free hit
counters
Stumbling engine - Troubles again :( - Page 3 - Engine/Ancilliaries - The Lotus Forums Jump to content
Sign in to follow this  
bzguy

Stumbling engine - Troubles again :(

Recommended Posts

Guess what ... a tiny pin of the ecu module (the esc part, that small piece covered with gel) was cracked, seemed to make contact and then not, as I can imagine those bumpy Belgian roads : no contact = CEL on, otherwise no roblem ...

In fact, when installing my #3 chip, I had to lift the esc part a bit to be able to install the new chip ; by that, that small pin leg must have cracked ... in fact, very hard to see !!!

So, "reinforced" the pin's leg by soldering with a smd soldeirng iron, put it all back together and went for a rtest ride ; idle was a bit high, so set it to 1200 rpm with Freescan ; and yes, NO PROBLEMS at all !

Great to hear you cracked it.

Which pin was it? Although it's unlikely my problem is the same broken pin (not ruling it out though), because my symptoms are so similar, it seems reasonable to assume a related cause. If I could find out what that pin connects to, it might help me to track down my problem too, e.g. if it's an I/O pin, it's probably connected to one of the sensors, so I could check the circuit from sensor to ECU.

Phil


More speed, less haste

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Great to hear that you solved it. I was folloeing the thread for a while, on e never knows hat may come up one day.

BUT as granny always said : The devil is in the details...... :P


Olaf S400 project www.esprits4.de

__________________________________

shapeimage_1.jpg

Share this post


Link to post
Share on other sites

it was the pin on the lower right side of the pic underneath (lower right side of the esc module) :

Chip_install_20.jpg

//edit : ecm module is right above the right side rear wheel, so quite sensible for bumps etc, so loose contact may result in CEL apparently ..

Edited by bzguy

- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites
it was the pin on the lower right side of the pic underneath (lower right side of the esc module) :

Chip_install_20.jpg

//edit : ecm module is right above the right side rear wheel, so quite sensible for bumps etc, so loose contact may result in CEL apparently ..

Thanks. That's actually the ground pin of the memcal eprom. If that was disconnected, you'd effectively have no memcal and the ECU would switch to limp home mode (hence the CEL). If the disconnection was intermittent, the system would switch back to normal mode once the connection was restored. You'd perceive this as a stumble. I'd be surprised if that's the cause of my problem.

I've been in discussion with CarlC, who has experienced similar symptoms twice, and they turned out to be related to leaky MAP sensor tubing. There's also a good description of a problem which also sounds like mine on the esprit factfile under Engine Stalling. When the throttle is released, the ECU turns off fuel and ignition for economy, the engine being turned by the car's momentum. When the clutch is depressed, this drive to the engine is removed and it runs down. As the revs approach idle rate, the ECU is supposed to restore fuel/ignition to prevent any further drop. Under some circumstances, the SE/S4 memcal apparently does not do this in time, so the revs drop well below idling speed or even stall.

My current thinking is that the two problems combine to form the symptoms. I.e. 1) faulty MAP sensing, particularly in throttle-off mode where the engine is pulling air through the system rather than air being pushed into it. 2) memcal settings which make the ECU unable to handle the dodgy readings, preventing the restoration of fuel/ignition in time. In my case, a third factor also comes in, which is that my gearshift is currently dreadful, so the time taken to change down is much longer than normal, providing a wider opportunity for the problem to manifest itself.

My plan is to check the MAP sensor tubing and the sensor itself. Then, regardless of whether or not the problem is fixed, upgrade the memcal to at least the latest S4s spec, which it is claimed has dealt with the problem. I'll also be sorting out my gearshift issues asap.

I'll post my results (good or bad) once I get round to doing this, so that anyone else experiencing this can benefit.

