Fox T-Bird/Cougar Forums

87 5.0 w/aod 20th anniv coug

symptom: engine feels like its missing under steady applied throttle.

~only during drive conditions if i apply just a tiny bit of throttle and **allow the transmission** to accelerate my car, there happens to be a feel of a miss as the engine is pulling me down the road.
I do not press in further or let off the gas, my foot stays in one spot.  I let the transmission run through its first to second, then second to third gear but somewhere during this low RPM acceleration event , the engine shudder happens **nearly all the time**.

this is a new event that showed up about a month ago.

What i did:
~i shot gunned the problem at first by tuning up with wires, plugs, cap rotor, fuel filter and additionally i installed a new TPS.  These things needed done anyway.
Problem remained after basic tune up.
~KOEO - pulled codes and have 34 only in KOEO &
~KOER - on demand = code 34.  Memory= 34 & 29

I recenly replaced the heater core and remove the PCV screen, replace some vac lines that were in bad shape, installed everything back to correct order and the problem still remains.

I do not know how to temporarily defeat the EGR solenoid in an appropriate manner in order to clear the code and simulate vac to the egr, so i am wondering if the "lack of" the egr opening at all would cause an engine shudder.

The problem is non existent in most higher speeds and / or random acceleration / deceleration events.

it only shows up when i am driving like a civilized human being simply chuggin along cool calm and collected letting the car pull me along. 

If i simply put my foot on the pedal a little bit to get me going, let the transmission bring me up to ever so slow increasing speed, at some point the engine shutters and i dont know why.  this symptom caused me to randomly drop in a TPS thinking there may be a minor flat spot on the element inside which which was F'ign with the eec. .... not the case apparently.

no i did not check for fuel moisture in the FPR vac line,, forgot to.
No i have not check my fuel pres yet, can do tomorrow but i would rather have the hose extender so i can read it through my windshield while driving down the road to verify fuel pres while under a load.

spark is whitish blue.

fuel injector screens are OEM
FPR is likely OEM as well.,, dono
can do compression test as well.

The EGR could cause this. If it's not operating properly exhaust gas can enter the combustion chamber and cause the stumble. If you unplug the EGR the computer should ignore it and operate the engine sans exhaust gas. This is unless the EGR valve is stuck slightly open, than unplugging it won't help. If the stumble goes away it's probably the EGR valve. I would also check the FP regulator just to be on the safe side.

sorry, forgot to add, i pulled vac on the egr and it holds very well.
I do not know if there is carbon build up on its seat preventing it from seating properly.
what i do know is,,,,,,,,, i confirmed the code because when i removed the egr solenoid, applied power, i was not able to confirm there would be air flow through the vac fitting paths.

I measured the resistance of the egr solenoid and got nearly a short, much lower resistance than expected , opened it up and found a diode across the top of the solenoid windings to be shorted.  As a test only i cut one side of the diode to remove the dead short and found perfect resistance.  I re-energized the solenoid but i do not believe its moving enough to allow a vac path which would ultimately end up at the egr.

i will check the egr seat tomorrow, i should do some PM on that anyway.

fuel pres is 36 with vac line disconnected and plugged.
Fuel pres is 42 with vac line on.

no fuel found in the fuel pres vac hose,, i grounded the tan light green wire at the eec conn to manually make the fuel pump run full time for testing.

KOER, fuel pres held steady at the same psi as when the car was not running.


Vac pres on the vac tree was a steady 18psi at idle.

There is a sometimes useful tool for checking solenoids.
It's called the Output State Check.
When KOEO finishes outputing codes it is setup for doing the output check. Each time the throttle is pushed to WOT it changes the state of the solenoids, Off to On, On to Off etc

fuel

yep, your right, posted it bass akwards, sorry.
i really dont care if the EGR solenoid is the cause, i would like a way to defeat the code to see if i can make the symtom go away.  I suppose i can just push a little harder on the gas pedal.  I was hunting down another solenoid like it in the car to borrow and use it in the egr line up. ,, was thinking of using one of the smog pump actuators to stand in place of the egr, easy enough to rig up for a test i suppose.

it feels just like something TPS , TFI or PIP related.  id hate to have to swap out the stator just to shot gun it but i may have to.  those hull effects like fuel pumps really dont give you any warning unless your really in sync with how your car "feels"



Softtouch~  our kidding me right?  this is an awsome tid bit, im seriously considering trying to understand where i missed out on this wealth of knowledge.  i will do this sometime today and just pick any random solenoid to see if i hear it click and change states

I have never heard of this either, cool stuff.

