I picked up a 2002 f-150 5.4 today and was told it needs 4 coils as its running ruff

Well I hooked up the scanner and it is giving me codes P0102 P0353 and P0113

I can tell from looking these up that it does need a coil but its Also giving me the codes for the MAF and IAT, so I got out the test light and I have power going to the MAF sensor harness but not to the IAT sensor harness

So Before I start replacing stuff, How can I figure out why there is no power to the IAT harness

Appreciate the help, Truck is in great shape, trans and motor were rebuilt 50k miles ago and being a truck in Michigan there is hardly any rust

 

The IAT is integral with the MAF.

https://www.f150online.com/forums/ot...ml#post3109931

I'd probably replace the MAF and clear the codes. Swap coil #3 with another and see if the code moves, if not there's a connector or wiring issue to #3. #3 is 3rd back passenger side.

 

is there supposed to be power going to the harness that plugs into the iat?

 

Well I found one of the coils not plugged in all they way. That took car of that code, but the truck still is running rough to say the least

At idle it’s not bad out when you go to drive it and give it gas it seems to stumble and sounds like a exhaust leak but the exhaust has been replaced.

It did sit for a few months, so could it be bad gas?

I rechecked the codes and now I am only getting the code for lean bank 1.

I checked all the hoses and vacuum lines and they seem to be ok.

Could it still be the maf sensor even though the code is gone?

 

Could be bad gas or dirty injectors, throw a couple bottles of Techron in the tank and fill it up with fresh gas. Change the fuel filter.

I'd pull the spark plugs and look at them, may need a new set. Use Motorcraft platinums, torque to ~28 ft/lb.

 

Well I found the bank one o2 sensor unplugged, so I fought like hell and got it plugged in

Ran a half of can of sea foam thru the brake booster vac line and half a can in the gas tank

It did smooth out the idle some, but as soon as I try to drive it the truck it still runs like crap. If I have it in park I can rev it up to 4000 rpm and its smooth like it is running perfect, but just at idle or driving it runs really really ruff

I ran codes and one keeps coming up and then going away p1131

So I am starting to think its fuel issue, pressure regulator, fuel filter or ??

I sprayed wd-40 around all the vacuum lines and everything was good. The best way to describe it is it runs like there is a major Vacuum Leak but no leaks are found

Thanks for the help

 

The P1131 is for that O2 sensor you found unplugged.

 

The code comes on, I reset the codes and it goes away but still runs the same

 

Change the fuel filter. Use Techron in the gas, NOT Seafoam.

With the engine off, disconnect the vacuum line from the FPT, if any gas drips out replace the FPR. If it's good, reconnect the vacuum line and hook up a fuel pressure gauge to the rail. Start it, 28 psi minimum, with it running disconnect the vacuum line again, pressure should rise at least 5 psi.

Inspect the PCV elbow behind the intake for cracks and mushiness.

Inspect the spark plugs.

 

The pcv behind the intake? Is it the one on the back of the TB?

 

Follow the pipe back from the PCV valve.

 

You got a truck with unknown issues.
If it sat so long is an indication the last owner could not solve the issues with this and that unlogged and ??????.
Multiple issues always confuse when thinking of only one issue.
You need more than just read the codes.
Code 102 and 113 are wire harness issues open and grounded. Then may be a parts issue after the circuits faults are cleared.
Each time you make a change, the issues won't clear instantly except for the coil not being plugged up.
A look at the long term fuel tables will tell you if the system is running too rich or to lean. May be a vacuum leak causing that.
This eliminates a lot of time end expense in solving each cause of a multiple cause situation.
Each time you do a code clear , the computer is re-booted into a full set of self diagnostics that clear all tables and delays and may cover up still existing issues untl driven long enough for them to show again. This is the value of looking at live dsaa with a Scanner to what is going on.
You got someone elses troubles so have to approach it from all and any points until all are solves.
May be old gas involved that will not clear very fast, added to it all.
Good luck.

 

The guy I bought it from was doing the work and had a heart attack a few months ago and stopped doing the tune up.

I did notice that it seems like there is a exhaust leak where the exhaust flange bolts to the manifold, that wouldn’t be a issue would it?

Im going to replace the fuel filter and add some of that textron stuff someone else mentioned.

Overall the truck is in great shape for a 20 year old michigan truck so I would like to get it running correctly.

I did disconnect the battery so it will clear any codes and memory so I will start fresh in the morning.

I do appreciate the help and advice, I am not one to not acknowledge the help!

 

Yes, an exhaust leak before the O2 sensor can cause mixture issues.

 

The Ox sensor will detect an exhaust leak before it's location in the down tube pipe and treat that Air the same as a Vacuum leak top side the engine. It does not know the difference. At certain RPM and exhaust gas speeds passing by the leak will draw inwards and not always a pressure outward.
It shifts the Long Term Fuel Table for that bank RICH trying to account for the extra air. This causes a rough idle and an imbalance between bank tables the computer detects and knows is not correct. It is written into the software.
If the power is disconnected to clear those tables, the engine may run and idle smooth if there are no other faults >until< that table shifts RICH again Then the roughness comes back after enough time has elapsed for the table to shift during drive cycles.
This is the value of using a Scanner to take a look at those tables and what they do.
Its a learning curve that is long and why parts cannot just be replaced to clear issues so easy.
Good luck.