start issue/occasional stall on idle/consistent surging under load (1

[ShadetreeSeattle]

got a bronco here that's baffling me. it has several issues which are an annoyance, at best... but alas, i'd like to try and gather some collective ideas on the subject, or at least some pointers on where to look for electrical troubleshooting. at this moment i believe it to be an electrical issue of some nature, as i have tested or replaced a bunch of stuff on this rig. (fixed a bunch of other problems, but never could shake these three as of yet) sorry if this is a lot of info, but i have been trying at this one for a while. i can split these into separate topics too, but thought they might be related.

1989 ford bronco, 4.9 inline 6, c6 automatic transmission, no fancy stuff done to motor besides a reseal/cleanup on the top end, vaccum line replacement everywhere and removal of air injection and a/c due to components being end of life. (yes i capped everything and whatnot, emissions is not required in my area) throws no codes except the air inoperative code... (it's how you know the computer still has a pulse. haha)

three possibly interconnected symptomscomputer related? well i tried another junkyard computer and it has the exact same symptoms across the board, except far more exaggerated than with original, which is odd, but shows it's perhaps not a dead computer) 

problem 1) possibly electronic ignition related slow crank 

it sometimes when warm/driven for a duration will have problems restarting.  when it has this problem it seems like the battery's dead. (cranks slow, lights sort of dim, etc) but it's actually not starter related whatsoever, from what i have at least gathered so far. i believe it to be ignition related, as it turns over just fine with the ignition module unplugged (accidentally discovered this by forgetting to plug back in while testing), but then with it plugged in it seems to light the plugs well before T.D.C. as it literally fights the starter, creating a slow crank condition, which ran the original battery dead several times. so i put in my truck's three year old agm battery in it and it now can crank for a while without running dead. sometimes if i turn back off the ignition and re-try it works just fine. like nothing's wrong at all. other times i gotta let it sit for a while and cool down. 

observations/things i have tested:

seems to happen when warm, (checked iat/ect and well within values)

at random, but more often after it was sitting for 2+ minutes (fuel injector? rail pressure test seemed to show no sign)

timing is on point, 10deg. before tdc spout disconected

timing light shows computer is advancing like it should when spout connected and throttled

distributor replaced and module too (stupid distributor-mount type)

wires replaced and routed away as they can be from eachother

tried a known good maf sensor from another inline 6. no change...

computer throws no codes except the 54 or whatever saying that the air injection is inoperative (removed capped etc. because it was shot) 

problem number 2) random stalling while shifting into drive or reverse from park

it does it more often than not when warm and only does it when shifting from park to drive or reverse (into a gear) and especially if i'm turning the steering wheel.

things i have tested:

psp switch works... atleast it doesn't throw a code on koer tests.

transmission range switch was shorting out so i replaced that...  (it's a c6 auto and it has the range switch has the extra 2 wires that go to the computer as an idle up signal) 

iac ports nice and clean as i had the intake apart when resealing the top end.

tried multiple iac valves with no difference in operation... also clean and when you push the valve with a pokey tool it moves freely

problem number 3) surging while under load

does it no matter what temperature engine is at and surging frequency is manipulated by how much gas you are giving it. the more pedal, the higher the frequency. if you lay into it, the frequency goes high enough it's less noticeable. at higher engine speeds it's less noticeable or not at all like when going down the freeway for instance. most noticeable when at a light throttle or acceleration at a low speed.

it feels like you are lifting your foot completely off the pedal for a split second, then goes back to where it was.

things i have tested:

tps looks great on my fluke with the simulated analog bar graph

fuel pressure is nice and hi in the 45-55 range. 

rear pump and tank replaced cause it leaked/sender was shot

FPR seems to do it's job/is not leaking into intake

possibly computer related? well i tried another junkyard computer and it has the exact same symptoms across the board, except far more exaggerated than with original.   

i'm at a loss! haha. i'm going to try and live monitor stuff as i drive down the road by setting the multimeter against the windshield and running leads to test stuff like tps output, egr valve solenoid, iac valve, etc. to get a better idea of what's going on. thanks for reading! drop a line if any of this rings a bell.

 

[miesk5]

Yo ShadetreeSeattle,

Welcome to the Zone!

It's most apparent that you have great electrical troubleshooting knowledge so I won't dwell on the sensors or actuators.

Does the computer have the same Calibration Code, aka  Program Code or Catch Code as shown on driver door or door jamb?



See typical Bronco codes @ http://www.fuelinjectedford.com/page17.html

Such as 

8PM 4.9 Bronco, F-x50 E-x50 Auto

etc.

You mentioned MAF Sensor, did you mean MAP?

