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Discussion Starter #1 (Edited)
rattle, pre ignition, tranny/gear?

Just noticed a rattle today, here is the best I can do to describe it.

1) Give the car a little load, say up hill in a low gear.
2 )Going 45 in 6th gear and letting off the gas. Once the rattle occurs give it any amount of gas and it stops. Also depressing the clutch stops it. It sounds a bit like pre ignition, maybe it is :shrug:

I believe the previous owner used 93 octane but I have researched this over and over. With ECU's today it really does not matter, the car will find the best combination of mixtures and use it. Yes, no? Maybe the car just need to adapt to lower octane?
 

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Discussion Starter #3
I guess the best advice is, "if it causes a problem go back". Also I found an interesting post saying

straight from Lotus, IF YOU USE LOWER GRADE OCTANE GAS OR THE WRONG WEIGHT OIL, YOU WILL VOID THE COVERAGE ON THOSE PARTS AFFECTED BY THOSE FLUIDS. You could gamble, but why? And trust me, Lotus will stick to their position.

I guess I'll just stop complaining and put higher octane in it. So much mixed reviews on this topic.
 

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It is not pre-ignition, but you probably meant detonation.
(Yes there is a difference.)

It should not ping coasting, and you should probably not be in 6th at 45 going uphill.
Driving in 6th and putting in low octane fuel is probably indicative.
 

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Gamera The Atomic Turtle
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93 baby. And 45 mph is second gear. :)
 

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It is not pre-ignition, but you probably meant detonation.
(Yes there is a difference.)


My thoughts exactly...

On my webpage for a more complete explanation of the very distinct difference...(click pic for link):

 

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Discussion Starter #7 (Edited)
It should not ping coasting, and you should probably not be in 6th at 45 going uphill.
It does make that ping noise costing though ?( in gear ). And 6th at 45 is just a way to produce it noticeably not my driving preference? Also Florida = no hills. Was referring to a gentle incline.

I put 93 OCT in already but tank was 2/3's full of 87 at the time. Not sure where that puts me but I certainly still here the issue. Took 1.5 weeks to show up, so I'm guessing at least that long to go away. I'm assuming that means driving her like she has new rings?
 

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Less is Better
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It is not pre-ignition, but you probably meant detonation.
(Yes there is a difference.)

It should not ping coasting, and you should probably not be in 6th at 45 going uphill.
Driving in 6th and putting in low octane fuel is probably indicative.
Technically, it's not really detonation, it's deflagration, but no one uses the right term.
 

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Correct in general... but deflagration is defined with the speed of the process being less than the speed of sound in the medium. When the speed of deflagration exceeds the speed of sound, as in pinging, it is no longer deflagration... But rather initial deflagration, which turns into detonation before the deflagration process comes to its natural end.
 

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Try disconnecting the battery. Hopefully the ecu will teach it to burn the lower octane until it is gone. Detonation is the worst thing for these engines.
 

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Discussion Starter #11
Try disconnecting the battery. Hopefully the ecu will teach it to burn the lower octane until it is gone.
Sorry for miss understanding. but is that not a contradiction? If the ECU has learned how to burn the lower octane would pulling the battery not undo that?

Also, not sure if it helps but I have Torque pro, does it have a reset adaptive learning?

Oh one more thing, is there an easier way to reset, like a fuse? I hate to reprogram that damn radio again.
 

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I don't believe pulling power will reset any learned parameters on our ECU, and I also don't think anything but a Lotus tool or Lotus-specific aftermarket stuff can reset learned parameters over CAN (I know FastWorks can). CharlieX had a "resetlearn" tool that would work with a popular tuning cable for a while, but took it down. Some people have posted various methods of corrupting the flash by removing power at a specific time while turning the car on and off, or opening the ECU, but they all sound slightly foolhardy/dangerous to me.

I agree that resetting the ECU doesn't make much sense in this situation anyway, if that's really the case. If your engine is actually knocking and you're extremely lucky, the knock sensor might pick it up and allow the ECU to apply octane scaling. Resetting the ECU will just reset the octane scaling to normal, the opposite of what you'd want.

