lurches mostly 3rd gear... no codes

DWilliamA

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Tons of things tried... already fixed codes 81/82 and 33.. currently throwing code 11 and 10

New EGR and EGR solenoid
New Air Diverter
New fuel pressure regulator
New vacuum lines
wires new
plugs new
Newer MAP ... pulling vacuum line from MAP makes it surge
pulling vacuum off EGR makes it idle high
vacuum lines to TPS may be suspect
TPS and MAP replaced within last year
New fresh air charge sensor
New coil
cap and rotor new last year

temperature sensor not new ????

It runs pretty good when cold, but when warm it lurches especially pronounced in 3rd gear going slow slight throttle up slight hill... it has a rich smell. as soon as you step on it and shifts down it clears right up and runs pretty good but still has a little hesitation going on during hard acceleration

has a history (couple times over the last 8 years or so) of burning up plug wires at the plug on the passenger side.. (EGR related?) currently has heat shields over the wires... wiring routing should be good 1&3 and 5&6 separated well... hope those are the critical ones ?

it threw a code.. forget the number .. that led me to look at the shift sensor or shift solenoid... because for awhile my truck was in limp mode ... only 2nd and 3rd and reverse worked.. found out that wires to the Transmission were on the exhaust and burnt .. replaced the wire harness plug and wires... no code.. no OD light coming on. shifts normal now.

Along the way I did discover the air intake tubes had disconnected from the air filter box... and the fresh air charge sensor was ugly dirty.
I discovered the vacuum line to the "thing" that sits right by cylinder 4 was off.. for how long I don't know.

haven't replaced the "thing" that is right behind the intake manifold that has I think the red vacuum tube running to it.

1990 5.8L auto Centurion... any ideas...
 

Tiha

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Code 11 means all clear

Code 10 means you should have stepped on the throttle during the test when it told you to.

Any idea what the RPMS are? and how far they jump?

IAC valve maybe? Also wondering about the TPS like you mentioned.

How many miles? Could be the motor is getting tired and doesn't have the HP it used to.
 
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DWilliamA

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Code 11 means all clear

Code 10 means you should have stepped on the throttle during the test when it told you to.

Any idea what the RPMS are? and how far they jump?

IAC valve maybe? Also wondering about the TPS like you mentioned.

How many miles? Could be the motor is getting tired and doesn't have the HP it used to.

I didn't know 10 means step on throttle... I will try that and see if I get a code out of it

Engine rpms are good and stable, cold start high around 1200 maybe... then drop to around 750 or so.. like it always has for 15 years. when the engine is cold it runs reallly smooth. fact is it is a pain testing it after each 'fix' because I always have to drive it for 10 minutes or more thinking I fixed it this time... but no... it still comes back.

I have had the TPS go out before...it caused all sorts of rpm/idle irregularities ... nothing of the sort now.

Is the IAC one of the "things" i mentioned above... intake air charge maybe...if so I replaced that.

The engine has around 150k... timing change done already .. burns a little oil ... I don't think the engine is tired and causing this .... I have owned 6 or 7 different broncos and experienced all sorts of engine failures... once you step on the gas it clears right up and runs smooth... especially when cold... when it gets warm it still clears out when you step on it... but it does hang on to a tiny bit of lurching at other times other than 3rd gear, but more like an annoying small misfire that needs to get fixed but I can get to work today.

about the timing change... before changing it (2 years ago) ... about 25% of the time when I stepped on the gas from a coasting cruising throttle it would buck once, engine light would come on briefly like the engine actually died for a second and then go like gang busters... timing changed fixed that. can see how a loose timing chain would do this... but I have had other timing chains wear out in other trucks ... and never had the symptoms I am having now... I would think if the timing chain were going out this bad it would cause problems and throw codes of some sort... maybe code 10 throttle test will show something.
 
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DWilliamA

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That's what your OD Off button is for.

The OD light goes on and off when you press the button like it should.. the only time I press the OD light on ... which turns OD off... is when going up hills pulling a load, or driving in snow ice. It could be shift solenoid unit or the shifter solenoid thing in the shift solenoid keeping the truck in 4th gear when it should be in 3rd ... if so it isn't throwing any codes about it. maybe doing the throttle test 10 thing will show something... I will try driving it with OD light on and see what happens.
 
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DWilliamA

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The OD light goes on and off when you press the button like it should.. the only time I press the OD light on ... which turns OD off... is when going up hills pulling a load, or driving in snow ice. It could be shift solenoid unit or the shifter solenoid thing in the shift solenoid keeping the truck in 4th gear when it should be in 3rd ... if so it isn't throwing any codes about it. maybe doing the throttle test 10 thing will show something... I will try driving it with OD light on and see what happens.


I just test drove it and it didn't make a difference light on or off .. immediatly going up the road in front of my house slight uphill it was lurching in what I suspect is 3rd gear until I stepped on it and dropped into 2nd.... with light on or off no difference ... rest of the test drive didn't make a difference either . Not 100% sure the OD off function is working though... as if the light comes on but the OD stays on still ... going to freeway test it now to see for sure if the OD function is works
 
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DWilliamA

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Code 11 means all clear

Code 10 means you should have stepped on the throttle during the test when it told you to.