Ford's NO CODE : Diagnostic Routine

Stall under load:

Vacuum leaks.  Suggest readinings at different engine heat ranges.

I haveva leak diagnosis @ http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/?p=125535 in post #20.

S

& some other possible suspects although you have most likely covered these too:

Air inlet atop radiator support to filter box and to throttle body; look for obstruction; damaged tubing
Fuel quality; Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.
Electrical connectors; inspect at coil, firewall, PCM, etc. especially those with broken locking tabs.

...

Here are some Waveforms; Alternator Diode, Knock Sensor, MAP, FUEL PUMP, INJECTOR @ http://web.archive.org/web/20100929170140/http://www.omitec.com/en/support/waveforms/

More Ford Waveforms, 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; Scroll Down on First Page, Click on each Section, then on next page, click on the pdf file; the complete book is over 85MB pdf and can be downloaded @ http://www.yunost.ru/docs/Ford-injectors-book/Book.pdf

 

[ShadetreeSeattle]

sorry, it's been a while since i had some time to write back. the computer's software code does not match the table posted, nor does the code in the door frame, nor does the computer... that being said, chips inside the computer date to 87, which seems right... totally could have been replaced with a junk yard computer from same year though. recapped the computer since a few were totally ***** with the rotting fish smell and leakage and whatnot.. still didn't solve the problem. needed it though i'm sure. i added little heatsinks to the voltage regulator daughter cards too! haha.

i did mean MAP sensor, sorry about the typo. i think i have narrowed it down to the ignition/computer wire harness as it seems like an ignition interference related problem across the board. the surging under load is absolutely spark advancing/retarding, (does not feel like fuel stumbling or surging) but rather an instant on/off that goes away under full spark advance (heavy throttle)

discovered that when it has the startup issue, unplugging the ignition module, then crank for a few seconds, then re plug and try again always clears the issue.

fuel is plenty good as i still daily drive the thing and put fresh gas in it from many different gas stations.

vaccum looks great, no needle hop, under heavy load does not appear to have the typical signs of plugged cat, etc.

don't have a scope to view waveforms, but frequency checking the MAP sensor looks like it's putting out acceptable data. per http://troubleshootmyvehicle.com/ford/4.9L-5.0L-5.8L/how-to-test-the-map-sensor-2

thinking that i will replace the ignition wire harness with a clean looking fender mount grey type harness as i hate the concept of ignition module on distributor setup. might take some mcguyvering to get the distributor wired up like a fender mount type. but i feel it's worth it. i'm going to check out the diagnostics guide you posted and see if i missed anything. thanks again!

 

[ShadetreeSeattle]

the bottom link you posted is super useful, thanks! i have been working off a 1985 f series fsm which covers the early eeciv stuff too. but this is a lot more useful. hope to get back on here soon with good news!

 

[miesk5]

Yo,

Great!

1990 Bronco Pre-Delivery Shop & Electrical & Vacuum Troubleshooting Manual (EVTM) by Kingfish Google Drive @ https://drive.google.com/drive/mobile/folders/0BzRTW4yeT2u4UkhzR0ZydDd3MzA?usp=sharing&tid=0BzRTW4yeT2u4NXB6NW5neFRoZGc

Slow scrolling.

Find page # of item desired in contents, then flip screen flip down like spinning a bearing then stopping periodically to see what page you are on.

 

[ShadetreeSeattle]

found out something with surging while under load problem. the computer is cycling the egr valve open and closed (like it's supposed to???) while driving (or off idle) causing a significant drop in vacuum which i assume changes intake vacuum enough that the map sensor swings lean/rich. unplugged the vac line to the egr valve and it goes away completely. a while ago i replaced the solenoid with a subaru egr solenoid as i found none of the junkyard ford ones held vacuum very well on the manifold side of the solenoid valve. so i decided to try out a ford one again and the problem is less than it was, but still there. perhaps the computer cannot duty cycle the subaru valve as easily as the ford one? not sure. perhaps the subaru one admits more air than the ford one. the problem still exists with the ford one though, but far less noticeable. are the ford valves supposed to admit a little bit of vacuum to the egr valve even when closed? or do the ford solenoids just **** at sealing up?

additionally, admitting false air to the intake seems to clear up the stalling while shifting into reverse/drive from park problem. should i adjust the throttle stop more open then? hmmm.

just thought i'd drop an update here. thanks all!

