Solving mysterious miss in 92' MTX (testing injector connectors)

[vortex2450]

Hey, I have just acquired a 92' MTX from forum member "stangeater" .

It has a miss, he has already inquired about this mysterious miss here :

http://www.shoforum.com/showthread.php?t=109810

I am 100% dedicated to solving this issue until it's fixed. So I'm going to be very thorough with what I'm doing and my descriptions.

From his thread he has replaced/swapped out:

DIS with 3 different ones.....didn't help
New Plugs..didn't help
New plug wires...didn't help
New Coil....didn't help
New fuel filter...didn't help
Swapped MAF..no change
Swapped ECU..no change

I have today:

Cleaned all points of the battery terminal connection.- No change

Ran the KOEO test and got codes 116 and 114, I attempted the KOER test and the car wouldn't start the first two attempts with the STI and Signal Return connected, on the third attempt with a little throttling I got it too start but then all I got was the CE light blinking 9 times in sets of 3 so I guess a code of "999" ?

Tested the 3 yellow wires between DIS and the coil pack for continuity (y/bk stripe,y/rd stripe,y/wt stripe) they all passed.

I cleaned both sides of the harness connections with MAF cleaner.. - Slight change, instead of just starting and stumbling to a stall the car would rev to 2000rpm then slowly drop back down to an idle slightly over 1200rpm and begin stumbling but wouldn't die.

I did notice the pins in the coil pack connector looked like they were pushed back a little and the palsitc clip that snaps the connector tight to the coil pack is gone, I simply pushed the connector in really firmly.

I am now halfway through replacing the injectors with a set that was sent with the car. I have the intake manifold removed, and the injectors out with the fuel rails laying in the engine bay. I tested both sets of injectors from impedance and my results are

Replacement set: 5 injectors @ 13.3 ohms, 1 injector @ 13.2

Set pulled from car: 3 injectors @ 12.9 ohms, 2 @ 12.8ohms, 1 @ 13.0 ohms

Before I put the replacement injectors in I want to know

A) What is the Ford spec for these injectors impedance wise?

B) How do I test the injector connectors for a proper pulse with the manifold removed and the fuel rails open (no injectors installed yet)?

Thanks guys.

 

[SHOspazz92]

nevermind, I did not readz well.

-Sam

 

[lowc]

i would get a node light kit and go from there. they hook up into the connector side and will illuminate brighter/darker depending on the pulse of the injector from the ecu

 

[vortex2450]

I went up to the local NAPA to get one but no luck. Would it be feasible to test each one with a multimeter ?

My current issue is am I able to turn the starter over and get a pulse at each connector (assuming they all work) bearing in mind that the intake and everything on it is not in the car?

And if I can will I be okay testing the connectors without the injectors installed (wouldn't want the pump to kick on and spit fuel out off the fuel rails )?

Or am I better off at least plugging the new injectors back into the fuel rail and reinstalling the assembly then testing the connectors?

Also I'm really dieing to know if those impedance #'s are compliment with Ford specs? (both sets)

I hope I get some good ideas on this, that's why I'm being so specific and detailed so someone will maybe read it and a possible fix will emerge that I just don't know of.

 

[Bob Gervais]

I read through the thread you linked, and I know there were a few others about the same car with this issue... But I think it's best to begin from scratch, which is what it seems like you're doing.

114 and 116 codes are ACT and ECT codes, and wouldn't have anything to do with a miss.

The SHO uses high impedance (10-16 ohm) injectors. I looked through my service manual quickly, and I didn't see a specific value mentioned. However, I'd be comfortable with the results you have.

Here's my advice, based on current situations, and forgetting about everything that was done to the car previously.

-Check compression while you have the intake off.

-Check ignition wires for proper routing, no terminals loose or disconnected, etc. Check them for resistance as well.

-Check plugs for cracked insulators, or other damage. Also, make sure they're either Motorcraft or Autolite.

-Check timing belt for proper installation. You don't have to take all the front covers off, just the top one. Get the engine @ TDC on #1, line up the crank pulley with the marks on the lower timing cover, and make sure the cam sprockets line up properly.

-If all of this looks OK, I'd suggest tearing into wiring looms while you have the intake off and they're easier to access. Check for shorted wiring, chafing, stuff like that.



As far as testing the injector connectors with the injectors and fuel rail out, I'm not sure if they'd get a pulse with everything removed. If you want to try, however, you could pull the fuel pump fuse, so you don't spray fuel everywhere.

Good luck with the repairs!

 

[vortex2450]

I wouldn't say from scratch, I'm starting off were the previous owner left off on troubleshooting which was replacing all the obvious components.

I found 114 being an ACT code and i think that's because it's not tightly mounted in the aftermarket fender-well CAI installed on the car.

