94 explorer,, rough idle cold,????

[siTTinLo420]

hello to all, i would first like to say that i have been browsing this forum for quite sometime, and i love how much information is available from everything to engine and drivetrain to suspension and lift kits,and lowering kits,,and even where the good wheelin trails are !!!!,, i love this place!!!!,,
this is my first actual post,and i have been having an ongoing issue with my 94 explorer xlt,, this is the 4th first generation explorer that i have owned,, i bought this one because i was immediatly drawn to how solid and rust free the body was,, and trust me,, a first gen with minimal rust is almost impossible to find here in michigan,, but i found one,,, however ,,lately i have been getting extremely frustrated as to why it has a rough idle when i first start it in the cold morning,,, but i guess that i should start from the beginning,,,,,

i bought this 94 explorer about august of 2009,, and right off the bat it seemed to have sluggish acceleration compared to my 93 i have and keep around as a "farm truck",, so i checked to see if the throttle body was opening all the way when the gas pedal was floored,,, it was only opening about 25%,, i did the "throttle cable" mod at the gas pedal,and that fixed that,,, slightly more acceleration now,, but still not like my 93,,
so i did a full major tune up using only ford mororcraft plugs and wires,,new air filter,new fuel filter, all that good stuff,,, with no change in its performance,, so i figured "well mabey the cats are clogged" ??? so after inspecting to see if i had o2 sensors after the cat,,and there wasn't one,, i decided to drop the cats,,hollow them out completely than bolt it back up,,, this kinda helped the pick up a little bit but still not very much,, so i just said "screw it,,,, just drive it,,,, its not a race car",,,,

the truck runs excellent,,no lifter chatter or any ticks or bumps,,all summer long,, than just recently,, i have been expieriencing some "idle issues",, it first started when i went to start it one day after it ran fine,,than it immediatly stalled ?? which it had never done before,, so i though to myself "well that was odd" and started it again,, the idle was rough but than smoothed out,, the next day the idle was at 1200 when i started it and stayed there nomatter what the engine temp is???? even at a stop light,,1200rpm,, than it would drop to normal again,,,but than every now and again,,out of nowhere,, the idle would just jump back up to 12-1300rpms in park,,in drive and even in traffic at a stoplight,,i almost rearended someone when it jumped up because it just wants to lunge forward,,, i had to put it in neutral at every light,, so i changed the IAC valve ,,Engine Coolant Temp sensor,,cleaned the MAF sensor,, inspected all my vacumm lines ,, and reset the computer,,, it ran good for about a week,, than started doing the same thing as before,,,
at this point i started to suspect that it was mabey TPS sensor issue,,,,, i changed that aswell,,,, changing the TPS seemed to help in regards to when the transmission would shift and a little more acceleration,,, but it did not correct the idle issue,, so next i took it to a "local mechanic" which i hate doing,,but i figure that he could use his fancy computer scanners and smoke machines to find cracks n stuff,, the only code that popped up he said was " octane pin adjust switch open"or something like that,,and there were no cracks of leaks in the engine when he did his magic smoke test,, he did however say that the vacuum lines were routed incorrectly and he sloppily re-roughted 1 or 2 of them and it still doesnt look correct,, because i have gone to the junk yards and inspected 3 other explorers how their lines were roughted and they are roughted differently than mine now,, and this "ase certified mechanic" supossibly changed the upper intake gasket,,,,

now ,,correct me if i am wrong,,but dont you have to REMOVE the upper intake to replace the gasket,,and to remove the upper intake this also includes DISCONNECTING THE EGR TUBE THAT COMES FROM THE EXHAUST AND GOES TO THE EGR VALVE??? well this yucko didnt disconnect the tube,,, i can tell,, im not dumb,, so im thinkin,,"did this guy just prop the intake up a tiny bit and just slip a new gasket in?? or did he not even do it???",,, prior to taking it in the shop to have it looked at, i bought a brand new egr valve aswell,,,,it was sitting on the passenger seat in the box!! and i asked him before he even did the supposed gasket change,,i said,,, "so,, in order to change the gasket,you have to remove the upper intake plenum,,and this also means that you have to disconnect the egr tube right??" and he said "correct",,, so i said "well if you're gonna take that off anyway,, would you mind putting on the new egr valve sitting on the passenger seat in??" and he said "sure that would not be a problem",,,

