Strange noise high RPMS , power issue
10-09-2018, 09:15 AM
#103
Mazda still cant find any air leak. They say they have checked whole engine bay and exhaust system. Mechanic said he used some kind of spray which will identify a leak by hearing change in rpms.
Since LTFT is clearly fluctuating when i rev the car, could it be clogged fuel lines? Im not sure they replaced injectors and fuel line when i got new engine back in 2011, i do have new fuel pump though replaced 2 months ago.
Since LTFT is clearly fluctuating when i rev the car, could it be clogged fuel lines? Im not sure they replaced injectors and fuel line when i got new engine back in 2011, i do have new fuel pump though replaced 2 months ago.
10-09-2018, 09:32 AM
#104
It's really difficult to say more without having access to the car and to the sensor data. It's possible that the MAF sensor is incorrectly measuring airflow, and the car is compensating with LTFT, but any mechanic worth his salt should be able to figure that out on his own. I'd bring it for a second opinion somewhere.
10-09-2018, 09:39 AM
#105
Maf was already replaced. LTFT fluctuates so much, sometimes its at 3% and it will push to 1% when i rev, other time its way up at 15-18%, like wtf. There is no other qualified dealer in Norway...Mazda HQ recommend this dealer for fixing the problem.
Last edited by kanie12; 10-09-2018 at 09:43 AM.
10-09-2018, 10:55 AM
#108
The important info is rpm, MAF rate g/sec, AFR (aka lambda), Calculated Engine Load, STFT and LTFT.
Also did they reset the computer after replacing the cat? It might still be remembering long-term fuel trims it learned while the cat was in bad shape. They should have reset it and force it to relearn.
10-09-2018, 11:17 AM
#109
Registered
What is the altitude you are at in Norway? High altitude could account for high percentage of long-term fuel trimming. That said, logically, it'd be leaning the mixture, not increasing the fuel delivered, so Loki's thought on a vacuum leak may be true. Could also be a weakness in the fuel system or sensor issue.
-Go back to a stock airbox for now, many aftermarket intakes can negatively impact IAT, and MAF reading accuracy. The only exceptions are the AEM/MS or RacingBeat.
-If you don't trust the forward O2 sensor, it is an expensive but worthwhile wear item to replace every 5yrs or 50k miles.
-You may want to use a bore scope camera (crappy ones that'll do the job are cheap on Amazon) to peak inside the rear O2 sensor port and see if the cat structure is damaged. Mine looked fine from the forward inlet but showed damage to the rear cell structure, odd but possible.
-Fuel system should be checked as well. Look for leaks (external and internal), fuel pump and regulator maintaining pressure goals, etc. If the injectors aren't working properly, one or more of them could be dumping more fuel in than requested.
-Go back to a stock airbox for now, many aftermarket intakes can negatively impact IAT, and MAF reading accuracy. The only exceptions are the AEM/MS or RacingBeat.
-If you don't trust the forward O2 sensor, it is an expensive but worthwhile wear item to replace every 5yrs or 50k miles.
-You may want to use a bore scope camera (crappy ones that'll do the job are cheap on Amazon) to peak inside the rear O2 sensor port and see if the cat structure is damaged. Mine looked fine from the forward inlet but showed damage to the rear cell structure, odd but possible.
-Fuel system should be checked as well. Look for leaks (external and internal), fuel pump and regulator maintaining pressure goals, etc. If the injectors aren't working properly, one or more of them could be dumping more fuel in than requested.
10-09-2018, 12:56 PM
#110
Fully warmed car idle; then fully warmed up car 4000rpm steady cruise, then fully warmed up car wide open throttle pull in 2nd or 3rd. But if it goes to 15-18% on a different scenario, definitely record that scenario.
The important info is rpm, MAF rate g/sec, AFR (aka lambda), Calculated Engine Load, STFT and LTFT.
Also did they reset the computer after replacing the cat? It might still be remembering long-term fuel trims it learned while the cat was in bad shape. They should have reset it and force it to relearn.
The important info is rpm, MAF rate g/sec, AFR (aka lambda), Calculated Engine Load, STFT and LTFT.
