First time posting, hope this works. I've changed the 02 sensor, PCV, gas cap, had a smoke test done and changed the air filter. I know the gas cap, air filter and PCV probably weren't the problems, but they were cheap and what the heck. Fuel filter has never been changed gonna do it this weekend, and gonna take fuel pressure. How do you provide vacuum to the evap purge control solenoid from the intake manifold side

 

To provide vacuum you can either run the car or use a mighty vac. In order to open the purge solenoid you need to supply a 12 volt source to the two pins on the solenoid.

Do you have any drivability issues with your car our just the DTC?

To test an oxygen sensor you really need a graphing meter or a lab scope. While observing the sensor voltage you introduce a hydrocarbon fuel source such as propane and watch for an increase in sensor voltage. Remove the propane and create an air leak, watch for the sensor voltage to decrease.

Did you replace the sensor with OEM or did you use a cheap aftermarket sensor?

A fuel filter which is clogged enough to cause a p0171 would likely cause a drivability problem as well. Nerve seen one clogged enough to cause either.

 

Yeah, I replaced my sensor with original OEM part. It has a little bit of a rough idle, it feels like a vacuum problem, but the smoke test found nothing. It drives fine, has good power and don't have any hesitation problems. I've been reading it could be a fuel injector problem, it might be leaking, or clogged. Have seen some videos of cleaning them myself, I'm really leaning towards it being the FPR, but I don't know. Just put $1600.00 into it with it's third timing belt, and some other stuff. Would really like to fix it myself. Thanks for your answer, I appreciate it.

 

Bring the vehicle up to operating temp and let it idle in Park. You should have close to 20 in of vacuum. You can measure that with a mighty vac plugged into a vacuum line that is not used during idle such as the EGR line.

If your vacuum is low, that would indicate a vacuum leak.

You could also measure the voltage at the MAP sensor. You should see around .9 volts at hot idle in park with no vacuum leaks. A vacuum leak will decrease vacuum and cause the voltage to increase.

It's almost impossible to confirm a clogged injector without removing the injector with the rail and watching the spray pattern.

You can use a graphing meter and watch the current ramp of the fuel injectors to make sure they are operating correctly, electrically.

A 5 gas analyzer ( smog shop ) can tell you the exhaust output composition. Enter the numbers from the result into a lambda calculator and the answer will tell you if the vehicle has a vacuum leak or if it is not getting enough fuel. Then you will know to either look for a lack of fuel such as a clogged injector or if you are looking for a vacuum leak.

Regardless, P0171 DTC's are a prime example why master technicians should be compensated well.

 

Thanks dude. Gonna take it to the shop, changed the fuel filter which cleared the lean code but now I'm getting an EGR code. Tired of messing with it. You were right about the master techs

 

The shop ended up replacing my fuel filter, which took them 1.5 hours. Glad I didn't try to do it at home. It cleared the lean code P0171, but now it has a P1491 and P0170 which I didn't find anything on the P0170 code. I read the P1491 is a EGR insufficient lift. My question is why didn't these codes show before the filter was changed.

 

Did you check the vacuum hose that you unplugged while taking a vacuum reading?Make sure the vacuum hoses are all properly routed and in good shape.The simple thing you can do is remove EGR valve and make sure the port is free(one that goes toward the manifold).If you have a vacuum pump,apply vacuum to EGR vacuum port and make sure it holds the it.By the way,did the lean code (P0171)went away?

 

Yeah man the lean code went away. Took the EGR off last night, and cleaned it with MAF cleaner (get conflicting reports on what to clean things with) and replaced the gasket, had a little build up on the EGR but both ports were pretty clean. All the hoses seem to be routed correctly. I just applied the vacuum to the EGR, and the vacuum held. I started the car, and applied about 18 in of vacuum and the car stalled.I don't know if the P1491 is still there though, still has a bit of a rough idle. I'm hearing it might be that circulation chamber under the fuel rail (not sure what it's called). Thanks bro

 

After clearing all codes ,the ECM has to run the monitors to trigger the codes (if malfunction is present) but if conditions have never been met the monitors wouldn't run so it will never detect the codes.I think conditions to trigger the EGR are: cruise at 90Km/hour for 5 minutes ,decelerate to 50km/hour (with no throttle ) ,do it for 3 times(just to make sure).This should trigger the monitors to run and if there is any codes related to EGR system it will illuminate the MIL.

 

hey man, the light came on again this morning. Had the veh maint guys at work put there scanner on it and it says I have code P1491 (insufficient EGR lift), and P0171(Lean condition) . It originally failed smog with the 0171, I changed my 02 sensor, air filter, gas cap, and had the Fuel filter replaced. The shop said the 0171 went away after changing the filter, but it wasn't a honda shop and generally felt like they didn't wanna touch it after changing the filter. I kind of think the lean code is fuel injector related but not positive, don't have all kinds of scan equipment. I am gonna change the EGR gas chamber filter and clean out my injectors this weekend. Lean could be the fuel pump too, and really don't wanna get involved in that. It has no sputtering or stalling problems and has good power. Other than a little bit of a rough idle it runs fine. Sorry for the book, but just trying to give as much information as possible. Am gonna try to check the fuel pressure also. It would be nice if it was just the FPR, thats an easy fix. Thanks for any help, appreciate your quick responses

 

Hoe about a tune up on your car?Cap ,rotor ,spark plugs,wires?Now for insufisient flow.There should be a solenoid for EGR vacuum supply.If the solenoid is start to seize up inside even when commanded to open it can't.Another thing ,check the solenoid's electrical line and make sure it gets the signal from ECM(I think the ECM controls the ground side of a circuit).

 

You don't have knowledge or diagnostic equipment. Both are required to efficiently diagnose your car. You have two options, take your car to a real technician or keep guessing and replacing parts until it its fixed.

 

No need to be insulting. I'm sure I don't have as much knowledge as most of you, but how did you get it. Training or hands on right. Well, I'm trying the hands on right now, I'm gonna try a couple more things and then take it in. Thanks for the advice I already new