Ford 4.2L cyl 1 & 4 misfires

63vette

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#1
Hello, I have a customer with a 1998 Ford F-150 with a 4.2L automatic that has two cylinders with steady misfires that just started this morning after having been on the road for 5 to 10 miles.

It has two cylinder misfire codes P0301 and P0304. I was hoping that they were paired cylinders on the coil pack but they're not. There are also the following codes:
* P1537 intake manifold runner control open - bank 1 (this code has has been present since he bought the truck about 2 years ago.
* P0455 EVAP gross leak
* P0153 O2 sensor slow response bank2 sensor1
* P1151 Lack of HO2S1 switches bank2 sensor1
* P0174 System too lean bank 2

With my enhanced scan program, I found the misfire total to be 15, 077. The plugs for those two cylinders are wet with fuel (obviously). They were replaced with Autolite single platinums early this year and have less than 5K miles on them. Both plug wires test OK statically with between 7 to 8 K ohms resistance.

Is there something common to cylinders 1 & 4 that I'm missing that would cause those two cylinders to be dead without affecting the other 4?

Thanks in advance for any help...Allen
 

billr

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#2
5K on Autolites? That's about right, in my experience, might be time to replace them. Why has that manifold runner code been left to fester? That can't help much. That bank2 O2 sensor 1 seems pretty suspect, have you tried a "known" good one (even a swap with bank1)?
 

kev2

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#3
quick thought I see plugs are WET with fuel... P030x that is where to start, Check Fuel pressure AND leak down, a noid light to be sure of pulsing..... what have you done to check coil? maybe a simple plug firing check.

I would correct misfire BEFORE working o2 sensor
 

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#4
Thank you billr. I have used Autolites in Fords without any reported problems for quite a few years. I was searching a couple of Ford truck forums for info earlier and saw that some people have a poor opinion of Autolite plugs, also. Regardless, I just find it hard to believe that both plugs would fail at the same time.

Since there hadn't been an issue with how the engine ran before, the owner didn't want to spend the money (he already owes me money & is on a "payment plan") to diagnose and repair the runner control issue. No doubt doesn't help but the code indicates that the runner is for bank 1. Since the problem cylinders are the front cylinders on opposite banks, I would think that problem would be bank specific.

Similar to the runner control code (except on the other bank), the O2 sensor codes are bank specific (bank 2) and probably wouldn't cause a sudden, hard failure.

I just ordered a set of Motorcraft OE (single platinum) plugs for this think but I would be shocked if that fixes the biggest problem. All of the other codes, except for the runner control, didn't exist prior to the misfires showing up on cyls 1 & 4. If the O2 sensor code(s) persist after the misfiring is gone, I will certainly look more closely at that, too.

Again, thanks for any thoughts and suggestions...Allen
 

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#5
Thank you kev2. I agree wholeheartedly to first priority being misfires but...

Wouldn't a fuel pressure problem affect all cylinders equally?

I considered a fuel injector problem but two to act up simultaneously? I'll check the circuits with a noid but would be surprised to see that as a problem - especially being on opposite banks. As far as wet plugs of the two misfiring cylinders (I should check some of the other plugs - they could be wet, too, just in better shape to not be misfiring [yet]), leak down of both of the injectors isn't likely at the same time...is it? I attributed the plugs being wet to not firing. Also, there is the lean code on bank 2. The freeze frame for P0301 indicated the short term value for both banks was 8.58 but the long term for bank 1 was 0 and bank 2 was 7.8.

I ruled out the coil because the two cylinders (at least the only ones the PCM is ID'ing) are on different coil pairs in the coil pack. Wouldn't the other cylinders of those pairs also be affected?

Again, many thanks for the reply and your thoughts to the above...Allen
 

billr

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#6
Since 1 and 4 are on opposite banks, I understand you thinking about nothing bank-specific causing the problem, but it also seems prudent to address any obvious (codes set) issues. I am, course, am only passing on my experience with Autolites, others may disagree and be perfectly right. As to the coils, there can be a failure mode that only affects one plug in the pair. If one coil tower, or the winding near it, or that plug wire were shorted to ground, then only the other plug would fire. The spark circuit would be completed by the short just as nicely as it normally is by the waste-spark.
 

kev2

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#7
simple easy inexpensive things first - I thought to ck spark and fuel for 1&4, the pressure test was to ck for leaking injectors.... as was the NOID flashing... The spark check for plugs a dbl check are they firing at all...
A coil pack, all in one - sure 2 could fail - I thought checking was too simple/easy to ignore.
 

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#8
billr & kev2,

You're both right...I guess I was getting lazy! :>(

billr, your point about wire terminals being unique is a very good one that obviously I wasn't considering. I will hit the obvious first thing in the am and report back.

Thanks so much for your responses...Allen
 

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OK...I got interrupted most of the day and just now finished checking this POS out. I verified spark to the plugs. KOEO fuel pressure 39#'s - OK and no drop for over 10 minutes. Checked cylinder #1 injector harness w/noid light - OK. So...there is spark and no apparent fuel issue so that only leaves one thing - an internal engine problem, i.e., little or no compression. So I pulled all of the plugs out (I was planning on replacing them as previously indicated with OE single platinum Motorcraft plugs anyway. After I hooked up the remote starter button, I found right off that cylinder 1 has 0, no, none, nada, nix compression. Cyls 2 & 3 OK and big shock - cyl 4 is also 0 (5 & 6 OK).

OK you Ford people (I'm not one), is there a common problem with the valve train on this engine - especially with the two front cylinders? I find it hard to believe that anything would happen to two cylinders at the same time like broken valve spring(s), bent/broken push rods, totally failed valve lifters or broken rocker arms. There must be something...HELP!!!

I know I'm looking at pulling the valve covers but I would like to know what I should expect to find when I do so. Thank you SOOO much in advance for any insight...Allen
 
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#10
How about a broken cam if engine has OHV?

You could put air into spark plug holes and then rotate engine (cautiously) with a wrench to see what the valves are doing.
 

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#11
Thanks Mobile Dan. I thought of a broken cam for a second until it occurred to me that since we are talking the two front cylinders, there is no way the rear four would be functioning if the cam was broken before the front cylinder lobes!

Not a bad idea to apply air pressure but that would only tell me that the intake valve isn't closing (since the plugs get wet with fuel) but not why. Still can't believe that both cylinders would fail at the same time!
 
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#12
Carbon avalanche from Intake manifold runner caught in valves, won't clear out because the valve train is no longer connected? Hell, I don't know...
 

billr

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#13
How about a crack from 1 to 4 through the valve-valley? Yeah, it would have to be big .
 

kev2

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#14
I would remove the valve cover look at the rockers, pushrods etc
 

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#15
Regardless, I have to remove the valve covers but I can't think of a logical explanation as to why the front cylinders on both banks failed at the same time. I have other jobs that I need to get out so I won't get a chance to pull the valve covers until Friday at the earliest :(