Personally I think your rattling sounds more transmission/driveline related than engine, but I haven't heard it myself so that's not a very informed opinion.
 

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Discussion Starter #13
Its not knocking, I have a very good idea what that sounds like. I dont know all of this info on pinging ect. but it sounds just like pre-ignition to me.

What I need to know is this

1) Should I try to avoid the sound? Driving in a manner it does not produce the sound.
2) Should I drive it like I just replaced the rings, slow and easy.
3) Should I keep filling up the 93 octane as much as possible? or let it go low and refill.
4) Should I take it to the dealer?

IMO with the lower octane in there I think it's best to get it out by driving it. Once its gone fill and run with 93. Drive it easy till the pinging is gone. Though I really dont know what is best.
 

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So they took a 135 hp engine and with clever tuning squeezed 190 hp out of it.

I would say that demands the highest octane you can find to keep it together and running correctly.

I am on deployment so I do not have my manual, but I know my Cayenne says on the gas door 91 octane minimum. I believe that is in the Lotus Manual also

I am not on the Lotus is the greatest engineers in the world band wagon, but I do feel that they did the best that they could with what they have. So I wonder what year they developed the ECU for the 2005? 2001-2 and spent time testing it.

So it is not these new ultra modern ECU's, its more like a 12 year old rewritten older Toyota ECU
 

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Discussion Starter #15
From what I know the ECU is written by some Italian group.
 

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Gamera The Atomic Turtle
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i had the "marbles in a coffee can" once - on my return trip from BOE. It was caused by bad gas - it was tough to find decent fuel in the midwest - 93 was impossible to find, and the 91 octane was optimistically labelled imo. As soon as i found real 91, or any 93, the problem subsided.
 

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Discussion Starter #17 (Edited)
I guess ill just keep pouring in 93 then. Its 3/4 full right now. I guess any amount of 93 has to bring up the octane some. My biggest concern is not that I put 87 octane in, it's that I drove it hard before I knew it was an issue. Though once I heard the strange sound I stopped.
 

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Discussion Starter #18
math... So I'm still in trouble here.

I added 93 at 2/3's tank
assuming 11 gal tank.
(87*7) + (93*4)
----------------------
11
609+372/11 = 89

I'm now at 3/4's and adding sunoco 94 would bring me up to 90
(89*8)+ (94*3)/7

So I best wait till the tank is lower i guess?
 

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I guess ill just keep pouring in 93 then. Its 3/4 full right now. I guess any amount of 93 has to bring up the octane some. My biggest concern is not that I put 87 octane in, it's that I drove it hard before I knew it was an issue. Though once I heard the strange sound I stopped.
:facepalm

Why are you being cheap!?!? At most its what $5 extra for premium? Heck, you should be using premium on a stock non-supercharged engine for crying out loud!

Now your situation is way worse! You have an aftermarket supercharger (according to your sig)!!!!! This means hotter intake temps and a larger chance for detonation, which is why you should use premium. Your other problem is that with an aftermarket supercharger you get an aftermarket ECU tune... Who knows how that reacts to low grade fuels... I somehow doubt it will "learn" to live on 87 like you suggested earlier!

You are just asking for trouble! Just pay the extra $5 per tank to protect your engine and make more power!

My advice, throw some octane booster in there and take it easy until you can get a refill.
 

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Discussion Starter #20 (Edited)
You completely miss understood me? I put the highest Octane in there I could, how is that cheep?

The problem, from reading many topics in the matter my consensus was today's ECU's will figure out the best way to burn octane. Evidently the threads I read were of bad choice because that simply is not true or more to the point bad for an Elise in particulate.

The fix, how to get the octane up, as I explained I'm trying to add the highest octane possible to fix the situate. This would be the opposite of cheep unless there is a faster way to do this. And if so I'd like to here it.

Since this was obvious not clear, I'll put it another way. My tank is 3/4 full of 89~ ( as I illustrated above ) octane how can I make it 93 ? Lots of options including emptying the tank but I'm looking for advice.

Octane boosters, again the consensus is they don't do jack crap and would make matters worse. Though if this will help great!
 
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