Phil

Edited by NoneShallPass

More speed, less haste

Share this post


Link to post
Share on other sites
Thanks. That's actually the ground pin of the memcal eprom. If that was disconnected, you'd effectively have no memcal and the ECU would switch to limp home mode (hence the CEL). If the disconnection was intermittent, the system would switch back to normal mode once the connection was restored. You'd perceive this as a stumble. I'd be surprised if that's the cause of my problem.

Same opinion, making/breaking contact must have caused that stumbling ...

Installed monday morning (" 1 am, haha) the original chip, went for a 50 km ride to bed in the chip, all fine ...

Monday afternoon, installed the nr 3 chip, went for a new 50 km ride to bed in the chip, had to restart twice (engine stalling when stopping the car), once CEL on, which was gone after restart.

This morning, drove very early to work, car stumbled a bit (twice) first 35 km's , had to restart twice to get rid of the CEL and stumble, went fine for the last 15 km's ...

I hope this is normal behaviour of installing and letting bed in the nr 3 chip ? Strange I didn't have the same problem when installing the original chip, bedding is was much quicker ...

Can someone confirm/deny this ?

Definitely, the loose contact is gone now !

//edit : maybe Marcus can confirm/deny this behaviour of nr 3 chip ?

Anyhow, in case this behaviour persists, I'll do a Freescan log ...

Edited by bzguy

- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

I've cotacted Marcus to get some more info on what to expect from learning mode, and in fact the car's behaviour was NOT normal at all !

Checked it, indeed a loose contact again (very tiny contacts, about 1 squere mm ! )

Soldeered it, should be ok, installed it back, checked with freescan, no errors ...

Now I know at least what it was definitely ...

Big thanx to Marcus for the great info ! And off course to you all <_<

BTW : if someone should have a spare memcal, please contact me :)


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Hello Hans,

Its always good to help out <_<

One more error-free Esprit on the road now, just great :P

Have fun and enjoy !!!!

Marcus

I've cotacted Marcus to get some more info on what to expect from learning mode, and in fact the car's behaviour was NOT normal at all !

Checked it, indeed a loose contact again (very tiny contacts, about 1 squere mm ! )

Soldeered it, should be ok, installed it back, checked with freescan, no errors ...

Now I know at least what it was definitely ...

Big thanx to Marcus for the great info ! And off course to you all :)

BTW : if someone should have a spare memcal, please contact me :P

Edited by Paula&Marcus

Marcus

Share this post


Link to post
Share on other sites
Hello Hans,

Its always good to help out :)

One more error-free Esprit on the road now, just great :)

Have fun and enjoy !!!!

Marcus

I'll keep my fingers crossed :)

BTW Marcus, I'll order some stuff next month, clear lenses etc ... I'll keep you informed ...


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Bad, bad, bad news :coffee:

Troubles again ... Started last week ...

To definitively avoid bad contacts in the memcal in the hope to solve the problems that re-occur,I've found a spare memcal with standard chip still in place @ espritisism ...

Received it today (thanx Malcolm for the fast and excellent service !), installed it, let engine run idle for 5 mins, took it for a gentle drive to work (3 km's small roads, 35 km highway @ 120 km/h, 2 km's small roads again).

Seemed to be fine, until halfway : rom needle boucning around (without actually making high rev's), no power at all, engine stalkling when idle, sometimes CEL on ...

Got to work, disconnected battery, reconnected battery, let it idle again, seems to be fine now, could'nt take it for a ride yet but will try tomorrow with a freescan ...

Any ideas what can be going on ? Maybe dirty fuel filter, dirty air filter, some sensor (O2 ?) ... ?

Sorry to bother again guys :crybaby: ...

BTW : tried to adjust the IAC setting screw, seems to be stuck :S ...


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Hi Hans,

Sorry to hear your still having problems after all this effort. Please can you post a new Freescan log file recorded during the time the issues are occuring.

I've re-read the thread in case I've missed something but Basically your first log file shows some wild rpm reading at idle and this was recorded during the time you were having problems with your car. The second log file was again short but recorded during the time the car was idleing correctly. All values in the latest Freescan log appear to show normal readings and the car was behaving as expected at idle.