 

[miesk5]

Yo,

I c& p the following:

Adjusting the throttle stop is not recommended.  .html

See IAC TEST @ http://www.fuelinjectedford.com/page39.html

Idle Air Control (IAC) gasket trim by nelbur @ http://broncozone.com/topic/22150-fast-idle-problem/?pid=115710

The EGR Vacuum Regulator (EVR); also called EGR Vacuum Solenoid ([SIZE=31.4281px]EGRV) [/SIZE]controls the vacuum bleed or venting of the system vacuum.   This solenoid has a vacuum connection to the  and a vent to the atmosphere.  It also contains a plunger that opens or closes the passage to the atmosphere. The EGRV is a normally open solenoid. This means that when the solenoid is deenergized the plunger is not blocking the passage to the atmosphere, so vacuum will vent to the atmosphere. When the solenoid is energized the plunger is lifted blocking the passage to the atmosphere so vacuum will be trapped in the solenoid.

How much is trapped?  Probable just enough.

EVR is supplied battery voltage from the PCM.   The solenoid is grounded inside the PCM through a Quad driver.   When the PCM senses a need for EGR flow it sends a pulse width modulated signal to the EVR through the driver.    This signal causes an electromagnetic field to be turned on and off, which raises and lowers the disc.   This movement opens and closes the vent passage allowing the correct amount of vacuum to be applied to the EGR valve. As with the EGRC and the EGRV,  if more EGR flow is required the duty cycle is increased, allowing more vacuum to go to the EGR valve.  If less EGR flow is needed, the duty cycle is decreased, decreasing the amount of vacuum to the EGR valve. A duty cycle of 86% is equal to approximatley a 6 in.hg vacuum signal.   A duty cycle of 33% is equal to approximately a 1 in.hg vacuum signal.

Will have to think about all this.  Bb in morning

 

[miesk5]

Yo,

Tomco Testing @ http://web.archive.org/web/20111125175520/http://www.tomco-inc.com:80/Tech_Tips/ttt32.pdf

See Attached doc

Excerpts;

"Next, disconnect the vacuum connection to the EGR shutoff, EGRC, or EVR solenoid. Hook up a vacuum pump to the supply port of the EGR shutoff, EGRC, or EVR solenoid (Fig. 3).  During the test you will have  to supply a Connection to vacuum source EGRV EGRC Connection to EGR  Valve Figure  3 constant vacuum to the port from the vacuum pump.  Hook up a vacuum gauge to the outlet port of the solenoid.  Have  someone cycle the accelerator pedal.   The solenoid should hold vacuum in one accelerator pedal position, and release vacuum in the  other.  The release of vacuum should be in less than 2 seconds. If the vacuum does not release, or releases too slowly, check the filter on the solenoid (Fig. 4, EVR filter shown).  If this is clogged it will inhibit the venting of the solenoid.  Some of the EGRV solenoids have  a vent hose that goes up to the throttle body. Electronic Vacuum Regulator (EVR) CAP FILTER EVR Figure  4 Make sure this vacuum line and the port in the throttle body are not plugged. If the vents are okay and the vacuum portion of the test just performed will not cycle correctly, replace the solenoid(s)."

More EGR Testing, , etc @ http:// web.archive.org/web/20111125175520/http://www.tomco-inc.com:80/techinfo.aspx

 

[miesk5]

Yo,

BACK to Throttle *****.

How to adjust idle speed (official Ford procedure) @ http://www.supermotors.net/registry/media/624983_1

 

[ShadetreeSeattle]

in short form, finally fixed the startup issue. it was the cam gear not being installed properly by some shmoe in oregon two years ago. it was not pressed on all the way causing the timing to be loose, causing ignition to light the plugs too early, probably also causing the stalling issue.

egr valve solenoid recap: (thanks for the info @miesk5!) 

the info posted was quite useful in helping troubleshoot the egr solenoid situation. the subaru one ended up not working out, as the computer had a tough time controlling it over the ford one. was plumbed the same, but it seemed to need a shorter duty cycle to open x ammount over the ford one... (the computer would rapidly cycle the egr open and closed with the subaru one, whereas the ford one would have a steady control of the egr diaphram) this caused the pulsating at throttle issue. so there's that. haha. lesson learned... 

startup fix long story:

As, for the other issues i posted about originally with this vehicle, (the startup issue specifically) i ended up bringing the rig back to my shop over the weekend and decided to take another look.

so to reiterate the original still withstanding issue that plagues this rig, it ran ok more often than not if it started, but always cranked super slow. to the degree that even a moderately good battery would not be able to spin the engine up fast enough. ran new wiring all around for the starter sometime last year... (new engine block ground right to the starter, new 12v line from solenoid to starter, new 12v line from battery to solenoid, new frame ground. even used copper washers between connections to really get them connected well. also tried two different starters. did ok with a fresh battery, but STILL would really tax the battery good if it needed to crank for a while, which usually was  the case when it was warmed up and attempting a restart... (like if you stopped at the gas station, etc.)  i realized a while ago that if the ignition was unplugged it would crank easily. so i started going down that path again this weekend of why it cranks hard when ignition is plugged in.

