Diagnosing failing injector/spark on decel with TunerPro.

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JohnDee68
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cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
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Diagnosing failing injector/spark on decel with TunerPro.

Post by JohnDee68 »

I am just wondering on others thoughts about this idea I have.

Using TunerPro logs, i have noticed this and I am thinking it could be significant sign for either a no spark or a poor closing injector.

While in Open Loop, and the O2 sensors are both holding around 20mv (Lean Condition). There are two or three significant spikes to around 600mv (RICH) in one O2 sensor (mine is the RHS). This occurred on rapid decel to 0% TPS.
This makes me think that there is either too much fuel still getting in to the cylinders (for mine being the RHS) from maybe a sticky or dirty injector. OR a no spark condition also on that side of the engine.

Would that be a logical diagnosis? Any other thoughts on that logic?

Also, O2 sensors that are not in phase, is that normal? Like 180deg out of phase at times.
Last edited by JohnDee68 on Wed Sep 08, 2021 7:48 pm, edited 1 time in total.
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Gareth
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Re: Diagnosing failing injector/spark on decel with TunerPro

Post by Gareth »

Could you post the log?
According to chemistry, alcohol is a solution...
JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Re: Diagnosing failing injector/spark on decel with TunerPro

Post by JohnDee68 »

Is a screen shot ok?
Attachments
O2 Spike imbalance - Suspect Injector issues.jpg
JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Re: Diagnosing failing injector/spark on decel with TunerPro

Post by JohnDee68 »

Another screenshot, same log, later on.
Attachments
O2 Spike imbalance - Suspect Injector issues v2.jpg
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vlad01
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Re: Diagnosing failing injector/spark on decel with TunerPro

Post by vlad01 »

No spark will always read lean even if there is lots of fuel as it is not burnt.


Could just be manifold fuel, but is odd how it's only one side. But that said all my engines get a rich spike on close throttle before going lean due to manifold fuel being suddenly boiled off due to the hard vacuum.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Re: Diagnosing failing injector/spark on decel with TunerPro

Post by JohnDee68 »

Ok, thanks for that feedback.
I am suspecting injectors, which I know are a mix of 3 unknown history ones and 3 originals. Yes, originals from at least 2004 when i got the car, with now 506,000km and the third motor they're on.
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