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2001 f-150 on second replacment engine and still having troubles

replaced engine at 225k miles due to wearing timing chain guides. first replacment had trouble from the start. very rough idle, declining gas mileage, loud valve tapping. after 18 months and replacment of, fuel filter, erg (?), and several other items jasper replaced engine. had to pay labor of 1600. reimbursed for part of this.
now second replacement is having same problems. gas mileage is below 10 mpg, truck idles rough, get valve noise, occasional squeal from front end at idle. and much more than I can write here.
first mechanic turned his back on me and told me that I had done something. second mechanic got frustrated, I cannot afford to keep paying for this kind of gas mileage and certainly cannot sell the truck as having a new engine…
NONE of these things were a problem with the original factory engine. got 380-400 miles per tank. get 230 now.
does anyone have any thoughts?

Did you do this replacement yourself?
Was it a short block or a long block?
Have you verified the valve timing?

each was done by certified mechanics. the second by one referred by Jasper.
it is an 8cyl 4.6
they have checked everything. I think the first mechanic messed up something since the second replacement engine is doing the same thing the first replacement engine was doing. Jasper after getting the first one back said the valves were leaking. (forgot to mention both replacements burn oil and smoke. sometimes when start, sometimes when sitting.) replaced pcv valve on 2nd an smoking stopped.
Also, the engine hesitates sometimes, badly, when I step on accelerate.
all symptoms are much worse in warm weather.

Mileage is 1/2? Original exhaust? Cat?

Do you know if the ECU was reprogrammed for the new engine?

yes. they say they have checked cat and not an issue. plus, this drastic drop in mileage came after the factory engine was removed. I was getting 15-18 mpg around town with the factory engine. it fell immediately with the first replacement and continues with the second.

is it possible that the first guy changed something or forgot to reinstall something or broke something that was supposed to be put back and not part of the replacement?

I was unsure whether your “yes” answer was to cavell’s questions or to my question about the ECU being remapped. ??? That could cause both engines to malfunction in the same ways.

Anything is possible. If the new engine was a “short block” (did not include new heads) the possibilities multiply. Since the symptoms are characteristic of valve train problems (valve timing and valve lash setting), the answer to the question might become more obvious if we knew the answer… short block (not including new heads) or long block (including new heads).


U install identical replacement motor and it runs perfect. Immediately. U don’t say if it ran ok for 1 week and than started idling bad or mileage started to drop. It sounds like it ran ok and never great. And u chased issues for months till shop/rebuilder agreed to replace it to make u quiet. How 2nd motor runs bad is clue something outside of motor is issue.

I will ask. I am not technically challenged. this is just not my area. let me find out on the short/long question. thx.

ECU? what is it and should it have been reprogrammed? Jasper has now sent me to yet another mechanic and like the others they just seem to be shooting in the dark and spending my money

Assuming that the “valve knock” is pre-ignition, I would look closely at the exhaust system for a restriction plus a restriction in the EGR supply.

Of course, I feel somewhat certain that Jasper has had some highly qualified mechanics involved with the shops that have worked on the truck and it amazes me that the problem remains unresolved after all these efforts.

And, BTW, is the engine a V-8, @jeff?------ I see that you posted the engine.

red. this has baffled me for 2+ years now. my factory engine, short of the noise from the timing chain guides, ran like a top, never shuttered. this truck is embarrassing now. EGR was replaced. gas mileage got a little better then fell right off again. also, power is weak. what are your thoughts on the symptoms getting worse in warmer weather?

cavell. that’s what I have been saying. they have had it on the computer multiple times. looked at every line of code. nothing close to even looking like it is going to trip the check engine.
doesnt the catalytic converter trip the check engine? even if the CE light was not working, nothing shows up when on computer.
is is possible that the first guy did something wrong to the exhaust and the second guy just didn’t catch it?

i’ll upload audio of the tapping as well as the squealing.

If no one has yet attached a vacuum guage to the engine and checked for the tell tale signs of a restricted exhaust I would highly recommend doing so, @jeff. And if there is restriction it would be worthwhile to remove the EGR and clean the incoming and outgoing ports.

The ECU is the computer that controls your engine’s operation. It controls the spark, the fuel metering, and… in this case perhaps more importantly… can be monitored to determine problems with things like fuel/air ratio, ignition problems, and spark timing. It also stores “fault codes” whenever any one of the sensors detects a malfunction. Many can be reprogramed for specific engine requirements; I confess that I don’t know if the Ford F150 is one.

Red. thx. am i understanding you to say that even though the egr has been replace that it should be removed to clean the ports coming into it OR are you saying to remove egr and clean in/out ports directly on the valve?

mountainbike. thx. one of the mechanics went over the readout line by line to see if anything might be ready to trip the CE light. did this on a few occasions with no luck. I WILL however ask if the ECU needs to be programmed to new standards for Jasper engines.

I’m assuming the replacement engines are just a rebuilt version of the same Ford engine as the original. If so, first thing I’d do – besides verifying the computer’s (ECM) software is compatible with this rebuilt engine – is insist the Ford scan tool specific for this engine be used. And that a tech trained in its use in real time mode be in charge of the diagnosis. You might have to go to a Ford dealership for this level of expertise. I think it would be cost effective even so.

I guess if I had this truck sitting in my driveway, and didn’t want to take it to a Ford dealership for a proper computer aided diagnosis, I 'd start by trying to simply. Remove unnecessary stuff. I’d disconnect everything possible and that would still allow the engine to run, or at least idle in the driveway. I’d bypass the cat and disable the egr for example, see if there was a way to eliminate the pcv function temporarily. I’d plug up all the vacuum hoses going to unnecessary peripherals like the transmission, HVAC, brake booster, transmission, power steering pump, charcoal canister, etc. I might even remove the alternator and the power steering pump and AC compressor. Then I’d check the compression edit: and intake manifold vacuum readings.

The entire length of the EGR system must be free flowing, @jeff. And the instructions that usually come with a vacuum gauge are quite complete as a rule.

And regarding the valve knock. would that be the sound of rattling a can full of BBs when you wish to accelerate after the engine warms up? And does the engine seem to fall on its face as you try to accelerate above 50 mph?