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Old 04-22-2009, 03:35 PM   #1
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Default Sudden rough running [resolved]

So a few times I have been sitting at idle, everything is fine, then all of a sudden the engine will start idling very roughly, then die. Revving the engine does not help, it still runs rough then dies. Once this happens, I cannot get it to idle well after restarting the engine unless I completely shut down power (turn key completely off) THEN restart.

Some things that may have triggered it:
1. LC-1 oveheating and throwing a E8 code (sensor too hot). This happened once, but another time when I had a rough idle incident the LC-1 was fine, no error code.
2. Saving a map file to the lap top. I was saving off a map after doing some driving while sitting at an idle. When I hit save, the car did the rough idle right after I hit the save button. When I shut it off and restarted, it was fine again.
3. I thought the rough running might have been due to bad AFRs at idle speeds below 1000 rpm but I think I have that licked.

Anyone have any ideas?
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Old 04-22-2009, 03:41 PM   #2
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I'm battling the same problem right now. One time up to the light, idles at 14.0. Another time it is lower, like 10.X. Another time it will die. You can't catch it with the throttle often either.

I've been working on idle and trying to balance a good lean idle with a richer idle to prevent the tip in problem. I don't know if they are related, but I know I have been trying to idle richer as it does help the tip in a bit. If I could get these two problems fixed, I'd be golden.
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Old 04-22-2009, 03:54 PM   #3
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Yeah I have been enriching the mixture at idle too to keep it from hunting, and to be more stable. Right now I am at about 12:1 with no load (no fans or ac) and about 14:1 with load (fans and/or ac). At first I thought that was it but now I am not so sure.

On a different subject, have you played with accel enrichments yet?
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Old 04-22-2009, 04:12 PM   #4
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Originally Posted by ZX-Tex View Post
Yeah I have been enriching the mixture at idle too to keep it from hunting, and to be more stable. Right now I am at about 12:1 with no load (no fans or ac) and about 14:1 with load (fans and/or ac). At first I thought that was it but now I am not so sure.

On a different subject, have you played with accel enrichments yet?
Crap, I didn't even think about electric load. Sometimes the fan is on, sometimes not. I need to investigate that. I haven't adjusted anything in the closed loop idle control for exta effort for electrical load. I did play with the recovery RPM and I could make it catch the dies but it was a super unstable idle.

I tried to work with the asynchronous settings which, according to the manual, is supposed to be like a power jet on a carb to get it off idle. I've tried everything from 50, to the 100 it was set to, up to 255ms which is the max it will allow and it doesn't seem to change anything at all.
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Old 04-22-2009, 04:45 PM   #5
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I haven't adjusted anything in the closed loop idle control for exta effort for electrical load.
I need to try that. My idle drops 300-400 rpm when the ac comes on. Is it pretty clear in the manual how to adjust it, or did you do something special?

Yeah the fans I have (Spal) add a decent load on the alternator. Idle drops noticeably when they come on.
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Old 04-22-2009, 05:01 PM   #6
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I need to try that. My idle drops 300-400 rpm when the ac comes on. Is it pretty clear in the manual how to adjust it, or did you do something special?

Yeah the fans I have (Spal) add a decent load on the alternator. Idle drops noticeably when they come on.
I haven't done anything with it, but in the IDLE tab, you can adjust extra RPM for electric load, along with extra effort fuel for AC, low battery.

I need to get in there and poke around more myself.
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Old 04-22-2009, 09:22 PM   #7
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Quote:
Originally Posted by ZX-Tex View Post
So a few times I have been sitting at idle, everything is fine, then all of a sudden the engine will start idling very roughly, then die. Revving the engine does not help, it still runs rough then dies. Once this happens, I cannot get it to idle well after restarting the engine unless I completely shut down power (turn key completely off) THEN restart.

Some things that may have triggered it:
1. LC-1 oveheating and throwing a E8 code (sensor too hot). This happened once, but another time when I had a rough idle incident the LC-1 was fine, no error code.
2. Saving a map file to the lap top. I was saving off a map after doing some driving while sitting at an idle. When I hit save, the car did the rough idle right after I hit the save button. When I shut it off and restarted, it was fine again.
3. I thought the rough running might have been due to bad AFRs at idle speeds below 1000 rpm but I think I have that licked.

Anyone have any ideas?
I've had something similar to me happen about 8 months ago. It was right after I had reflashed. I loaded a new map up and when I took it upstairs the the car just fell on its face. Thought I'd popped the motor. I reflashed again, and 8 months later and some 9000 miles, I've never had another hiccup. It seems like the solution to anything weird is to reflash. Once you get a good flash in there are no problems. I have feeling it is only an issue because we are using these USB to serial inputs. If it was straight serial the quality of the flash would probably be better, as something more then likely gets lost in translation along the data conversion that causes the ECU to be unstable.
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Old 04-22-2009, 10:08 PM   #8
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I thought about trying a reflash so I'll do that next. I think there is a new firmware release anyway. I have a straight serial port on the laptop I am using so that should help.

The sudden rough running happened twice on the drive home. No commonality that I could pinpoint. Once was at idle, the other while cruising at 65 in 6th gear.
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Old 04-22-2009, 10:15 PM   #9
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I thought about trying a reflash so I'll do that next. I think there is a new firmware release anyway. I have a straight serial port on the laptop I am using so that should help.