i go to pick it up a week later?? and the egr is still in the box,,, it doesn't even look like a wrench went anywhere near the egr tube,which leads me to believe that this guy didnt do ****,,,and he also said,,,"we werent getting a proper reading from tour TPS so we had to modify it a little",,,, im thinkin what the?? i popped the hood and basicly this clown reamed the holes that hold the sensor to the throttle body,and said he had to "re-clock it to get a reading",,,,, what a crock of ****,,,basicly ,,, the brand new tps sensor i put on is all rigged now and it still runs like ass,,, at this point i am extremely frustrated,,,so i went to my auto parts store and seafomed the motor and replaced the,,
IAC valve again
ECT sensor again
MAF sensor
PCV valve
DPFE sensor
IAT sensor
both o2 sensors
reset the computer again

this seemed to help out,,it ran great for a few weeks,,, no wierd idle fluctuations and no mising,, but than guess what ,,,,,,it started idleing rough again,,,, so now im thinkin "well i've already replaced every information sensor to the computer,, the idle control valve,the maf,,,, why?" so now i decided,,,,, well im gonna do a coolant flush and change the thermostat,because i noticed that it would take too much time to get up to temp,, and even when it was warm,,it was still running cold,, the guage was just before the n in normal,,,when i removed the thermostat i discoved that whoever installed it prior had put it in backwards????
i thought that this was the answer to all my problems,,, new t-stat,,fresh clean coolant,,and a new radiator cap,,,, reset the computer again,,and it runs excellent now,no jumping idle and good power and acceleration,,when up to normal operating temp that is,,, but when i let the vehicle sit overnight in the cold michigan winter,,, the truck has an extremely rough idle when i first start it,,but only when cold?? when its warm,and up to temp ,the truck runs great,,i'd drive it to alaska and back,,but its only when its cold????

at this point i dont know what to do anymore,,,, the only things that i haven't replaced was the fuel pump,alternator,EGR valve,and the VSS sensor,, i just went to a junk yard and pulled a computer from another explorer,and this was going to be my last resort i think,,,plus i need to go around and inspect all my ground points in my electrical system,, im getting a steady 14.4 volts from the alt,, but at this piont im stuck,,,,,,, i am completely stumped,,,???

i really do love this truck,, otherwise i wouldn't even waste my time on it ,but why does it keep doing this??? i cannot find a vacuum line diagram ANYWHERE and for all i know,, thats all it is because the way that yucko the clown mechanic ran my lines does not appear to be correct at all,,, he did NOT put on my egr valve,,and im wondering if he even replaced the supposed gasket,,, and if he did ,,, i know that it was done incorrectly,,i think he just wedged a new gasket into the little gap he made and torqued it down,,, hack ****,,,usually you want to remove all reminants of the old gasket and clean both mating surfaces,,,,how is this possible when the actual upper intake was never removed???? its not i don't think,,,

but im just at my boiling point with this truck and i would HATE to get rid of it just because it idles ****ty when its cold outside,,, but lately,,, it's just been one thing after another,,and im tired of just throwing money into it only to have it still run like ****,,im tired of fixing "this" and now it does "that" and all these hack ripoff mechanics around here,, all seem to have an answer,,, just not any solutions,,,

if any of my fellow explorer owners have expierienced this problem,, please drop me a line and let me know if you have any other suggetions on how i could fix my cold idle problem,,, any kind of info would be greatly appreciated,, thank you very much,,, paul, and dora the explorer,

 

[westfield]

holy crap...waaaaay to much and hard to read....

 

[Mirge]

Welcome to the boards

I'm not reading that post.

 

[siTTinLo420]

i guess thats what i get for trying to be thorough,,and explain everything,,

 

[Mirge]

i guess thats what i get for trying to be thorough,,and explain everything,,

Do us a favor, and separate your enormous post into readable paragraphs. Then people will be far more likely to help you.

EDIT: that's better, thank you

 

[joe doe]

you need to replace the upper plenum gaskets if thats a 4.0 ohv engine .not the intake gasket but the upper plenum .
over time these gaskets get compressed and no longer seal properly,when its cold out they are compressed even more ,when the engine warms up they swell enough to be driveable but still cause driveability issues .

you have wasted alot of greenbacks troubleshooting this the wrong way .
should have had your codes ran from the start .this is a common problem with the 4.0 ohv engine .i done mine last year and my engine light went out and has not returned .

this is the fix ,dont waste anymore money.there are 3 sets of gaskets that go in there .buy them at the dealers ,they are affordable.one set for each runner,3 sets.

ps--get another mechanic too he should have known this.

