Problem still exists!!

[TrevorB]

Those of you who have been following the trial and tribulations that Merlot has been having over the past 12 months either on
this forum or the Facebook LEC group will know that there have been some issues.

Those issues have consisted of: Overboost, not firing on all cylinders and annoyingly an intermittent problem where the engine at
4000rpm stutters and won't allow any further boost or acceleration.

It is the latter that I want to focus on as despite ALL the work that has been done, which I will list shortly, still frustratingly
persists.

The following work has been done, either by myself and Tony but mainly Maidstone Sports Cars.

New Turbo boost solenoid
New Coil Packs
New HT leads
New Spark plugs
New Fuel Injectors
Refurbished Turbo (at a cost!)
New Vehicle Speed Sensor

I finally got Merlot back from MSC after they had it for a few months to do the Turbo work but the problem still came back and they took
it back because of the error code 24 which was still showing hence the VSS being changed.

However, this week after a short while of sitting in garage I took Merlot out for a drive in the sunshine only for this problem to reoccur.
What is so annoying about this problem is the fact that the car runs perfectly and I can go through the gears past the 4000rpm mark and
everything is perfect. It is when the engine has warmed up the problem starts. When it reaches 4000rpm the acceleration stutters and
doesn't want to go any further so I have to come off the accelerator. There is no CEL indication and problem then remains so I don't push
the car anymore. Another frustrating issue is that MSC have not been able to recreate the problem.

I have contacted MSC again and informed them of the reoccurring issue. They are as much confused about this and do not know what's going
on. Merlot will be going back as it's due an MOT and service in a couple of months.

My plea to ALL you experts out there is: WHAT IS THE PROBLEM?

I know MSC would be grateful of some help.

Thank you VERY MUCH.

Merlot and Trevor

[HJ2]

Since the problem only occures when warm, i think it is sensor- or closed loop-related.
Can you do an elanscan of the entire warm-up transcient upto the overboost problem?

How is the CTS by the way?

[RonR]

Hi Trevor,

Sounds like what you need is something to plug into the ECU to record every journey in Elanscan format - I could rustle something up for you to borrow in a few days. It needs an Ignition controlled power source which can be taken from the unused AC switch position (assuming you don't actually have AirCon).
You'd just need to make a note of date & time when the problem occured and you'd have an Elanscan file contaning the problem for the gurus to analyse.

[TrevorB]

Since the problem only occures when warm, i think it is sensor- or closed loop-related.
Can you do an elanscan of the entire warm-up transcient upto the overboost problem?

How is the CTS by the way?

Thank you Henk. Merlot doesn't have closed loop configured. I will mention the CTS to MSC.

Hi Trevor,

Sounds like what you need is something to plug into the ECU to record every journey in Elanscan format - I could rustle something up for you to borrow in a few days. It needs an Ignition controlled power source which can be taken from the unused AC switch position (assuming you don't actually have AirCon).
You'd just need to make a note of date & time when the problem occured and you'd have an Elanscan file contaning the problem for the gurus to analyse.

Thank you Ron. I know MSC have an Elan Scan and I did discuss with them about plugging it in whilst out testing the car. This will have to be
another option when the car goes back in. Thanks for your offer though. Maybe before it goes back we can arrange a meet up and you can see for yourself
what the issue is? That's assuming it happens of course!


I appreciate any other wise words from the members of the Forum.



Trevor

[Tuga2112]

Trevor.

as you not being the "hands on" type, and relying on a garage.

have you considered the possibilty your garage is just not skilled enough to handle an ELan, and taking it to a different place would work ?

i believe ive seen in the past you refering the garage was a "specialist" but i would look for a different one regarless.

ive taken my elan to a lotus specialist to do the front suspension alignment..... they didnt have shims to replace the ones in my car, and they just kept forcing the wheel into position with the wrong shim size because they didnt have the tools (or in this case the consumable) to do the job propely.

after witnessing that from a self claimed specialist (who has a lot of elise business ) i dont believe the writting at the door anymore, even if there are 5 lotuses at the door.

next time i need geometry alighment i wont be going to that place for sure.

just my 2 cents.

[Fredjohn]

Trevor, hope you can get it sorted, but I'm really surprised MSC hadn't done an Elanscan as a matter of course.

Apart from the CTS, what about the FPR(fuel pressure regulator)?
My guess as it is heat induced, it's a fuel rather than electric issue.

