jiggly

for the past two weeks my 97 ford expedition 5.4 has been running with a rough idle, on cold starts she will run perfect untill she warms up, once the truck warms up it will idle rough at stop lights or when stopped , when driving it will run perfect, untill i stop at a traffic light.

things i have tried so far,

brought the truck to auto zone, they put it on there scanner and she spit out two codes " PO171 & PO174 " the guy sad these two codes meant my MAFS " mass air flow sensor " was no good, i replaced the " MAFS " two times , and the truck still ran with a rough idle after she warmed up.

the next day i brought the truck back to auto zone for one more test, the same codes cam back, he now said , it was my O2 sensors , i then replaced all 4 o2 sensors, this did nothing for my rough idle.

the same night i asked a friend for advice he recommended i change my " EGR valve" i changed the " EGR " and this did not help.

the next day i decided to have the fuel injectors cleaned, & changed the fuel filter ,this also did nothing for my rough idle.

at this point i am in the hole for some big $$$ and i am also lost on what to do or try next... any advice would be greatly appreciated.

Johnny Mullet

You have a vacuum leak or an intake gasket leak my friend.

jiggly

97 5.4 L Triton ford expedition. rough idle and spiting out codes
PO171 & PO1714 ,spent the last 4 days diagnosing the problem, PVC valve assembly was melted behind the throttle body causing rough idle and multiple misfires, Auto zone had me buying " all 4 -02 sensors ,EGR Valve , MAFS ,vacuum hoses , spark plugs , professional fuel injector cleaning , gas filter. needless to say, after buying all this, none of the above was the problem, it was the PCV VALVE assembly. it was the week from hell !!


thanks for your reply.

wright73

A lot of what I m reading sounds like my 01 expedition is having. I have replaced maf, o2 sensor,pcv, and a couple of vacume hoses . Could it be the hose going from pcv the the back of intake? I know that this part is a dealer item do you get the hose from the pcv to the back of intake? there is 2 elbows one @ pcv and 1 @intake right? if this is the problem great I am not looking forward to changing the intake gasket

jiggly

Go to your local ford dealer , tell them you need the PCV VALVE assembly, total cost should be no more than $20.00 , go back home and install it your self, total install time should be no more than 2 minutes.

PS you will notice th elbow closest to the intake will be week or melted.. that's what is causing your rough idle.

wright73

So this should take care of problem? if not what else could be doing ti?

jiggly

yes.....post back & tell us how she runs.

dwidacki

We dealt with the rough idle for the last 3 months dumping a lot of $$ into the truck with no results. It was checked out by both private mechanics and dealer mechanics with no results. I read somewhere that o'rings could be the problem. So, this weekend, my husband and neighbor changed out all the o'rings on the injectors and guess what? IT'S RUNNING LIKE NEW AGAIN!!!!!! It is so smooth I hardly know it's running. Good luck. Hope this helps.

97Xbox775

Ok, so i have a 97 xbox, i have a rough idle, and a shutter @ 1500-2200rpm. Igot a p0304 code, replaced cop, plug, and injector. still runs a rough however, no codes are coming up on the reader.... checked the vacuum lines near the fire wall. wondering if any one had ideas to help, im at wits end. ha