Mechanical Problems

does it have an air inlet temp gauge. did you check the timing.back fire is very bad on a fuel injection system.if you cant check the timing go to a parts store that will hook the diagnostic tool . this will show you your timeing. a bad knock sensor will advance you timing and not turn on the check engine light,but will come up with i think code p0380 ? on the tool. i think it would have been cheaper to just buy a new truck

I did check the timing and I've even had a mechanic work on it and he could not fix it. It seems to be a fuel problem it's running too lean.At low end RPM's it backfires and it runs good at high RPM's. I think you may be right about the new truck.

At the risk of sounding condesending, why did you do all that? For the cost of all those parts you could have bought a high dollar code reader that would have diagnosed the problem. I'm old and weak so I pay my mechanic to fix mine, but it's newer. I wouldn't know where to find any of that stuff anyway.

You might want to check some of the Ford forums, but we do have some good mechanics who hang out here, so just wait for them to get back from the lake.

Good luck.

I did buy a code reader and the code reader showed codes on everything but the TPS sensor and fuel pressure regulator. If the engine didn't have but 40,000 miles on it (which I bought new) I would junk it.

What is the average compression of all cylinders? Is there one cylinder that has very low compression?

listen for a wining noise at idle in the front of the engine,(not the type from the wife). if the timing ,belt ,chain or adjuster is very warn it will have play in it at low rpm,as soon as you put a bit of tq on it,it takes up the slack.at low idle the timing could be variable do to the warn parts. had this on a Pontiac grand am.how many miles do you have on it. also there is a lot of time a way to get to the adjuster without much problem.

Are you sure you don't have a vacuum leak anywhere?

One of the more insidious places to have an air leak is the fuel injectors. The 'O' Rings get hard and don't seal so good. You can test this by squirting some WD spray (WD40,RP7) or a cheap aerosol degreaser (that uses Kerosene as its main constituant) around the interface of the Injector and the inlet manifold while the engine is running. If there is a leak the wd/degreaser will get sucked into the manifold. The engine may stumble a bit but at least you know where the leak is. Injector 'O'Ring replacement kits are cheap and easy enough to do.

You can also spray wd around the interface of the inlet manifold and the heads infact anywhere there is a gasket/mating surface to see if there is a leak.

I take it that when the engine gets warm it runs ok? That'll be because the engine management is compensating by enriching the mixture due to seeing the signals from the EGO sensor. While in cold start mode its just working from the "Open Loop" map without any ability to compensate from the "Lean" situation.

Earlier fuel injection systems had a "fifth" injector to enrich the intake during startup and cold operation. Your F150 doesn't have that as the engine management system enriches all the injectors by a preset margin until the temp sensor cuts in when the engine reaches operating temperature, it then takes and processes the signals from the MAP(MAF)/EGO sensors.

Try the spray see how you go.

Hi Tobugrynbak,

I believe you are 'spot on'. In my opinion, you are a brilliant diagnostician.

There could be a leak between the inlet pipes and the engine head.

'Disgusted Ford Man' should not despair. The solution could be as simple as described by Tobugrynbak.

unusually when the injector o rings go bad you can smell a light whiff of gas when you walk by the vehicle. did you check the plugs for color,even after you changed them and drove it a bit.did you take it to ford ?? did you check if there is a TSB on it.You can go on f150.com and ask,or search.

Id look at the possibility that the timing chain is shot and if this one has plastic gears that it jumped a tooth. That causes all sorts of grief, you would need to pull the valve cover and confirm the valve position against the crank pulley index mark to get a check of it. Woody

no need to pull the valve covers.put the engine on TDC on the compression stroke. pull the distributor cap and make sure the rotor is pointed exactly towards the number 1 cylinder,you can mark if just below the cap. i do not see how pulling the valve covers would tell you squat.also they usually do not run if they jump time.. now if you pulled the timing chain cover and lined up the timing marks and the rotor Wasnt pointed at TDC that would tell you.i have not heard of an engine with a timing chain jumping time since they did away with the synthetic gears. now a timing belt is another thing.

I could be wrong because I've never owned one, but I believe your engine uses pushrods. The cam is directly driven of a gear on the crankshaft, therefore there is no timing belt or chain. This would rule out any belt/chain slippage concerns.

Also things like a bad MAF sensor or ignition coil could give you rough acceleration, low power, bad MPG's...without triggering the engine light.

Many newer engines also use the thermostat (or another temp sensor) to trigger a cold start tune. This cold start tune doesn't utilize the MAF or O2 sensors to modulate A/F ratio, but instead uses a generic rich tune until the engine warms up. I'm not sure how this could generate your issues though.

The F150 uses a Windsor V8. The Windsor uses a Hivo cam chain which unless the engine has been poorly maintained is good for over 500,000km. The Winsor V8 has a non interference type valve arrangement. It is a pushrod engine of mature design, with a reputation for being long lived (at least in Oz).

When the chain gets worn they will slap around a bit and will cause erratic timing. But it has to be a really high milage motor for that to happen.

There are aftermarket twin roller cam chain gear sets and gear drives available but the gear drives are not recommended for daily driver use. They are very noisy, and are only suitable for (ultra)high performance applications, not F150's.

