance) but I'm sure a Lotus designer would simpley say that if we want to start changng parts on a car where all the parts are designed to work together, you're on your own pal.

That why people like Alan, Brian and others have done the thinking to deliver overall performance increases designed to work specifically with what the Elan has onboard already - not just slapping in an exhaust or super chip.

I understand your intentions when it comes to exploring options, doing it different ways, seeing what the turbo and wastegate can do with the exhaust, etc. But, for what its worth, it was so much easier for me (and others) to go with the flow and the sensational knowledge of those here who have done EXTENSIVE research into what can be done safely with the car. These aren't weekend grease monkeys either. These guys know their stuff. This is evidenced by the overwhelming acceptance of the Everest chip, the procedure of porting the wastegate with a large bore exhaust added, better brakes, etc.

Hey, its your car and you should do what you are comfortable with. But, you simply can't go wrong with what is a proven enhancement to the car as is documented by so many people here. I LOVE the chip. Others have it with a new exhaust, have ported the wastegate and report great results. Its a proven and tested methodology for better performance. I doubt you'd be able to coax any more performance than has been doen with this work. And, it works.

Just my 2 cents (or pence) worth.

[vi11ain]

Elanlover

Yes, with regard to the obvious pool of knowledge and talent available here, I'm in complete agreement with you. I've read a lot of the postings here with much interest before I said anything - most people seem to have been there well before me, that's for sure.

I used to work as an engineer in the car industry back in the mid 1990's - with the engineers at Lotus, Ford, Vauxhall, as well as Triumph motorcycles. It certainly had it's interesting moments (the Lotus factory was my favourite - I badly wanted an Elan back then, or the as-yet-unlaunched Elise!), but I wouldn't go thinking that the car industry is even close to the Holy Grail of engineering excellence! I was frequently shocked by the "knife and fork" nature of a lot of the design work, not to mention the terrible quality control (although I have to say that Lotus weren't nearly so bad as the mass manufacturers there).

With their limited budget Lotus had to raid parts from wherever they could find them, so it comes as no great surprise to find the odd compromise, and I think they made an excellent job if you ask me.

My comment about the standard exhaust/BCFV/wastegate combination being a bit of a bodge may sound harsh, but to my mind it seems very much like they went to the effort of designing what is a fairly complex system to prevent overboost, only to find that the wastegate was too small, so they then had to squish the exhaust to keep the boost under control. Again, this wouldn't surprise me greatly, as they'd probably spent too much money on the engineering already, so the exhaust squeeze would be a nice cheap way out (much cheaper than retooling the turbo casting anyway!).

I'm going to carry out some further tests on my BCFV hoses to make sure I haven't got any leaks there, as the boost "creep" that I'm experiencing is fairly fast, which is why I have my doubts about the replacement chip being able to prevent overboost and fuel cut-off for me at the moment. The everest chip increases the cut off from 0.92 to 0.98bar, which is only an increase of 0.06 bar or less than 1psi, which I think my car is quite easily capable of at the moment

It may turn out that the Peco exhaust has uncovered a problem with my BCFV or it's hoses, in which case the boost creep should be much less when I've got them sorted! In any case, the max boost of the turbo certainly isn't under the control of the ECU at the moment - something I fully intend to rectify once I get the time!

I hope I haven't upset or annoyed anyone with my opinions - I've owned my Elan for over seven years now and it's far and away the best car I've ever had, in every department (except interior storage space!).

Thanks again with all your help and advice

Ben

[Doug]

creep should only really happen in higher RPM range under loads at WOT.

it sounds like if you are getting "faster creep" then it may be the wastegate is not fully opening or the pressure solenoid(whatever it's called) that moves the rod may be a bit duff ??

it could maybe be the BSV functioning but that would be third in line with the 2 above being more likley . . .

[Elanlover]

I hope I haven't upset or annoyed anyone with my opinions...........

Not a bit I think