Can you tell me what all has been done at this point to correct the problem please?
If you are haveing a problem with cyl8 then the cyl you need to be checking will be the back cyl on the drivers side, not the passanger side.
Yes drivers side. Two separate mechanic diagnostics based on check engine light codes and in one case additional testing including replacing the coil.
Perofrmace is good but obvious misfire at idle and at times when driving. Strange thing is the check engine light does not show much if not most of the time.
Also NO obvious catalyst issues so far - inspection report good. Would like to know what might progressively occur, assuming this is a valve issue?
Have you had a compression test done ?
Yes the testing was extensive.
And, Hi and thanks for responding
DO you know what the test results where for the compression test? Where all 8 cylinders tested?
No I do not recall at this time. The vehicle was teated by the dealership, my local machanic (family business) and also an engione specialist, the latter doing the extensive testing. I know plugs and coils were also replaced during testing. Each shop come to the same conclusion - cyl 8 exhaust valve.
That makes things kinda tough.
I would realy like to know what the compression readings where before I give any possible solutions for this problem.
The readings would tell me more about what is going on in the engine.
I see. I did not see your further comment. Is there potenmtially another solution to replacing the head. And can the condition deteriorate; or if all else seems well, to be run as is.?
There again it depeds on the comp readings. If the compression test shows the cylinders to all be with in 10 lbs of each other, then it is unlikely that the valve is the problem, but it could be that the valve is only sticking from time to time.
Can you call your friend and see if he remebers the comp readings?
I could try that but would take timeif possible, as more than a year ago. I may also have a report filed from the engine specialist, but not sure of this. In any event, will take me some time to find if I do have. Assuming for now the exhaust valve is the issue, the misfire IS always there, if more obvious when the weather is "damp" and this also coincides with the check engine light coming on.
With the problem being more pronounced when the weather is damp, it is very unikely that the valve would be the problem. If the valve where bad. then the enigne would run the same nop matter if it where wet or dry out.
That is why the comp readings are so imoprtant. There can be amny things that would cause a miss, and if the cylinder has not been fireing correctly for some time, then compression would be lower then normal. with the dampness causing it to miss more, this ells me that the problem is an electrical problem not a mechanical one.
I agree, but the change is very small and as i say accompanied morer often than not with the check engine light appearing.
I would agree, and these conditions confused me initially, but again more expierianced minds said the valve. Also in part why I hesitated in making the suggested repair. However, now I am faced with towing a trailer 4000 to 6000 pounds (loaded) and thought to try again to find a solution not wanting some failure to result. During the past year have driven about 3000 miles with no obvious changes or affect (other than the rough idle - that is without a trailer) the trailer would be a new condition.
Pulling a trailer will not change the way it runs to much, but you would need to be easier with the gas pedal then normal. Once you are moveing, momentum should keep things rolling. how long have you been fighting this problem?
The issue began about 2 years ago (75,000). I have owned 5 years and since 43000 miles. The rough idle began but no CEL and everyone said without a code nothing could be diagnosed. Eventually the CEL came on (if intermitantly) but enough for a test. Over the next several months I had the various guys take a look. I have ignored for the past year until now.
PS: If I do trailer, the plan isd for easy going, not to make any high speed runs!!!
PS: Also for the past year usually no CEL
I highly doupt that the valve is your problem if it has not goten worse in 5 years.
Here is the thing. If the valve where bad, you would be dumping raw fuel into the exhaust. This would cause a catalist code for sure.
Ok good thought. So far my inspection readings have not indictated any problem and the readings as I recall pretty constant. The issue first showed up about two years ago - next inspection in June/July. I can check with my local guy re the inspection readings to be sure re the catalist code.
Sounds like a plain to me. Just get back with me when you have some data and we can go from there.
Ok Thanks for your time on this. Not sure how the progeam works. How do I get back to you?
PS: Also in fact I recently spoke with my local mechanic and he agreed the problem should show up at the catalist. Will chaeck the readings and etc as you ask.
If you look in your email, there should be an email from the site. It will have a direct link to bring you back to this question as well as your log in info.
Ok thanks. Bye.
Have a good day.
