Lotus Elan Central

by **dans** » Fri 27.10.2006, 22:18

Hi all,

Haven't used my Elan much over the last month due to other commitment but have tried to run at at least once a week. Took it out today and it is running very poorly.
Sounds lumpy on idle and doesn't really pull when driven. I would guess it is not running on all cylinders properley. Having looked through other posts on here I am thinking the things to check are leads, coil packs and injectors. So will start trying these things.
I have attached a brief ElanScan of the engine on idle. Can anyone see anything significant in there? I could see a fault flag on "Map High", but I don't know what that means, or if it is a cause or effect.

Any hints would be appreciated, before I start buying new bits!!

Cheers,
Dan

by **GeoffSmith** » Fri 27.10.2006, 23:02

It's not a lot of help but... I believe that the MAP high error is flagging up that the Manifold Absolute Pressure is high - but the plot of MAP looks sensible (nominally 0.4 bar peaking to 1 bar as you open the throttle and dropping to 0.25 bar when you close the throttle. I had assumed that the MAP high/low flags were derived from the MAP signal but it looks like they may be seperate sensors.

ESM or John_W should hopefully be able to give you a more authoratitive reply.

Geoff

by **dans** » Sat 28.10.2006, 09:19

Thanks Geoff.

Will try running the car around a bit today and see what happens.
And get a scan of it running too.

Cheers,
Dan

by **ESM** » Sat 28.10.2006, 11:04

The error is indeed derived from a MAP sensor reading. It sets the error flag when a clearly wrong reading is detected and and the flag will remain set for 50 starts (or whatever it is) before clearing even if the fault resolves. In this case it obviously happened at some point but it seems ok now - it might just be down to the car sitting about too long. I'd disconnect the battery to clear the code and see if the it recurs before worrying too much about it. The sensor readings in the log all look ok.

The poor running does sound like it may be electrical in origin.

by **dans** » Sat 28.10.2006, 12:04

Thanks ESM, have cleared the MAP error and it hasn't come back.

I have taken the sparkplugs out now. At least one of the leads isn't looking great.
More worrying is that I could see some oil in the space under the sparks plug cover. When I took the RHS (looking at the engine bay from the front) plug out there was a lot of oil around the plugs thread, and the spark gap itself was slightly blacker than the rest.
Is it possible that some seal has gone? Where would oil come from in this area?

Been reading about Stefs valve stem seal problems. Could this be the culprit?

Cheers,
Dan

by **ESM** » Sat 28.10.2006, 19:29

Is the CAS seal ok? That seems the most likely origin. Leaking valve stem seals dump oil into the cylinder producing black smoke from the exhaust on the over-run (when the cylinder pressure is very low) rather than oil around the plugs.

by **John_W** » Sat 28.10.2006, 20:21

Dans,
Don't panic,lad. A bit of oil always finds its way into the space below my spark-plug cover, and it's certainly not because I slop it about during oil changes (it's too expensive to be spilling any). And that's with the cover having a gasket (of sorts). Mind you, the gasket has limited effect since the end where the spark plug leads enter is still wide open, and that's right next to the two well-known oil leaks on the engine.

The only way I can see the oil getting in is as ESM says - it's probably from a small leak in either the CAS oil seal or its twin the blanking plug oil seal. You say there's quite a lot of oil, but with the small amount of space down there there's probably less than a teaspoonful.

When my blanking plug seal was oozing Mobil1, some of it found its way past the spark plug leads and rested in no 4 plug bay (RHS as you look under the bonnet), and it must have fried on, cos I still can't get rid of the deposits.

John

by **dans** » Sun 29.10.2006, 22:04

Thanks John, sounds identical to what I'm seeing at the moment. Guess I'll have a bit of clean up around there and keep an eye on it.

Having taken the 4th plug out and cleaned it out the car runs ok on idle but is still rough under load.
Will get some new plugs and go from there for now!

Cheers for the help.

Dan

by **DaKa** » Tue 31.10.2006, 12:08

Please post the results of your changes as I reported exactly the same thing on the forum recently. My Lotus went from running badly to great performance just by changing the plugs - it only lasted about 3 weeks before it started mis-firing again!.
Despite changing plugs, checking leads etc it was running like a dog again this weekend.
It must be something 'sensitive' as the car was running perfectly. Q. Can coils start and stop working properly? or are you and I more likely to be suffering from a bad connection somewhere 'Leads'? and does the routing of the Plug Leads make a difference?

by **dans** » Thu 02.11.2006, 10:13

Woo hoo!!!

She's runnin' sweet again!!!

Changed the plugs last night and that seemed to do the job.
My guess is that some of the oil may have contaminateed a plug.
BTW the NGK plugs came supplied with exactly the right gap on all four!!
Now to fix the oil leak!!!

Had a fantastic drive in today to celebrate, roof down 7am, managed 15 miles out of the 35 miles to work, so I think I did pretty well!!!!! :roll:

Thanks for the help once again!!!

by **M100 TWO** » Thu 02.11.2006, 10:38

DaKa if your misfire is on boost I would think about changing the coils

by **dans** » Mon 20.11.2006, 18:25

Having changed the CAS seals on the weekend I was trying to reset the timing but it seemed to be all over the place. Took it for a run down the road and sure enough it wasn't running at all well under load again.

Had another look at the number 4 spark plug and again there was a fair amount of very fresh oil on the end of the plug. I had only done one 80 mile round trip to work in the car in the last couple of weeks since I changed the plugs so wouldn't have thought enough oil could have come from the CAS seal to do this....????!!!!

Tried cleaning the plug up but still wouldn't run properly, will try replacing it again and seeing if that helps. Any hints/tips on cleaning the oil out of the bottom of the valve (?), ie. is there anything delicate down there? Can I wrap a rag round a stick and get worst out? Or will it just burn itself off?

Have got some HT leads now so will try them as well, and may also get the coild if possible, in case there is more than one culprit here!!

Cheers,
Dan

by **dans** » Sat 25.11.2006, 01:45

hooray!!

Changed the leads and the coils tonight and all is running great again!!

Hopefully it will stay that way. Taking the car down to Wales for the weekend to give it run... and see what goes wrong next :wink:

Now time for :cheers:

by **DaKa** » Tue 28.11.2006, 08:45

I got some new coils as suggested from American Auto Parts and changed them. It was a bit of a fiddly job (which is why I put it off) but, boy what a difference.
Hope your keeps running as well as mine is now - thanks for the tip.
DaKa

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