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Autel Maxidas DS808 Short term fuel trim oscillates
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4 years 6 months ago #33854
by Noah
"Ground cannot be checked with a 10mm socket"
Autel Maxidas DS808 Short term fuel trim oscillates was created by Noah
Is the short term changing between 4 and 14 just sitting at idle in closed loop with the accessories off?
Could you please include the code definition for p0037? It just makes it easier for everyone reading.
Thanks Monde
Could you please include the code definition for p0037? It just makes it easier for everyone reading.
Thanks Monde
"Ground cannot be checked with a 10mm socket"
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4 years 6 months ago #33857
by Chad
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
Replied by Chad on topic Autel Maxidas DS808 Short term fuel trim oscillates
The oscillation of the downstream sensor is what is causing the P0420. The downstream should be fairly steady, and slightly RICH.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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4 years 6 months ago #34297
by The_Floss
Replied by The_Floss on topic Autel Maxidas DS808 Short term fuel trim oscillates
I did some digging on Infinity's DTC setting criteria, and it looks like to throw a P0171 and P0174, you need to be in closed loop at cruising speed, and the ECU compares the reading to a previous benchmark from an old trip.
Link: Infinity DTC Criteria
I can't attest to the accuracy of that list, but it seems reasonable to me.
Link: Infinity DTC Criteria
I can't attest to the accuracy of that list, but it seems reasonable to me.
The following user(s) said Thank You: Monde
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4 years 6 months ago #34338
by Tutti57
Replied by Tutti57 on topic Autel Maxidas DS808 Short term fuel trim oscillates
Did you have to fix anything? I'm curious what your Alpha was while this was happening, if you noticed?
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4 years 6 months ago #34359
by Tutti57
Replied by Tutti57 on topic Autel Maxidas DS808 Short term fuel trim oscillates
In the sense that it is an immediate response. Since there isn't another trim, like long term to reset a baseline, I feel like it's more of just a total trim. Stoich is 100.If a car with a vacuum leak comes in, it will be like 120 but drop down closer to 100 with some RPM, liked you'd see with fuel trims.
I'm still used to using global obd2 fuel trims but am giving in to the enhanced data, since it's the make I work on daily.
I'm still used to using global obd2 fuel trims but am giving in to the enhanced data, since it's the make I work on daily.
The following user(s) said Thank You: Monde
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4 years 5 months ago #34436
by Tutti57
Replied by Tutti57 on topic Autel Maxidas DS808 Short term fuel trim oscillates
So they do use something sort of like long term in a PID called self-learning. I think it's described as being used if the trimming is outside of the Alpha trim range. I think the highest Alpha is like 125, so it might have pegged out there and also show up under self-learning. I have just been looking at Alpha though, since it seems to give all the info you need on the current mixture.
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4 years 5 months ago #34467
by Tutti57
Replied by Tutti57 on topic Autel Maxidas DS808 Short term fuel trim oscillates
No problem! I read about that information in the Nissan/Infiniti OBD2 training manual. I haven't gone to school for that class yet, so if I do and learn that I misunderstood any of that, I'll update the info here.
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4 years 5 months ago #34491
by Tutti57
Replied by Tutti57 on topic Autel Maxidas DS808 Short term fuel trim oscillates
Yes, especially with so many cars using A/F sensors now up front. All of the Nissans use them, so I expect to get a lot of experience with them.
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