TURBO CUTS AND ENGINE LIGHT COMES ON

[Pants9210]

Hi, I´m a newbie to site and to the Elan, Ive just bought a 1991 SE with 60K miles which suposedly has an Everest chip, I say supposedly because I have no paperwork to verify this!, the car was owned by a wealthy collector who supposedly upgraded everything, suspension , brakes, wheels and the chip.
The car and turbo seems fine when i finally get it to normal operating temperature which takes a while but on a run the temperature drops down to below the 1/4 mark on the gauge, if i then have a play and floor it the turbo cuts out at about 0.5 bar and the engine check light comes on for ten seconds and goes out, if i then sit in traffic and it warms up to 1/2 and the fans cut in then its fine and i get to 0.9 bar without any probs.
As it takes so long to heat up I wandered if the thermostat could be stuck in the open position and the ECU is preventing the turbo from boosting as a safety measure as i read that if the temperature is not above 50ºc it wont boost past 0.5bar, or someone has taken the stat out!!
Could i be right or could it be a Temp sensor somewhere, I have just ordered the stat and the three temp sensors on the stat housing so at least I know there good
any other suggestions greatly appreciated
thanks Rob

[dapinky]

Hi and welcome to the forum.

Firstly, 1/4 on the temperature guage is 'normal' for Elans - the fans should kick in at about 3/4, and cut out when it drops to half - all figures approximate, and is a frequent worry for people new to the cars!

Secondly, if the boost guage is going up to 0.9bar it indicates that there is indeed a chip fitted - otherwise it should max out at 0.64bar.

I assume that the weather (and therefore air temperature) is quite hot where you are - and this is probably what is causing the issues with the engine light.....

It is a 'common' problem with miss-matched/incomplete/incorrect upgrades to the power of the engine - not a problem with any one thing, but an accumulation of issues - all of which are overcomable.

Basically, the engine is running marginal at high boost, ie, the fuel injectors are only just able to provide sufficient fuel to keep the fuel/air ratio within safe limits to prevent catastrophic engine damage - as soon as the ECU senses that the ratio could go lean, it has a 'fuel-cut' mechanism which drops the whole lot into a safe 'limp' mode for 20-30 seconds.

This point is reached quicker at high temperatures when the air is less dense, so if you are getting it at the point which you thought was 'normal' (which is actually 'hot'), this may help to explain why.

Has the exhaust pipe been changed? The phenomenon usually ocurrs when the engine breathing has been improved (2 1/4" exhaust fitted), a 'chip' has been fitted, or other modifications.

Basically, the wastegate is unable to dump the excess boost quick enough through its 16mm orrifice, and you get 'boost creep' above the limits which the ECU likes - lots of extra power, but unsafe for the engine - so the ECU cuts the fuel for a while.

This can be relieved by porting the wastegate out to 20mm diameter - there are numerous threads on the site about this procedure - most of us have done it at home, but some have had it done at a garage or machine shop.

Once it has been done, it should stop any recurrence.

It is NOT a fault of whoever has done the work so far - some cars suffer, some cope - as I say, it is all very much on the margins of what the car will cope with.

[rip]

Basically, the engine is running marginal at high boost, ie, the fuel injectors are only just able to provide sufficient fuel to keep the fuel/air ratio within safe limits to prevent catastrophic engine damage - as soon as the ECU senses that the ratio could go lean, it has a 'fuel-cut' mechanism which drops the whole lot into a safe 'limp' mode for 20-30 seconds.

This point is reached quicker at high temperatures when the air is less dense, so if you are getting it at the point which you thought was 'normal' (which is actually 'hot'), this may help to explain why.

Are you sure you have that bit the right way around?

The chargecooler works more efficiently when it is cold so you get higher amounts of charge which require more fuel...which is why overboost is more common in winter.
I have a larger exhaust with a standard wastegate. I occasionally hit overboost in winter but I have never done it in the summer when I am little more throttle happy.

