High idle and drop very slowly - Page 6 - LotusTalk - The Lotus Cars Community
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post #101 of 145 (permalink) Old 05-14-2015, 06:52 AM Thread Starter
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Mine's very similar to RBH. The little blip or hang at 12-1300 rpm is a bit random (not exactly the same every time), I've always considered it normal. I think it's just a by-product of the ECU tune. I have a KoldFire tune, but I think it is pretty much the same with the stock S240 tune (though idle is more steady on the KF tune). FWIW, I did have an intermittent stalling and "lean bank 1" issue when my car was new, the dealer replaced the SC/intake manifold gasket on warranty, and it's been fine since.
SC O Ring between the goose neck or Intake mainfold gasket on the head?

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post #102 of 145 (permalink) Old 05-14-2015, 09:07 AM
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SC O Ring between the goose neck or Intake mainfold gasket on the head?
Sorry I wasn't clear, it was the intake manifold gasket on the head.

-Ed
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post #103 of 145 (permalink) Old 05-14-2015, 09:39 PM Thread Starter
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Sorry I wasn't clear, it was the intake manifold gasket on the head.
So, it fixed the random blip or lean code?

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post #104 of 145 (permalink) Old 05-15-2015, 02:56 AM
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So, it fixed the random blip or lean code?

It fixed the intermittent lean code and occasional stall at idle. I consider the brief hang or blip at 12-1300 rpm to be normal.

edit: My guess is that the brief hang or blip when rpm's are dropping rapidly toward idle is intentionally programmed in the ECU to avoid stumbling (briefly dropping below idle rpm) or even stalling, effectively creating a "softer landing". It wouldn't be hard for the ECU to respond to the specific combination of conditions with a brief fuel and air blip. The conditions would be rapidly falling rpm combined with zero throttle/full lift, rpm passes through 1300 rpm trigger. The DBW ECU could do a brief throttle blip, older ECU's with a cable throttle could use the idle air controller to effectively do the same. Much better than having a stumble or stall under the same circumstances. I could be wrong, but what does it matter?

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Last edited by AustinP; 05-15-2015 at 04:40 AM.
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post #105 of 145 (permalink) Old 05-15-2015, 05:38 AM Thread Starter
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It fixed the intermittent lean code and occasional stall at idle. I consider the brief hang or blip at 12-1300 rpm to be normal.

edit: My guess is that the brief hang or blip when rpm's are dropping rapidly toward idle is intentionally programmed in the ECU to avoid stumbling (briefly dropping below idle rpm) or even stalling, effectively creating a "softer landing". It wouldn't be hard for the ECU to respond to the specific combination of conditions with a brief fuel and air blip. The conditions would be rapidly falling rpm combined with zero throttle/full lift, rpm passes through 1300 rpm trigger. The DBW ECU could do a brief throttle blip, older ECU's with a cable throttle could use the idle air controller to effectively do the same. Much better than having a stumble or stall under the same circumstances. I could be wrong, but what does it matter?

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But as far as I can't remember ( in my air head ), my girl didn't blip at all

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post #106 of 145 (permalink) Old 05-17-2015, 10:02 PM
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Drove the car today and mine does it also. My idle is at 1100 so it will jump for a second to ~1500 and settle back down. It doesn't happen all the time. Once in a while.

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post #107 of 145 (permalink) Old 05-17-2015, 11:02 PM Thread Starter
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Drove the car today and mine does it also. My idle is at 1100 so it will jump for a second to ~1500 and settle back down. It doesn't happen all the time. Once in a while.
HAHA, LOL, OMG, HUM, FXXX.........what should I say

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post #108 of 145 (permalink) Old 05-28-2015, 04:28 AM
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Hello. Lotus SC 2008. I have the same problem . it all started after cleaning the throttle body . I did everything , the problem does not go away . I think that the problem is in the throttle body . logs throttle position sensor did not like my servismen. throttle position sensor is located under the black cover. Perhaps little of the cleaning liquid from getting inside the central axis . and broke sensor.

It explains why the dirty throttle your friend worked well in your car. It explains why your cleen throttle was not working on the car of your friend, but does not explain why not work with the new throttle out of the store. may be new from the store is broken? you do clean the throttle from a store?

The second idea is a learning process with the throttle pedal and the ignition key. I do not know how to do it in the Lotus

sorry for my bad English

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post #109 of 145 (permalink) Old 05-28-2015, 05:41 AM Thread Starter
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I bought 2 new throttle body, and their results same same....
I did not clean the new throttle body.

