HELP!!!! - Rough running, SPOUT doesn't change timing - possible bad ICM?

[Carguy3J]

HELP!!!! - Rough running, Intermittent on cyl. 1&5 only- possible bad ICM?

I have a 1993 Ranger 4.0L-OHV, 5spd, 4x4

It has been running rough, at idle, as well as at speed, for a little while now. It doesn't feel like it is down on power, nor is it a "dead" miss, but its not right. It is very noticeable if the throttle is held at 1500 rpm.

It seems to have started, or least become really noticeable, immediately after I did some welding on my cab mount brackets, as well patching/plating the rad support.

The plugs and wires were changed in late December, so I doubt it is that. Plugs were Autolite, I believe. The wires are Motorcraft OE style.

IAC valve and TPS are new, along with the gaskets. I had a slight leak at the TB, but the new gasket fixed it. The TB was just thoroughly cleaned (off the vehicle), as well as the IAC passage.

I just tested the coil pack primary and secondary resistance, and they are all in spec.

Fuel pressure is 30psi at idle, jumping to 40psi under load, both exactly where they are supposed to be. All 6 injectors have been replaced within the last year.

I found both the the SPOUT connector, and the Octane Shorting Bar, but I;m not 100% sure which is which. The one near the left front headlight, by the evap canister, has 2 PINK wires coming out of it. I THINK this is the SPOUT. The other one is in the left inner fender, by the Power Distribution box, bundled near the Diagnostic Test Plugs. This one has 1 Green and 1 Grey wire.
EDIT: Ignore this part. Removing the spout DOES do what is supposed to. See Post#3 for details.
Now here's where it gets interesting. According to my Snap-On Scanner, my ignition timing is bouncing around between 17-21 degrees, at idle, warmed up. When I rev the motor up, it steadily increases timing, up to a max of 35 degrees, at approx 2500 rpm. I shut the truck off, and pulled the SPOUT connector (I think- the one with the 2 PINK wires). This had NO affect on timing at all. It still idles at between 17-21deg (at about 750-800rpm) When I plugged that back in, and pulled the other connector (which I think it the Octane Bar- green/grey wires), the timing decreased about 3-4 degrees, across the board. Idle timing varied between 14-18 degrees, and max timing was 31deg, at 2500 rpm. Removing the Octane Bar also eliminated an off idle stumble and ping.

So a.) Is it ok to drive w/o the octane bar installed for a little while, since it seems to help.

and B.) What is wrong here? Shouldn't the timing be "locked" at 10deg, with the SPOUT connector removed? I really can't afford to just throw parts at this, so I need to really be sure what is wrong before replacing expensive electronics. Is this a sign of a bad ICM, ECM, or Crank Sensor (CKP)? or something else entirely????

 

[Carguy3J]

OK, well I found a wiring diagram. I am now sure that the one with the 2 PINK wires is the SPOUT connector. So, with that removed, I think timing should be locked at 10deg BTDC. But, it doesn't seem to do that.

C'mon. Nobody has any idea? I've searched here, TRS, and Google. I can't find anything helpful. I'm really surprised nobody here has any thoughts.

Who are the EEC-IV "gurus" around here?

 

[Carguy3J]

The following is an email exchange I have been having with a member from The Ranger Station, w/ email address redacted: Being an email thread, the timeline is backwards, with most recent message first.
Dale,
I did change the coil Saturday morning. I did not have time to test the wires, as I needed to leave immediately for my grandfather's funeral. I did quickly throw the timing light back on. No change. It is still missing intermittently on cylinders 1 & 5.

From my understanding, this EEC-IV EDIS-6 system isn't that complicated. It would seem that the coil, the ICM, and the CKP (crank position sensor) are really all there is.

The ICM tested good, but what is the likelyhood that it could be bad anyway?

The CKP is clearly the original part (1993!). Would a CKP fail in a way that might cause an intermittent misfire on only 2 cylinders, or is it an all or nothing kinda of thing? I don't see a way in which it could affect only those 2 cylinders. Am I wrong? Should I change the CKP?

I guess the only other thing I can think of is the trigger wire for that #1 coil, between the ICM and the coil pack, or the plug/connector.

What do you think?

