Misfire

The Oily Bits S2 Specific Topics
1

Hi!
I was attending a trackday this weekend with my 06 Exige (federal).
And towards the end of the day, the sound of the engine changed tone a bit from approx 7100rpm and upwards (sounding almost like a false tone).
I initially thought it was just a resonance from some place in the car so I kept on driving for a (little) while untile I then got lots of valve tapping(noise), at all revs. So I stopped driving the car for a while(let it cool down a bit) before heading home . (driving carefully)

After a few km�s on the road the tapping noise disappeared, and I tested the car at high revs, (7100rpm +). I then got the same “false tone” from the engine at high revs, and the check engine light came on.
I just read the codes and the reader reported a P1302 (which says “Misfire level causing catalyst system damage”)
Any Ideas on how to proceed to diagnose the problem? open the top cover and check the cams? plugs?

(There is no Lotus dealership around here to approach for a diagnose)

Thanks in advance

2

sounds like it could be the dreaded worn cam lobe problem :frowning:

3

Does that only affect the “hot cam”?
My current problem only seems to be apparent on high revs (after the initial valve tapping disappeared)

4

Do a search on cam lobe wear, been quite a few cases and it usually affect the high rev range only

5

Pull the can cover off and have a look… any check engine light on ?

6

P1302 he stated on the first post Frank

7

Is there any danger of further damage if I drive the car carefully (staying on the lower cam) in case it is the cam problem?
I need to get the car to my father’s place to get to a workshop with proper tools, so It would be convenient to drive it.

I’ll open up the cam cover when I get back from my holiday in october.
Flying off to sunny california :slight_smile:
Just a bit annoying knowing that I have to spend the winter repairing the darn thing, rather than upgrading it

8

Yes worn cam lobes - I had this at 27k with my current Exige S.

Will only get worse until the car basically goes into a limp mode and second cam is not available, MIL light on.

I was lucky and got it done under warranty. Now up to 55k miles no further issues.

The performance deterioration is insidious before it is obvious, so you’ll be pleased with the new found sprightliness of the car once the cam is replaced…

9

Ah I have ro read slower…

Here is a link to check engine codes…click on the attachment.
http://www.lotussport.org/viewtopic.php?f=7&t=4536

10

Thanks!
Useful link, even if it doesn`t suggest potential reasons for my current misfire.

[quote=frank]Ah I have ro read slower…

Here is a link to check engine codes…click on the attachment.
http://www.lotussport.org/viewtopic.php?f=7&t=4536 [/quote]

11

That’s why you have a warentee… Let your dealer do the work.

12

Excellent link :smiley:

13

Hi!
I finally got around to check my cams. This is how they look:

DSCN0004 by wseight, on Flickr
And

DSCN0003 by wseight, on Flickr
They seem to be the culprit for my misfire.
Too me it looks light the “hot lobe” on both the exhaust and inlet cam is worn on all cylinders. Isn�t that a bit atypical?
I expected just a couple of lobes on the inlet cam to be worn, based upon what I have read.
Is there anything else I need to check?
I assume I need to replace both the inlet and exhaust cams with their associated rockers. Or are there anything else I need to check/replace?
Is monkeywrench racing the best place to buy these bits?
Their prices seems reasonable, See here

Have I understood the problem correctly if the solution to avoid it reoccuring in the future is to set the valve gap slightly larger than it currently is? (what should it be set to)

Thanks

14

Anyone?