Any idea what the RPMS are? and how far they jump?

IAC valve maybe? Also wondering about the TPS like you mentioned.

How many miles? Could be the motor is getting tired and doesn't have the HP it used to.

code 10 step on throttle... this is a KOEO test... ????
 
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DWilliamA

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Ran KOER test 33, 44, 72 and 73... this after I ran the truck up a small mtn pass 1400ft and if I didn't stomp on it to keep the rev's up probably wouldn't have made it up.. lurching the entire way... and running bad at idle afterwards too .... Def going to fix the TPS...

EGR thing.. brand new body and solenoid... must be electrical... or TPS bad keeping it off its feed bag...

thing about the EGR and Thermactor stuff.. I made all the changes above and none of them made a difference along the way.

The OD confirmed working normal.

thats where it is.
 

Motech

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Code 10 means you should have stepped on the throttle during the test when it told you to.

Code 10 is also a separator code between CONTINUOUS and KOEO Self Test results.

So if everything passed, you'd get 11 _ 10 _ 11

If you had a memory code 33, you'd get 11 _ 10 _ 33
 
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DWilliamA

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Code 10 is also a separator code between CONTINUOUS and KOEO Self Test results.

So if everything passed, you'd get 11 _ 10 _ 11

If you had a memory code 33, you'd get 11 _ 10 _ 33

before I ran the KOER test... after fixing 81 and 82 supposedy it threw a 11-10-33 and I installed the EGR body and solenoid as a pair ... then it threw 11-10-11.
then I ran the KOER test literally 20 minutes ago and it still throws EGR Stuff and then some ... 33 -44 -72 -73

the way its running.. the TPS makes perfect sense... the EGR stuff not so much
 

Motech

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Ran KOER test 33, 44, 72 and 73.

EGR code 33 and Thermactor Air code 44 are both directly related to the red vacuum hose.

Insufficient MAP Sensor response during KOER throttle snap code 72 and Insufficient Throttle Open during KOER throttle snap code 73 are consistent with a weak or missing throttle snap.

That throttle snap needs to be WFO. PCM is testing MAP, TPS and KNOCK sensors (when equipped) during that snap.

If you are positive you're giving it a robust, to the floor snap when requested, then start looking at your throttle linkage.

I noticed you mentioned a new throttle body, and many times stretched cables, bent brackets, or bunched up floor mats can prevent full wide open throttle. I have repaired a lot of power loss problems in the past by restoring full throttle, many who did not even have a complaint. Imagine their stoke when they pick up their trucks and they get up and boogie now! You might be surprised how many small block Fords out there are not achieving it.

If that is your problem, it might also solve your lurching issue too.
 
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DWilliamA

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EGR code 33 and Thermactor Air code 44 are both directly related to the red vacuum hose.

Insufficient MAP Sensor response during KOER throttle snap code 72 and Insufficient Throttle Open during KOER throttle snap code 73 are consistent with a weak or missing throttle snap.

That throttle snap needs to be WFO. PCM is testing MAP, TPS and KNOCK sensors (when equipped) during that snap.

If you are positive you're giving it a robust, to the floor snap when requested, then start looking at your throttle linkage.

I noticed you mentioned a new throttle body, and many times stretched cables, bent brackets, or bunched up floor mats can prevent full wide open throttle. I have repaired a lot of power loss problems in the past by restoring full throttle, many who did not even have a complaint. Imagine their stoke when they pick up their trucks and they get up and boogie now! You might be surprised how many small block Fords out there are not achieving it.

If that is your problem, it might also solve your lurching issue too.

I did not snap full throttle... just held rpms up at 4k or something pretty high for 5 secs or a bit more.

I replaced the red vacuum tubes.. but that indicates the things it connects to.

Will check reservoir.. looks good but maybe it is leaking..

Will start with tps... vac res... full throttle snap... see what happens.
Thx
 

L\Bronco

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Tons of things tried... already fixed codes 81/82 and 33.. currently throwing code 11 and 10

New EGR and EGR solenoid
New Air Diverter
New fuel pressure regulator
New vacuum lines
wires new
plugs new
Newer MAP ... pulling vacuum line from MAP makes it surge
pulling vacuum off EGR makes it idle high
vacuum lines to TPS may be suspect
TPS and MAP replaced within last year
New fresh air charge sensor
New coil
cap and rotor new last year

temperature sensor not new ????

