This topic contains 31 replies, has 2 voices, and was last updated by 
ms2000 2 years, 1 month ago.
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Topic
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1999 Integra LS with 144k miles and Auto, B18B1 – no mods
Well maintained. Due to the random misfire at idle (car shakes too), did the following still an issue:
P0300, P0304 and at times P0303 – now all cylinders
– sparks (OEM), wires (after market)
– front O2 sensor (OEM)
– cap & rotors
– valves adjusted 22k miles ago
– air filter has 8k
– cleaned IACV
– Compression were from 175 to 190
– Spark plugs did not show any abnormality
– Swapped ignition coil but no change
– Batt and Alternator tested fine
– cold start gave gas smell through exhaust
– at times smelt gas under the hood but no sign of leaks
– engine compartment is mostly dry – needed to put new O-ring on Dizzy – the issue started before this repair
– Lately idle misfire goes away when warms up but happens at 2500rom – then misfires on all Cyl
– only known issue is the car would need jump start if you don’t drive for 2 weeks & high NOxFuel Trim:
Originally:
1500 rpm 2500 rpm
LTFT 6.2 6.2
STFT 6.2 8.6After I disconnected the battery and let all the Capacitors discharge at idle:
LTFT – 4.6 4.6
STFT – 7.8 – 12.5Had the car for more than 10 yrs.
Any help? How can I get Eric to reply?Can 87 vs 91 gas or additives cause misfire?
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Replies
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P0171 lean condition
Commonly caused by a vacuum leak
Have you looked at freeze frame data?
Have you performed a proper engine and EVAP smoke test?
You appear to be resistant to actually doing the called for proper diagnostic testing in favor to a parts cannon fix.
I doubt anyone will offer up a course of repair without having a certain amount of proper diagnosing being done.Actually, the shop diagnosed my car for 2hrs – they changed the injectors and the IACV gasket. Beyond that they could not diagnose.
Shop said valve adjustment (which I had it done 20k miles ago) and there is no guarantee that it will fix it. Shop did not have a Smoke m/c. Valve adj cost another $300.Ok,
You started out with a random miss fire and a lean condition.
You state the shop changed the injectors.
They changed the injectors based on what exactly?
Did they perform a flow rate test on the injectors?
Did they mechanically or electronically fail?
Did they perform a fuel pressure test?
Did they check for pressure holding.?
Did they test the pressure regulator?
Another concern…
You state the shop doesn’t own a smoke machine.
This is cause for worry, a smoke machine is a basic, needed tool for testing.
I have one sitting in my basement just for shade tree mechanics on the weekend.
This would makes me wonder about their capabilities to properly diagnose and trouble shooting a vehicle.
On the shop invoice, did it state what and how the diagnostics were done exactly?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.
Injector cleaner is only designed to clean injectors.
It doesn’t add any more fuel to the system.
Just as a reference, your total fuel trim (adding both STFT & LTFT together) should be 10 +/- anymore the ECM may display a CEL.
Here’s some info you might find useful:Will you pass inspection?
Not without all the readiness monitors passing I would think.I’ll say this again.
Without seeing the vehicle, my first thought is a vacuum leak.
You’ll need to have the engine and EVAP system properly smoke tested and a skilled tech to perform the tests.
I’ve seen techs pull their hair out while doing smoke testing.
Some leaks are difficult to see.
I repeated the experiment Scanner-Danner did.
As u can see LTFT step by step increases with time irrespective of RPM – RPM went from around 750 to 1500 to 2500.
As I said before, LTFT comes down when I drive normally. Around city LTFT settles at 12.5. So this does not readily support vacuum leak as supported by Scanner-Danner. If u click the link below image opens on a new page. Some sort of sensors malfunctioning?Unlikely a bad O2 sensor if that is what is displayed.
Unless your map/maf sensor is miss reading.
At this point I still say get a proper smoke test done on the engine and EVAP
Why your so adamant about not going to get it done is beyond me.
Unfortunately, with out starting the process of elimination via testing, you can fire the parts cannon and pay the costs without solving the issue.– The O2 sensor in the photo is the rear one. The takeaway is that FT level didn’t get better with RPM.
