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Discussion Starter #1 (Edited)
My Exige with Koldfire and Larni 8" exhaust is dynoing less then stock. 179rw hp....:facepalm

Any suggestions on troubleshooting? First reaction is belt slip?? the A/F meter popped off right at the end but A/F look ok right up until that point. Would like to get some suggestions before I start pulling cam covers and stuff.
:shrug:

I have the OBD2 reader and torque app:
What should I be monitoring/logging? Boost? Fuel? timing??
reading spark plugs?
 

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Next time at the Dyno, use your koldfire cable to reset the learned parameters in the ECU. Looks like standard octane scaling off the cuff...

Be sure to get the latest software from our site to make sure your up to date....

-Phil
 

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Discussion Starter #3
Thanks for the quick response Phil.
What does that mean in English? :) I'm guessing to the effect of I had some bad fuel and the car thinks its running lower octane and the ecu backed off the timing?

How do I reset the learned parameters?
 

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Discussion Starter #4 (Edited)
ok.. I think I have the ECU reset. Whats the root cause and how do I fix it permanently?
 

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Is there a "before" dyno, or any helpful relativism's?

SuperFlow dynos aren't too common, but compared to the usual brands it's way down on torque across the whole RPM band. The AFR's are wiggly but not out of the general region where they should be.

Start with the obvious stuff. Check compression. leakdown, every clamp in the entire intake including the intercooler, exhaust fitment, etc. until you've determined the engine is in reasonable health and nothing is broken or loose.

Do you recall a point in time where the car suddenly or gradually started feeling slower?
 

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Discussion Starter #6
sorry no before dyno... but the shop specializes in Lotus and the operator stopped on #2 of 3 pulls because its way lower then its supposed to be. I've seen some stock Exige S baseline at 200whp so its way down. (also, the curve is way too "wavy" compared to then other dyno tunes he had on file)

Thanks for the advice.. I'll check those items.

what about the SC bypass valve?: http://www.lotustalk.com/forums/f160/low-sc-boost-question-68461/ specifically post#13 & 15
 

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Could be octane scaling (as Turbophil said), or could be bypass valve stuck open, or could be a big air leak. If an ECU reset does not clear the problem, carefully check the last two options.
 

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Thanks for the quick response Phil.
What does that mean in English? :) I'm guessing to the effect of I had some bad fuel and the car thinks its running lower octane and the ecu backed off the timing?

How do I reset the learned parameters?
"Octane scaling" is a parameter that is stored in the ECU for each cylinder. If the ECU is detecting "knock" (via a piezoelectric sensor bolted to the engine) under conditions that wouldn't normally cause knock, it assumes that the octane level of the fuel is substandard... and sets an "octane scaling" number for each cylinder. The effect of having a non-zero octane scaling number is that the ECU will not advance the spark timing as much as it normally would under high load conditions. Less spark advance means less power.

"Resetting the ECU" will reset all the octane scaling numbers back to zero (no scaling).
 

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Discussion Starter #9
that makes sense. knock detected, pull timing, got it.

So that bring us to the question of why knock is detected in the first place?
It seems like this whole octane scaling thing is a common occurrence in tuned cars based on my search of the forums and Phil's response. Whats the permanent fix?

(And please don't say Fastworks because I'm not going to pay more money for yet another tune after I've already spent good money and cable for a tune. I know its got fancy octane scaling doodad but I'd rather fix the root of the problem (Knock detected) vs covering it up with software)
 

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Discussion Starter #10
also.. I tried to manually actuate the sc bypass valve. Its definitely not stuck, but it does squeak a bit. Not sure if its normal...
 

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Have someone goose the throttle hard (with the engine running), while you are observing the bypass. Just because it moves by hand, does not mean it will move from the vacuum differential.
 

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Discussion Starter #12
Have someone goose the throttle hard (with the engine running), while you are observing the bypass. Just because it moves by hand, does not mean it will move from the vacuum differential.
ok. I'll see if we can do that on the dyno. (I don't see how it can be done otherwise)
 

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Why some ECUs/tunes/engines/etc seem to octane scale (even on 100 octane race gas) while others don't has never been fully explained. Some cars had nearly every component replaced (from ECUs to knock sensors to wiring harnesses to complete engines) without solving the problem.

Worse, there aren't many ways to tell if your car is actually octane scaling, without hooking up a Lotus factory scan tool and reading the octane scaling registers from the ECU.
 

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Don't take this the wrong way, but good to see others have this problem and documented. This way the more people dyno the more we'll see and hopefully finally solve this junk.

that is definitely knock sensor. My car still suffers from this sh*t.

My car did show 99% on Cyl 2 & 3 before I installed FW tune. Haven't checked since, because no local dealer. But I have taken data with FW and knock values are high. Like 2.0, 3.0.

AFAIR my car didn't always do it. Was only after I started messing with the pulley it started. Switching over to FW didn't solve it either.

Also, knock/scaling still happened even after using 3 different ECUs
 

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Don't take this the wrong way, but good to see others have this problem and documented. This way the more people dyno the more we'll see and hopefully finally solve this junk.

that is definitely knock sensor. My car still suffers from this sh*t.

My car did show 99% on Cyl 2 & 3 before I installed FW tune. Haven't checked since, because no local dealer. But I have taken data with FW and knock values are high. Like 2.0, 3.0.

AFAIR my car didn't always do it. Was only after I started messing with the pulley it started. Switching over to FW didn't solve it either.

