Hey guys, i have a 2001 f150 4x4 supercrew 5.4. 150k. most recently i was driving, and lost alot of power. Engine was shaking whenever i hit the gas, drove it like that about 20 miles back home. Took it to have codes pulled. Had multiple codes... faults on cylinders 1-4. o2 sensor on same bank had no reading at all, and truck was running open loop. I took it 2 dealership to have diagnosed. it sat at dealer overnight. And the next day it wouldn't even start. of course the dealer said i needed new plugs. (i just changed them 10k miles ago) they wanted $300 lmao. So i towed it to my place and started looking into the problems. I have replaced all plugs (oem motorcraft) prior to problem and just put new ones in to be sure they were not fouled. All cops were also changed about 5k ago (uneek ebay coils) I swapped in my old cops to see if the new ones were at fault, and still wont start. Checked all my wiring and connections, including to pcm, and they all seemd fine. Pulled my wires away from ac accumulator. checked fuel pressure and it was 40 psi. Ran compression test with following results

cylinders
1-120
2-110
3-150
4-150
5-0
6-80
7-90
8-60

Obviously i have some major internal engine issues. Also voltage at cop connectors was around 7 volts for cylinders 1-4 and 12 volts for 5-8.

My first question is will the bad compression in the engine cause the truck to not start at all.

And could the o2 sensor or maybe plugged cats cause truck not to start.

I am def not a mechanic, and will appreciate any comments...

Little background... this is my work truck and is constantly towing a variety of trailers


also what kind of $$$ will i be looking at for engine rebuild.. dont really want to let the truck go. as i just replaced all front suspension components (moog). And recently had complete transmission rebuild with shift kit and heavy duty torque converter.

THANKS

 

I would guess head gasket since the whole bank is out. With those numbers I doubt it would run, if it did it would be like crap. Who did the compression test? Was a leak down done after the first test?. Might want to have a hydrocarbon test done on the coolant to confirm a HG. Finding a good used low mileage engine would be cheaper than a full rebuild. You can find engines with say around 50k miles for 1200-1400. If you did the rebuild yourself you could probably save a few bucks, if not, full rebuild (pistons, rings, boring, bearings, gasket sets, oil pump, timing assembly etc...) costs including machining and assembly would be twice that of a used engine.



What were the actual codes, that would help also to figure out what is going on with 1-4

 

i did compression test myself (1st one ever) did not do leakdown test as not sure how or what tools are requiered. will look into it tho

thanks

 

dont have actually codes, as dealership started changing plugs without pulling codes, and they were erased (jack@ss's). truck not showing any codes now, but guessing that because it wont start

 

I believe places like autozone rent the hydrocarbon test kit. Did you follow the procedures recommended for the compression test? If not done properly, results can be wrong. This is Jbrew's write up

https://www.f150online.com/forums/ar...ng-proper.html

All these variables are important. You don't need the auxiliary switch if you have a second person (i believe it was there for a one person scenario?) Setting the gas pedal/throttle plate in the open position is important, it shuts the injectors off so no fuel is being pumped in during the test. Or you, as some have can trip the inertia switch under the passengers side kick panel, that also shuts the pump off. The key is to make sure all the plugs are out, and the same amount of compression strokes are used to test each cylinder. Sometimes its hard to count because with the plugs out, it turns over a bit quicker. So some people will use time, like 3-5 seconds. I doubt you could have gone so wrong that your numbers are completely off, either way you have atleast 1 dead cylinder, and 3 more on the same bank showing well below pressure. The last part of the write up is to help determine the cause of low pressure. Read up

 

thanks will try leak down test and hydrocarbon, and post results

 

With all that, go find a good used engine.

 

junkyards the best place to start looking???

 

www.car-part.com

 

What makes you mention the bad cat? I would think that if you did a compression test with the plugs in (1 cylinder at a time) a plugged cat could throw off the results.

What ever you do, exhaust all the possibilities before yanking the motor.

 

i had these codes
P0351 Ignition Coil A Primary/Secondary Circuit
P0352 Ignition Coil B Primary/Secondary Circuit
P0353 Ignition Coil C Primary/Secondary Circuit
P0354 Ignition Coil D Primary/Secondary Circuit
P0306
and the last one i cant remember but it was the 02 sensor pre cat same side as coil codes
the 02 sensor was reading 0


if that helps... will be working on it all day tommorow

 

Looks like you got some cut wires.

Didn't some one else here have a problem with one side going bad like this. IIRC it was a CHT or something like that.

 

I think it was the CHT sensor, yep.

 

It ran like a bag of snot because the coils on the passenger side were not firing correctly. Check the noise suppression capacitors. Actually unplug them to see if the truck starts. When you did the compression test did you disable the fuel pump? If you didn't you may have washed down the cylinders on the driver side so your test was low. #5 at 0 is either a valve stuck open or broken, a hole in the piston or worn rings. Did you recheck the low side compression with a few drops of oil in the cylinder. This seals the rings and brings the compression back up. You need to remove the valve cover on the driver side and inspect the valve train. Make sure the valves are moving and returning to the closed position. Any mods done to the truck?

 

Where are the noise suppresion capaciters located? I havent got a chance to look at it yet. Got the Flu. I did not disable fuel pump, and am going to and redo compression test. Thanks