I would be very interested to see a new log file now with the problems occuring as with any luck this will confirm that there appears to be an issue with something like the engine speed sensor (rpm). As the guys in the know here already pointed out this was showing values of 10k+ rpm and later on in the first log file the rpm value goes to 65545 or something similar which is probably the maximum value the ECU/software can handle. Point is, the rpm value is off the scale.

So lets have another look at a new file....

Edited by CarlC

Share this post


Link to post
Share on other sites

Thanx Carl,

worst news ever : drove home this morninig, couldn't get more than 70 km/h on the highway, and shaking like hell, rpm needle going crazy, so I needed to pull over and let the car rtow away to the nearest Lotus dealer, had no other choice :coffee:

They'll keep me informed on what it is, most likely bad ground maybe or some sensor going crazy .... after all my soldering skills on the memcal seem to be not bad at all, as the problem was e-occurinig ... Strangest thing is that it happens randomly and most of the time when the engine is hot ...

Big mistery will be solved soon, and I'll post off course the reason for that odd behaviour ... and in fact, I will be very pleased to be able to rely on my car again :animier:

SO : to be continued ... :animier:


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Thanx Carl,

worst news of all : this morning car had to be towed away :coffee:

Came back from work, car couldn't do more than 70 km/h : no power, rpm needle going wild without actually revving, car shaking like hell, so decided to pull over for security, way too dangerous with all that heavy traffic !

Car is in the nearest Lotus garage now, I'll give them a call to know if they know already something ... called the guy this morning, he said probably bad ground or some sensor going crazy ... he'll sort it out ...

I'll be very happy that the problem will be solved, will be able to rely again on my car, as it was not funny at all to drive with it now ...

Strangest thing was that it happened randomly, and most of the time with a warm engine ...

To be continued, and the big mistery will soon be solved , I'll keepyou all updated :animier:

Edited by bzguy

- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Oh dear, lets hope the specialist can get to the bottom of it. I look forward to hearing its all sort and what the cause turned out to be...

Good luck...

Share this post


Link to post
Share on other sites

Hi Hans,

Here are my personal thoughts ...

1. Are you shure it definitely is a MemCal out of an Esprit ? Maybe its out of some other GM car (Pontiac, Vauxhall, ...). These of course donot work in an Esprit regardless what chip you will install.

2. If it is out of an Esprit it could also be out of a MY88 (without c/cooler). Both MemCals look the same.

3. If the MemCal actually is out of a post MY89+ (SE,S4,S4s no S300 or GT3 !!!) and is not faulty, it should work properly. If it does not maybe you have an intermittent hardware problem with your ECU itself. Maybe a cracked line or a faulty connection or whatever.

If I were you, I would try to get a whole ECU from another Esprit friend to do a test. This will tell you within some minutes if your problem is ECU-related or not.

BTW, there is NO idle screw and no IAC screw ! Are you talking about the minimum air rate screw ? Please dont touch this screw unless you have your freescan connected and monitoring the IAC-counts while doing this !

Dont you have the workshop manual ? I strongly recommend everybody who tries to work on Esprits to learn Section EMH in the manual by heart.

Cheers

Marcus

www.PUKesprit.de

Bad, bad, bad news :coffee:

Troubles again ... Started last week ...

To definitively avoid bad contacts in the memcal in the hope to solve the problems that re-occur,I've found a spare memcal with standard chip still in place @ espritisism ...

Received it today (thanx Malcolm for the fast and excellent service !), installed it, let engine run idle for 5 mins, took it for a gentle drive to work (3 km's small roads, 35 km highway @ 120 km/h, 2 km's small roads again).

Seemed to be fine, until halfway : rom needle boucning around (without actually making high rev's), no power at all, engine stalkling when idle, sometimes CEL on ...

