P0171/P1443 Check Engine Light Help

[macd7919]

Hi Guys,

I've been researching this issue and have done the common things but still have this check engine light coming back and am sick of dealing with it. The truck is a 1997 Ranger 4.0L XLT with a manual transmission.

Occasionally it will go off on it's own (last night it went off for example) but it's generally on 99% of the time. Very rarely does it shut off by itself. I also have been getting poor gas mileage this whole time, in the neighborhood of 11-13mpg around town, maybe 15mpg on the highway.

So far I have:

Replaced the MAF with new
Checked for vacuum leaks thoroughly and manifold leaks
Replaced the PCV
Replaced the DPFE

I checked vacuum at the EGR and it seems to be getting a good pull, outside of directly related things I have replaced the filter and also changed all the plugs. Using the scanner I was able to get the following information:

Fuel Sys 1: CL
Fuel Sys 2: NA
Calc Load %: 68.2
Ect (F): 165
STFT B1 %: 6.2
LTFT B1 %: -5.4%
STFT B2 %: 3.1
LTFT B2 %: -5.4
RPM: 1649
Speed: 16

Codes are: P0171 and P1443

Any help would be appreciated, is it possible this is an O2 Sensor issue?

Off topic but the truck leaks fuel from the filler when I fill the tank, not tons of fuel but it definitely drips while the gas is being put in, doesn't drip while driving or once fuel so I'm assuming the filler neck needs to be replaced/patched at some point. Not sure if this would cause a vacuum condition or something but putting it out there so the experts have all the info. Thanks for any help guys!

 

[adsm08]

OK, the p1443 is probably the root of the issue, with the 171 being secondary.

P1443 is basically the system being unable to pull a vacuum on the evap system and fuel tank. If the filler neck is cracked that could do it. IIRC the evap connection on the 97 4.0 is on the passenger side of the manifold, meaning that all that extra air is being pulled in over there, and mainly effecting bank 1.

I would replace the filler neck, clear the codes, and drive it, see if it comes back.

 

[HAPPY+RANGER+GUY]

This will help you troubleshoot. Pretty simple and straight forward little circuit.
http://www.tomshints.com/FordRanger/FR_EPS.htm

The 4.0 setup should be very much the same.

I don't believe the filler neck will help, mine has been leaking for a long long time without causing any codes.

 

[adsm08]

The filler neck is far from the most likely part to cause the issue, you are correct. I'd say a canister vent or purge valve is a far more likely suspect, but the filler neck COULD cause it, and it is a known issue on his truck, so lets fix what we know is a problem, and go from there.

Also, I still think it's likely the two codes are related.

 

[HAPPY+RANGER+GUY]

fuel leaks

Good valid point...fuel leaks should be addressed regardless.....one of these days I'll get motivated for the task...ha,ha.

 

[macd7919]

Hi guys,

So I checked out the link provided above for diagnosing the EGR solenoid and sensor. The solenoid was cycling when voltage was applied but no matter which position it was in you couldn't blow air through it. Got a new one and tested the same way and you could blow air through no problem (when it was in the position for allowing so) and it was sealed otherwise. So regardless that was something that wasn't working and has been fixed.

I also checked the voltage on the EGR flow sensor and it seems to be ok, with it plugged it drops down to about .9V and with it open and pulling vacuum it rises to roughly 2.25V. Just for testing purposes I plugged in a new sensor to compare readings. The new sensor would drop to about 1.2V and rise to approx. 2.6V, since it was close to my original I didn't leave it installed. The delta between the old sensor and new sensor was roughly the same so I would imagine the ecu is able to decipher that there is vacuum or not.

So moving on, as I don't drive my truck very often (less than 75 miles a week on average) I didn't want to reset the ecu and figured I could wait and see if it went off by itself so I would know that indeed the solenoid was the issue. Under normal circumstances about how long should I be waiting? I have put about 80 miles on the truck with 2 or 3 cold starts and some highway driving as well. Should I be waiting a bit longer for it to clear or should I start looking for other issues? Thanks guys!

 

[HAPPY+RANGER+GUY]

Great job with EVAP

Hey keep in mind you're dealing with the EVAP here not the EGR circuits. People get these confused a lot but completely different animal.

You can wait, probably take several start ups for it to extinguish by itself. If you get tired of waiting you could clear the codes and see if anything comes back...or you could perform a drive cycle on it to satisfy all monitored tests and get a quicker answer.

 

[aspevacek]

I fixed a long time random P1443 on my truck by going to the deaerl and shelling out the cash for the purge solenoid kit they sold.

Well after swapping their parts in I decided to toy with the original parts as I had them laying here and I was bored. I noticed that my original solenoid was not closing fully and there was a very small piece of rubber in there that was from the hose that was breaking down. That could very well be the issue you are having with yours. it looked closed and some times it would close full others I am thinking it would stick open. I have not had the code pop up again since I replaced it. so check your hoses to and from that solenoid as well just because they feel good to the touch does not mean they are not stating to break down inside.

 

[macd7919]

Sorry had a brain fart between egr/evap. Well the solenoid was def not working, I've got about 80 miles on it now with 3 or 4 cold starts and the light is still on. What would be a reasonable amount of time/mileage/cold to warm cycles to wait before looking for other issues?

 

[Dune Runner]

Fix the filler neck like adsm08 said. When your truck goes into purge mode it will suck in fresh air through the filler neck and cause the lean condition. I had the same problem due to the vent line on my fuel tank being off. I put it back on and it fixed my problem.

 

[macd7919]

Will probably be a bit before I can fix the neck. When I am able to get to it is it the main portion of the neck (the one that requires removing the bed) or just the too portion that usually causes issues?

 

[Dune Runner]

You will have to check it out. Could be either one. Pulling the bed is the easiest way to do the job. I have seen the complete hose and neck on epay cheap.