Inconsistent running and mapping
Discussion
I'm been having an issue for a while where I seem to get the mapping spot on one day and then next time I take out the car it runs differently. The car is a 5.0l with megasquirt for fuel and spark.
For example I had the car out for a good run yesterday with the intention of sorting out the mapping. The car was initially running rich, especially at low speeds and cruise, but was running well higher up the rev range. After a few stops to check the megasquirt logs and autotune results, I leaned out the map across the problem areas and it ran perfectly for the rest of the day.
Today I took the car to work and had the opposite; running lean at low speeds, cruise and a pig to drive in traffic. I didn't have time to make any changes to the fuelling, but did have autotune running which richened up the map in the same areas that I'd leaned it out yesterday.
No sure sure what could be causing this, thoughts so far are:
Stepper motor
Dodgy fuel injector
Fuel pump
Fuel pressure regulator
TPS sensor
Wide band sensor or controller.
Any other ideas before I waste to much time and cash pon the trial and error approach.
For example I had the car out for a good run yesterday with the intention of sorting out the mapping. The car was initially running rich, especially at low speeds and cruise, but was running well higher up the rev range. After a few stops to check the megasquirt logs and autotune results, I leaned out the map across the problem areas and it ran perfectly for the rest of the day.
Today I took the car to work and had the opposite; running lean at low speeds, cruise and a pig to drive in traffic. I didn't have time to make any changes to the fuelling, but did have autotune running which richened up the map in the same areas that I'd leaned it out yesterday.
No sure sure what could be causing this, thoughts so far are:
Stepper motor
Dodgy fuel injector
Fuel pump
Fuel pressure regulator
TPS sensor
Wide band sensor or controller.
Any other ideas before I waste to much time and cash pon the trial and error approach.
angus337 said:
I'm been having an issue for a while where I seem to get the mapping spot on one day and then next time I take out the car it runs differently. The car is a 5.0l with megasquirt for fuel and spark.
For example I had the car out for a good run yesterday with the intention of sorting out the mapping. The car was initially running rich, especially at low speeds and cruise, but was running well higher up the rev range. After a few stops to check the megasquirt logs and autotune results, I leaned out the map across the problem areas and it ran perfectly for the rest of the day.
Today I took the car to work and had the opposite; running lean at low speeds, cruise and a pig to drive in traffic. I didn't have time to make any changes to the fuelling, but did have autotune running which richened up the map in the same areas that I'd leaned it out yesterday.
No sure sure what could be causing this, thoughts so far are:
Stepper motor
Dodgy fuel injector
Fuel pump
Fuel pressure regulator
TPS sensor
Wide band sensor or controller.
Any other ideas before I waste to much time and cash pon the trial and error approach.
I'll add an intermittent vacuum leak to your list, or a vac to your fuel pressure regulator perished hose, or 1000 other guesses because TBH the list is endless, and sadly the issue is not something you're likely resolve over an internet forum.For example I had the car out for a good run yesterday with the intention of sorting out the mapping. The car was initially running rich, especially at low speeds and cruise, but was running well higher up the rev range. After a few stops to check the megasquirt logs and autotune results, I leaned out the map across the problem areas and it ran perfectly for the rest of the day.
Today I took the car to work and had the opposite; running lean at low speeds, cruise and a pig to drive in traffic. I didn't have time to make any changes to the fuelling, but did have autotune running which richened up the map in the same areas that I'd leaned it out yesterday.
No sure sure what could be causing this, thoughts so far are:
Stepper motor
Dodgy fuel injector
Fuel pump
Fuel pressure regulator
TPS sensor
Wide band sensor or controller.
Any other ideas before I waste to much time and cash pon the trial and error approach.
My best advice is (in the first instance) stop trying to find the issue with you're laptop, put the laptop away and go back to basics. Having moved to the Canems system I myself have fallen into the trap of trying to fix everything with the Canems software, in the end I had to have a word with myself and put the my laptop away to go back to basics.
You need to reassure yourself everything is mechanically in order before you try to fix things using your MegaSquirt software.
For example if you did have an intermittent vacuum leak (just one suggestion) you'll never tune the fuelling reliably until it's physically fixed, check your engine breather hoses especially at the 'T' joiner just forward of the plenum.
The oily blow-by vapours that pass through these hoses is very corrosive, they tend to attack and relax the rubber hoses making them go baggy, these hoses are just a push fit, with no Jubilee clips used when they go baggy over time vacuum leaks are inevitable.
These hoses are connected directly to the plenum so with the engine at idle and the throttle butterfly closed are subject to strong vacuum, if the hoses are baggy at the push fit 'T' connector or worse still split you will never be able tune your fuelling effectively to give a consistent AFR.