Got to work, disconnected battery, reconnected battery, let it idle again, seems to be fine now, could'nt take it for a ride yet but will try tomorrow with a freescan ...

Any ideas what can be going on ? Maybe dirty fuel filter, dirty air filter, some sensor (O2 ?) ... ?

Sorry to bother again guys :crybaby: ...

BTW : tried to adjust the IAC setting screw, seems to be stuck :S ...


Marcus

Share this post


Link to post
Share on other sites
Hi Hans,

Here are my personal thoughts ...

1. Are you shure it definitely is a MemCal out of an Esprit ? Maybe its out of some other GM car (Pontiac, Vauxhall, ...). These of course donot work in an Esprit regardless what chip you will install.

2. If it is out of an Esprit it could also be out of a MY88 (without c/cooler). Both MemCals look the same.

3. If the MemCal actually is out of a post MY89+ (SE,S4,S4s no S300 or GT3 !!!) and is not faulty, it should work properly. If it does not maybe you have an intermittent hardware problem with your ECU itself. Maybe a cracked line or a faulty connection or whatever.

If I were you, I would try to get a whole ECU from another Esprit friend to do a test. This will tell you within some minutes if your problem is ECU-related or not.

BTW, there is NO idle screw and no IAC screw ! Are you talking about the minimum air rate screw ? Please dont touch this screw unless you have your freescan connected and monitoring the IAC-counts while doing this !

Dont you have the workshop manual ? I strongly recommend everybody who tries to work on Esprits to learn Section EMH in the manual by heart.

Cheers

Marcus

\www.PUKesprit.de

Hi Marcus.

1 & 2. Malcolm from Espritism ensured me memcal is from a early SE, so should be the right one.

I suppose if it's not the right one it wouldn't work at all ?! And in fact, it did to his job, I do have in fact the same problem as with my old memcal ...

3. that's what the guy @ Lotus said me as well, could be a very stupid bad ground somewhere or so ...

It was indeed the minimum air rate screw I found, I had my laptop along with Freescan to hook it up to adjust readings from 60 to about 25-40 as mentioned in the manual ...

I'll try to get in touch with Lotus today ...

//edit : called the Lotus garage, they suspects an error in the ECM itself

Found on Dermot's website that GM n

Edited by bzguy

- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Went to see my car yesterday, the checked everything out ... as suspected, it is the ECM ; they've tested with a good ECM for hours, no problems anymore, checked up everything else (sensors etc), all in perfect shape !

I'll order a new ECM from the States.

2 interesting addresses :

http://www.autoecms.com/main.htm (found on Dermot's site) and http://micro-tech-auto.com/ (thanx Olaf)

So now it's waiting time ....


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites
Went to see my car yesterday, the checked everything out ... as suspected, it is the ECM ; they've tested with a good ECM for hours, no problems anymore, checked up everything else (sensors etc), all in perfect shape !

I'll order a new ECM from the States.

2 interesting addresses :

http://www.autoecms.com/main.htm (found on Dermot's site) and http://micro-tech-auto.com/ (thanx Olaf)

So now it's waiting time ....

Glad to see the concern is nearly sorted!

Don't know how much youve been quoted for the new ECM, but I have a new one available and if you don't now need the new memcal you bought from me last week I can take this back as PX.

All the best

Malc Holmes

www.espritism.com

Share this post


Link to post
Share on other sites
Glad to see the concern is nearly sorted!

Don't know how much youve been quoted for the new ECM, but I have a new one available and if you don't now need the new memcal you bought from me last week I can take this back as PX.

All the best

Malc Holmes

www.espritism.com

ECU would cost me 100 $ without TVA and shipping, so about 200 EURO's in total ...

Thanx for the offer to take back the memcal, but I think I prefer to keep it in case of emergeny, you never know ... I thought it was fixed with the new memcal, but as you see it was the ECU going bananas :thumbup:


- Nulla tenaci invia est via -

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...