missfire with spark rattle

[waynes world]

Hello,

As stated in my brief intro, I have a 1991 EB Bronco 5.0 with e4od.

engine misfires warm in OD when the converter wants to lock up.

absolutely will not misfire until fully warmed up.

Can also duplicate the misfire while brake torque @900-1800 rpms.

Compression shows 150 psi on all eight with no ignition leakage what so ever.

all spark plugs read identical.

no service engine light on (light does work) and no service codes.

Have verified base timing and also watched timing while engine is misfiring under load.

The timing stays very stable while misfiring, guessing that it was 38-40 degrees btdc while that is going on.

Missfire is there in both open and closed loop, 0.96v at tps at idle speed.

I have been able to set any codes I choose by swapping eec components.

Have read almost all of the old service bulletins even the one about the pip shielding and found nothing.

new ignition module and stator, fuel pressure well in specification and even removed all injectors and manually tested.

The only time this unit will NOT miss is when the timing shunt is removed.

Maybe 20 years is too long to be away from this , but I USED to be pretty good.

any help would be greatly appreciated.

                                               waynes world

 

[miesk5]

Yo,

Is the PIP Shielding that you discounted?;

Intermittent No-Spark: Spark w/SPOUT Connector Un-Plugged, but Falter and/or No-Spark w/SPOUT Connected (similar to Hesitation, Stumble, Stall, Miss, No Start, No Spark); "It seems that the insulation around many PIP sensors breaks down prematurely - a condition that leads to shorting of the wires leading to the TFI ignition module. I always replace a PIP sensor along with a defective ignition module, if it has "soft" insulation...This month's column is about a Ford Ranger one of my students (Drew) said "would only run for about a mile, then die." Since we were in the middle of our electrical and engine performance unit, this vehicle would serve as a perfect troubleshooting opportunity. The story from my student went as follows: The vehicle began stalling intermittently during driving, but would usually restart right away. Sometimes, however, it would have to sit for a few minutes...  yada yada... 

A Break I noticed that when I unplugged the SPOUT connector to check base timing, and let the engine run at base timing, it never died. Unfortunately, this pointed me back to the PCM as a possible cause of my fault. But, when I plugged the SPOUT connector back together, I could make the engine falter and die by gently twisting the harness. Yes! I was sure I had located the fault, and I was right. Look at the figure with the yellow spark output signal wire that is without a section of insulation. This section happens to run through a shield ground that provided a convenient ground source for the SPOUT signal. Just the right bump in the road or vibration from the engine would provide a path of lesser resistance for the SPOUT signal, killing the coil trigger..."

..

 

[waynes world]

miesk5,

Stripped the harness from 60 pin to tfi an d found no bare wiring at splices, cleaned each wire and re wrapped foil tape.

Also added a second layer of foil tape that I got from my e&i department it looked nearly identical to the stuff that the company used.5

I made sure that I got as close as I could to all 4 of the connector ends as I could.

NO DICE same misfire, did a wiggle test while in gear and torqued up to induce miss, no change.

Watched timing as it missed, I thought it was quite stable.

Should not the timing be quite jumpy if the pip signal was shorting ?

Thought I read that timing should go from leading edge to trailing edge of the reluctor if  it shorted ?

The pip sensor was changed at the same time as the tfi module.

Would like to see what a timing curve for this configuration SHOULD look like vs. load

when this condition occurs the timing is at approx. 38-40 degreed btdc.

Still have not completely ruled out engine mechanical.

Have never been able to duplicate this issue in d2

Could the pip signal be shorted internally in the ecm ?

any other suggestions would be greatly appreciated.

                                                          waynes world

 

[miesk5]

Yo Joel,

Ok.  Will get to most of your questions later.

Some other possibilities:

Diode Pattern Waveforms, Bad; "...This waveform was captured using the diode pattern test located in the engine tests menu. This particular alternator has a bad rectifier, causing an AC voltage to ride on top of the DC voltage signal. This AC voltage affected the pip and spout signals (Ford primary ignition signals) causing a no code driveability problem. The fix was to replace the alternator. This waveform was captured using the diode pattern test located in the engine tests menu.



This alternator, like the previous alternator, has a bad rectifier. This is another example of how a bad rectifier can affect the diode pattern. The fix was to replace the alternator. This waveform was captured using the lab scope. This is a good example of how an alternator with a bad diode can affect other signals that the ECM looks at. In this case it is an IAC motor. When viewing waveforms that have a lot of hash always look at the alternator diode pattern as a possible cause..." 
Source: by omomitec.com

  

...