The vacuum leak idea is just one of many theories so it's not offered as a cure but merely given as an example of how you need to start by putting your laptop away and going back to basics first. You will never fix a fundamental physical issue such as a vacuum leak staring into your screen and pressing keys.
If you do have a vacuum leak you need to get your screwdriver out and fit some Jubilee clips and or fit some new fresh hoses, see... no laptop required
ChimpOnGas said:
I'll add an intermittent vacuum leak to your list, or a vac to your fuel pressure regulator perished hose, or 1000 other guesses because TBH the list is endless, and sadly the issue is not something you're likely resolve over an internet forum.
My best advice is (in the first instance) stop trying to find the issue with you're laptop, put the laptop away and go back to basics. Having moved to the Canems system I myself have fallen into the trap of trying to fix everything with the Canems software, in the end I had to have a word with myself and put the my laptop away to go back to basics.
You need to reassure yourself everything is mechanically in order before you try to fix things using your MegaSquirt software.
For example if you did have an intermittent vacuum leak (just one suggestion) you'll never tune the fuelling reliably until it's physically fixed, check your engine breather hoses especially at the 'T' joiner just forward of the plenum.
The oily blow-by vapours that pass through these hoses is very corrosive, they tend to attack and relax the rubber hoses making them go baggy, these hoses are just a push fit, with no Jubilee clips used when they go baggy over time vacuum leaks are inevitable.
These hoses are connected directly to the plenum so with the engine at idle and the throttle butterfly closed are subject to strong vacuum, if the hoses are baggy at the push fit 'T' connector or worse still split you will never be able tune your fuelling effectively to give a consistent AFR.
The vacuum leak idea is just one of many theories so it's not offered as a cure but merely given as an example of how you need to start by putting your laptop away and going back to basics first. You will never fix a fundamental physical issue such as a vacuum leak staring into your screen and pressing keys.
If you do have a vacuum leak you need to get your screwdriver out and fit some Jubilee clips and or fit some new fresh hoses, see... no laptop required
+1 My best advice is (in the first instance) stop trying to find the issue with you're laptop, put the laptop away and go back to basics. Having moved to the Canems system I myself have fallen into the trap of trying to fix everything with the Canems software, in the end I had to have a word with myself and put the my laptop away to go back to basics.
You need to reassure yourself everything is mechanically in order before you try to fix things using your MegaSquirt software.
For example if you did have an intermittent vacuum leak (just one suggestion) you'll never tune the fuelling reliably until it's physically fixed, check your engine breather hoses especially at the 'T' joiner just forward of the plenum.
The oily blow-by vapours that pass through these hoses is very corrosive, they tend to attack and relax the rubber hoses making them go baggy, these hoses are just a push fit, with no Jubilee clips used when they go baggy over time vacuum leaks are inevitable.
These hoses are connected directly to the plenum so with the engine at idle and the throttle butterfly closed are subject to strong vacuum, if the hoses are baggy at the push fit 'T' connector or worse still split you will never be able tune your fuelling effectively to give a consistent AFR.
The vacuum leak idea is just one of many theories so it's not offered as a cure but merely given as an example of how you need to start by putting your laptop away and going back to basics first. You will never fix a fundamental physical issue such as a vacuum leak staring into your screen and pressing keys.
If you do have a vacuum leak you need to get your screwdriver out and fit some Jubilee clips and or fit some new fresh hoses, see... no laptop required
The only other thing I'll add is if you're running any form of closed loop (fuelling, idle ect) you need to disable it when you're doing your mapping work.
For example you need to get your open loop tune as close to your closed loop AFR target table before you actually reactivate the closed loop fuelling feature, doing things this way ensures when closed loop is switched back on the ECU is only ever required to make tiny adjustments to hit your closed loop targets.
Basically closed loop works best when your open loop map is already as perfect as you can make it, then and only then should switch the closed loop feature back on.
Doing things this way will give you more consistent fuelling and consequently a smoother drive, also look at your closed loop settings, you don't want the ECU adding or subtracting fuel in big percentages or doing so too frequently or you'll find closed loop delivers big undesirable swings in AFRs.
In summary and in all in all cases, the golden rule with closed loop is always the same.....
"less is more"
For example you need to get your open loop tune as close to your closed loop AFR target table before you actually reactivate the closed loop fuelling feature, doing things this way ensures when closed loop is switched back on the ECU is only ever required to make tiny adjustments to hit your closed loop targets.
Basically closed loop works best when your open loop map is already as perfect as you can make it, then and only then should switch the closed loop feature back on.
Doing things this way will give you more consistent fuelling and consequently a smoother drive, also look at your closed loop settings, you don't want the ECU adding or subtracting fuel in big percentages or doing so too frequently or you'll find closed loop delivers big undesirable swings in AFRs.
In summary and in all in all cases, the golden rule with closed loop is always the same.....
"less is more"
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