Try running a cylinder balance test at least twice in a row. Pretending its weak spark, bad timing, or fuel injector, it should show up here. That way you can rule out the individual fuel injectors or timing problem.

Emission Diagnosis Shop Manual Volume HC. Quick Test Appendices. Appendix D-- Output State Check (84 Shop Manual)

You may want to check the EVP sensor voltage with key-on engine not running. Code 34 may mean the voltage is too high with the valve in the closed position. Voltage should be between .25V and .67v between the sense BR/LG and sig rtn BK/W.

Have you run KOEO with the EGR solenoid disconnected. I think the missing (open) solenoid should cause  83 or 84 Code.
Don't think it should cause a 34 code.

no sir,have not done that.  code 34 calls out this item though and it was a shorted diode that i cut out of the solenoid for test purposes.
will also check the voltage like you mentioned.

what i do know is i can not manually get air to pass from the lower to the upper vac fittings if i energize the solenoid.  there must be  crammed in there or something.  tried carb cleaner and it flowed through slowly,,

let it dry out then applied wd40, still cant blow through one tube out to the other with power on the solenoid.  i can move some air but not much.

They call those EGR solenoids Vacuum Regulators. They replaced the old two solenoid set-up, where you had a control solenoid and a vent solenoid. The vacuum regulator does both the vacuum control and the venting with one solenoid. You should be able to move air into the nipple that goes to the EGR valve with the solenoid on or off. In one case it goes to the vent hole to atmosphere, in the other case it goes to the vacuum supply nipple. I don't know whether the solenoid being "on" connects it to the supply or the vent.

correct, de-energized the white vac line is to vent.--if i blow through it.

If energized, i can blow ever so slightly through the the top and out the bottom but not much at all to the point im calling it nothing.

Holy ,
Moving the throttle wide open and Letting it return deenergize is the EEC relay.
Moving the throttle again once more wide open re energizes the EEC relay.

Once more all characteristics of solenoids come into play depending on their state

Well lookee here, it looks like somebody thought they were an electrician. Space looks like my orange white wire has been twisted together and sealed up with silicone. I'm a fix this before MoveOn

fixed the orange / white wiring and now i have my EGR working.

apparently the EVP solenoid **IS** providing a vac path.

the egr is moving in and out **but** after a few warm up cycles, the code 34 remains.  it is my only code now, perhaps i will just run it for a while and see what happens.. maybe it will go away, who knows.

You sure it's the EEC relay? Seems like if the EEC powered off it would forget it was running the test.

i knew after i washed up and thought about what i typed it was word vomit.  i meant WOT relay.
I also felt the smog pump solenoids clicking as well.

im gonna give it a few warm up cycles then recheck codes later on. 

i did not test the evp millivolt reading yet, i was assuming you wanted me to do this with the evp connector on and thats what i was going to do until i found my hidden mess.
Its a very difficult spot to get to unless i stick pin the wires and gator clip,, then no problem.  will get to this tomorrow hopefully

 i do know that i had about 3.4vdc from those wires with the evp connector off and reading on the connector end  a week or so ago. Its actually the very first test i did.
 I do have 5.2vdc from the org to ground, kinda makes sense per the 87 diagram.

Code 34 clearly pointed to the EGR positioner. The ecm was seeing a high voltage from it at closed pintle. Another words it was seeing an EGR valve that was stuck open. That code should have sent you their not the solenoid.

Code 34 is set when the ECM sees a closed EGR valve and sends .6 volts or higher back to the ECM. I have never changed a solenoid on a ford for the EGR valve. The ECM will not set a code for a defective solenoid. It monitors the EGR positioner for movement not the solenoid

i went directly to the evp first off like the code said.

my test showed the egr never moved from a cold to a warm engine state.
i removed the evp and swapped in a known good 1year manuf date older (had same total resistance , had same center tap resistance, had good readings from what a digital meter can provide).  I do need to still get an buttstuffog meter.

I pulled vac on the diaphram and the egr held vac for as log as it took me to walk in the house and reload coffee.

in my mind, i saw that the diaphram never moved and the EGR solenoid makes that happen.
i removed the egr solenoid and powered it up off the battery and heard no audible click any sorts, no state change, no smoke either.
I measured the egr solenoid coil resistance and got odd readings like i was across a capacitor ( i was expecting some resistive valute) , found a diode atop the coil inside the solenoid and it was shorted.
I concluded the diode was there for filtering purposes and cut one side just to see if anything changed, the resistance went from an odd reading to a steady ohm value i have now forgotten. 