Also, knock/scaling still happened even after using 3 different ECUs
Actually, switching over to FW did solve the issue in that it told us your motor is loud--- even louder than most. You also have much LESS scaling than before switching to my Torque tune. We can keep desensitizing your tune, but not being there, it's hard to feel real comfortable giving that my blessing. You have a couple other maps that are desensitized even more and you're welcome to run them. I'm just not there to collect good data, so on special "problem cars" you just need to tread lightly... Switching sensors and ECUs won't help. It's all in the sensitivity tables...

The knock sensor sensitivity is just way too aggressive from Lotus. So much so that it tends to pick up false knock as the SC is very loud and at a frequency that's similar to what Lotus used to dial in the knock sensor. I have rescaled the knock sensitivity on the torque tunes from data I have gathered on my dyno. I'm comfortable with the current knock maps I have in there that they will protect the motor and in most cases eliminate false knock.

Unfortunately, with Kold-fire (or VF/Sector/Etc), there is no access to these tables.... so on cars that are running into octane scaling issues, the options are to continue to reset the scaling or switch over to the Torque tunes where I can change those maps to help mitigate or eliminate the problem.

Hope that helps,

Phil
 

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Shay2nak,
Did you ever consider using an analog circuit to tune out excessive engine noise? An Op-Amp with a band-pass filter (centered around 6khz) may help, but your tuner will likely have a far better solution.
The band-pass filter will eliminate extraneous noises, but let the fundamental frequencies of the "knock" to pass. This reduces false out-of-band engine noises from triggering the ECU.
Sub Note: my knock sensor only gets unhappy at 5k-ish rpms under very light throttle. I simply avoid that range under light throttle (shift before 4500 rpms if I am under light throttle). My WOT tune is rich enough that knocking does not occur at 5k RPMs (cam switch over point on my tune).
 

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Discussion Starter #17 (Edited)
Would you get false knock readings if you have a loud exhaust? My Larini 8" has gotten pretty loud recently and probably need to be repacked.

resetting my ecu hopefully doesn't throw a wrench into troubleshooting. I guess I can put it on the dyno again to see if I make more power.

Are you guys saying that there is no fix for it and I have to reset my ecu every time I drive it to make the advertised power? I like the idea of a bandpass filter but it still crazy to have to apply a bandaid. If there is actual knocking on some cars and to filter it or reduce sensitivity seems pretty risky.
 

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Does it happen only if you have a loud exhaust? My Larini 8" has gotten pretty loud recently and probably need to be repacked.

resetting my ecu hopefully doesn't throw a wrench into troubleshooting. I guess I can put it on the dyno again to see if I make more power.

Are you guys saying that there is no fix for it and I have to reset my ecu every time I drive it to make the advertised power? I like the idea of a bandpass filter but it still crazy to have to apply a bandaid. If there is actual knocking on some cars and to filter it or reduce sensitivity seems pretty risky.
No, I'm not saying any of those things...

Exhaust won't fix it... It's most likely the blower. Some of the 62s are louder than others, etc... It's clear as a sunny day when monitoring the harmonics on the dyno. NA and tubo motors are perfectly quiet and make near the same noise at red line as they do at 4,000RPM. Strap a blower motor down to the rollers and listen with the same frequency and gain, and you'll see what I mean...

As I said prior: It's not a sensor. It's not the ECU and it's not necessarily something dangerous... The problem took me a lot of work and expensive equipment to remap and that remapping works on most cars. The official fix from Lotus Cars is to remove the knock sensor and zip tie it to the firewall. No joke. They cannot remap the knock sensor. I can and do.

As I mentioned, the new maps I made for the knock sensor are still plenty sensitive enough to protect the motor and in MOST cases eliminate false knock. If an ECU still picks up knock with one of my maps (Torque maps), I simply recommend that we really tread lightly before desensitizing further to be sure they we're truly diagnosing false knock vs real knock... The problem is that I've ran into exactly 3 other shops on the continent that understands tuning. Every other dyno shop I've encountered has that expensive piece of equipment and the only thing that they even sorta know how to do with it is do some full throttle sweeps. So gathering data to truly fix problems cars from afar is quite challenging:shrug: That's probably why so many problem cars end up at my shop.lol...

As they say, if it were easy, everyone would be doing it :eek:

As for resetting... simply take your KF cable to the dyno or use Robs... He has one... Do a pull and then plug the cable in and hit reset... The power will pop right back up and the dyno sweep will look fine again...

-Phil
 

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Discussion Starter #19
ok now we are getting somewhere.
what is it about a specific SC that sets off the knock sensors but not others?
Would some kind of spacer between the SC & block help? You can get phenolic spacers for intake manifolds and its supposed to isolate heat, I wonder how well it does in isolating noise. OR is it something else that can be fixed like rebuilding the SC or porting it to get rid of induction noise. Additionally what about adding a mass (GASP adding weight?!) to the SC to change the resonant frequency?
My SC is actually not particularly loud. I can barely hear it actually, esp with my friggin exhaust progressively getting louder

As I said, the Fastworks is not an option for me. I've already spent the money on KF and I'm not about to spend it on another tune. I'm don't have money to burn like some of the guys here. If KF doesn't make the advertised power on MY car and it actually loses power, because of a loud SC or whatever, what other options do I have? I guess go back to stock and chock it up to bad luck and eat the cost of the tune and cable?:shrug:
 

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I agree not all mp62's are identical. They try to get the bearing spacing for the rotor pack consistent. They try to get the rotors to an absolute shape (machined spirals are very hard to produce identically). When any of those factors are not spot on, there is either greater gap between the rotors or a slight interference fit on the rotors. The coupler in the nose can also have some slap and make noise. The supercharger can make significant noise when the world is not right.
 
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