It runs pretty good when cold, but when warm it lurches especially pronounced in 3rd gear going slow slight throttle up slight hill... it has a rich smell. as soon as you step on it and shifts down it clears right up and runs pretty good but still has a little hesitation going on during hard acceleration

has a history (couple times over the last 8 years or so) of burning up plug wires at the plug on the passenger side.. (EGR related?) currently has heat shields over the wires... wiring routing should be good 1&3 and 5&6 separated well... hope those are the critical ones ?

it threw a code.. forget the number .. that led me to look at the shift sensor or shift solenoid... because for awhile my truck was in limp mode ... only 2nd and 3rd and reverse worked.. found out that wires to the Transmission were on the exhaust and burnt .. replaced the wire harness plug and wires... no code.. no OD light coming on. shifts normal now.

Along the way I did discover the air intake tubes had disconnected from the air filter box... and the fresh air charge sensor was ugly dirty.
I discovered the vacuum line to the "thing" that sits right by cylinder 4 was off.. for how long I don't know.

haven't replaced the "thing" that is right behind the intake manifold that has I think the red vacuum tube running to it.

1990 5.8L auto Centurion... any ideas...
Here's where I'm stuck, The EGR valve should be closed at Idle (no vac signal)
If the idle increases or improves when the vac line is pulled, it indicates the EGR is open when it should be closed.
Try removing and plugging the vacuum line to the EGR and go for a road test.
If it improves, check the vacuum line routing to the EGR control solenoids and check their operation.
EGR flow during light accel will make it hesitate badly, and WFO will get rid of the vacuum that is opening the valve.
I suspect mis-routed vac lines or failed control solenoids.
Hope that helps
cheers
 
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DWilliamA

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after figuring out how to run the KOER test properly ... I get 44 thermactor air system fault .. that's it. one of my EGR vacuum lines was unattached. once attached no EGR codes.

and after further inspection the reservoir has a single hole in it, like it got punctured.. not rust out... going to patch.
 
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L\Bronco

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after figuring out how to run the KOER test properly ... I get 44 thermactor air system fault .. that's it. one of my EGR vacuum lines was unattached. once attached no EGR codes.
Awesome, next, I would verify fuel pressure while its acting up. Gauge taped to the windshield…
Good luck!
Cheers
 
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DWilliamA

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I fixed the hole in the vacuum reservoir ... it definitely pulls a vacuum through it now... when I started the truck it definitely was different.. idled almost too low but the engine kind of gradually increased idle as it adjusted to the new scenario... thinking that is good.

Throws no codes KOEO

Still throws code 44 KOER

the vacuum line that runs to the TAD... TAB ... and the Diverter.... all pull a vacuum.. The Diverter is pulling a vacuum on the line to the EGR at idle ..... the front of truck TAD/TAB unit ... (not sure which is which) does not pull a vacuum (at idle if that matters) at the tube running to the "thing" just behind the intake manifold... The TAB/TAD closest to the cab does pull a vacuum (at idle) on its tube to whatever it runs to... I think its the "Thing" right next to cylinder 4...

I actually wouldn't mind replacing the TAB and TAD but heck if I can find them at a parts store ... I have already replaced the diverter right in front of the TAB/TAD

this is a work truck... these are all old parts wouldn't mind just replacing the thing behind the intake (What is this called) and the thing next to cyl 4 (what is this called) ... even the smog pump if I have too. Any thing else?.

I worry about the "thing" next to cyl 4 .. both cyl 3 and 4 have had a history of burning up spark plug wires.. like it gets real hot there.. missing a heat shield or something? not having a good running EGR I think can make the exhaust run hot I think I have heard that... ???

any thoughts
thank you in advance.
 
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DWilliamA

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Awesome, next, I would verify fuel pressure while its acting up. Gauge taped to the windshield…
Good luck!
Cheers

I can do that... wasn't thinking related to code 44 stuff... but I will check everything at this point. just check it.... right around 37 to 38... revving it jumps to 39,, decel drops to 36.. mostly hangs around 37.5 to 38
 
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DWilliamA

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Here's where I'm stuck, The EGR valve should be closed at Idle (no vac signal)
If the idle increases or improves when the vac line is pulled, it indicates the EGR is open when it should be closed.
Try removing and plugging the vacuum line to the EGR and go for a road test.
If it improves, check the vacuum line routing to the EGR control solenoids and check their operation.
EGR flow during light accel will make it hesitate badly, and WFO will get rid of the vacuum that is opening the valve.
I suspect mis-routed vac lines or failed control solenoids.
Hope that helps
cheers
later on I talk about getting the reservoir fixed and all the lines except 1 seem to pulling a vacuum.. it does pull a small vacuum at idle at the EGR. the only thing that doesn't pull a vacuum is the TAD/TAB sensor closest to the diverter which I think runs to the "thing" by cylinder 4.
 
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DWilliamA

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ever since I ran the truck up the mtn pass.. its been running worse even at idle... exhaust smells rich too... whatever is going out is getting worse. code 44 related thermactor something. I used to have to let it warm up and then drive it to get the lurching to start up mostly in 3 or 4th gear, now I can tell at idle that it is coughing and not fixed.
 

Motech

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Smack your TAB & TAD solenoids smartly a few times with a screwdriver handle.
(Not kidding. They can get stuck after setting a while)
Then run your KOER self test again and see what happens.
 

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