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Reply To: Random misfire on Acura – and seems mysterious

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Part 1:
– Shop diagnosed a IACV (idle air control) vacuum leak. When this was fixed with a new gasket, P0171 symptoms started while it is also misfiring.
– Shop properly diagnosed and figured one of the 4 injectors was Mechanically bad. Previously they all passed ohm test. No flow test. Moved injectors around to see misfire moving with it.
So all 4 were changed with reman Honda injectors from a lab.
– Shop also tested for fuel pressure with and without regulator – all were good. I saw with my eyes Pressure gauge was connected with and without the regulator and the engine was running – all normal including pressure being held.
– Does Redline injector cleaner send more fuel to injectors?

Part 2:
– Car was released to me and I had it idle a lot before changing oil – resulted in P0171
– Took it back to the shop and he tested as per the manual: Fuel Pressure, O2 Sensor (he did say somewhat slow at times – NTK O2 is new), EVAP purge solenoid. The next step is adjust valve followed by replace injectors (again)
– We wanted to think about it so took the car away.

I have been driving around without P0171 – IM Monitor is still not ready on EVAP yet – I let the gas to empty and filled it half way today. 6 out of 7 on IM is complete/ready.

It looks to me when it idles on D4, trim (FT) is not surging – but it surges on Park which eventually triggers P0171. Symptoms might have lessened but I am cautious.

When I drove on Freeway with AC on, LTFT increased to 14 from 7. It has come down to 12.5 around city.

So again, idling on Park gear causes P0171.

If I were to take it to another shop, I need to ask them for a specific diagnoses – which one are you recommending? The shop was busy to write up diagnosis so I only have the CC receipt. They are buying time to give the diagnosis report to me.

Also, am I safe to go for SMOG in California (San Jose area) despite this lean condition? Last time it failed due high NO – HC was low so were others. Just the NO was high once at 25mph and later at 15mph. By this time misfire developed.

  • This reply was modified 2 years, 7 months ago by ms2000 .
  • This reply was modified 2 years, 7 months ago by ms2000 .