 

[siTTinLo420]

i appreciate the reply,, and i did have the codes read at first and all that came up was something about the octane udjust pin switch open,,, which i did some research on this,and learned that on the passenger side of my 94
by the blower motor is 3 plugs
1 for the computer diagnostics
1 for the octane adjust pin
and a 3rd one to prime the fuel pump? i believe?

so i checked the plug and i saw that there was nothing in there,,than i went to inspect under the hood of my 93 and found that there was a gray plastic "plug" type thing in there

so i ran to the bone yard and grabbed this gray plug and plugged it in,,it made no noticeable difference,, i tried to find out more info about this plug thing and from the info that i have gathered that this plug is pulled out if you get a tank full of bad gas,, by removing this plug,, it will reset the computers parameters to run safely,,
and my 94 has a pushrod motor so i do not think that the gaskets you speak of are the issue, but i appreciate the input,, thank you

 

[siTTinLo420]

disregard that last post,,, im an idiot,,,, but these were the gaskets that the guy supposibly replaced,,, and i thought that you were talking about the explorers with the plastic intake,, with the o-rings,,,

 

[joe doe]

of course it has a pushrod motor,by that you mean a overhead valve engine correct?
well so is mine .this is the fix ,stop throwing money away .if you can wrench on a engine it wont cost much to do this .
i done my research early last year befor i had mine fixed ,i did not waste money on parts that did not help.
i used this forum ,input my computer codes and read,read,read everything i could befor jumping into the repair .
and this was the repair .and it worked the first time and ive never looked back .

good luck.

ps-i am talking about the plastic intake with orings......would yours be different because it has a cast upper?

the issues sound the same

 

[siTTinLo420]

i appreciate the input,, i would have done these gasket myself but no matter what i tried,, heat,pb blaster,, aerokroir,,more heat,, i could not get the egr tube disconnected,i tried and tried to the point where i thought i was going to break my aluminum intake,, so i couldnt remove the upper intake,, thats why i took it to a "professional",, but ill keep researching ! thank you

 

[fixxxer]

I know you said you replaced the IAC valve but:
Idle Air Control (IAC) Valve: Description and Operation
PURPOSE
The Idle Air Control (IAC) solenoid allows the Powertrain Control Module (PCM) to accurately control engine idle speed under a variety of conditions.
The IAC solenoid is driven by an output signal from the PCM and allows intake airflow to bypass the throttle plates. In addition to normal idle speed control the IAC solenoid also functions as a deceleration dashpot and allows for idle speed changes during periods of increased engine load (A/C, electrical).
The IAC solenoid also plays an integral role in Adaptive Strategy correction. The PCM monitors the engine condition and adjusts the IAC calibration to correct for wear and aging of components.
NOTE: Whenever an IAC component is replaced or cleaned it is recommended that the Keep Alive Memory (KAM) be be cleared. The vehicle may exhibit idle concerns until new adaptive values are learned.
CONSTRUCTION
A duty cycle driven solenoid is directly linked to a reverse seated pintle valve. The IAC solenoid may be constructed in one of two different styles.
Hitachi
This type of IAC solenoid is serviceable and may be removed and cleaned of sludge deposits that accumulate within the valve.
Hitachi With Vent/Filter
This type of IAC solenoid is not serviceable and cannot be cleaned.
OPERATION
The IAC solenoid receives a 12 volt signal from circuit VPWR. The ground supply to the IAC solenoid is controlled by the PCM. The PCM controls the amount of IAC operation by varying the duty cycle of the ground signal.
The IAC solenoid is linked directly to a pintle valve which controls the amount of intake airflow allowed to bypass the throttle plates.
RELATED DIAGNOSTIC TROUBLE CODES
DTC 412 Indicates that during the Key On Engine Running (KOER) self-test, engine rpm could not be controlled within the self-test limit band.
DTC 415 Indicates the IAC adaptive learning has reached the minimum learning limit (the valve is reducing air flow as much as possible).
DTC 416 Indicates the IAC adaptive learning has reached the maximum learning limit (the valve is admitting as much air flow as possible).
NOTE: Idle speed surging commonly results when the IAC solenoid reaches the limits of its operation. The IAC solenoid cannot compensate for the required change in idle speed which results in the engine surging between the upper and lower limits of the IAC system.

Gaskets and vacuum hoses are not the only thing effected by the cold. If you have a bad electrical connection you can have intermittent operation due to heat expansion of electrical connections, including ground connections.

