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Purchased this truck for my son ($1,000). He will start driving soon and I aim to surprise him with it this week, pending I can get it to run right.
On initial test drive the truck idled extremely rough and stalled when decelerating toward a stop sign. Stalled again after grabbing reverse to return the truck. Stalled again in neutral coasting back to owner's residence. All of this happened within 4-500ft. Truck was warmed up for 10 mins during my pre-trip inspection.
Went home to mull it over and read through these threads for potential fixes. Decided to buy it. Drove it home the following day and noticed the truck had a serious lack of power from 1200-3000rpm in 2nd gear, then it took off like a scalded dog after 3000rpm. Truck died 3 times during trip home, but idled in driveway when I arrived.
Pulled CEL codes:
P0113 - IAT high voltage
P0171 - System Lean
P0302 - Cylinder 2 misfire
P0304 - Cylinder 4 misfire
After the talk on the threads and the codes, I replaced MAF, air filter, plugs, Intake Air Temp sensor, and did an oil/filter change. After all of this the truck would start, jump to 1500rpm and then stall/die. I ended up throwing more parts at it they are as follows: Idle Air Control Valve (took old one off to clean it and the valve was caked with gunk. After cleaning, the valve would shift side to side as I rotated it in my hand. Spring was not operable...), EGR solenoid on passenger side, throttle position sensor, fuel pump... no change. Truck still started and died after dropping down from 1500rpm. Truck would respond to pressing the throttle, but would buck as it climbed in rpms. Would not maintain rpms and would eventually fall to 700rpm and then die.
After all this I checked inertia safety switch, all fuses, and then chased vaccum lines. Found one broken going to heater control. Ended up replacing all vac lines (truck has heat now!). Following the vaccum debacle, I did a spark test on all 8 plugs, they were good.
Then I did a fuel pressure test:
Key on Engine off=40psi(+/- 2)
Truck started= 63psi.. after truck was off it held 40psi for the remainder of the day.
Compression Test (dry): tested with stainless 45° tube and tapered rubber nose. Hose and plug fitting would not slide past shoulders of fitting to catch threads....
Decided to put old MAF on to retrace my steps and the truck started, idle significantly improved, and truck drove without dying. However, the idle is still not great and that last compression being low is very concerning. No CEL codes on the drive this evening. Had truck running for 30 mins. Tested head gasket with blue/yellow fluid over rad catch tank and it didn't indicate any leaks.
What do I do to figure out this compression issue and get the idle corrected? Cylinder 4 in my scenario is closest to firewall and I might not have got a good seal on plug hole during test, but the value was repeated, which leads me to believe that its accurate. I apologize for the book I typed, but I felt that giving the most information was the best opportunity to get an answer. Any feedback will be apprecaited!
Last edited by Bjatchsn; 01-04-2021 at 12:40 PM.
Reason: Change title, fix some values in text
It's too late now but you should always start with the compression test. But anyways it does look like #4 is a major issue. 1 and 3 are not the best. Did you do a wet test on 1 and 3? And you may want a different tester. Make sure it is the one that threads into the plug hole. If your not getting accurate results that is as bad or worse because you are chasing a problem that may not even be there! Remove all plugs from exhaust side and make sure you have a strong battery when doing the test.
Looks like at least a head / valve job and if #4 is correct you may be rebuilding the whole thing.
It's too late now but you should always start with the compression test. But anyways it does look like #4 is a major issue. 1 and 3 are not the best. Did you do a wet test on 1 and 3? And you may want a different tester. Make sure it is the one that threads into the plug hole. If your not getting accurate results that is as bad or worse because you are chasing a problem that may not even be there! Remove all plugs from exhaust side and make sure you have a strong battery when doing the test.
Looks like at least a head / valve job and if #4 is correct you may be rebuilding the whole thing.
I did not do a wet test on any other cylinders. The threaded plug hole fitting will not make it down far enough to catch the threads. The shoulder on the fitting hits the head before it can make contact with the recessed threads.
I just completed a leak down test 5 minutes ago and can actively hear and feel air rushing out of the exhaust. None in coolant, oil fill, or coming out of intake. This is assuming I have found TDC on cylinder 4. My original thought after the wet compression test was a bad valve or cracked head. Now I am leaning towards an exhaust valve.
Can someone confirm the process of the combustion? Firing order is 1342 and there are two "TDCs" in the 4 strokes.... Intake, compression, combustion, exhaust. Both valves should be closed on both TDCs? Plug fitting.
I did not do a wet test on any other cylinders. The threaded plug hole fitting will not make it down far enough to catch the threads. The shoulder on the fitting hits the head before it can make contact with the recessed threads.
I just completed a leak down test 5 minutes ago and can actively hear and feel air rushing out of the exhaust. None in coolant, oil fill, or coming out of intake. This is assuming I have found TDC on cylinder 4. My original thought after the wet compression test was a bad valve or cracked head. Now I am leaning towards an exhaust valve.
Can someone confirm the process of the combustion? Firing order is 1342 and there are two "TDCs" in the 4 strokes.... Intake, compression, combustion, exhaust. Both valves should be closed on both TDCs? Plug fitting.
I had a recorder when I did it the first time and I didnt check the notes when I posted originally. This has verified the original compression test. The first results listed above were incorrect.
Completed a leak down test on all cylinders as well. Cylinder 1: No leaks at all
Cylinder 2: Slight hiss and airflow out of tailpipe
Cylinder 3: No leaks at all
Cylinder 4: Active hiss and extreme airflow out of tailpipe
This leads me to believe that exhaust valves are not seating or something is hindering their ability to close/ function.
