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JohnJL's Avatar
 
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Al, also yes I am logging. Here is the last log of today when I move the ignition back, lock the idle valve and adjust the throttleplate. I cant seem to attach the raw file, here is a screenshot.



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Old 06-09-2017, 10:04 PM
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Your screenshot is very difficult to read. I would recommend that you provide a log file that captures the condition that you are describing. If you provide a log file with notations.....I'd be glad to review and provide any suggestions I might have. If you PM me I'll provide my email address and you can send me the file.

It is difficult to tell from the screenshot, but at your marker line it looks like you are at 1600 RPM or so and 12:1 AFR. I'm assuming that after that marker line represents the effect of closing the throttle plate. When the throttle plate is closing, you are decreasing the airflow, but your fuel is the same...so i think that your A/F mix may be going rich at that point.......hard to see in that screenshot, but it does look like the A/F mix gets richer and the engine hunts and eventually bogs down.That is why I am thinking that you might want to lean it a bit as this occurs to compensate for the change in airflow. That is my take, based on your description...i could be wrong.

Also, I'm not a 3.2 t'body/manifold expert, but if I'm not mistaken, the throttle plate is typically set to a factory spec of .0015" gap and then the idle is set using the idle adjust.

regards,
al
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Last edited by al lkosmal; 06-10-2017 at 09:06 AM..
Old 06-10-2017, 08:44 AM
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Old 06-10-2017, 08:55 AM
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Quote:
Originally Posted by al lkosmal View Post
I would recommend that you provide a log file that captures the condition that you are describing. If you provide a log file with notations.....I'd be glad to review and provide any suggestions I might have.

regards,
al
I cant seem to post a file, just images. Would you pm your email?

You are very generous, thankx.
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2007 911 Turbo - Not a toy
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1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 06-10-2017, 09:04 AM
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Originally Posted by JohnJL View Post
I cant seem to post a file, just images. Would you pm your email?

You are very generous, thankx.
Pelican won't let you post files, just images. You can try changing the file extension to .jpg, but more likely you'll need to use a Google drive or Dropbox account. Email probably easiest.

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Old 06-10-2017, 09:21 AM
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You've been PM'd. I'll take a look at your logfile and msq, over the weekend, and see if I can help.

regards,
al
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Old 06-10-2017, 09:27 AM
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I had this problem also years ago with ms2, someone said earlier about injector dead times. Very important, also on your ignition map and ve map need to be somewhat smooth around the idle area. I would also like to see your tune if you would like to send it to me. Frank
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Old 06-10-2017, 09:54 AM
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Anybody have injector dead times and voltage offsets for 30 lb Accel injectors (I'm running them as 30 PSI).

Don't mean to hijack, but just would like input from the Megasquirt crew while you're here as I have been trying to work through my idle oscillation too. Similar to John's but less severe. Smoothing out the VE around idle when warm helped.
Old 06-10-2017, 10:05 AM
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Email on the way Al, thanks so much. Your Kung Fu is the best.
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1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 06-10-2017, 10:25 AM
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The older injectors accel,Siemens etc are leaps and bounds behind the " newer" ones. It used to be that the bigger injectors for big power were super hard to get a stable idle but now injector clinic, injector dynamics just to name two are so stable at low pulse widths it's insane. My 930 with 1100cc inj clinic linjectors on e-85 idles like a prius. Well worth the $ vs time wasted trying to tune an injector almost incapable of playing nice.
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Old 06-10-2017, 02:05 PM
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Quote:
Originally Posted by Marwil View Post
Check your VE table. I have a partly similar set up - 3.0. SSI, Carrera intake. My MS 2 oscillates between 800 to 110 rpm too before fully warm still. Fully warm is not bad at around 1000 rpm. It oscillated all the time at Idle until I messed around with the VE table. I set a block of 6 cells at about the same value (about 45) and this improved the warm situation immensely.

