Sudden rough running [resolved] - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-23-2009, 11:27 PM   #21
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Thanks Chad. Yeah though the symptoms point to vapor lock, I am not so sure that is what is going on. I do have a Walbro 255HP pump sitting on the shelf in the garage. I think I will install it tonight.
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Old 04-23-2009, 11:58 PM   #22
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closed loop just makes corrections to the pulsewidths based on O2 feedback (based on AFR target). it doesn't permanently change the map.

open loop injects what's in the map regardless of AFR target.

I plan to run closed loop as a permanent solution once i'm tuned.
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Old 04-24-2009, 12:05 AM   #23
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The ONLY common element I could find is that it only did it when the coolant temp was above about 210 deg F.
The base map has the fans coming on at 85c (185F) and shutting off at 60c. With the fans wired in parallel, I don't think mine's ever run that hot but summer is coming.
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Old 04-24-2009, 12:16 AM   #24
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Yes it is already getting into the 90s here. Plus I was running the A/C.
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Old 04-24-2009, 12:20 AM   #25
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The base map has the fans coming on at 85c (185F) and shutting off at 60c. With the fans wired in parallel, I don't think mine's ever run that hot but summer is coming.
I could have sworn that I changed that. It didn't make sense to have the fans come on before the thermostat was open. I had 93/75 but I just checked and mine is back to 60/85. I think when I got an update from Travis it defaulted back. I'm going to change it back.
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Old 04-24-2009, 12:23 AM   #26
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I raised mine too for the same reason.

That is one of the things I tried changing this evening, lowering the fan set points to where they were basically on all the time. I still had the same problem.
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Old 04-24-2009, 12:24 AM   #27
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how fast are your temps going up?
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Old 04-24-2009, 12:25 AM   #28
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I could have sworn that I changed that. It didn't make sense to have the fans come on before the thermostat was open. I had 93/75 but I just checked and mine is back to 60/85. I think when I got an update from Travis it defaulted back. I'm going to change it back.
Good point - I'll have to change the set points.
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Old 04-24-2009, 12:34 AM   #29
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Back to the original thread, I did some reading on the Adaptronic board and there is a detailed procedure for setting idle that I haven't done. First thing they say to do is zero the max value and adjust the idle by the bypass screw. I've not done anything like that. I've been trying to do it all by ECU.

Here's the thread:

How to tune idle

I'm way over my head when people start talking about open loop idle and closed loop idle when I don't really even know the true difference between the two.
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Old 04-24-2009, 12:57 AM   #30
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Letme email Rob and see what he thinks, there has to be somethign weird going on. Maybe a triggering sensor isn't reading correctly, a long shot could be the adaptronic itself is not functioning properly, but I've never heard of a failure...


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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 04-24-2009, 01:01 AM   #31
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Letme email Rob and see what he thinks, there has to be somethign weird going on. Maybe a triggering sensor isn't reading correctly, a long shot could be the adaptronic itself is not functioning properly, but I've never heard of a failure...
It's gotta be tuning if a couple of us are having the same problem. I was on their board today and there are a lot of threads about idle tuning problems. I think that we just haven't had the "right" procedure. I'm planning on trying the one that I linked this weekend, but I'm still blind leading my blind-assed self.
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Old 04-24-2009, 10:53 AM   #32
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if I ever get mine running, we'll be able to rule out if it's your idle tuning. I plan to let the mazda ecu run idle.
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Old 04-24-2009, 10:57 AM   #33
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Keep in mind this is just not happening at idle, but also at cruise, so I do not think now it is just an idle tuning issue. I drove all the way into work today without changing ANYTHING (I did not install the Walbro) and it ran great. Idle, cruise, WOT, all OK. No hiccups anywhere. I was not running the A/C but I drove the same route.

So far the common element seems to just be the coolant temp when it gets over 205F (96C) or so; this morning it was cool outside, and I did not run the A/C, so the coolant temps were lower. So either there is something in the code that flips out when the temp gets over a certain point, or there is a setting that triggers the rough running at that coolant temperature point. Or it is non-ECU related, like I have vapor lock, or the coils are overheating. But, if it was the coils overheating (and misfiring?), it seems like the AFRs would go down instead of up since there would be more fuel in the exhaust.

Last edited by ZX-Tex; 04-24-2009 at 11:27 AM.
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Old 04-24-2009, 11:30 AM   #34
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Quote:
Originally Posted by TravisR View Post
Letme email Rob and see what he thinks, there has to be somethign weird going on. Maybe a triggering sensor isn't reading correctly, a long shot could be the adaptronic itself is not functioning properly, but I've never heard of a failure...
Thanks Travis.

Speaking of sensor wierdness, I noticed yesterday while sitting in a parking lot trying to figure out what was going on that the MVSS was doing something unexpected. When sitting still, with the car in neutral, if I revved the engine, the MVSS would climb and fall. That is not what I would expect to see, since I thought it is tied to the speedometer sensor input.
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Old 04-24-2009, 11:46 AM   #35
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But, if it was the coils overheating (and misfiring?), it seems like the AFRs would go down instead of up since there would be more fuel in the exhaust.
O2 sensors sniffs just that...oxygen.

Along with the unburnt fuel you also have all the oxygen that didn't combust with the fuel...gauge would read hella lean.
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Old 04-24-2009, 11:55 AM   #36
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^^ Ahhh OK good point maybe you are right. So that could be it. Would it not be strange though for all of the coils, or at least two or three of them, to all start misfiring at the exact same time? I wonder if the wasted spark batch firing (in pairs) could do it. If one misfires, do both in the pair misfire?
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Old 04-24-2009, 03:43 PM   #37
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UPDATE:

Today going to lunch I noticed that the car was running better off idle. Still spiking, but only to the 15's and not stumbling instead of pegging at 17.9 and stumbling. It went this way for a couple of miles. Didn't die at stoplights. On the way home I was fully hot and it died at a light and the lean stumble was back. I didn't have a laptop hooked up so not sure of WT, but it was likely warmer than when I went to lunch. So, maybe more to your temp thing. Could be temp enrichment, coils (for me) or plug wires, but it runs out great after I get past the stumble. I don't know how old my plug wires are, which should be it's own reason to replace them. My coil is 3 years/20K miles old.
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Old 04-24-2009, 05:13 PM   #38
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Hmmm... interesting. That still sounds similar to what I am seeing. So you tend to see the problem also when the car is warmer?
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Old 04-24-2009, 05:28 PM   #39
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Hmmm... interesting. That still sounds similar to what I am seeing. So you tend to see the problem also when the car is warmer?
Definitely yes. The dieing is only when hot. Stumble off idle is less before temps hit 100 the first time. Never put it together until today.
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Old 04-24-2009, 06:06 PM   #40
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Travis have you heard anything back from Adaptronic?

Stein which firmware are you running?
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