Getting back to you re the miss-fire issue. Compression testing was not done on all cylinders. Based on the computer code (when the "check engine light was showing") the code indicated a problem with cyl #8, and a known engine fault per Ford's diagnostic reporting - repair procedures - requiring a new cylinder head.
Comp testing at #8 showed 20% loss; a second test showed 16% loss.
If you have an alternative repair suggestion it will be helpful. However, based on what is known I am asking: a) do you have expieriance of this condition and the recommended repair; and b) do you think the car can be driven "as is" without repair, and without causing any extensive additional damage (other than the catlytic converter as discussed previously). Thanks RH
Sorry for the delay. If the compression test wasnot done on all 8 cylinders, how do you know there was a 16-20% decress in compression? If you had a valve issue, there would have to be a bigger drop in compression then just 16-20%. There are a few things that can cause compression to drop. If the cylinder is not getting enough fuel, and is dry fireing, or the spark is not strong enough to burn all the fuel " due to a bad spark condition, or an injector that is leaking" then a wet soak can also wash out the rings causeing compression to drop. What I need most of all is a good compression test done and all 8 cylinders labled with there exact compression readings please. From this I can best help you. I just had to fix a 03 f150 with a 5.4 that had low compresion. I found a bent rocker arm. It looked good by itself and in the head, but when taken out and laid next to another rocker, it was clear that I had found my problme. the engine made no noise, but had no miss at idle and cruzing speeds, but a definant indication of of a miss under load. and the check engine light did not come on the whole time I was testing the vehical " but it did come in with a code for cylinder 5".
This is just one instance of an odd thing that can happen with new ford engines.
Hi Thanks fro your reply. The compression testing was done by two qualified agencies - first, my local family service facility, and second, an "engine specialists" company. In both cases the spark plug and the coil were replaced and the condition remained. The engine specialist replaced the plug and coil twice. Again, based on information given to me, and confirmed by the local dealership, the problem is supposedly the exhaust valve (or the seating). I was hoping that via an independent party the true seriousness of the condition might be verified (as we discussed earlier) - meaning if the replacement head is urgent or necessery.
Your suggestion is appreciated, but this will need a new test, and will take time to undertake (presently dealing with serious health issues). Might you also have an idea of the typical cost of a full compresion test.
AND, PS, I had an issue with a 2004 F150 like you describe (under load), long story and cannot tell all!!! Thanks again, XXXXX XXXXX
No poping, and runs great. RH
Being a Navigator, well insulated, but definately not heard any poping. Thinking of the compression test, by your remarks it seems if a compression test done than all cylinders would have been checked - and if so - suggesting no loss elsewhere. Do I assume correctly?
Yes it is true. The condition will vary - somewhat - but not significantly. Runing this week was definately there (the miss-fore) BUT less noticable than of late. Check engine light was on.
I know about ignition issues, being a Brit (and also owning a 1965 classic here in the US); owned Mini's (1960's) and the early models would not run in the rain (distributor placed in front of the engine and exposed to spray!!!)
I wil try your suggestion, hopefully one day next week.. RH
Gottaya! I will try your suggestion and see what results. If no solution will look into getting a "qualified" compression test - noting the points you say required.
The web-site keeps confusing me, so not sure how you get paid under the arangemnt I thought was set up. Guess you input something, but I will try to access the needed screen - I do find the site confusing.
Thanks for now. RH
Follow up re the miss-fire and checking the wires
Hi: You are definitely on to something!
Looked at the wires as you suggested. Almost impossible to reach the rear of the block. However, removed the cover and air intake and located four wires at the front and played around without finding or achieving much (the engine running – but would not run after removing the air-intake ). BUT, on putting back together, the “miss-fire” was almost gone, and the check engine light off (had been on for the past three months); leaving only a very slight vibration; and since not noticeable at all at initial start up, but after driving for a few miles, and also as before – if now very slight - at around 1500 - 1700 rpms down the highway in over drive.
IF there is a valve problem, the tinkering made a huge difference, therefore suspecting a possibility of a sensor or something associated with the air-intake, unless TWO issues. Needed to let you know your suspicion of electrical could be on target, and ask if any further comment on this – the improvement so good could live with for now!!!? Roger Hall
OK noted. That will be next. Thinking you are on the East Coast, where is your shop?