Thanks,
Jared

From: wicked_sludge@
To: carguy3j@
Subject: RE: Ignition issue w/ 1993 Ranger 4.0L-OHV
Date: Fri, 7 Jun 2013 13:57:06 -0800

I would probably try a coil anyway. Even if you wanted to get a junkyard coil for cheap then later replace it with a new part if it fixes the problem (or if you have really nice parts guys and they let you return a new coil if it doesn't solve the problem).

Even though your wires aren't that old, you should still check their resistance just to be sure. You should get less than 7k ohms per foot. Wiggle and flex the wire while measuring the resistance to see if the reading changes drastically.

As far as compression goes; a low voltage condition in the secondary ignition system can cause a plug to not fire under normal engine compression. The more compression in the cylinder, the higher the resistance is between the two plug electrodes and thus the more voltage necessary to jump the gap and create a spark. Low compression in a cylinder will create less resistance and thus make jumping the gap that much easier. In other words, low compression will not make a plug fail to fire. If anything, it only makes the plug easier to fire.

And feel free to post these emails on explorerforum. If nothing else it adds more cached data to googles search, adding to the collective database that is the world wide web
Date: Fri, 7 Jun 2013 13:28:04 -0400
Subject: RE: Ignition issue w/ 1993 Ranger 4.0L-OHV
From: carguy3j@
To: wicked_sludge@

Thank you for replying.

Interesting, regarding the scan tool and advance. I never would have thought of that.

I double checked with a timing light, and sure enough, with the spout pulled, timing was, mostly, at 10deg. It occasionally jumped a little, so something still isn't right.

I had the module tested at Autozone. It came up good. I even had them test it about 6-7 times in a row, to make sure it wasn't an intermittent failure.

The CKP sensor shows a resistance of only 650ohms, measured both at the sensor, as well as across terminals 5 and 6 on the ICM harness connector. From what I can find, the spec is supposed to be 2,000 - 3,000 ohms. I tested a brand new one at Autozone, and it also showed 650ohms.

What I did find, with the timing light us this. With the inductive pickup, for the light, on the wires for either cyl.1, or cyl.5, which are the paired cylinders on coil 1, you can see an intermittent spark dropout. Ie, you can see the timing light "skip". It gets worse as rpm increases, with more frequent, and longer missed ignition pulses. It only happens on those 2 cylinders. This would lead me to suspect the coil pack, given that the module tested good.

I doubt it is the wires, as in both cases, the inductive clamp was placed on the first inch or so after the coil towers.

The coil also tested "in-spec" for both primary and secondary resistance, on all 3 terminals and tower pairs.

What do you think? Most likely the coil pack? I believe it is the original, or at least a very old replacement.

The electrical "guru" at the parts store suggested that low compression in either of the paired cylinders could cause a missile in both, but that doesn't make sense to me. Sure, low compression can cause a missile, at the plug/in the cylinder, but that shouldn't effect what I'm seeing right at the coil, with the timing light, right?

Thanks again for your help. I really appreciate it.

Also, is it ok with you if I post our email exchange to the thread on explorerforum?

-----Original Message-----

From: Dale P.
Sent: 6 Jun 2013 07:06:52 GMT
To: J. Hayes
Subject: RE: Ignition issue w/ 1993 Ranger 4.0L-OHV

The reason you are still seeing timing advance on your scan tool with the SPOUT unhooked is because you are reading the PCMs output. The PCM sends timing advance signals to the ignition module through the SPOUT. When you unhook the SPOUT, you interrupt that signal and the ignition module fires the coils based on the signal from the CKP sensor, with no ignition advance. The PCM doesn't care that the SPOUT is unhooked and continues to generate an ignition advance signal on the SPOUT wire even though the signal never reaches the ignition module.

I believe the DIS module is mounted on the radiator support. I wonder if it got an electrical surge or overheated while you were welding in that area. Most parts stores will test ignition modules for free if you bring the part in to them....that might be the easiest/cheapest place to start.

From: carguy3j@
To: wicked_sludge@
Subject: Ignition issue w/ 1993 Ranger 4.0L-OHV
Date: Wed, 5 Jun 2013 20:16:21 -0400

Your name/email came up in several threads on The Ranger Station, so I though I would give this a try.
I am having some issues w/ my Ranger running rough. I have searched, Explorer Forum, The Ranger Station, and did a Goggle search; but I haven't been able to find any good info.

Here's the details:
http://www.explorerforum.com/forums/showthread.php?p=3161342#post3161342

I figured it would be easier then re-typing everything.

I would really appreciate some advice, if this is something you know about.
Thanks.