If anyone has some killer advice on the idea oscillation thing both John and I suspect others would be quite happy!
I'm using MS1 and LC-2 wideband with the Bitzrace EFI kit - but had the exact same problem. Tony recommends a 4700uf capacitor installed to the wideband due to the electric distortion in the engine bay of our old cars (ignition components etc). It seems the wideband is sending oscillating voltage readings to the MS which then causes the oscillating idle. After installation (2min job) the oscillation has almost completely disappeared on my car.
Old 06-10-2017, 11:07 PM
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John,

If you are running MS3, then I would use the Idle VE and Idle Advance correction functions if you are not already so you do not have to change VE values and timing values in the main VE and Timing tables. It is tricky to get a stable idle. Small changes to VE values had a larger affect on idle than I thought when tuning mine. Also, my idle advance varies (when the engine is running close loop idle) between 11.5* - 13.5* depending on load/engine speed using the Idle Advance table values. My idle varies about 50rpm's in Tuner Studio between 950 & 1000rpm's, but I do not see the car tachometer move. My tachometer does not read the same as TS at low rpm's.

It does seem like you may have a vacuum leak somewhere. Have you checked the condition of rubber coupler that connects the two halves of the Carrera manifold?
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Old 06-11-2017, 10:10 AM
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Having just sorted something similar to this, albeit with a DTA ecu, I would start from the basics again. Check the timing marks on the pulley are indeed TDC, pull a plug and feel the piston come up to TDC. Then set all your throttle plates evenly, make sure all your idle screws are wound all the way out first. Once all the plates are closed at the same point you can wind in the idle screws and set it so it will idle at 1500rpm .

Get yourself an airflow meter like this https://www.efihardware.com/products/325/Synchrometer-Flow-Meter
try and trim the bypass screws so that it reads the same on each body, then you can lower the idle back to 900RPM.

Make sure you TPS settings are set correctly and that both throttle banks open at exactly the same time, if the bank without the TPS opens first the engine will fall flat on its face as the ecu wont know to enrich the engine.

I'd set idle timing at 8 deg BTDC and set the cell below it at 800rpm or whatever it is a little highe,r say 12 deg... to stop it stalling if the rpms dip.

Also make sure the engine is at operating temps before you do any of this, you can adjust the cold start enrichment later. Mine like to be a little on the rich side to idle properly....13 or 13.5 :1AFR
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Old 06-11-2017, 10:46 AM
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Quote:
Originally Posted by Nux View Post
I'm using MS1 and LC-2 wideband with the Bitzrace EFI kit - but had the exact same problem. Tony recommends a 4700uf capacitor installed to the wideband due to the electric distortion in the engine bay of our old cars (ignition components etc). It seems the wideband is sending oscillating voltage readings to the MS which then causes the oscillating idle. After installation (2min job) the oscillation has almost completely disappeared on my car.
I have done this.
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2007 911 Turbo - Not a toy
1985 911 Cab - Wife's toy
1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 06-11-2017, 11:17 AM
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With twin plug, 14 degrees at idle is way too much. Yes it works but the best idle quality and best emissions for example on 964/993 engines come at around 1-2 degrees BTDC. From factory it is around the same (or more closely to 0, it also adjusts idle advance on the fly).

2.2 percent throttle opening is way too much, with idle valve present close the throttle plate completely so that it is closed, and also calibrate your TPS so that MS knows when throttle is closed (TPS 0%) it goes to idle mode.
With idle valve forget about adjusting idle with throttle stop and adjust idle valve duty cycle and PID.
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Old 06-11-2017, 11:59 AM
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Sounds like the programming on your idle valve is not correct.

Use the output test mode and vary the number of steps to achieve minimum idle speed when warm. Note this value because you will use it to set your "warm idle" setpoint.

Then adjust air bypass screw on the TB to slowly bring the RPM to your target. With these cams you should be able to see 750-800 rpm and smooth idle.

As you drop the rpm you will see that your AFR will start to change and your timing will shift. This is because you are moving on the VE and spark table. You will need to tune these areas to keep up with the changing idle conditions.

I agree that 14 BTDC is a lot. With this cam and twin plug you should run much less. Once you have the idle speed fixed you can dial in final timing to get lowest MAP value.
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Old 06-11-2017, 07:24 PM
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Quote:
Originally Posted by Nux View Post
I'm using MS1 and LC-2 wideband with the Bitzrace EFI kit - but had the exact same problem. Tony recommends a 4700uf capacitor installed to the wideband due to the electric distortion in the engine bay of our old cars (ignition components etc). It seems the wideband is sending oscillating voltage readings to the MS which then causes the oscillating idle. After installation (2min job) the oscillation has almost completely disappeared on my car.
NUX - I did put a the capacitor on the +12v feeding the wideband about two weeks ago and it did appear to reduce the oscillation of the AFR signal being sent to the ECU. I also flattened out my VE table around idle and watched the EGO correction as I adjusted the table-this resolved a whack of oscillation issues when fully warm though it idles high at about 1000 rpm.