so i warmed it up in the shop and started doing some testing.. 

was it carbon lighting fuel prematurely and causing over advanced ignition of fuel while starting? hmm. disconnecting the coil only (not the whole ignition module) proved that to not be the case as it cranked fine while injectors were firing, minus spark. plug coil back in and it cranks slow as f.

was the distributor to blame? tried another known good motorcraft dizzy, still the same issue...

so i pulled the engine bay harness and completely split away the ignition related stuff from the rest of it, then taped back up the engine harness and plugged back in everything.. decided while i was there to come up with a remote mount module plan as i never liked the dizzy mount setup. i will post a separate article about how i did the remote mount project as i think people will find that info useful. anyways, inspected each wire to make sure there was no hidden damage, like splices, nicks, etc. made sure rf shield was intact on all signaling wiring, no shorts, nothing stood out as a problem. got the fender mount grey push start module installed and made a 'dummy' module on the distributor that caries out the spout signal to the fender mount module. super cool project! but alas, the bronco still has this problem when it gets hot, where it cranks slow. in fact, now sometimes it just does it even when cold. now i'm wondering if it's camshaft or timing gear related as i have exhausted all other options here.

it always made a terrible sound at idle and when coming off throttle, and seemed to be coming from the timing cover. never got into it b/c my friend who owns rig said it was replaced two years ago... alas, my curiosity got the best of me and so into the timing cover i go. 

pull the radiator, pull harmonic balancer, pull cover, and what do i discover? the ****** that replaced the gear for my friend two years ago pressed it on halfway.. (cam was 3/8 inch inside the cam gear still instead of 1/16 out like i usually see them.  the sound it was making was the cam walking in and out, contacting the cover. the guy also stripped out the bolts on the timing cover to the oil pan and ruined the front main seal by not properly aligning the cover when reinstalling. i realized that the distributor's timing was probably affected by the walking of the cam... although not by too much? since the clearances inside the timing cover are still pretty small. but i sure was not going to leave it that way, even if this didn't fix the problem. so i picked up a steel/aluminum timing set and pulled the fiber pos that was on there. so i get the gear off and the half moon shaped key was to blame for why the dude had not been able to get the gear on all the way. (it slid back and out) i also broke the ****** plate while removing the gear... so off to the junkyard, to get a timing cover and ****** plate.. get back and continue on the job... i'm getting ready to pull the crank gear so that the new aluminum one can be mated to a matched set and i discover the Fn crank gear has no puller bolt holes... great. made up a heat shield so i didn't burn the oil pan gasket and started map gassing the crank gear to get it to expand... sprayed it with some pb blaster, wedged some chizles behind each side and was able to get it far enough off i could fit a (modified) jaw puller on it. what a pita. thought i was going to ruin the ****** bearing on the crank or bbq the front bearing by blowtorching... got it off finally. phew. proceed with rest of installation which went fine from thereafter. aluminum gear pressed on much easier than the steel ones i have done before. i'd also like to do a writeup someday about timing gear swaps, since there's quite a few ways people can ***** this job up. get it all back together and guess what. it totally did fix the problem. while i was pressing the cam gear on i had the dizzy cap off to see how much the rotor moved per camshaft travel and was surprised to find the rotor moves quite a lot for even 1/8 inch of end play on the camshaft. this made me feel pretty confident in that i had found my problem. get it all back together and not a problem so far whatsoever. can't believe the cam wasn't damaged from 2 years of misalignment. drives better than it ever did. starts instantly, whether hot or cold. problem solved. 

moral of the story, the cam gear if not pressed all the way in can absolutely cause a cranks slow issue, as well as sloppy timing. even with only being able to travel in and out 1/8 an inch within the timing cover. hope this info helps someone else out there. it's also worth noting the 4.9 inline 6 survives this kind of abuse. haha.

 

[miesk5]

Yo,

Thanks for your step-by-step detailed narrative!   It still amazes me what a previous owner or shop would mangle.  Usually, it's wiring hacks that defy any form of human  logic, but then it's a Ford dealer "technician" that forgets to torque the front wheel bearing nut beyond finger tight.  My much better half had 30k service done on the 96 at local Ford dealer.  She picked it up on the lot and started to drive towards tge highway; Bronco decided to go hard left and her thumb was in tge way of the steering wheel spokes.  Ford paid for new spindle, etc.

Looking FWD to your icm relocation article!

Al