i powered up the solenoid with 12v and now i had an audible click.
I could not blow air through one vac fitting to the other,, concluded the path inside this sucker was clogged somehow.
sprayed cleaner up in both holes and re-installed , now the egr is moving, therefore the evp sensor is also now getting a signal.

the reasons for my fooling with the egr solenoid is because the egr was not moving so the egr control solenoid does this job.  now the egr moves , perhaps i do have a path for vac flow after spraying stuff in there.

doing the wide open throttle test after codes are dumped did not energize this solenoid either.


i see what you are saying though, the code is what it is, however, probing the connector is impossible with the egr installed.  I opted to removed and test the evp on its own and see if the egr held vac, both passed in my opinion.  the input was couldnt have been good for sure.  Oddly enough, the tps had good input voltage which was amazing to me but apparently there was enough contact that the previous owners work may have been working "well enough".  something did change after repairing the orange white wire(s) though, the egr started to work.

Jay with all due respect the ECM was telling you that the EVP was out of range and returning to much voltage. Hence a code 34. Code 34 once again tells yo the EGR valve is off it's seat. That is accomplished br the EVP sensor. What you should have dun was unplugged the connector from the EVP then run codes. Or remove the EVP from the egr valve and see if you cleared the code. A stuck EGR valve open sets code 34 as i explained. The ECM does not monitor a relay in this system. Bottom line my brother you ignored the ecm screaming out to you that the EVP was the issue. Thanks for listening and i respect the hell out of you . You are not ashamed of admitting a mess up. Either way you nailed it and all is good in the world, Thanks!

well, i did go straight to the evp but when i pulled codes and when it passed, i had to look at associated devices,  truely i didnt think about the egr being partially off its seat.

maybe this was  a two person job during start up because i never saw the EGR move until after i fixed the org wire.  Apparently it must have been off its seat like you both are saying but i never saw it move ever until i soldered that bonding point.

i look at the egr diaphram by eyeball, then walk around and start the car, then i rev the throttle a little bit with no results.. egr never moved.
fixed org wire and now when i rev the engine it flutters or opens up.

i see what your saying though, in order to get rid of this code, im gonna have to take some evp measurements following the emissions shop manual step by step.

i prob wont do this for a couple days of running the car though... thanks

Well i have trimmed many of the plungers and or have shimmed them to clear that code. GOOD LUCK

yep, i was wondering that after comparing a couple evp's i have lying around, wondered about the "height" off the vac diaphram and how calibrated it is.

took the car out for a spin and i cant make the problem happen right now.  this is good news,

now i have code 23 and 34 on demand and 34 in memory.... LOL

23 should be tps if I remember correctly...

yep,, and the green wire has .845vdc with closed koeo and closed throttle so that part is good., tps is new.

A code 23 indicates some type of problem obviously.

I'd run a quick sweep all the way through, makining sure there are no dead spots. The tps is basically a pot screw, and shouldn't throw a code unless you have a break in a wire or bad spot in it.

i agree, something is up,  i wonder if i introduced the code by cycling the trottle plate to test the solenoids after the codes finished.

Code 23 TPS out of range!!!! Best tested with a scope not a meter. The scope will indicate NOISE. But if a meter is all you have a digital one is best.

naw,, buttstuffog is better for pots, thats prob what you meant.
my / most digi meters flip scales from 100's to thousands and you loose clairty of what was in between cause the screen blinks form one scale to the other,, you know what i am talking about.
have you ever busted one apart?  thin film of plastic with a narrow band of carbon glued to it.

this tps is new but im gonna put the motorcraft one back on, i just picked one up to toss on when i was shot gunning the issue.

i dont own an oscope ,, a Huntron is on my christmas list or a simpson 260 or 360, we will see how much coal get instead.

wait a minute, perhaps i need to say  "why do you say a digi meter is better"?  just curious.

I have a FLUKE that does not have a stabelizing circuit to see the blips in the resistance or voltage sweep. I also use an buttstuffog meter also. I think the fluke has a better way of seeing a dirty sweep. But the bottom line is the scope. Scopes are cheap now and will paint a better picture of a Noisy TPS

:hick::mullet::burnout:

I've never had to buy a anolog meter or a scope to find a bad spot in a tps. I have mostly used a $2.99 cheapie harbor freight volt meter. You just turn the key on, slowly move the throttle by hand, and any dip or drop in voltage while increasing throttle means bad tps. I have gotten 2 bad tps sensors from the pars stores as well.

As long as idle is .49-1.17v's, and maxes out at least 2.5v's above idle value, you should be golden. It I possible you slightly had your foot on the gas pedal when you started it or something like that as well. I'd reset the computer, run codes again, then check the tps one more time.