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post #110 of 145 (permalink) Old 05-28-2015, 06:38 AM
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I bought 2 new throttle body, and their results same same....

I did not clean the new throttle body.

A little background may help, so here is how the typical DBW ECU controls idle:

If pedal position>some value, it will enable idle. Otherwise, it listens to the pedal.

Assuming pedal is low enough to enable the idle flag, it goes to a default throttle position and spark timing (this is the pre-control). It then goes into a closed loop control where it primarily uses spark timing to adjust idle speed as this is fast and accurate. However, it is also limited. You can cook things very quickly if you pull out too much timing, so that's where the DBW comes into play. There is a time delay from when the throttle moves and the idle actually changes, so the ECU knows to only move the throttle slowly. Otherwise your idle will oscillate.

This also means that it is normal for DBW to "self drive" if you slowly let the clutch out in any gear. The throttle will slowly open to try to maintain idle speed. This is how I taught my wife how to drive a manual actually.

Now, it sounds to me like the changes to the calibration (tune, intake, etc) are throwing off the pre control. S111 suggested what I'd do - follow that cycle and allow the ECU to relearn the pre control. Also, the tune may have bumped the base spark up, leading to a higher idle for a given throttle angle. Lastly, the tune may have changed the closed loop idle parameters and is causing the behavior you are seeing.


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post #111 of 145 (permalink) Old 05-28-2015, 06:58 AM Thread Starter
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A little background may help, so here is how the typical DBW ECU controls idle:

If pedal position>some value, it will enable idle. Otherwise, it listens to the pedal.

Assuming pedal is low enough to enable the idle flag, it goes to a default throttle position and spark timing (this is the pre-control). It then goes into a closed loop control where it primarily uses spark timing to adjust idle speed as this is fast and accurate. However, it is also limited. You can cook things very quickly if you pull out too much timing, so that's where the DBW comes into play. There is a time delay from when the throttle moves and the idle actually changes, so the ECU knows to only move the throttle slowly. Otherwise your idle will oscillate.

This also means that it is normal for DBW to "self drive" if you slowly let the clutch out in any gear. The throttle will slowly open to try to maintain idle speed. This is how I taught my wife how to drive a manual actually.

Now, it sounds to me like the changes to the calibration (tune, intake, etc) are throwing off the pre control. S111 suggested what I'd do - follow that cycle and allow the ECU to relearn the pre control. Also, the tune may have bumped the base spark up, leading to a higher idle for a given throttle angle. Lastly, the tune may have changed the closed loop idle parameters and is causing the behavior you are seeing.


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Wow, waited for year, some light finally.

But my another stock OEM 260 ECU behaves the same

How to have the ECU to relearn the pre control?

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post #112 of 145 (permalink) Old 05-28-2015, 07:14 AM
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Wow, waited for year, some light finally.

But my another stock OEM 260 ECU behaves the same

How to have the ECU to relearn the pre control?
I always passed over this thread since I have an '05. However, I also wrote DBW software that has been running in Grand Am/Tudor/American Le Mans...

Since this thread has been going on for awhile, let's kinda start over - do you presently have a CEL? What modifications are done to the engine at this point in time? Do you have an OBDII scanner? If so, you can get things like spark timing, air mass flow, throttle angle, etc.

From watching that video, it really looks like the pre-control is off. I don't know the exact structure of the code in the car, so I can only guess from experience. Typical learning is pretty reasonably limited (from the service manual, you'll get a CEL if it has to learn more than 15% and it still is 200rpm too high). What S111 suggested sounds like a re-learn process, so try that if you have not. Then you'll need a re-flash if it does not adapt. A freer breathing intake and exhaust could do that in an extreme case. Heck, if you combine that with dense air, low friction (engine oil, supercharger, supercharger oil, etc) then you may have an engine that simply idles too well, and the ECU doesn't think it is normal.

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post #113 of 145 (permalink) Old 05-28-2015, 07:30 AM Thread Starter
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No CEL.

My mod:
- Blade 300 ECU
- 260 Fuel Pump
- Cup air box
- RLS big cooler
- 2.9" pulley
- 550 injectors
- Stock header + Stock Cat + Stage III muffler

Yes, I have OBDII scanner.

What did S111 mention?

