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Something wrong

2K views 17 replies 10 participants last post by  soundu 
#1 ·
So today I dove in to replace the PCV valve and plugs, I was doing this because it had a erratic idle that would happen intermittently and was idling high. So a new Motorcraft PCV valve, new tube and rubbers, new Autolite spark plugs gaped to .050. Replaced the intake gaskets and a new EGR gasket. Started up and idled like it should of, took for a test drive, had a misfire and flashed the check engine light under heavy load but was ok under cruise conditions, returned home and shut it off to check for loose spark plug wires. Once I went to restart it it would catch then immediately die, only way it will run is if you throttle it once it fires but it doesn't run well, misfires, pops and chugs but will die it llf you let off the gas. I pulled code P0171 and P0174 but that could be from before this happened. Anyone have a clue as to what has gone wrong? Seems odd that it was fine then suddenly this happened.
 
#2 ·
Based on the information you've provided, it could be several things. You've also not provided some information eg year and engine.

The codes are lean on both banks. Which means more air than fuel. Since you've taken things apart, you might have not sealed things up correctly and have unmetered air going into the engine.

Your spark plug gap of 0.050 inch is wrong for both the Duratec and the Vulcan engines.

How did you retrieve the codes? If you have access to a scanner then you should be able to pull up other data that can help the diagnosis.
 
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#5 ·
Those codes are also to do with too much air.

Spark plug gap for DOHC is 0.054". Range is 0.052" to 0.056" so 0.050" is not too far off but it will result in weaker combustion.
 
#6 ·
I have done '01 and 3 '-3's. I always take the intake off. Hard to do plugs, wires, coils and such, also PCV best done with the intake off. In the pic, right side see the vertical hose. I have left this off more than once. PCV hose to intake, and to engine can leak. On the back of the intake there is a hose that goes to the EGR solenoid. I have had one fall off the nipple. Check the hoses from the accordion to the valve covers, the rear is hard to feel and check. If ll hoses are OK get a stethoscope and listen for the leak.
-chart-
 

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#12 ·
A way I found my air leaks was took off air intake and put a bag on it after the mass flow sensor to seal up the manifold, than used a vacuum hose to blow cig smoke into engine to see where it was leaking from. If you don't smoke just don't inhale. It took me less than 2 puffs and 30 seconds to find my leaks with smoke.

Or make a DIY smoker. Glass jar with a old rag in it, fill with mineral oil and have a soldering iron sticking in from the top. Put a inlet hose and outlet hose and turn on and wait 5 mins for smoke to start. Use a bike pump or blow into inlet and watch the smoke find any leak in seconds! Good Luck finding them leaks!

Automotive tire Tool Floor Flooring Wood

Build your own smoke machine
 
#14 ·
flashed the check engine light under heavy load but was ok under cruise conditions
Perhaps it has something to do with the other thing both banks have in common: the fuel pressure. Can you drive the car and at the same time check the fuel pressure (parameter 0A = FRP) with a scanner? It should be around 40 PSI. When was the last time the fuel filter was changed?
 
#15 ·
Car is '02 it uses variable voltage equivalent to the pump to satisfy the PCM. It it can't achieve desired pressure it will set a code. Unlike '01.
To confirm vac leak, see fuel trims at idle and at power cruise.
Vac will be high at idle, OK under load. Best be sure you have a leak before chasing it.
-chart-
 
#18 ·
make sure the larger vacuum hose to the brake booster is on and not cracked and leaking. dont ask me how i know....
 
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