I would assume the next step is to pull the valve cover to ensure all components are in their respective places. If so, I'll move on to the head and do a valve job.
I am concerned with messing with timing as I have no experience in getting something back in time. While I'm in there should I just replace the head? Rockauto offers complete head, assembled with all gaskets for $400-500 after core charge. Or do I just replace valves? Should I go ahead and hit the timing belt/ water pump replacement too?
I had a recorder when I did it the first time and I didnt check the notes when I posted originally. This has verified the original compression test. The first results listed above were incorrect.
Completed a leak down test on all cylinders as well. Cylinder 1: No leaks at all
Cylinder 2: Slight hiss and airflow out of tailpipe
Cylinder 3: No leaks at all
Cylinder 4: Active hiss and extreme airflow out of tailpipe
This leads me to believe that exhaust valves are not seating or something is hindering their ability to close/ function.
I would assume the next step is to pull the valve cover to ensure all components are in their respective places. If so, I'll move on to the head and do a valve job.
I am concerned with messing with timing as I have no experience in getting something back in time. While I'm in there should I just replace the head? Rockauto offers complete head, assembled with all gaskets for $400-500 after core charge. Or do I just replace valves? Should I go ahead and hit the timing belt/ water pump replacement too?
Not sure about your area but I contacted a local machine shop I used when I was building racecar engines (Only place I trust) and the cost to do everything with new valves was about $85 more and a 2 week lead time than what I got off the internet from a machine shop that had really good reviews and came with the same 1 year warranty.
I also replaced the timing belt, water pump, and serpentine belt. No sense in putting old parts back on!
You need to pull the valve cover to inspect the valve train but you most likely need to remove the head.
Not sure about your area but I contacted a local machine shop I used when I was building racecar engines (Only place I trust) and the cost to do everything with new valves was about $85 more and a 2 week lead time than what I got off the internet from a machine shop that had really good reviews and came with the same 1 year warranty.
I also replaced the timing belt, water pump, and serpentine belt. No sense in putting old parts back on!
You need to pull the valve cover to inspect the valve train but you most likely need to remove the head.
Had a ford mechanic friend bring his computer out tonight. Ran it through several tests and found a major vaccum leak. We didn't chase it down with any spray. I don't recall the actual value, but he said a leak that large would be discoverable during tear down. The relative compression test confirmed my findings and even corrected my improvised compression test technique. Cylinders 1 thru 3 were all within 1% of eachother hovering around 150psi mark. Cylinder 4 was 25% of the others. From that test and my findings on the leakdown, his professional opinion thinks it is either a "tuliped" or recessed exhaust valve. After pulling the intake side plug on cylinder 4 he noticed unspent fuel showing the cylinder rarely fired if at all....
Next step is tear down. I will post my findings on here. I will also list the avenue I chose, either doing a valve job here, sending it off to a shop, or ordering a remanned pre-assembled head.
I'm trying to get a list together for the job. I'd assume an entire gasket set from top of block up to throttle body, head bolts, vaccum line (in case I break or crack any during dissasembly), timing belt, serpintine belt, water pump, t-stat....?
Had a ford mechanic friend bring his computer out tonight. Ran it through several tests and found a major vaccum leak. We didn't chase it down with any spray. I don't recall the actual value, but he said a leak that large would be discoverable during tear down. The relative compression test confirmed my findings and even corrected my improvised compression test technique. Cylinders 1 thru 3 were all within 1% of eachother hovering around 150psi mark. Cylinder 4 was 25% of the others. From that test and my findings on the leakdown, his professional opinion thinks it is either a "tuliped" or recessed exhaust valve. After pulling the intake side plug on cylinder 4 he noticed unspent fuel showing the cylinder rarely fired if at all....
Next step is tear down. I will post my findings on here. I will also list the avenue I chose, either doing a valve job here, sending it off to a shop, or ordering a remanned pre-assembled head.
I'm trying to get a list together for the job. I'd assume an entire gasket set from top of block up to throttle body, head bolts, vaccum line (in case I break or crack any during dissasembly), timing belt, serpintine belt, water pump, t-stat....?
Yes to all this. ^^^^^
Keep us posted with what you find and pictures always help if possible.
Soooo that was a nightmare. I do not like working in tight spaces like that, very frustating. I attempted to removed the head by taking the least amount of parts off as possible. Needless to say, that didn't pan out.
After pulling the head, I believe I verified my original thoughts of a "tuliped" exhaust valve on #4. The first picture is of valves on #4. The exhaust valve is seated but there is an air gap around the entire thing. Picture 2 is of cylinders 3&4 for comparison on valve seating. I also found a hairline crack between intake and exhaust valves on #4, that is picture 3. Picture 4 is another hairline crack between valves on cylinder 1.
I feel that I properly diagnosed with the help of this forum. However, I did have an additional issue with timing. Pictures are attached of oil gear and cam gear. Oil gear lined up and matched the tick mark on harmonic balancer/ timing cover. The cam gear did not. It seems as if its one tooth advanced. When I put it all back together, should i replace it how i found it or do i line up cam gear with marks?
I'm having trouble finding a head. Rock auto is saying my VIN is invalid and Oreillys is way too expensive for my taste. Thermostat bolts are 6mm. Any suggestions with that? #4 exhaust valve air gap 3&4 for comparison Crack between valves on #4 Crack #1 Oil gear timing marks Cam gear 5 o'clock timing marks not lining up Cam gear 12 o'clock timing position at 12:30-1 o'clock, not lined up.
Thanks for the update. Good catch on the cracks too.
Check ebay for a replacement. That is where I got mine. I forget the user but it was about $500 for the complete head.
01-03-2021