The OP mentioned that when the temp is cool the turbo will only boost to 0.5. I believe the ECU does limit boost when the coolant is below a certain temp.
Elanscan will help. It does not just give you fault codes but tells you what the ECU is seeing from all sensors, so you'll see what temperature the ECU believes it is.
Have a read about it on here & if you have someone close by who can hook up theirs then ask a favour. They will probably be keen to help.

[Rambo]

I thought it was as you describe too Rip. About it working more efficiently in cooler weather

[dapinky]

As I was writing it, I was thinking to myself "Is this correct, or arse about face?".....

..... so I put loads of thought into it (I was eating at the time) and decided that cooler air is more dense, so if it was hot, there would be less of it and it would all go wrong.....

so it appears that I got it the wrong way round on that bit

Okay, to clarify, the rest of the post is correct - it is hitting fuel-cut due to getting to the limits that the ECU will cope with - and this could be caused by something really simple like a "wastegate wiggle" to free off a stuck mechanism, leading to overboost.

It *should* be less likely to occurr when it's warm weather - so that could indicate a defective CTS (Coolant Temperature Sensor) which is fooling the ECU into thinking that it is receiving cooler air than it actually is...

Rob, where are you based?

[HJ2]

Don't you mean MAT sensor?

Anyway: check both and measure temperatue on the coolant hoses to see if the thermostat opens ok.
Wastegate wiggle is always a perfect troubleshooting start.
Also: check that the spark plug gap is 0.8 mm NOT 1.1 mm.

[Pants9210]

As I was writing it, I was thinking to myself "Is this correct, or arse about face?".....

..... so I put loads of thought into it (I was eating at the time) and decided that cooler air is more dense, so if it was hot, there would be less of it and it would all go wrong.....

so it appears that I got it the wrong way round on that bit

Okay, to clarify, the rest of the post is correct - it is hitting fuel-cut due to getting to the limits that the ECU will cope with - and this could be caused by something really simple like a "wastegate wiggle" to free off a stuck mechanism, leading to overboost.

It *should* be less likely to occurr when it's warm weather - so that could indicate a defective CTS (Coolant Temperature Sensor) which is fooling the ECU into thinking that it is receiving cooler air than it actually is...

Rob, where are you based?

Hi Dave, I´m on the Costa Brava, Spain.
I forgot to mention that when I start her up all is good, choke is good but after a couple of miles when the choke cuts off and I stop at traffic lights as I depress the clutch the revs drop right off and it stalls, it starts up again fine but can do this 2 or 3 times until it gets warm enough

Can someone tell me what a "wastegate wiggle" is and do you do it alone or with the wife????
Regards
Rob

[GeoffSmith]

http://wikilec.com/view/Releasing_a_sticky_wastegate

[dapinky]

Hi Rob,

I assumed that you may still be in Spain as the only Google entry I found with your email address was the For sale advert for your 1972 Mercury.....

..... What you really need is someone local to you with Elanscan......

....and the knowledge of what it all means.....

....Smiffy (but he is still in the UK until September)

[Pants9210]

http://wikilec.com/view/Releasing_a_sticky_wastegate

Great, thanks for the link,
Ill change the stat and all the sensors first, that way at least I can rule them out for any future problems.
I have also stopped using the battery cut off switch which had been installed as I read in the Lotus Service Manual that the ECU has the ability to learn but if you disconnect the battery it looses its memory! or doesnt it matter?

[Pants9210]

Hi Rob,

I assumed that you may still be in Spain as the only Google entry I found with your email address was the For sale advert for your 1972 Mercury.....

..... What you really need is someone local to you with Elanscan......

....and the knowledge of what it all means.....

....Smiffy (but he is still in the UK until September)

You assumed correctly I live near Girona and from what I can tell there are only 4 o 5 Elan M100 in Spain and none near me so the possibility of borrowing an "Elanoscano" here is going to be virtually zero, ill bridge the ALDL plug and see what code it gives me.
Thanks again
Rob

[dapinky]

You assumed correctly I live near Girona and from what I can tell there are only 4 o 5 Elan M100 in Spain and none near me so the possibility of borrowing an "Elanoscano" here is going to be virtually zero.....

