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1999 Ford Expedition Malfunction - Fuel System
Question: emissions problems, carbon in carb, how to clean, what will keep it clean, what else needs to be replaced to get engine light off(egr switch??)
thanks
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Technican: Do you have the actual trouble code number? IE- P0401
This is important. If you don't have the trouble code no. Autozone or Advance (there are probably others too, call ahead) will check the codes free of charge.
Let me know.
Owner: NO I DON'T HAVE CODES BUT I WILL GET! THANKS
Owner: I HAVE NOW GOT CODES PO401, PO171, PO174, AND PO305
I HAVE REPLACED AIR FILTER, OIL AND OIL FILTER, TRIED TO CLEAN EGR VVE, LIGHT WENT OUT BUT CAME BACK ON, WHAT CAN I DO?
Technican: Sorry for the delay.
First of all, did you clean the egr valves passageway in the intake?
Do you have any other symptoms besides a check engine light? Do you notice a misfire/stumble or a change in performance since the problem appeared?
Owner: I BELIVE THERE IS A MIS FIRE, SO I AM NOT SURE WHERE THE INTAKE IS AND WHETHER I CLEANED IT, THE EGR AND WHERE IT CONNECTS, SEEMED TO HAVE A LOT OF CARBON IN IT, I HAD THE SAME PROBLEM LAST YEAR, BUT PAID TO HAVE IT FIXED, WOULD LIKE TO DO MYSELF, THEY REPLACED PLUG WIRES AND PLUGS, OTHER THAN THAT I AM NOT SURE, I USED CARB CLEANER TO TRY AND CLEAN PARTS.
Technican: Okay, where the egr connects there is a passageway. This passageway can become plugged. A stiff piece of wire is ideal for cleaning the passageway (the idea is anything that you can use to scrape the junk out of the passageway). This may not be the problem, but we want to eliminate it first before replacing any parts.
I will need engine size to give you information on the misfire code (P0305).
When was the last tune-up and how many miles? The remaining codes are for a lean fuel mixture on both banks (or left and right sides) of engine. This can have a number of problems- the most likely causes are-
1. Low fuel pressure (IE- a partially plugged fuel filter) If the fuel filter is overdue to be changed this is a good time.
2. MAF (mass airflow sensor). This sensor detects how much air is coming into your engine. Your vehicles computer (which is actually named a PCM) uses the amount of air calculated by the MAF to adjust fuel mixture. If the MAF is under-reporting the amount of air entering the engine the computer assumes the engine needs less fuel. This in turn will cause the Oxygen sensors to correctly report there is to much air and not enough fuel (this sets the trouble codes). People make the mistake (some mechanics too) of assuming the Oxygen sensors are bad when this code sets. The sensors can and do go bad, but rarely simultaneously. Usually when they both (you have one on each bank) report the engine is lean they are correct.
Let me know.
Owner: ENGINE SIZE 4.6L V8, I WILL TRY THE STIFF WIRE, THE PASSAGEWAY IS IT THE SILVER TUBE THAT HOOKS TO THE BACK OF THE ERG AND DO I RISK CLOGGING IT, OR CAN I SUCK IT OUT WITH A SHOP VAC? THANKS FOR YOUR CONTINUED HELP, FUEL FILTER REPLACED LAST YEAR SAME FOR TUNE UP.
Technican: I will try to find a picture for you in the morning. The passageway should be where the egr bolts on. It comes from the tube, passes through the valve and then flows through the passageway. You could still have a sensor problem, but I'd like to rule this out first.
Owner: WILL DO!
Technican: More information on the MAF sensor for the 171 and 174 codes. Ford claims the sensor must be replaced if there is a problem with. Others have claim to have succesfully cleaned the sensor. Simply spray the sensors filament with a spray can of electrical cleaner. Worth a try before replacement. Also check for any vacuum leaks for this code. A small broken/cracked vacuum hose is common on many fords.
Let me know if you found the egr passageway to be restricted.
Technican: BTW- If the passageway is okay the sensor that overwhelmingly causes the P0401 is called a DPFE sensor."
Owner: where are sensors located!?
Technican: It would probably be easiest if I sent you pictures. If you leave your email address I will send images of the sensors.
Owner: thanks i appreciate your help!
Technican: Check your email.
Owner: OKAY I KNOW WHERE THE MAF IS THE OTHER I WILL LOOK FOR. IF I CLEAN THE MAF AND IT DOSEN'T SEEM TO HELP SHOULD I REPLACE BEFORE DOING ANYTHING WITH THE OTHER SENSOR, I HAVE A 180, 000 MILES ON THE VEHICLE IF THAT APPLIES, WOULD LIKE TO GET RID OF BUT CAN'T, JUST LET ME KNOW WHAT YOU THINK!
Technican: Clean the MAF sensor then disconnect the negative battery cable for about five minutes. Reconnect the battery cable and test drive. Note- This step is to erase trouble codes. This step can also be performed with a scanner. Some Autozones will do this for you. Some are not allowed to because it violates government regulations. In areas where they are restricted from doing so Autozone will loan you the scanner (for a fully refundable deposit) and you can do it yourself.
After the codes have been erased the check engine light will likely stay off for a little while. Within 40-60 miles the light will probably come back on. At this time you will need to recheck the troublecodes. Let me know what troublecodes you have then.
The misfire code (P0305) has not been addressed. It is possible this cylinder has a lean misfire as a result of the lean codes (P0171 & P0174). For this reason we will try to eliminate the lean codes first.
Don't use the battery disconnect method if you have a 'theft lock' radio, etc- unless you have the information to reset. I usually throw this line in just to be on the safe side.
BTW- Are you simply trying to eliminate the check engine light or are you do for an emmissions inspection?
Owner: i am do for an inspection, so i am trying to get it off so i can get it inspected!
Technican: We recently started doing emissions inspections in NY. It really creates a burden for motorists.
Note- As soon as the check engine light comes on you can have the codes read.
Let me know what codes return.
What state are you in? In NY if you fail the emissions inspection you are given a ten day sticker. If the engine light stays off for a couple of drive cycles (this basically means you start with a cold engine and drive up to highway speed and let it sit overnight again...) which typically happens after about 40-60 miles- your vehicle should be ready for the test. The drive cycles allow the computer to run monitors, if the monitors have not been completed it will fail the test.
Owner: I tried cleaning maf, didn't work should i get dpef sensor? truck runs good after hooking negative cable back up, but then starts missing or idling rough again!!
thanks david
Technican: If you still have the P0401- yes it is time to try a new sensor. A scanner is all but required to accurately condemn sensors, but in this case DPFE failure is so common- even it happens to be okay now it in all likelyhood will fail soon enough.
After you install the new sensor, clear the codes and test drive.
If the check engine light comes back on have the codes checked again and let me know. Here's How To Get Guaranteed Solutions In Minutes
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