[alan e]

I think i have a Elanscan cable in the garage if you have a laptop i can post it to you if that helps.

[Simon_P]

Difficult without a scan.

Do you have any additional electrical items. switches, chargers, USB cables... anything that was not part of the car when new?

[Rambo]

Just a thought.....what exhaust do you have on Merlot Trevor? Or have you perhaps changed it recently?

It seems odd you don't get a CEL despite the error code.

[peteoddcar]

Trevor
What a b!

Some more questions - sorry not answers

Elan scan might be the most efficient way to solve this

Are there currently any fault codes stored? ( CEL paper clip check )

It sounds to me like it going into limp home but with no CEL that’s weird.

when did problem this start, gradual sudden ? Was it after some work was done ?

Before the problem starts is everything normal boosting / reving / pulling ?

How many miles approx before it starts ?

Your answers
Might give us a few more clues for armchair diagnostics

[TrevorB]

So today Merlot came out of the garage with the plan to do a 'paper clip' test and see what codes were showing.
I was surprised that Code 24 came up as MSC had told me that they had changed the VSS module. So I'm assuming that the code
was still in the ECU. I disconnected the battery to clear the code and did the test again. Code 24 still showing?!

Am I correct in disconnecting battery to clear codes?

Now the frustrating part of this fault. Took Merlot for and went through the 4000rpm level in all the gears and even
after a good 45 minutes with the engine good and warm the problem DID NOT occur In fact everything went perfect.
I was out for an hour and covered 30 miles.

So this is good example of how intermittent the issue is and why MSC are baffled and why it's so frustrating.

When I got home tried the 'paper clip' test again but just couldn't get it to work this time, aargh Gave up in the end. I will try again sometime in the week.

Thanks for your responses, now to answer them:

Trevor, hope you can get it sorted, but I'm really surprised MSC hadn't done an Elanscan as a matter of course.

Apart from the CTS, what about the FPR(fuel pressure regulator)?
My guess as it is heat induced, it's a fuel rather than electric issue.

MSC tell me they have done an Elanscan. I will inform them of your suggestion.

I think i have a Elanscan cable in the garage if you have a laptop i can post it to you if that helps.

Alan, I do have a cable but don't have Elanscan downloaded on my laptop! Not sure I would know what to do if I did

Difficult without a scan.

Do you have any additional electrical items. switches, chargers, USB cables... anything that was not part of the car when new?

Simon, nothing additional added since I've had the car.

Just a thought.....what exhaust do you have on Merlot Trevor? Or have you perhaps changed it recently?

It seems odd you don't get a CEL despite the error code.

Mark, Piper 2.5" which has been on the car since 2012. MSC did check the exhaust and manifold for any cracks.

Trevor
What a b!

Some more questions - sorry not answers

Elan scan might be the most efficient way to solve this
Agree

Are there currently any fault codes stored? ( CEL paper clip check )
See above

It sounds to me like it going into limp home but with no CEL that’s weird.
Once I come off the accelerator everything is ok.

when did problem this start, gradual sudden ? Was it after some work was done ?
I can't actually remember now as it's been going on for a while now.

Before the problem starts is everything normal boosting / reving / pulling ?
Yes, car runs perfectly.

How many miles approx before it starts ?
On the previous occasion I had only been out for 20 minutes before it started, probably only 10 miles.

Your answers
Might give us a few more clues for armchair diagnostics

Trevor

[Simon_P]

Are the ground for the coil pack and the plenum properly secured?

[TrevorB]

Are the ground for the coil pack and the plenum properly secured?

I can check the coil pack ground, but where is the plenum ground?

Cheers

Trevor

[FunElan]

This sounds similar to an issue that I had, except my car is closed loop. It would stutter like this, only on boost, when warm. A CEL would appear maybe 2 or 3 boost runs later, but the code that would trigger was for the O2 sensor. Maybe you’re not getting a code because it’s open loop.

My issue turned out to be a vacuum leak for the secondary throttle solenoid. Basically it would run lean after a few uses of boost which then in turn opens the secondary throttle flaps.

I’d bet it’s something like this or the CTS. ElanScan will help a ton.

[peteoddcar]

“Once I come off the accelerator everything is ok.”
Do you mean by that it corrects itself and drives and boosts again ?
Another question
Have you tried to stop the car key the engine on and off and try again ?
Does it still have the problem if you do that ?

