my engine knocks - How bad is it ? - Solutions ?

[Alex]

Hi all,<br><br>I did an ES log trip yesterday and saw on the datalog that my engine knocks under high rpm / high boost conditions. I'm running the car with an MBC at about 0.85bar (with some spikes,obviously). <br><br><br>I had a blown engine last year and don't want to repeat this, thus what should I do ? <br>Fit bigger injectors, as the duty cycle is going above 80 when the knock occurs? <br>Install one of those wonderful boost enhancement chips which sould control the boost better then my solution or is just my timing out?<br>I appreciate any feedback or suggestions <br><br>Alex

[davidjt]

Alex<br>Obvious (silly?) question, but without knowing the rest of your set-up, are you using the German equivalent of super-unleaded, and/or an octane booster additive?<br>From what I've read, wouldn't expect to need bigger injectors until you're getting over 1 bar.<br><br>David<br>

[John_W]

Alex,<br>your graph shows that you've picked up 7 knocks but doesn't show where or how. Also does ElanScan show the ECU ever attempting to retard the ignition as a result of knocks?<br><br>I'd check the timing anyway, as it's pretty easy to do. http://www.lotuselancentral.com/timing.htm<br><br>More info needed to be able to help, but 7 knocks doesn't seem many, and I don't see you picking up any at all during the time covered by your first graph.<br><br>No doubt ElanscanMan and Doug will be along in a minute.<br><br>Nice amount of boost by the way.<br><br>John

[Alex]

Thanks for the fast replies guys,<br><br>I created some new graphs that show where the knock occured.<br><br><br>Well, the knock definetly increased with the boost, but the engine did not retard the timing anywhere on the trip. And this happend only once. My fuel is Super plus unleaded which should have 98 octane, but I didn't use "brand" fuel.  ??? ???<br><br>Alex

[Doug]

Alex,<br><br>Nice graphs.<br><br>I would definitely recommend you actually check your base engine timing, the spark plug conditions, and the plug gaps!!  <br>I'll await Alan's review, but I think you should get some more logs and see if this knock is isolated to that drive, or if it occurs with routine driving, or even with the car idling in the driveway.  Could just be errant sounds falsely interpreted as knocks or could be real ??  Alan can tell you how the numbers compare to others' log files.<br><br>

[F1 LOTUS]

Mine does the same but there's no corresponding timing retardation? Loose connector perhaps???

[John_W]

Alex,<br>in all honesty this doesn't look bad to me. Maybe I'm missing something but I'm looking at your logs on a friend's computer which doesn't have broadband (God it's SLOW!!!!).<br>I'll have a look on Tuesday when I'm back home.<br><br>JOhn

[Alex]

OK,<br><br>I've removed the MBC, used better quality "brand" fuel and have done more logging.<br>The graphs show an one hour drive with one break. It looks like the knock (even more) occurerd on every drive, this time the engine did retard the timing. <br><br><br>I'll check the timing sparks and spark gaps today, hopefully this helps. Another interesting thing is the power curve, except the 600hp   Power spike max power  is 140hp  :-/<br><br>Are these spikes normal or is my engine on the racing edge ?<br><br>Alex

[ESM]

I need a new monitor - none of the graphs fit on this one. <br><br>Anyway - I don't see anything to worry about here. The knock sensor on the Elan is basically a microphone and is prone to false readings as a result - I always get more 'knocks' when I turn off the engine than at any other time. The ECU ignores the knock counts unless they occur under conditions where knock is likely to occur. If knock is detected under such conditions then the 'knock retardation' parameter is increased until the knock ceases and then decayed until knock is detected again or it returns to zero. <br><br>So the best way of identifying a knock problem is to look at the 'knock retardation' parameter rather than the 'knock counter'.  If knock retardation does occur consistently under heavy throttle then check sensors, fuel pressure, injectors & timing. As I said - in this case I don't think there's a problem.<br><br>Alan

[John_W]

Alan,<br><br>I agree that this doesn't look like a real problem, however remember Stevo's (real) knock at Donington which you traced to a faulty sensor?  I can't remember which sensor it was, but ElanScan did record it as being very noisy, so maybe that would be another check for Alex to make (if you can recall which sensor it was)?<br><br>John

[ESM]

It was the MAT sensor - but since Alex doesn't actually have a problem....

[Alex]

I'm happy to hear that this isn't a real problem. I checked the timing yesterday and it was indeed 4 degrees to much. The spark plugs and spark plug gaps were ok. I did a test drive and the knock counter still counted. Unfortunately I had an accident on this drive. Thus further  Elan driving (and knock investigation) is not going to happen anymore this year, I guess. Somebody took my right of way and I hit a curb with one side of the front bumper when I tried to avoid the accident. Obvious damage can be seen at the bumper, the oil cooler and Radiator and it looks like the mudguard is a bit out of position. Does this mean the longeron on this side is also damaged?.  Has anybody experience with such kind of accidents ? I appreciate any hints where to look for damage because I doubt that the value of the insurance claim will be evaluated correctly.<br><br>Alex :'( :'( :'( :'( :-[

[Doug]

Alex,<br>that is horrible!  Sorry!<br><br>If you post pics we can try to help.<br>

[ESM]

Alex,<br><br>Very, very sorry to hear that.<br><br>Have a read through the service manual http://lotus.jayjaymedia.com/ - it provides all the information you need to assess accident damage.<br><br>Alan

[Alex]

Hi all,

after a long time (almost a year) and neverending bureaucratic hurdles, I'm finally sueing the opponent's insurance and the opponent himself. The car had severe damage including oil cooler, oil cooler assembly, water cooler, a/c cooler and the front chassis parts required complete new alignment. The front bumper and tyre were also damaged. I decided last year to change the car against a newer S2 in midnightblue with low mileage. The new S2 is definitly the best Elan I've ever seen in real life. But due to a job change and half a year of garage for the new one I decided to sell it and to take a brake in my Elan quest. So, if you are interested, the new S2 can be found at http://www.midnightblueelan.de
Thanks all of you for your dedication and help with my Elan, this is definitly the best community I've ever seen. Keep on the good work.

Alex