The injectors have a range that wide? that's surprising given how sensitive most everything else electrical is on the SHO. Then low 13 values seem pretty much down the middle which I can live with.

Okay I will do those things but I don't have a compression gauge to check compression, but that is undoubtedly vital so I should probably make that investment right?

How can I safety rotate the crank to where I want it in this scenario?

Thanks,
Josh

 

[St Louis SHO]

12.5-13.0 is ok. Anything more than .3 difference is not good.

 

[St Louis SHO]

Forgot to say that temp will make the numbers change +/- 1.0. So the new ones are ok. The old ones aren't great.

 

[93rev2sev]

Take the MAF out of the equasion. Just unplug it. Allow the computer to use it's preset fuel curve. The car will run slightly rich, but if there's a fuel delivery problem, unplugging the MAF may make the biggest difference.

 

[vortex2450]

It was about 50 F when i test the injectors and the car had not been running anytime before that if that helps.

Im taking lunch now but..

I've got the top timing cover off and the timing belt exposed, I don't know exactly how I should rotate the assembly to get cyl #1 to TDC but I assume I can just pull the fuel pump fuse and have a helper click the starter over until it's there, am I close?

I did find something alarming but it could be nothing important...

I pulled the battery out to make pulling the timing cover out a little easier (man the MTX engine bay is even tighter than the ATX) and discovered this...



Being as it has the remains on inline fuses on it I think it's after market, the 2 wires it's connected too are small gauge (20 perhaps) and the are colored solid red and red w/ a white stripe. I also has a small ground coming out of the same loom.



I traced the path of the wires into a larger loom here..


Where they come out at this messy junction..



And then they go into the firewall (the small loom resting on my middle finger).



I assume this is the wiring for the alarm system that was installed in the car because the system doesn't work as far as I know and the wiring doesn't look factory. But just in case it isn't I didn't wanna leave anything unnoticed..

I also found that the ground for the ECU ( I think that's what the angled harness plugging into a component on the pass side of the firewall is going to) didn't look very promising..



I'm going to clean that up and apply some dielectric grease to it once lunch is over.

Then I'll checking the plugs for any irregularities and also check the impedance of the wires. Any idea what sort of numbers I should be expecting?

Next is going to be checking the wires inside the injectors harness as well as checking the wires inside both ends of the DIS harness. Then onto the task of installing the newer set of injectors and testing the connectors with a multimeter.

After that I'm going to go ahead with clicking the starter over a couple times to get cyl #1 to TDC unless someone else chimes in before that time.

And once I'm pretty confident I've done what I could I'm going to reassemble the intake and if I haven't pegged it this round I'll try unplugging the MAF..

 

[93rev2sev]

That's the ground for the DIS (in the last pic). The ground for the ECU is in the Second picture. It's the factory ground that's sitting UNDER the aftermarket crimp with the blue shielding.

If the plugs are out, you can rotate the assembly by hand, simply by grabbing the crank pulley and turning. The starter will be very difficult to stop at TDC.

 

[St Louis SHO]

While the intake is off, double check the ground thats in the valley of the block by the knock sensor.

 

[vortex2450]

Which is the DIS ground? The metal ribbon that attaches to the intake bracket or the two wires which go into a harness? Either way it's getting cleaned up and greased.

And the ground in the 2nd picture attaches to one of the secondary screws on the negative terminal correct?

And is that all there is too it? Pull the plugs. I should have known that. haha now I do. I can also check them for anything out of the ordinary while I'm at it. Two birds with one stone.

Ohh man there's a ground in that valley? You don't even wanna know how much grime, gri, and dirt is laying down in there... I'll just tape off intake and get out the pressure washer if I can't find it.

 

[St Louis SHO]

you dont need a powerwasher. just reach down there and make sure its attached...

 

[vortex2450]

I probably don't, but if I tightly seal the intake is it gonna hurt cleaning that out?

EDIT: UPDATE

I'm coming in for a break and I do have news..

But first let me show you the ground points.

DIS/Intake Ground Before:



DIS/Intake Ground After Some personal time with the wire brush:



Installed with some grease:





ECU Ground Before:



After:




If you noticed not only did I clean the terminals with the brush but I also cleaned the bolts up considerably and brushed the paint off the mating surface for the extra comfort. Of course i Then smothered then entire connection with the dielectric grease.


Now, I pulled the plugs and here what I got...



A) they aren't autolite or motorcraft but NGK Iridiums Not sure if I wanna put them back in, opinions? Meanwhile I'm going to steal my ATX's plugs which are Autolite Platinum's ( I bought these without knowing that the preferred plug is the Double Platinum ).

B) They are arranged in the same way that they were in the engine, the top three being the rear bank ordered #1-#2-#3 and the bottom three being #4-#5-#6.

May I also point out that 5 of the 6 plugs are fouled the loner being in cyl #2.


