I need Help... BAD

[1991XLT]

Howdy all.. I am hoping someone can help me with a major dilema.. I will give vehicle specs. first

1992 Explorer Eddie Bauer 4 door 4x4

4.0 V6 Auto Trans.
180,000 miles on chassis 80,000 on Engine

Started off as a tuneup, changed plugs and wires then after restarting engine it ran on only 5 cylinders.. thought maybe plugs wires were not on secure.. checked that.. all looked fine.. thought maybe one of the new plugs was deffective.. so installed 6 more new plugs and wires ( I own a 91 explorer aswell and had plugs and wires for it aswell) engine still missed.. thought well maybe its just a coincident and that the engine was just finally tired.. so gave it a compression test and the guage is not very dependable and showed only 60 pounds on one cylinder.. soooo.. got a good used engine from the local wrecking yard out of another 92 explorer.. went through all the hassles of the engine swap put all new seals in the used engine before putting it in.. anyways.. got it all in and everything connected and give it the initial start.. Take a Guess.. its still running on 5 cylinders I have it pinned down to the cylinder in the front on drivers side.. not sure what cylinder number that is at the moment.. but when pulling plug wires off and or injector wires it shows no change when pulling the fuel or spark from that cylinder making it certain only that cylinder is not firing.. I have tested about everything I can think of including pulling parts from my running 91 explorer such as the main computer in the passenger side kick panel.. got a used EDIS6 module from a wrecking yard thinking it was maybe all of a sudden faulty.. checked for spark on the cylinder in question.. has spark.. pulled a injector from the old engine from a cylinder that I know was firing.. checked for voltage pulse on injector wire for the cylinder in question.. checked fuel pressure at rail 40 pounds.. so in theory.. it should be running on 6 cylinders.. it has Fuel, Compression and Ignition.. and both engines cannot be bad on the same cylinder.. as I honestly think the old engine should of been running on 6 yet.. as the guage we used to check compression is faulty.. so with all this said.. what more can I check for? I know its not a fuel issue.. I sprayed small bursts of ether into the intake with it running thinking if it was a lack of fuel on that cylinder it should fire on the ether.. that didnt affect it at all.. ran on 5 cylinders burning the ether.. it has to be an issue with the ignition not firing on the cylinder at the right time.. or???? So if anyone has any kind of clue please clue me in.. Thanks, Shawn

P.S. forgot to mention on the old engine the Fuel Pressure regulator was bad as there was fuel in the vacumn line.. but this is now corrected with the replacement engine..

 

[MattPersman]

wild guess and maybe a dumb suggestion

since no one has attempted anything I will give a shot in the dark. Maybe you have tried this already though.

Have you tried switching one of the injectors that you know works to said?

is the EDIS6 the distributorless ignition box? maybe the wire harness that hooks up to it, the wire for that cylinder is cut or pinched somewhere down the line making even a new tested one not fire? I don't know much about this ford engine and its setup but my guess there is a wire harness that plugs in to that ignition thing and maybe your problem lies there? electrical gremlins are the worst.

hope you get it figured out. Maybe this post will spark some more thoughts

 

[JDraper]

2 thoughts from here. 1: Have you been using the same coil packs on both engines? It is possible you are getting a very weak spark that just won't fire the cylinder, or as Matt said, a faulty wiring harness. The second thought is a very dumb question. Are you sure that you have the spark plug wires on the proper cylinders? I would guess so since you changed out your own engine, but it's worth asking.

 

[dogfriend]

Two suggestions to verify fuel and spark at problem cylinder:

1. Hook up a inductive timing light (the type with the pickup that goes around the ignition wire) on the problem wire and make sure that the ignition is firing steady.

2. Hook up a 'noid' light to the injector in question to make sure that you are getting a signal to fire the injector from the computer.

Dead Link Removed

I found this at www.eastwoodcompany.com but I have seen the noid lights at Pep Boys , Napa, etc

 

[1991XLT]

I have done so much testing I even forgot everything I have done.. Yes I changed out the coil pack from my 91 and the 91 is running on all 6 just great with the pack from the 92.. I have done exactly that with the timing light and also with another sparkplug grounded out on the engine to verify it has nice strong blue spark.. "noid" light? guess that isnt what I used.. I used a standard 12v test light and the light bulb on it pulsed very rapidly, telling me there is current going to that injector.. One more thing.. do all three injectors on each side of them engines fire all at once? maybe this noid thing you are talking about could help me more with that? I studied the wiring harness for the injectors.. and there is the Same Red (+) wire on all six injectors.. then there is a White and a Tan .. White hooked up to all the drivers side injectors and Tan on all passenger side injectors.. One more thing.. wouldnt this rule out a fuel problem being when I sprayed ether into the throttle body intake that it has no change on its running? wouldn't you believe in theory it should fire on all 6 cylinders for a few seconds by me injecting ether? and yes.. EDIS6 module is mounted on core support in front of the battery.. it is connected with a "weather proof" plug and it appears to be fine.. I also taken alot of other wiring harness loose and checked for broken wires or corroded connections with no success.. I am very frustrated with this thing.. as it is my mothers and she is gonna need anti-depressents soon if I don't get her Explorer running for her..