 

[fixxxer]

Idle Speed: Adjustments
NOTE: Curb and fast idle speeds are controlled by the Powertrain Control Module (PCM) and Idle Air Control (IAC) valve assembly. The IAC valve
and idle speed is not adjustable. A large increase or decrease in closed plate airflow from the calibrated level will not allow effective idle speed control.
Throttle bodies with sludge tolerant design are identified with a yellow/black decal. The throttle body must NOT be cleaned inside the bore, as this
cleaning will impair the sensitive coating. Sludge accumulation will not affect the idle air flow. The cleaning procedure for the IAC valve still applies.

If the idle rpm is not within limits, eliminate the following possible causes:
- Battery and charging system integrity
- Contamination within the IAC component
- Lack of fuel system control (excessively rich or lean)
- Throttle sticking or binding
- Engine not reaching operating temperature
- Incorrect ignition timing
- Incorrect or clogged PCV system
- Vacuum leaks (intake manifold, vacuum hoses, vacuum reservoirs, power brake booster, etc.)
- Exhaust system, EGR.

 

[fixxxer]

1994 Explorer Vacuum hose routing

 

[siTTinLo420]

yes sir,, i have flip flopped my iac bac and forth from the new one back to the stock one after i took it apart and cleaned it out good.. and disco'd the battery each time,,let it sit for about an hour with the dome light on,,to drain everything i guess,, than after i reconnect the battery,, i start it and let it sit and idle for 10 mins,, than i put my foot on the brake,put it and drive and let it sit idleing in drive for approx 10 mins,, than i always drive it at least 20 miles,, and it always seems to run great,,
than a week later ,,, rough idle

i am beginning also to suspect mabey a bad alternator or ground somewhere,, because sometimes my voltage will be at 10v on the guage and than jump up to 14v ,,,?? and every now ang again,, the 4x4 lo range indicator light will come on but it will be very dim ,,?? but im not in 4x4 mode? this thing has all sorts of gremlins huh?
but every time i try something different it seems to work for a little while ,,than out of no where,, rough idle,, that is also why i grabbed a new pcm for 10 bux from the boneyard,, but this was going to be my last resort attampt fix,,, but i really appreciate all the input,, but you're saying that it could be the iac acting up?

 

[siTTinLo420]

awesome !!!!!! a vacuum diagram !!!!! i really really appreciate that !!!!!! you are the man!!!

 

[fixxxer]

Since the PCM regulates the IAC position and thereby the idle speed, it relies on having the correct voltage for proper operation. If you have an electrical fault somewhere causing fluctuations, that could be the root of several of your "gremlins".

 

[siTTinLo420]

yes i think this will be my next thing i look at,,, i have to find where the ground points are ,,and clean them up, and have my alt checked and or replaced,,because i do have 2 100watt hella driving lights and a rediculous stereo system in there,, i did upgrade the grounds at the battery and the engine block with 0 guage wire, and added a 2 guage wire from the pos post on the alt to the battery,, which i disconnected this wire to weed it out as a possibility for the cause of this idle situation,, but yesterday,, i let it sit idleing,, with my digital multimeter on the battery..14.4v at idle,, than i turned on every available accesory ,,, the head lights, driving lights ,,a/c full blast, wipers on full speed,,rear wiper,rear defroster, and my stereo blasting,, the voltage never dropped below 13.2,??? but when i turned all this stuff off,, it ran for a min,than the idle jumped to like 1300 for about 20 seconds than smoothed out,, ?
i did the exact same thing again trying to replicate the first time,,but this time ,, the idle did not jump when i turned all the accesries off,,??

 

[fixxxer]

As I stated earlier, the IAC controls the idle speed and the PCM controls the IAC position. If your idle fluctuates like you are describing, something is either throwing the IAC valve off, either a bad signal from the PCM or something interfering with the proper mechanical operation of the IAC valve. That "something" could be:
- Battery and charging system integrity
- Contamination within the IAC component
- Lack of fuel system control (excessively rich or lean)
- Throttle sticking or binding
- Engine not reaching operating temperature
- Incorrect ignition timing
- Incorrect or clogged PCV system
- Vacuum leaks (intake manifold, vacuum hoses, vacuum reservoirs, power brake booster, etc.)
- Exhaust system, EGR.

 

[siTTinLo420]

awesome,, i really appreciate the advise ,,the diagrams,, the codes,,and all your help,, as soon as i figure all this out,, you will be the first to know what it was,, i am very grateful for all your input,,

 

[fixxxer]

Yes, please do let us know if you get this resolved or not