So then I checked attached a ratchet with a 7/8 bit to the crank bolt and turn the engine until I I was satisfied with being as close to TDC @ cyl #1 as I could tell with a flashlight

Here's cylinder #1 through the plug well:



And here's what it's looks like at the timing belt:





I counted 8 teeth from the indent to the white line on both cam sprockets..

This is my first time even taking the timing cover off but I'm pretty sure those lines are supposed to be line up with the indentation on the sprocket right?

Needless to say I wanna do this right about now.. .

 

[Bob Gervais]

By saying from scratch, what I meant was not to trust someone else's diagnosis or work, especially if they didn't get the car running correctly. (no offense to anyone, but sometimes it's easier to start all over again than to second guess someone's work)

Those lines on the timing belt line up with the indents on the cam sprockets when the belt is originally installed. Once it's rotated, the lines hardly ever line up again. That's not really important. What is important is that it appears that the indents on the sprockets line up with the rear timing cover lines, from what I can see. It's a little hard to tell exactly because the pics are taken at an angle. However, what you're looking for is the indents on the cam sprockets lining up with the vertical stamped marks on the rear timing belt cover.

I'm pretty sure others have used NGK plugs without an issue, however I can't give any personal experience on that. Personally, I'd replace them anyway, just to rule them out.

Usually, places like Autozone or Advanced Auto rent compression testers. If not, they can be had cheaply enough, maybe $30 or so. Since you have everything off anyway, I'd strongly suggest checking compression. To crank the engine for the compression test, remove the fuel pump fuse, and crank away.

 

[vortex2450]

I was thinking on it, as long as the indent on the cam sprocket lines up with the line on the back of the cover?

I'll go get some better pics for you, gimme two minutes..

EDIT:

Here our face on shots, the teeth are were they are supposed to be as far as I can tell.





Does knowing that cylinders 1,3,4,5,6 are fouling their plugs help me diagnostically at all?

Also, isn't it very possible that those grounds being so mucked up before could have been the issue?

IDK where the fuse for the fuel pump is but I'm gonna go search it up right now..

 

[Bob Gervais]

As long as you're on TDC on #1, and the crank pulley mark lines up with the timing cover, your timing is perfect.

As for the fouling of the plugs, that could be crappy wires, weak ignition coil, or simply crappy plugs. Come to think of it, I did install some NGK iridiums in a 5.4 Expedition and had misfiring issues. That doesn't guarantee that's your issue here, but it's something to look into for sure.

About the grounds, cleaning them up definitely isn't hurting anything, however I'm not sure that would be causing a miss. For those grounds, they either work or they don't.

 

[vortex2450]

Well then my timing is perfect because those marks are dead on. :woo-hoo:

I checked out the wires and they have no name brand label but are stamped to be 8mm and all the boots/coil pack connections were in pristine shape. I've also tested all 6 wires for impedance @ the 20k setting:

Wire # correlates to cyl #.

1. 8.46
2. 7.58
3. 7.48

4. 6.70
5. 5.08
6. 5.23

Wires 1 & 4 were longer than the other two in there bank which explains higher resistance. Wires 2&3 and 5&6 appeared the be the same length so I'm pretty comfortable with the tolerances in the wires themselves.

I'm a tad hesitant to start cutting up the thick shell of the injector harness which protect those wires from everything that is thrown into that valley but I did test the connectors for voltage and the right pins all read out a constant 3.56 volts whether cranking or not.

I tried hooking up an injector and cranking but I got nothing and I'm hesitant to stick a straight 12v through an injector that normally gets pulsed 3.56v.. That is IF 3.56v is right...

I need a definitive way to test those connector before I put this back together so I can cross them out but I want to put this back together soon because I want to run the car down to advance and test the compression.

So I'm going to install the new set of injectors now and maybe buy some time for a solid explanation on what I can do to test the connections.

I have a spare coil pack and MAF which I will swap out if I'm still missing.

 

[Bob Gervais]

Plug wires seem fine. 5k ohms per foot of length of the wire is what's considered acceptable.

The injectors should be getting 12v to the red wires with the key in the on or start position. The ground to the injectors is what is switched via the PCM. If you're only getting 3.56v, something's wrong. Since every injector is getting the same voltage, I would assume that it's either the CCRM, or the wiring to it. I've seen at least three of these cars with shorted wiring in the loom going to the CCRM.

What you need to do at this point, is to check for 12v (or close to it) at the CCRM. For the injectors, you're looking for the only solid red wire on the connector, pin # 24 if you have a schematic.

Also, for the compression test, it's done with a gauge that screws into the spark plug holes. Much easier to do with the intake off, and most likely not something that Advance will do for you.

Here's a pic of a compression tester, maybe it'll help my explanation.

http://www.northerntool.com/images/product/images/800507_lg.jpg


*edit*

BTW, props to James for confirming injector info!