The OP has a tuning issue but it is most likely a vacuum leak not anything "mechanical".

Do a compression test. Sounds like an intake valve is not seating.

Check your idle air control. I have a 1989 Ford Truck and had the same problem. Changed the idle air control and the problem was fixed.

all standard,conventional American v8 engines use timing chains,and all have push rods,what do you think goes between the cam and the rocker arms.today you can buy noisy or quiet gear drives. if a timing chain is very loose it is a matter of time before it wears a hole in the side of the timing chain cover. I can see you guys have money and never have had the pleasure of fixing your car at 2 am so you could get to work the next day.

With all due respect, I am a busted arse radio mechanic. As a result I can't afford to take my cars/trucks/bikes to "The Man" to get it repaired, and when I do I usually have to repair the repair..

At the risk of trotting out the "when I was a lad" cliche's. I have effected many a makeshift get me to work/home/wedding on time repairs in my time.

I have owned over 60 vehicles in my 30 odd years of driving and been involved with thousands more in one way or other. Yes I have also worked as a motor mechanic.

My vehicles have been as simple as a 58 split screen Kombi, a 2 cylinder 2 stroke 360cc Daihatsu Carry van, to the more pedestrian(if you can call V8's pedestrian) 302/351 Windsor/Cleveland powered Falcons, Fairmonts, Fairlaines, Landau's and F100/350's. I've had exotics like the 78 2litre twincam Alfa Romeo Alfetta, A stove hot 69 Mk2 Cortina GT with twin SU's and a wild 1600 Kent motor, as well as a Classic 86 SAAB 900 Turbo. Now in my fleet I currently have a 88 Volvo 740 gl 8V, 89 740 16V twincam, a 78 Landcruiser HJ45 diesel, a Peugeot 405 SRDT diesel, a Peugeot 205 Si, and a GM Holden VYII V6 S Ute. All of which I tend to, on a regular basis for maintenance and fettling.

I might also add that I've never owned a new car. I've had them as company cars and what a royal pain in the arse that can be. All responsibility and no authority. Always at the mercy and behest of bean counters and dealership mechanics...

This motor (per the OP) reportedly has only 40,000 miles on it which is barely run in by Ford V8 standards unless it has been seriously mistreated. It should have at least another 300,000miles before anything is really out of sorts like the timing chain. Unless of course it has not had regular maintenance. I've put hundreds of thousands of miles on Ford V8's with just good regular maintenance.

As for the Idle Air Control valve, if its full of gunk then you can clear it out with some Kerosene based degreaser or Carburettor cleaner. This is a common problem on Bosch Electronic Injection cars but usually it wont idle at all if this is the case (of it being gunked up).

I had the same type of symptoms on a 94 GMC. The timing was off. Had the timing set and everything worked fine after that. If the timing is computer controlled, you need to make sure that the computer control is disabled prior to setting the timing. A good Chilton's or Haynes manual should tell you how to accomplish that. It's usually better to perform a complete diagnostic check prior to wholesale changing of parts.

IAC

I have checked the PCM voltage to the IAS solenoid.I have checked the ohm's of the solenoid and they showed within limits. I have cleaned the valve itself.Everything checks to be okay on the IAS.I am leaning toward an intake vacuum leak or a bad computer.Thanks

Guest comment #20 is mine I forgot to log in (new at this).I have been using a Hayne's manual.

"I have been using a Hayne's manual."

Yup, that explains why you are now here..

I have replaced the plugs,plug wires,distributor cap,TPS sensor,EGR valve,power steering switch,fuel pressure regulator,02 sensor and checked for vacuum leaks,and changed ignition module,

I have some push rods for a 350 Chevy, and some Oldsmobile rocker arms. They will not make your truck run any better than the rest of the parts you have bought so far, but I could sell them to you cheaply, and you can save time by not in stalling them. At least I could come out of this with some cash.

Or, you could stop guessing, and test. Compression test will show the sealing of the piston rings, head gaskets, and the valves. It will also check the valve timing. Have you done that. When reading codes in the computer, write down the codes, and then erase them, then repair any new codes. Do you have access to a vacuum gauge? There are more things that can be diagnosed with a vacuum gauge than I can remember off hand.

Stop throwing money and parts at it, and test. Or send me the money for the push rods and rockers. $3 each. Take your pick.

You said that you were getting a backfire is it through the carb or tail pipe.

I would be looking for a bad lifter ( not pumping up) or push rod that has worn/bent or have a worn lobe on the cam. All will affect your timing when cold depending on which it is.

The bad lifter not pumping up will give you the same effact as a stuck valve or partly closed valve. The push rod that is bent may bind in the cold, and the worn cam will/ can give you the same as a stuck/partly open valve.

You can check your rocker/push rod actions by using a timming light on them.

There is a fuel diagnostic valve.With the truck running a cold startup, does a fuel pressure gauge attached to the fuel pressure diagnostic valve read the required 35-45 psi.required ? Does the fuel pressure increase when vacumn hose on fuel pressure regulator is disconnected ?