BTW, I went through these Waveforms with no relative info:, PIP, SPOUT, IDM in Push Start & CCD, Page 122 in Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993;  http://web.archive.org/web/20110704124152/http://www.yunost.ru/docs/Ford-injectors-book/Part06/Part06.pdf

...

Then read the E4OD Section in my 96 workshop manual and dwelled on the EPC:

The Electronic Pressure Control solenoid is a variable force solenoid. The variable-force type solenoid is an electro-hydraulic actuator combining a solenoid and a regulating valve. It supplies electronic pressure control which regulates transmission line pressure and line modulator pressure. This is done by producing resisting forces to the main regulator and the line modulator circuits. These two pressures control clutch application pressures.  Failed on — minimum electronic pressure control pressure (minimum transmission torque capacity). Limit engine torque (partial fuel shut-off, heavy misfire). Flashing transmission control indicator lamp. Then that led me to search for the EPC and intermittent misfire.

To http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1304534771

with waveforms.

"SPOUT signal looks like trash on top" & "The consensus was a problem with the EPC driver in the PCM, confirmed by removing that wire from the harness at transmission. I installed a switch inline to open and close the circuit while watching the scope. With the PCM in command of EPC the PIP, SPOUT and basically all circuits that shared the power feed from the PCM relay were trashed. It also had about 365mv AC riding on that circuit. The AC voltage would decrease with an increase in engine RPM, not sure why. With the EPC control switched off everything returned to normal including the AC voltage dropping to <20mv. I checked the EPC solenoid for a short to ground and resistance(5 ohms), both were in spec. I am having a hard time understanding what exactly happened here, how can the EPC driver create AC voltage? Was the AC voltage causing the PCM to wig out? Was the AC voltage being created somehwere in that circuit and the PCM had a bad capacitor? KOEO it had 265mv AC on that circuit, that's w/o the fuel pump running, where is that coming from? I attached two more waveforms with and w/o EPC control, the w/o EPC control is identical to the waveform after the PCM was replaced."

EPC @ EEC IV PIN 38

EEC IV PIN Legend

W/Y wire, ckt 925

91 Bronco E4OD Wiring Diagram @ http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=11307
What do you think of this?

 

[waynes world]

miesk5,

Sorry I have not been on here since my post (work thing)

This is all a lot to grasp since I no longer have the privilege of the tsb,s at my fingertips or just calling the ford hotline.

Will sift thru all of what you are suggesting here.

undid the full wave rectification control unit (alt) and no change

a few other things I want to look into; will verify that the harmonic damper has not shifted, could be causing spark knock.

will do another functional check of the egr system although I did unplug  tab, tad egr and canister purge thinking one of those solenoids could be causing me grief, as some share a common source of power distribution.

I did cteck resistance of all of the trans solenoids at the ecm and those values were all within specifications.

Just trying to break the whole thing down, cause it could be more than one concern.

thought I had it when I found and replaced a broken LEFT motor mount and found that the mounting studs were very uneven and even the trans mount was bolted down at an obscure angle.

got that all settled in, some improvement but no fix.

2 more days and I will try again, going to borrow a better scan tool than the one I have, if I even remember how to operate the one that came after star 2 , oasis ? or whatever I was trained on when I left for the chev store.

 thanks for all of your help.

                                             waynesworld

 

[miesk5]

Yo Joel,

Here are some wiring diagrams (partial, 86 through 96) and Technical Service Bulletins, (80 through 96) @ http://www.revbase.com/BBBMotor/Wd

Bronco Sensor & Actuatot Diagnostic Values



Was looking @ EEC-IV MONITOR: Symptom Charts — Chart 9

RUNS ROUGH - MISSES - BUCK/**** - HESITATION/STUMBLE - SURGE - BACKFIREShttp://www.thedieselstop.com/faq/9497faq/maint/vra/leftside=vras7al.htm&rightside=vras7ar.htm

Since you mentioned the  the rorating harmonic dampener (Can also duplicate the misfire while brake torque @900-1800 rpms. & warmed up; )

I l like this suspect: 

[SIZE=10pt]Check camshaft timing .[/SIZE]

 

[waynes world]

miesk5,

just in for some lunch today.

verified that the harmonic balancer was ok this AM

less than 2 degrees off

going to do the old timing chain slack by a visual at the distributor while turning at the balancer and  seeing how many degrees

it takes for movement.