Also did they reset the computer after replacing the cat? It might still be remembering long-term fuel trims it learned while the cat was in bad shape. They should have reset it and force it to relearn.
Last edited by kanie12; 10-09-2018 at 01:03 PM.
10-09-2018, 01:11 PM
#111
Registered
Awesome, to hear it is back to a 'good' baseline for troubleshooting. I am sorry for the misunderstanding; I only read the first and last pages of the thread.
For comparison from my car: It trims quite a bit (I've seen 15-20% in some cells) as well despite being in good working order, though it is now running at an avg. altitude of 7,100ft above sea level. The MAF is clean and reads within expectations for a stock car with stock calibration, the fuel injectors were cleaned and flow-tested, all solenoids were tested good, all intake valves cleaned and confirmed as working, all new seals, coils are Mazda 'C' revision with 30k miles on them, new plugs and wires, engine is a Mazda reman making great compression after break-in, and I placed a vacuum on my intake tract to assure no leaks. The only sensor I'd question on my own car is the forward o2 sensor due to age, but I've not experienced any other oddities in power delivery, responsiveness, or fuel economy.
Again, logically trims should lean at high altitudes, but on both my RX-8 and on my '16 Miata, I saw enrichening at altitude.
For comparison from my car: It trims quite a bit (I've seen 15-20% in some cells) as well despite being in good working order, though it is now running at an avg. altitude of 7,100ft above sea level. The MAF is clean and reads within expectations for a stock car with stock calibration, the fuel injectors were cleaned and flow-tested, all solenoids were tested good, all intake valves cleaned and confirmed as working, all new seals, coils are Mazda 'C' revision with 30k miles on them, new plugs and wires, engine is a Mazda reman making great compression after break-in, and I placed a vacuum on my intake tract to assure no leaks. The only sensor I'd question on my own car is the forward o2 sensor due to age, but I've not experienced any other oddities in power delivery, responsiveness, or fuel economy.
Again, logically trims should lean at high altitudes, but on both my RX-8 and on my '16 Miata, I saw enrichening at altitude.
Last edited by furansu; 10-09-2018 at 01:34 PM.
10-09-2018, 03:29 PM
#114
Heck maybe that's in play in Kanie's problem. Maybe the BARO is lying or is blocked, so it's learning very strange things.
10-10-2018, 05:37 AM
#115
Fuel trims map on calculated load, which itself depends on delta between ambient pressure (via BARO) and standard sea level temperature and pressure. So it's possible that it learns to enrich because a particular combination of ambient pressure, temperature, rpm and base map results in lean operation.
Heck maybe that's in play in Kanie's problem. Maybe the BARO is lying or is blocked, so it's learning very strange things.
Heck maybe that's in play in Kanie's problem. Maybe the BARO is lying or is blocked, so it's learning very strange things.
10-10-2018, 12:15 PM
#117
So i checked the connection for the baro sensor and wires, just pushed and straightened out wires and, look at the sudden change in LTFT(video) Sadly after i restart the car, numbers went back to previous levels. Not sure whats causing the problem.
10-12-2018, 10:32 AM
#118
Fully warmed car idle; then fully warmed up car 4000rpm steady cruise, then fully warmed up car wide open throttle pull in 2nd or 3rd. But if it goes to 15-18% on a different scenario, definitely record that scenario.
The important info is rpm, MAF rate g/sec, AFR (aka lambda), Calculated Engine Load, STFT and LTFT.
Also did they reset the computer after replacing the cat? It might still be remembering long-term fuel trims it learned while the cat was in bad shape. They should have reset it and force it to relearn.
The important info is rpm, MAF rate g/sec, AFR (aka lambda), Calculated Engine Load, STFT and LTFT.
Also did they reset the computer after replacing the cat? It might still be remembering long-term fuel trims it learned while the cat was in bad shape. They should have reset it and force it to relearn.
Correction it did go down to zero eventually and threw a CEL, but no difference in LTFT. Whats this other baro?
Last edited by kanie12; 10-12-2018 at 12:49 PM.
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