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post #114 of 145 (permalink) Old 05-28-2015, 07:49 AM
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From 11/14/2013:

S111 told me to do the following:
1. Reconnect the battery.
2. Just start the engine, and let it idle for more than 10 mins. Then drive off
3. After the drive the car, I have to let it idle 10 mins, before turn it off
4. Start the engine, and let it idle for more than 10 mins. Then drive off
5. After the drive the car, I have to let it idle 10 mins, before turn it off
6. Start the engine, and let it idle for more than 10 mins. Then drive off
7. After the drive the car, I have to let it idle 10 mins, before turn it off
8. Start the engine, and let it idle for more than 10 mins. Then drive off
9. After the drive the car, I have to let it idle 10 mins, before turn it off

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post #115 of 145 (permalink) Old 05-28-2015, 07:54 AM
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No CEL is interesting. Hook up an OBDII scanner and see what the exact rpm is. Also, what is your ideal idle speed with the new tune (hot idle)? Since you don't have a CEL, then you may just have a poor calibration (too slow). In that case, you need to deal with S111 and do what they suggest. They should understand the tune well enough to know what was changed with regards to the idle.

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post #116 of 145 (permalink) Old 05-28-2015, 07:57 AM
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Quote:
Originally Posted by cyow5 View Post
From 11/14/2013:

S111 told me to do the following:
1. Reconnect the battery.
2. Just start the engine, and let it idle for more than 10 mins. Then drive off
3. After the drive the car, I have to let it idle 10 mins, before turn it off
4. Start the engine, and let it idle for more than 10 mins. Then drive off
5. After the drive the car, I have to let it idle 10 mins, before turn it off
6. Start the engine, and let it idle for more than 10 mins. Then drive off
7. After the drive the car, I have to let it idle 10 mins, before turn it off
8. Start the engine, and let it idle for more than 10 mins. Then drive off
9. After the drive the car, I have to let it idle 10 mins, before turn it off
They actually "borrowed" that suggestion from me, but messed up the message...

Disconnecting the battery doesn't do anything.

Following an ECU reset (only accomplished with Lotus tool, BOE fastworks software, or Koldfire cable), you warm the car to operating temp, drive for 10 minutes, and then let idle for 10 minutes before shut down. That will typically dial in the idle tables after a fresh reset.

-Phil


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post #117 of 145 (permalink) Old 05-28-2015, 08:06 AM Thread Starter
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No CEL is interesting. Hook up an OBDII scanner and see what the exact rpm is. Also, what is your ideal idle speed with the new tune (hot idle)? Since you don't have a CEL, then you may just have a poor calibration (too slow). In that case, you need to deal with S111 and do what they suggest. They should understand the tune well enough to know what was changed with regards to the idle.
Will do that this weekend.

S111 can't help, they only suggested to reset the ECU.

I have a Japanese Lotus ECU expert, he couldn't fine anything wrong with the B300.

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post #118 of 145 (permalink) Old 05-28-2015, 08:09 AM Thread Starter
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They actually "borrowed" that suggestion from me, but messed up the message...

Disconnecting the battery doesn't do anything.

Following an ECU reset (only accomplished with Lotus tool, BOE fastworks software, or Koldfire cable), you warm the car to operating temp, drive for 10 minutes, and then let idle for 10 minutes before shut down. That will typically dial in the idle tables after a fresh reset.

-Phil
I have the Koldfire cable, HK Lotus dealer borrowed it and reg. with their VIN. Koldfire in Germany promissed to reset the cable for me, but they never did.

Will try S111 this reset again. How many cycle I need to do?

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post #119 of 145 (permalink) Old 05-28-2015, 08:11 AM
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Will do that this weekend.

S111 can't help, they only suggested to reset the ECU.

I have a Japanese Lotus ECU expert, he couldn't fine anything wrong with the B300.
There is always room for improvement with calibrations, so it could be a matter of the calibration being a little slow which is better than being too aggressive sometimes. Doesn't mean anything is wrong. In fact, if he looked at the calibration and DIDN'T see room for improvement, then I wouldn't go to that guy anymore

Try the re-learn process first though, and see what happens. If you have had the answer in front of you for over a year now, I demand CF for my time

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post #120 of 145 (permalink) Old 05-28-2015, 08:14 AM Thread Starter
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There is always room for improvement with calibrations, so it could be a matter of the calibration being a little slow which is better than being too aggressive sometimes. Doesn't mean anything is wrong. In fact, if he looked at the calibration and DIDN'T see room for improvement, then I wouldn't go to that guy anymore

Try the re-learn process first though, and see what happens. If you have had the answer in front of you for over a year now, I demand CF for my time
Why not?

But this is a long waiting.

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