Can I tune away this problem?
Jul 17, 2020, 10:34 AM
#16
EvoM Community Team Leader
Scavenging does not apply on the specific case, gasses or oxygen from the leak are not drawn from, they are forced frontwards/outwards. Scavenging would apply much later down the pipeline of the exhaust system. But still even if there is oxygen drawn into the pipe by a leaking gasket it will not affect the o2. You can actually try it if you want actual first hand evidence. Just loosen up the bolts of your o2 housing a bit so that a thin piece of paper can be squeezed in there and then start the car. You will notice no difference in idle. You can also do the same by removing one pipe of the sas system i.e on the exhaust manifold, or the bolt if you have removed the system, you will also notice no change in idle, but you will notice the extra sound frequency and pitch.
Marios
Marios
Jul 17, 2020, 10:46 AM
#17
Evolved Member
No worries on that but I haven't challenged anything, I merely stated facts. Well if you wish to turn your assumptions into facts you can try what I mentioned earlier.
Also the honda guy, must have had a sensor on its way out or his problem was something else, such as the sensor not being completely tightened up, if he removed and re-bolted the sensor as there is no way his cracked manifold changed idle afrs. Besides oxygen leans afrs it does not make them richer.
I'm sorry but that is not something I will believe.
Marios
Also the honda guy, must have had a sensor on its way out or his problem was something else, such as the sensor not being completely tightened up, if he removed and re-bolted the sensor as there is no way his cracked manifold changed idle afrs. Besides oxygen leans afrs it does not make them richer.
I'm sorry but that is not something I will believe.
Marios
Last edited by Evo8cy; Jul 17, 2020 at 10:50 AM. Reason: typo
Jul 17, 2020, 10:56 AM
#18
EvoM Community Team Leader
No worries on that but I haven't challenged anything, I merely stated facts. Well if you wish to turn your assumptions into facts you can try what I mentioned earlier.
Also the honda guy, must have had a sensor on its way out or his problem was something else, such as the sensor not being completely tightened up, if he removed and re-bolted the sensor as there is no way his cracked manifold changed idle afrs. Besides oxygen leans afrs it does not make them richer.
I'm sorry but that is not something I will believe.
Marios
Also the honda guy, must have had a sensor on its way out or his problem was something else, such as the sensor not being completely tightened up, if he removed and re-bolted the sensor as there is no way his cracked manifold changed idle afrs. Besides oxygen leans afrs it does not make them richer.
I'm sorry but that is not something I will believe.
Marios
the mixture reading lean would lead to a positive fuel trim as the ecu would add fuel to compensate for what it thinks is a lean condition.
Jul 17, 2020, 11:17 AM
#19
Evolved Member
It seems that you did not understand what I said. The o2 feedback will be lean and since the ecu will compensate, the actual afrs will be back to normal, and will not be richer, and so if you use an afr gauge you will see that the afrs are how they are supposed to, stoicho-metric i,e, or whatever your tuner set them up to be. So idle condition and operation of the engine will not be affected.
This only happens though when there is a big opening on the exhaust system, otherwise the o2 sensor is not affected as it only needs a small amount of gasses to function properly. A very small leak does not dilute the amount of gasses coming from the engine. Or during winter time where the exhaust gasses contain increased amount of un burnt oxygen molecules, since the inlet air is denser in oxygen.
And yes I do say so. Now whether you agree with that or not, it really makes no difference to me.
Marios
Last edited by Evo8cy; Jul 17, 2020 at 11:27 AM. Reason: typo
Jul 17, 2020, 03:36 PM
#20
OP,
It can be tuned out, but as a temporary solution you could increase your idle speed using the BISS and see if it helps keep the car running when coming to a stop. It's likely an issue with what the gents are discussing above with too much fuel being dumped in.
It can be tuned out, but as a temporary solution you could increase your idle speed using the BISS and see if it helps keep the car running when coming to a stop. It's likely an issue with what the gents are discussing above with too much fuel being dumped in.
Jul 17, 2020, 06:16 PM
#21
Scavenging does not apply on the specific case, gasses or oxygen from the leak are not drawn from, they are forced frontwards/outwards. Scavenging would apply much later down the pipeline of the exhaust system. But still even if there is oxygen drawn into the pipe by a leaking gasket it will not affect the o2. You can actually try it if you want actual first hand evidence. Just loosen up the bolts of your o2 housing a bit so that a thin piece of paper can be squeezed in there and then start the car. You will notice no difference in idle. You can also do the same by removing one pipe of the sas system i.e on the exhaust manifold, or the bolt if you have removed the system, you will also notice no change in idle, but you will notice the extra sound frequency and pitch.
Marios
Marios
Jul 18, 2020, 12:13 AM
#22
Thanks for all of the feedback, everyone. So it turns out that I went with the simplest approach first, which was to clean my garage and leave the Evo idling for 20 minutes. After doing that, it idles great at stops. Steady RPMs and doesn't die on me anymore. Fingers crossed.
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AllanL (Jul 22, 2020)
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