PO171 and PO174 mechanic cant fix

[khx]

ok so PO171 and PO174 have been on for about two months now. I have to get inspected so im getting it fixed now. after testing he fine that he has to replace the intake manifold gaskets so he did. Next day the CEL comes on again so i take it back to this mechanic. he checks all lines..no vaccum leaks or nothing, he cleans the MAF sensor and clears code with battery dissconnect to erase keep alive memory. says its good to go. so as im driving it home it sputters a little tiny bit and CEL comes on. i turn around and he says i was going 38 around half load on engine (just to keep anyone aware incase if that helps). says its got to be the MAF sensor is bad. ok so then he clears it, i drive to my house with no problem. drive to my friends house. call autozone..they have one left. we take another car there and i buy it. i go home install it. i drive to a wawa about 20 minutes in car. i get half way..and the CEL light comes on, drives fine but CEL is present. so this morning i take it to him, i tell him i replaced the MAF sensor and it still came on. He take the intake manifolds apart 3 times today, checking it over and over. Says he fog checked the pcv valve system and no leaks. He says there is a small leak from the egr and from somewhere else (i dont remember where). he doesnt think that that would throw the code though. what do you all think. any answers would help please!!!!

 

[CDW6212R]

Make sure that you have 38-42psi of fuel pressure(1998).

 

[khx]

the mechanic said fuel pressure is good. unless they are different for our vehicle maybe? how can you test fuel pressure?

 

[manaen]

there is a schrader valve on the fuel rail that the fuel pressure gauge screws to. you can get a decent gauge for about $30

always test fuel pressure when the engine is cold. This is a lot of pressure in there and some fuel will be spilled when connecting the gauge.

do you have the returnless fuel system ? if so your pressure should be about 62psi

 

[manaen]

Oh the schrader valve is under a blue or green cap depending on the year, and it looks just like a tire valve.

 

[ThePhoenix]

i dont see any mention of the IAC....that fixed mine

 

[ThePhoenix]

My P0171 and 0174 are fixed....thank you guys

try it.....

 

[manaen]

i dont see any mention of the IAC....that fixed mine

the key difference is he says his happens while he is driving, the IAC will only effect the idle rpm range once you put your foot on the gas the IAC is no longer in use

 

[ThePhoenix]

you would think....but if its stuck open...wouldnt you will get a lean condition?

Unless my lean condition was only upon start up and that trigger a code that stayed on....but

I swear it feels smoother during acceleration now that I dont have a stumble....

 

[manaen]

You would if the IAC was unmetered, however the IAC like most other systems flow through the MAF, so the computer know how much air is going in and meters the fuel appropriatly

the only thing the IAC does is provide a computer controlled bypass for the throttle body.

 

[manaen]

I swear it feels smoother during acceleration now that I dont have a stumble....

the off idle acceleration will feel smoother, but once you have your foot on the throttle will have little effect.

 

[khx]

update

well i replaced the gasket on my egr and i replaced the IAC and the light is still on. Also he said the last week or so an engine theft code or something to that effect has come on too. niether of us know what the hell else it could possibly be. any more suggestions please reply.

 

[96XLTRanger]

unplug your negative terminal, put it in neutral, push it off a cliff? lol j/k

that will clear the codes. then drive it and see if it feels better, and if the light comes back on, keep asking for advice

 

[CDW6212R]

What is the fuel pressure, with and without the vacuum line attached?

 

[khx]

unplug your negative terminal, put it in neutral, push it off a cliff? lol j/k

GOOD idea.... i did disconnect the battery before and that was when it came on. the fuel pressure idk much..just whatever the guy told m. He did say that it was at 42psi but idk if that was with or without vac lines or if that was idling or driving. im bringing iot to the dealership tomorrow to just put this to rest. its going to cost me im sure but oh well..i have to pass inspection before the end of the month.

 

[manaen]

42 psi is an interesting number, it is less than the 62psi high pressure system but too high for the 35psi system.

 

[CDW6212R]

The pressure will bu under 40psi with the vacuum line connected. With the vacuum line off(which tells you what is happening at WOT), the pressure should jump to near 40-42psi.

 

[ThePhoenix]

time to get a new mechanic...

 

[winsorcoke]

I'd check that PCV again. Start your engine and wiggle it around and listen for leaks. You also said your mechanic found a couple other things leaking but didn't think it mattered??? If somethings leaking and he didn't want to fix it, find another mechanic.

 

[khx]

F**k

well i just decided to make it easy. i took it to ford. Turns out my MAF that i bought at autozone was bad. BUT it took ford 10 hours to find out that that was the problem. so my bill came out to $1200. They know me so they charged me $825 but still...ten freagin hours to find that the MAF was bad, i mean come on PLEASE. so pissed. So autozone said they will give me my money back. But in order for the dealership to hand it to me they have to charge me a $75 core. So i would end up getting $25 in my pocket..not worth it. But i really think autozone should pay my bill. i wouldnt have had to bring it to ford and get charged this if it wasnt for their bad sensor. let me know what you all think