– I hear you – smoke test on the engine and EVAP – I will find a different shop and take it there.BTW, Should I ask to diagnose for P0171 or leak via smoke?
– I called around shops and asked if they have a smoke test m/c. Two of then never answered the question. Another might give a time soon. Not sure if he has it either
– I had a used, but newer, MAP sensor – so I swapped it – seems a little better.
– With the newer one, when the car is idling (Closed loop) on Drive gear, MAP is giving higher reading of 5.36psi. If I shifted to Park (still idling), MAP gives lower value, 4.2psi and STFT increases, hence LTFT increases. You can see it in the photo below.
– Does this have anything to do with Idle Air Control Valve? Faulty?– This is soon after changing the MAP – car was resting for just 1 hr. You can see the STFT slowly ramping. The red is the front O2 sensor.
– This issue started soon after vacuum leak on IACV was fixed with a new gasket. Wondering if I should remove the IACV gasket and see if the issue goes away?
https://lh3.googleusercontent.com/_8FEwqOpKaoxI_-2H7rFL9SxHUmqEMzDxGQ4wTkaEF2kyetP8tWi3zz_bhSdLkpCB0obOPhW1yUtTOBUqliigQvAoDyeYRVyHgW78nLr9J5YubfnD24wn32ALveji2UFeBR8B6Lx9xjHVOMn23-CBvAdkYXVcIV0mrH7UzG2GCGWbDr_ZvwAzfhIv2O_wm8v7wqeybgRp_W4VxioyAIVG30qx2M7tr-t6UbhbIqF_wrmlMaCLu7lz__SVB4inTv4bybgCOBcAjeicorCgWGgLDludL1QEER0yOYFcqTzL2Nci8v0CGGkH_l0hdJosv-3pUdINhIUJq_fUO52n29K3_C5BqSGToq3DLpXwxXGBiVPMLsBRWCEktRW4SenuDrJq9rLDiYwfLa1mXa_dWyGhrrKy4UiCtEbHJS8ODuIwzD-g0NTDzBSfz–1g4_LNF_siao6y9mz1qFoJ3exm10y0oJ3rm0aMOKkume2oLmLZTUF0U5_IJek6sTp7rxFDA51wFS2NtkXKmv5RYHut-EtMCyBGDUdIMPywgMKbZeHGZzAXkiJmu7zINZOFtYJhb4mjVwVCFkwABKyqcaNRkkZW18TQRm5dNJcLBi0NBfiWxLsBxcXyWiVMg36OnzvwgIU12aZN3_7ft14IjtDNqTWDMAVm0Ai8YJZGUi7UAEeeDjwHlrCm47RLfBoVeIbKsqhbXTJryx6hEafybUEpLvy1iH=w353-h763-no?authuser=0Just for giggles…
have you checked the intake boot for any signs of splitting or cracks.
Also that the clamps are tight.
One thing you might try is using a propane torch (without the flame)
With the engine running and monitoring the fuel trims go around the engine where any possible leak can occur with the propane.
If done correctly and there is a vacuum leak on the intake side of the engine the propane will introduce more fuel into the engine thus lowering your fuel trims while your watching.
A good test but not 100% accurate.
Another is to spray water around the intake area and listen for the engine to stumble.Are u saying leak on the intake before MAP can also be the culprit?
In this car, the MAP is on the throttle body. Plastic intake doesn’t have a crack but it has a port where a hose from the engine (not PCV) connects which is loose.
Not usually.
But even a cracked or split vacuum hose may cause a lean condition.The problem started when shop put a new gasket to IAC valve recognizing a vacuum leak. The following were done while on Park and Closed loop
– so I loosened the bolts on the IAC (introduced a leak) and watched the FT for over 2 mins (130secs) – LTFT did not increase. RPM had few spikes as per OBDII but did not here a significant engine rev sound.
– After tightening the bolt, it took 50secs for LTFT to increase.Thoughts?
Also lat year P0505 was thrown. I just cleaned the IAC.
I am going to swap the IAC with a borrowed part. If it does not fix, I will be smoke testing.
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