[TrevorB]

This sounds similar to an issue that I had, except my car is closed loop. It would stutter like this, only on boost, when warm. A CEL would appear maybe 2 or 3 boost runs later, but the code that would trigger was for the O2 sensor. Maybe you’re not getting a code because it’s open loop.

My issue turned out to be a vacuum leak for the secondary throttle solenoid. Basically it would run lean after a few uses of boost which then in turn opens the secondary throttle flaps.

I’d bet it’s something like this or the CTS. ElanScan will help a ton.

Thanks, all good information for MSC to consider.

“Once I come off the accelerator everything is ok.”
Do you mean by that it corrects itself and drives and boosts again ?

Yes, that's correct, but once I reach 4000rpm it happens again.


Another question
Have you tried to stop the car key the engine on and off and try again ?
Does it still have the problem if you do that ?

Haven't tried that but will consider next time it happens.



Trevor

[chrism]

Just a thought - could it be that your bigger 2.5" exhaust bore might be causing this?
Is it over-boost? (I ask naively... ) Wasn't the original pipe restricted to curb over-boost? Or has your larger pipe been working okay in the past?

[TrevorB]

Ron Russell very kindly came over today with his 'magic box of tricks' called a 'logger'. He has developed this to pick up the data from ECU and then
transfer it into a file to be used on Elan Scan. Merlot was to be the guinea pig to trial it out.
So it was plugged into the ALDL and indications showed that it was communicating to the ECU, so a good start.
The ultimate test would be to go for a drive and record what happens.

After yesterdays drive when the problem didn't occur I was hoping that the fault will happen and get recorded so we can finally find out what is going on.

It didn't take too long into the drive for the problem to happen, yes, it came back! I was glad it did in some respects but then again was not surprised.
As I've said previously, it is so intermittent.

Ron might like to explain in his words what the problem feels like as he is one of few to experience it as it happens.

Once we got home the 'logger' had done it's thing and on the card was the information. Ron copied it to his laptop and presented it onto Elan Scan.
I'm definitely no expert but Ron went through it.

Ultimately it showed that things appeared to be running ok but there was the one fault recorded which was the VSS.

We would like some further expert opinions on what is showing so I've attached the Zip file.

2210010-85630.zip

Thanks Ron Russell for taking the time to come over and do this testing.



Trevor

[dapinky]

Trevor,

The VSS is a £20 part at SJ's (there is another thread about them at the moment!)..... but it is a simple Vauxhall part. Changing it is an instrument panel out job as it is held with a small screw and the 3 legs are soldered in.... so with labour costs, it probably isn't worth trying to save a fiver with a Vauxhall part.....

.... that said, what *may* be worth a thought is to borrow a complete instrument panel to fit temporarily to see if it cures the problem, and prevents the fault code.....

I'd just do a temporary fit of another one (as long as the bits plug in it doesn't have to be fully fitted for the test) and see what happens.

I don't know if a spare instrument panel is something which MSC would have lying around, but it is a Vauxhall Astra F/Vectra A/Calibra/Cavalier part.

(If they don't have one laying around, but it is something you fancy having a go at, then give me a shout before buying one on eBay - I can send my nurse out into the garage to see what she can find, and post it to you)

[RonR]

It was good to catch up with you Trevor, and to have a short outing in Merlot - even if it was just a diagnostic run.

The logger was originally designed by Matthias Here, I just made a few changes to enable the logging whenever the engine runs.

To describe the problem - the car behaved perfectly normally for the first 13 minutes or so, thereafter every time Trevor tried to accelerate through 4000 RPM the car would 'Hunt' 3-4 times per second. When he lifted off everything went back to normal.

We had a quick look at the Elanscan file, and the first thing we noticed was the VSS error flag was on right from start-up. The second thing was the 'Speed' graph read very low (between 0 and 32mph) for the first 540 seconds, then went missing entirely! Odd considering we were on the A2 doing 60-70mph (Honest!) for some of the time. All other graphs seemed OK.

So I have a couple of questions for the Gurus:
1. Would a duff VSS cause these symptoms?
2. MSC have stated that they replaced the VSS, so could there be a dodgy connection or a wiring fault between VSS and ECU?

Any further help from experienced ElanScanners would be welcome!

Cheers,
Ron