The other thing that I have learned, not original engine.

This Bronco does seem to have quite a bit more power than I remember these units to have.

5.0 ** ?

Will have to check into that as a possibility.

going to have a go at the e4od solenoid connector in a little bit.

I stated that I had checked all of the trans solenoids (and I did) however I checked them at the 60 pin connector because it was more convenient at the time.

What about an intermittent short on one of the solenoid circuits, such as the brake on/off (BOO) ?

Going to see if I can unplug that connector  and check from there to ecm

                                    waynesworld 

 

[waynes world]

No success yesterday,

Moved on to the suspension on my 71 Mach and low and behold it came to me in a dream.

Recheck the distributor mechanical, thought about that and got a known good shutter wheel from a 95 351 W and installed it and

the vehicle ran differently (NOT REPAIRED) different.

base timing did not change, takes longer in the heat cycle to miss and misses less often.

I knew that #3 cylinder misses more often than the others so I drew out the firing order on the shutter wheel and low and behold 2 ever so small  marks on the tooth of the wheel for #3 cyl.

Does anyone have a run out spec for this distributor ?

also took one of my old test adapters that was still in a drawer of my tool box and tapped into the hego, the misfire is leaning me out because of the excess oxygen from the misfire, there is the spark knock.

will try and find a distributor (or bushings) to see.

would be nice to be able to buy just the mechanical part of the distributor.

Will check first, cause I don't remember what material the gear was made of.

Hope this is the end of this saga.

                                                         waynesworld

 

[miesk5]

Yo,

What do you think about this?

"Tech Tip: Magnetized Shutter Wheel

Application: All Ford, Lincoln, Mercury, Ford Truck with EEC-IV computer systems and TFI ignitions.

Symptoms: Misfires, rough idle, surge, ping-knock.

Theory: Inside the TFI distributor is a Hall-Effect sensor that provides an RPM and POSITION signal to the Ignition module and ECM for fuel and ignition control. Mounted to the distributor shaft is a "shutter-wheel" that passes through the Hall-Effect sensor. The slots or windows cut in the shutter-wheel are what makes the Hall-Effect sensor switch on/off to create the signal it sends out. The shutter-wheel is supposed to be a piece of "dead" steel but can become magnetized. A magnetized wheel can cause very erratic operation of the Hall-Effect and resulting erratic output signal.

The Test: There are a couple of ways to check for this condition. One is to simply pull off the distributor cap and see if something steel will "stick" to the shutter-wheel. Make sure that whatever you are using to check the wheel with isn't magnetized itself. A more accurate method would be to watch the wave-form on the "SPOUT" wire with a Vantage or Lab-Scope. The SPOUT is the wire with the connector in it that you unplug to set ignition timing. Monitor the wave-pattern on the SPOUT with the timing-connector in. If there is anything erratic about the wave-form, unplug the timing connector and re-check the wave-form. If the pattern "cleans up" all of a sudden, chances are good that you have a magnetized shutter-wheel.

The Fix: Most shutter-wheels can be removed from the distributor shaft with a couple of screws. Everybody seems to have their own way of de-magnetizing the wheels but good success has been had with bulk audio-tape erasers or by placing the wheel in an engine parts cleaning oven and baking it. That last one sounds weird but it works."

http://web.archive.org/web/20150215120608/http://web.archive.org:80/web/20020806143543/http://www.snapon.com/newsletter/sonews_08_2002.asp

 

[waynes world]

miesk5,

Distributor shutter wheel (both of them) will not attract a 0.0015 feeler gauge.

maybe I cleaned the distributor shaft and housing (too good) when I had it apart.

Note: not only do I have to worry about missed ignition firing events but also injector firing events.

could be that the injector pulse width got way too short to support combustion.

That would also make the fuel trim go lean and cause the spark knock.

Rebuilt distributor less module, cap adapter and cap arriving this afternoon.

hopefully it has New sensor, not giving up the core till this bronco is at 100%

                                                                         waynesworld

 

[waynes world]

This case has been resolved.

Replaced distributor housing, runs perfect in every way.

As a side note: voltmeter which had always registered somewhat low, is somewhat higher now.

Will never again try to save a buddy money by replacing distributor components.

this vehicle started out as a no spark no injector pulse, strange where it ended up.

Wayne stated that this bronco never before exhibited these drivability concerns before it quit running

and I still believe him.

                                      waynesworld

 

[miesk5]

Yo Joel,

Great!

And ty for the update.