The sudden rough running happened twice on the drive home. No commonality that I could pinpoint. Once was at idle, the other while cruising at 65 in 6th gear.
That blows that theory out of the water. I always thought it was the USB to serial interface... Maybe its the program?? Who knows, but what I do know is that if you reflash it it goes away!
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Old 04-22-2009, 11:38 PM   #10
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OK I reflashed and verified the ECU with the same firmware version you sent out Travis. So far so good. I'll report back in if I still have the same problem. I was datalogging when it went wacky both times today so if I have the problem again I'll look at those logs closely.
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Old 04-23-2009, 12:40 AM   #11
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Speaking of wacky, have you had any time, generally fairly early on when the car is cooler, where it will just stutter/shudder for a fraction of a sceond? Just a hiccup. It can be accelerating, at cruise. It's random. I can feel it, but it really doesn't show up on the datalog as a lean spot, injector issue, MAP pressure, anything...just an anh... and it goes along like nothing had happened.

I'm going to try a reflash as well.
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Old 04-23-2009, 01:33 AM   #12
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Quote:
Originally Posted by ZX-Tex View Post
So a few times I have been sitting at idle, everything is fine, then all of a sudden the engine will start idling very roughly, then die. Revving the engine does not help, it still runs rough then dies. Once this happens, I cannot get it to idle well after restarting the engine unless I completely shut down power (turn key completely off) THEN restart.
I had this happen for a while. I think I figured it out though.
Changed:
Control Band from 300 -> 100
Neutral timeout from 3000 -> 500

Now it idles solidly at 900rpm. I still have some weird warm up issue, sometimes. Overall though it idles much better now. I haven't tried increasing the control band since I changed the Neutral timeout.

At some point I also increased the minimum value to 60 w/o out doing this it would try to idle low regardless of the idle target.
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Old 04-23-2009, 11:33 AM   #13
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Originally Posted by Stein View Post
Speaking of wacky, have you had any time, generally fairly early on when the car is cooler, where it will just stutter/shudder for a fraction of a sceond? Just a hiccup. It can be accelerating, at cruise. It's random. I can feel it, but it really doesn't show up on the datalog as a lean spot, injector issue, MAP pressure, anything...just an anh... and it goes along like nothing had happened.
Yeah I have had that too. I'll watch for that as well now that I have reflashed.
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Old 04-23-2009, 11:35 AM   #14
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Originally Posted by TurboRoach View Post
I had this happen for a while. I think I figured it out though.
Changed:
Control Band from 300 -> 100
Neutral timeout from 3000 -> 500

Now it idles solidly at 900rpm. I still have some weird warm up issue, sometimes. Overall though it idles much better now. I haven't tried increasing the control band since I changed the Neutral timeout.

At some point I also increased the minimum value to 60 w/o out doing this it would try to idle low regardless of the idle target.
I need to try that too. My idle RPM is all over the place from 800-1400 depending on what is going on. Thanks.
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Old 04-23-2009, 01:49 PM   #15
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Quote:
Originally Posted by TurboRoach View Post
I had this happen for a while. I think I figured it out though.
Changed:
Control Band from 300 -> 100
Neutral timeout from 3000 -> 500

Now it idles solidly at 900rpm. I still have some weird warm up issue, sometimes. Overall though it idles much better now. I haven't tried increasing the control band since I changed the Neutral timeout.

At some point I also increased the minimum value to 60 w/o out doing this it would try to idle low regardless of the idle target.
Do these setting have an effect when you're in slow or rapid converge fuel mode or just when in closed loop?
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Old 04-23-2009, 02:18 PM   #16
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I know it works for slow and closed and I'm almost certain it works for rapid as well.
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Old 04-23-2009, 02:23 PM   #17
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Stupid question but, am I supposed to be daily driving in closed loop or open loop? I've been in open loop for the last three days. The way I read it, open loop is for when tuning is "done".
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Old 04-23-2009, 04:50 PM   #18
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You want to run closed loop for daily driving. Open loop ignores the O2 signal.
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Old 04-23-2009, 11:13 PM   #19
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I think he meant while still tuning the map, not once the map is tuned. I ran open loop while tuning the map with the megasquirt.

OK it is still definitely doing the same thing. The flash did not fix the problem. It took me about two hours to get home because it kept doing this popping/hesitation/death thing same as described above. I changed about everything I could think of in the ECU settings, even stuff that did not make sense but tried anyway and it still did it. Coil dwell, air temp corrections, coolant corrections, turned off MVSS, etc. etc.

The ONLY common element I could find is that it only did it when the coolant temp was above about 210 deg F. If I stopped, let the car cool off, it would be OK for a bit, then do it some more once it warmed up again. Every time, the AFRs would go very lean and jump all over the place, like 17-19:1, wild swings between. When the problem went away the AFRs were steady. I checked the logs and it looks like the inj pulse is staying about the same when this happens. So I do not think it is the ECU freaking out and dropping the injector open time.

I suspect vapor lock, especially since this is a returnless system and there is no continuous circulation. Do the 99-00 systems vapor lock?

On the one hand I never had this problem until now. And, though I have seen this before, it was on carbureted engines with low fuel line pressures. I would think with the higher rail pressure a fuel injected system would be less likely to vapor lock.

On the other, the car is making more power so it is generating more heat. Plus I added a fan shroud and the fans are flowing better, thus they could be blowing more heat onto the fuel line. And, it is a returnless system. The only flow for any of the fuel under the hood is what is going through the injectors. At idle or even cruise that is not much of a flow rate.

I searched through old threads on vapor lock and did not see anything on this. I also looked at m.n in the NB forum and saw nothing there.

Oh yeah the same thing happened with the tank nearly empty and the tank completely full.
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Old 04-23-2009, 11:24 PM   #20
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I have never heard of vapor lock on the NBs, not once. Nor have I ever experienced anything like what you're describing. Hopefully these issues don't show face tomorrow when I try to get the car running well. If I come up with anything I'll let you know though I'm still oblivious to everything adaptronic currently. Guess I should start reading.
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