Intermittent Misfire

[Scotty2]

Changed plugs and leads but still get an intermittent misfire.

 

Went for a logging run with freescan and it started around 600 counts. It manifests itself as almost cutting out, then really rough running for a few seconds, put your foot down and it stutters then comes back to life. It then disappears for a while sometimes coming back at the next junction, sometimes not. Has also happened while cruising at 70 on the motorway - as if the ignition has been switched off, backfiring a bit and comes back to life if you plant your foot.

 

It had a new coil pack recently so I am tending to discount that - unless they have modern quality standards so don't last...

 

No fault codes coming  up apart from once - misfire.

 

Anyone want to see if I am missing something on the log?

 

I now know I need a chargecooler impeller

 

Misfire 200913 - 01.xls

[Vulcan Grey]

I do see a couple of things right away.

 

Your BLM vs BLM Cell shows that the ECU is adjusting trim for lean and for rich conditions.  So you probably have both going on.

Also your wastegate duty cycle is not right at all.. Looks like the ECU is almost never commanding the wastegate to open.

[rizla603104]

Did you replace both modules on the coil pack - or the whole thing? There are two packs on the coil pack - one for cylinders 2 and 3 and one for 1 and 4. It could even be corrosion.

[Vanya]

Silly question, but having just gone through a bunch of issues with stutters and rough running...how's your O2 sensor? Has it been changed recently, and is it an aftermarket one or a genuine?

[Scotty2]

The O2 sensor was new when I bought the car so it's 10 years old. No fault code coming up.

The coil pack was changed as one unit - all 4 cylinders.

Not sure what I can do to alter the rich/lean wastegate issue?

[Vanya]

Ok, 10 years might be too short of an interval for the O2 sensor to fail, however don't count on it informing you when it's on its way out - a CEL will trigger if it's totally dead and stops receiving signals, however degradation doesn't throw any lights. 

 

Another poor chap on this forum had weird kind of running issues for a decade, changing loads of hardware in the process, until it was finally discovered that some silicone sealant had worked its way into the ECU pin connectors. Hope your solution isn't so obscure!

[SteveSmith]

That's my car you're referring to Vanya but the problem wasn't proven to be due to the silicone sealant in the ECU connectors.

Scott - have a read of the LONG thread if you have a few hours spare but want to seek inspiration.... http://www.thelotusforums.com/forums/topic/52757-integrator-value-very-low-ideas/

 

My car had LOTS of issues but it is believed that some form of electrical issue was the cause of the very poor running and stuttering/misfire. Unfortunately Sparky couldn't confirm for sure what the electrical issue was. He cleaned/cycled every connector in the loom TWICE (as well as SOOOOO many other things). It then ran fine...

 

Hope you get to the bottom of your problem. I know how it feels to have a poorly Esprit...

[Vanya]

Thanks for chiming in Steve - that thread of yours was epic. So much info on possible sources of trouble! Is your car still running ok?

[mr.oogieboogie]

Id say coil pack. Seen these corrode inside as water gets in . I put the msd coils on. From my freescan log it looked like the ecu.

[Scotty2]

Where did you get the MSD coil pack? Sounds like the best place to try next.

 

Oops did some searching,

 

MSD 8224

 

Looks like I need two and use the existing backplate?

Edited September 27, 2013 by Scotty2

[Vulcan Grey]

yes, takes 2 of the same MSD 8224 coil packs.  Re-use the existing base plate, I remember reading something about the baseplate being Lotus specific and a similar GM version not working...

[Scotty2]

Thanks guys. Two ordered. Knuckles prepared to get skinned if I remember from last time...

[Vulcan Grey]

It is tough with the AC hoses in the way.

 

The bolt is a 5.5mm hex if I remember correctly.

[mr.oogieboogie]

yep it's a 5.5mm socket you will need i found a 1/4 inch drive with an extension is the best tool. remove the air box. clean up the connectors and backing plate.it earths using the bottom bolts. i also run an additional earth wire between the two bottom bolts and onto the chassis. one of the aircon pipes is in the way but can be moved down witha little bit of force.

all the best.