Ah, but if Geoff is driving down to his 'Winter Palace' he is the man who understands elanscan (and builds/supplies the leads) - but he isn't going to be travelling for a few weeks - hopefully you will be sorted before then, but if not, it may be an option (I'll volunteer him for anything!).

[Pants9210]

You assumed correctly I live near Girona and from what I can tell there are only 4 o 5 Elan M100 in Spain and none near me so the possibility of borrowing an "Elanoscano" here is going to be virtually zero.....

Ah, but if Geoff is driving down to his 'Winter Palace' he is the man who understands elanscan (and builds/supplies the leads) - but he isn't going to be travelling for a few weeks - hopefully you will be sorted before then, but if not, it may be an option (I'll volunteer him for anything!).

By the sounds of things i´m going to need the elanscan lead anyway (thinking of the future) so ill have to contact him and acquire one along with the software.
Thanks again.

Ps How do I put a picture of my car as an avatar??

[GeoffSmith]

By the sounds of things i´m going to need the elanscan lead anyway (thinking of the future) so ill have to contact him and acquire one along with the software.
Thanks again.

Posted or hand delivered?

Ps How do I put a picture of my car as an avatar??

User Control Panel | Profile | Edit avatar | Choose File | OFAH.jpg

[Rambo]

Can someone tell me what a "wastegate wiggle" is and do you do it alone or with the wife????
Regards
Rob

Basically, if you can find your wife's G spot you'll have absolutely no problems with the wastegate wiggle

[HJ2]

Why just the wife?
I can do this blind

[Pants9210]

Hi Rob,

I assumed that you may still be in Spain as the only Google entry I found with your email address was the For sale advert for your 1972 Mercury.....

..... What you really need is someone local to you with Elanscan......

....and the knowledge of what it all means.....

....Smiffy (but he is still in the UK until September)

You assumed correctly I live near Girona and from what I can tell there are only 4 o 5 Elan M100 in Spain and none near me so the possibility of borrowing an "Elanoscano" here is going to be virtually zero, ill bridge the ALDL plug and see what code it gives me.
Thanks again
Rob

Took the car for a spin upto the foot hills of the Pirineas (eat your heart out TopGear!!!) ESL came on (temporarily) whilst boosting, went home and bridged the ALDL and got a code 31 ( boost control system fault ) great, so I now know I have a fault and I know what its called but.........anybody any the wiser or is it a case of the wiggle the wastegate and see ????
Rob

[GeoffSmith]

Overboost and fuel cutoff Rob. Most likely the wastegate is sticking. Does it have a larger diameter exhaust?

PS I drove back from Moraira via Vielha in March... but it was in the Golf.

PPS Didn't you like the avatar I put up for you?

[Pants9210]

Overboost and fuel cutoff Rob. Most likely the wastegate is sticking. Does it have a larger diameter exhaust?

PS I drove back from Moraira via Vielha in March... but it was in the Golf.

PPS Didn't you like the avatar I put up for you?

yes its got a 2 1/2 inch all S/Steel all the way through, it pops and bangs everytime i take my foot off or drop down a gear is that normal? ( hope so as it sounds great) oh and the avatar was great in the eighties!!!

Ive got a ongoing 91 Golf GTI 8V project but sort of lost interest since I met the Elan
Rob

[GeoffSmith]

2½" exhaust is probably the problem then Rob. The stock wastegate is not up to controlling the boost, so you will need to port the wastegate. Search the main site of check the Wiki...
http://wikilec.com/view/Porting_the_wastegate

PS Pops and bangs are usual but it might be worth checking you base timing.

PPS My Elan was a replacement for my '84 Scirroco GTi.

PPPS The Golf is an '09 GTD with knackered ABS and currently on the third replacement to try and get it through the MoT (due 1st April)... If only everything in life was as reliable as my Lotus.