My remaining issue is a from about 2 minutes after start up to fully warm. Pulling up to a light every young hot head thinks the borderline pre-geezer is challenging them to an off the line sprint. I think it may be partially a function of the older technology of the Accel injectors as another poster has noted, but I'm beginning to think (after a bit of reading) that X-Tau at the warmup stage to fully warm may be at play. When fully warm the fuel injected can evaporate more readily and may not accumulate on the walls; at cold maybe there is some puddling that gets sucked off as globs, spurs an oscillation, more fuel accumulates....and the cycle repeats. Apparently modern OEM systems have X-Tau factoring built into their idle fuel mapping or maybe I'm just talking out my arse. The other issue I have is heavy fuel consumption - part of it is my right foot but another significant part is my mapping.

Like John and many others idle mapping seems to be the major challenge with the system. Making power certainly is not an issue though!
Old 06-11-2017, 08:25 PM
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I see some comments about various correction factors.

Turn all of these OFF until you have a good fuel map, spark table, idle quality, MAT correction, warmup, ect. This includes, EGO corrections, Xtau and any others that your particular EFI system can handle. The corrections will mask issues and errors in your tune. The corrections are designed to enhance transitions in the tune and variations in environmental conditions, not correct inaccurate baseline.
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Old 06-12-2017, 05:24 AM
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Quote:
Originally Posted by dap930 View Post
John,

If you are running MS3, then I would use the Idle VE and Idle Advance correction functions if you are not already so you do not have to change VE values and timing values in the main VE and Timing tables. It is tricky to get a stable idle. Small changes to VE values had a larger affect on idle than I thought when tuning mine. Also, my idle advance varies (when the engine is running close loop idle) between 11.5* - 13.5* depending on load/engine speed using the Idle Advance table values. My idle varies about 50rpm's in Tuner Studio between 950 & 1000rpm's, but I do not see the car tachometer move. My tachometer does not read the same as TS at low rpm's.

It does seem like you may have a vacuum leak somewhere. Have you checked the condition of rubber coupler that connects the two halves of the Carrera manifold?
Hi,
Thanks for the suggestions. Yes, I've checked that coupler, and at all teh various leak sources I could find with starter fluid and no change in idle. I just cant seem to find a leak.
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2007 911 Turbo - Not a toy
1985 911 Cab - Wife's toy
1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 06-12-2017, 06:02 AM
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Quote:
Originally Posted by jpnovak View Post
Sounds like the programming on your idle valve is not correct.

Use the output test mode and vary the number of steps to achieve minimum idle speed when warm. Note this value because you will use it to set your "warm idle" setpoint.

Then adjust air bypass screw on the TB to slowly bring the RPM to your target. With these cams you should be able to see 750-800 rpm and smooth idle.

As you drop the rpm you will see that your AFR will start to change and your timing will shift. This is because you are moving on the VE and spark table. You will need to tune these areas to keep up with the changing idle conditions.

I agree that 14 BTDC is a lot. With this cam and twin plug you should run much less. Once you have the idle speed fixed you can dial in final timing to get lowest MAP value.
Hi JP, thanks for the feedback.

I have eliminated the idle valve as the source. I have disconnected it completely, blocked it off, reconnected it but programmed it to shut and confirmed its closed condition without any change in that oscillating warm idle.

I also dialed the advance way back to 0, then 5, then 7.5 then 10. 7.5 seems the most resilient to the oscillations and VE changes.

I did some smoothing of the VE where I would like it to idle, and throughout the oswcillation range in the table. In fact, I set every cell in the VE table = 41, closed the idle valve. almost closed the bypass screw, TPS to 1.9%, ignition locked to 7.5, and I STILL get the wild oscillation. AFRs stay ~13-14 but it still idles between 900 and 2000.
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2007 911 Turbo - Not a toy
1985 911 Cab - Wife's toy
1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 06-12-2017, 06:07 AM
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