I own an 2004 F150 LOBO, (that's because i'm from Mexico) and I have a rare trouble that maybe you can help me.

That's the specs of my truck:

- 5.4 triton
- gibson headers in 3"
- Procomp 6" lift
- Yukon 4:56 gears
- 37x14.5/20 Nittos terra graphler
- 20x9 Helo wheels
- hypertech power programmer III
- 2 chips on the exhaust system (1 on each exit) simulating the converter work, so the computer doesn't detect there are no cathalitic converter.
- K&N filter (complete)

And that's pretty much the modifications of my truck.

The trouble is this :

In the highway, when I take an uphill at 55 mph-75 mph the truck makes backfires (because of missfires) and pulls back many many times, and eventually the truck slows down to reach the 35 mph, if I push the gas pedal to recover the speed level, then a lot of backfire and pulls back are present, making the driving very difficult.

This failure only happens in uphills, when the road is flat there is no problem and there is no missfires or pull back.

I've changed a lot of things, looking for the trouble, including scanning the computer, and there is only the P1000 and the missfire DTC codes, without the specification of what cilynder is working the wrong way.

- The Fuel tank was cleaned
- The fuel pump was changed
- The filter was changed too
- The spark plugs was changed...all !
- The transmission was taking down, and repared all, including the torque converter.
- The injectors was taken to the laboratory, then diagnostics was made, and the report is that all of them are ok
- The 8 coils was changed for new ones
- All the parts are motorcraft, provided by a Ford authorized dealer.


The trouble is present for the last 30,000 miles, the truck have now 60,000 miles, and I'm tired of all the mechanics and all the stuff I've bought to make the truck working well.

Right now, other troubles are present too. The travel computer is making some rare things, like the fuel economy indicator skips from 21-22 liters/100 km to 60-40 liters, and then skips to 3-6 liters/100 km; this kind of behavior happens in a flat road, at the same speed, and without a push of the gas pedal.

Another strange thing happens when I open the switch and crank the engine, the gauge neddles of the gas, temperature and speedometer jumps quickly, and the starter gets slow, like the way it works when you have a bad battery, or a discharged battery. But it only happens one time, when I crank the engine for the second time, there is no slow cranking and there is no jumping needles.

The check engine sign is allways on, when I travel in highway; but when I only drives in the city, without te uphills and at lower speeds, the sign dissapears, and if I connect a scanner, there is no DTC codes reported, WITH OR WITHOUT THE CHECK ENGINE SIGN.

So, that's life with my F150 LOBO truck.

Can anybody help me ?

Thank's a lot.

 

The back fires, missfires up hill might be caused by low octane or the tune you have loaded my require more octane than you have available. Try loading a lesser tune ( one for lower octane) or buy better gas.

 

When I notice the trouble, some changes were done.

I changed the Hypertech to the 83 octane mode, move to different modes and finally the truck is in the stock mode, only changing the gears and tire sizes in the hypertech, so the speedometer can works well with the 4:56 gears and the 37's

I put 92 octane gas every time I fill the tank.

don't think is the gas, maybe something else.

thks

 

Backfiring is usually caused by to much timing, so you might want to look in that area.

 

Backfiring is caused by mixture igniting in the intake, or exhaust.

Common cause of backfire out the tail is too rich thus allowing fuel to light in the exhaust manifold.
Another common cause is timing too retarded, thus allowing ignition while exhaust valve is open.
Since you can not possibly have a cracked distributor cap, or crossed wires due to you having coil on plug ignition that only leaves the tuner as a cause of faulty timing.

Perhaps you should return it to stock, and then clear the memory by disconnecting the battery. Drive it on a test run, ignoring the errors on the speedometer and that will tell you if the tuner is causing the fault.
The maker of the tuner would expect you to have the cats, stock intake etc.
The chips you use to spoof the PCM about the missing cats would be a prime suspect.



Fuel starvation from any of six or seven reasons will cause backfiring on a hill, but again, the back fire is in the intake, not the exhaust.

Too lean can cause backfire in the intake manifold.



However, I suspect the problem is too lean. You are using no cats, which can lean the system a lot, and then you are using a full intake, which can also lean the system.
The chips that falsely report the cats could be the source, or just plain old too lean from the three mods (intake, exhaust, and tuner).

You may want to pull a plug and see what it looks like. Dark and sooty, too rich. Blistered and white, too lean.

Look at the tail pipes and see if they are black and sooty to check for too rich.


Best of luck with it
Chris

 

Thanks Chris,

I've 2 cats working, the truck comes with 4, but the 2 pre-converters were removed when the headers was installed.

right now the 2 cats are installed, and the chips are connected between the cats and the computer, so they're sending to the computer the false signal, assuming that there is a cat working all time.

I've never disconnected the chips, but it's a good idea, maybe this is the problem.

This is going to be the next step, in a few days I'll tell you what's going on.

thks a lot !

 

Hi! Did you fix your truck? What was the origin of this nightmere?

 

Thanks for bringing up a 2+ year old thread.. haha

 

After reading this post, it sounds like his problem was the chips he put in for the cat delete, more pecisely, where he put them. It sounds like he put them on the front set of O2 sensors which is a big no no. The front set is used for feedback to the PCM in closed loop operation to adjust your fuel as needed. The rear set is used to tell the PCM if the cats are there and/or working. He basically put them on the wrong set thus tricking the PCM into thinking the truck was in steady state cruise all the time and when he was under load (such as going uphill) it would backfire.