 

[mrboyle]

The injectors have constant power to them with the ignition on. The computer grounds the injector in order to fire it.

 

[mrboyle]

Did the origional engine run fine before the tune up, or was it missing?

 

[1991XLT]

Figured it out... WARNING: Do NOT buy Haynes Repair manuals.. They have false information in them.. it ended up being the firing order in the so called "manual" was wrong.. and I finally took a look at the order they are on in my 91 and corrected the order.. now it runs fine.. now I just need to fix the headpipe leak I created during the engine swap any tips on removing the Exhaust manifold bolts? I am affraid of twisting them off in the head...

Thanks for all the replies though.. This is a pretty good board.. and am glad you all did throw some ideas out there.. much apreciated

 

[1991XLT]

Oh.. one more thing.. what is the "usual" compression on an engine like that with 80,000 miles on it? I got a "good" compression reading from the engine now.. and it shows 140 pounds this sounds substantial to me.. just wondering what you all think?

 

[MattPersman]

No idea on proper compression

I am glad you got it running just fine!

140 sounds about right though for most engines I have tested

 

[JDraper]

Originally posted by 1991XLT
Figured it out... WARNING: Do NOT buy Haynes Repair manuals.. They have false information in them.. it ended up being the firing order in the so called "manual" was wrong.. and I finally took a look at the order they are on in my 91 and corrected the order.. now it runs fine.. ..

?? Not sure what Haynes manual you have, but mine is correct. Are you sure you didn't misread which engine you have? Your 4.0 OHV motor does have different wiring from the coil pack to the motor than the newer 4.0 SOHC motors do.

Here's the pix out of my Haynes:

 

[dogfriend]

re: Compression Test from 97 Service Manual

Compression Test


Compression Gauge Check

1. Make sure the oil in the crankcase is of the correct viscosity and at the proper level and that the battery (10655) is properly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all spark plugs (12405).

2. Set the throttle plates in the wide-open position.

3. Install a compression gauge such as Compression Tester in No. 1 cylinder.

4. Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position use the auxiliary starter switch to crank the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required to obtain the highest reading.

5. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.


Test Results

The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading. Refer to the Compression Pressure Limit Chart.


If one or more cylinders reads low, squirt approximately one tablespoon of clean engine oil meeting Ford specification ESE-M2C153-E on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.


Interpreting Compression Readings

1. If the compression improves considerably, the piston rings are faulty.

2. If the compression does not improve, the valves are sticking or seating improperly.

3. If two adjacent cylinders indicate low compression pressures and squirting oil on the piston (6108) does not increase compression, the head gasket (6051) may be leaking between cylinders. Engine oil and/or coolant in cylinders could result from this condition.

Use the Compression Pressure Limit Chart when checking cylinder compression so that the lowest reading is within 75 percent of the highest reading.

I can't easily post the chart, but it shows a chart with groupings of pressure starting with Max =134psi,Min = 101psi. The chart increments by 2 psi each time and ends with Max =250psi, Min = 187 psi, i.e. if you get 250 as maximum in one cyl, you have to have at least 187 in the lowest cyl

 

[1991XLT]

My haynes doesn't even have that pic in it.. Hmmmm and yep.. I was looking for 4.0 OHV and not SOHC..

 

[mrboyle]

Re: re: Compression Test from 97 Service Manual

Originally posted by dogfriend
Compression Test


The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading. Refer to the Compression Pressure Limit Chart.

75% The standard rule in determining if an engine is bad is a minimum diference from max to minimum of 15%. Meaning, the weakest cylinder should be no less than 85% as strong as the strongest cylinder.

 

[dogfriend]

Re: Re: re: Compression Test from 97 Service Manual

Originally posted by mrboyle
75% The standard rule in determining if an engine is bad is a minimum diference from max to minimum of 15%. Meaning, the weakest cylinder should be no less than 85% as strong as the strongest cylinder.

I cut and pasted this from the 97 Ford Service Manual without changing or editing it.

I believe that you are probably correct; 15% difference from strongest to weakest is a better guideline than 25%

 

[SteveVB]

Re: Re: Re: re: Compression Test from 97 Service Manual

Originally posted by dogfriend
I cut and pasted this from the 97 Ford Service Manual without changing or editing it.

I believe that you are probably correct; 15% difference from strongest to weakest is a better guideline than 25%

FWIW my 91 FSM gives the 75% figure also