Having idle issues and can't figure out the solution

[Reballion]

Hi there I'm new to this forum and hope this is the right place to ask this question since I can't find anyone with the same issue as me. I have a 1992 ford explorer 4.0 I just but this about a month ago. So the issue is when I first start it up the rpms jump to 2000 then slowly go down then settle at 900 to 1000 rpms but if I tap the gas it will jump to 1500 and stay there till I press the clutch in does even have to be all the way in and they will again settle otherwise they will stay at 1300 to 1500 rpms. Driving it is a little different if I get rpms to 3000 and shift to another gear the rpms will stay till the the transmission brings it back down due to vehicle speed. And if I'm going down the road with the vehicle in neutral the rpms jump from 1000 to 1500 till either I hold the clutch in or come to a about 10 mph and just completely stop. I have replaced iac valve and tps and checked for any vacuum leaks on the top side of engine and still nothing. It will be great to get this figured out and am glad to be apart of this forum

 

[swshawaii]

Trouble codes?

How To: Pull Trouble Codes on a 1st Gen Explorer (paperclip method)
http://www.explorerforum.com/forums/showthread.php?t=255962

 

[acschilling]

Hi there I'm new to this forum and hope this is the right place to ask this question since I can't find anyone with the same issue as me. I have a 1992 ford explorer 4.0 I just but this about a month ago. So the issue is when I first start it up the rpms jump to 2000 then slowly go down then settle at 900 to 1000 rpms but if I tap the gas it will jump to 1500 and stay there till I press the clutch in does even have to be all the way in and they will again settle otherwise they will stay at 1300 to 1500 rpms. Driving it is a little different if I get rpms to 3000 and shift to another gear the rpms will stay till the the transmission brings it back down due to vehicle speed. And if I'm going down the road with the vehicle in neutral the rpms jump from 1000 to 1500 till either I hold the clutch in or come to a about 10 mph and just completely stop. I have replaced iac valve and tps and checked for any vacuum leaks on the top side of engine and still nothing. It will be great to get this figured out and am glad to be apart of this forum

Kinda experiencing the same thing. Fast start up around 2000RPM and if I put it into neutral to use the brakes to slow down to a stop with no clutch the RPMs will hang at about 1500 until hitting the 10-15mph mark on the way to 0. I can't figure out why. The fast starts are usually when it's cold. I have brand spanking new heads on mine and have even newer clutch and flywheel and rear main seal. Had a compression test done the other day and #1 came out at 130 dry and 175 wet. My rings were most likely the next weakest spot from the upped compression from the new heads..not sure if it's all related. Before the heads I had a steady 650 rpm at idle and after around 900-1000 at idle.

Any chance you're using a significant amount of oil?

 

[Reballion]

Nope even with my slight oil pan leak the oil level has not dropped and is still very clean after 1500 miles. If I unplug my iac it doesnt do the high idles but will still jump up and down when going a certain speed but doesn't do it all the time I went ahead and ordered another iac to be sure they didn't give me a bad one I work with a toyota dealership and have the ability to use the obd 1 scanner so I will do that and see what comes up

 

[acschilling]

I'll be interested in what you come up with

 

[Reballion]

Hmm so couldn't get troubles from the scanner when vehicle running and went ahead and cleared dtcs will scan again tomorrow to see what comes up did get pictures will post when using a computer not phone

 

[Harpua216]

do you know how long the plugs and wires have been in the car? when the last time the fuel filter was changed? what is the origination (state) of the car. I know in that model, if memory serves me, some had EGR's and some did not depending on the state it was being shipped to.

i also remember chasing down vacuum leaks and fixing the problem....

...until i cracked the head by fouling out one of the valves. not saying thats your problem, thats what happened to me, the old 5-6 gap?? (i think ) crack. a common occurrence on these blocks.

easy enough to fix that, ill take the engine over the trans on the 92's any dayl.

 

[Reballion]

So I'm pretty sure I figured the problem did sparkplug and wires couple days go no cracks that I could see and my oxygen sensor is think my system is running lean so my engine is throwing more fuel into it then what is need wich is cause high idle I will see if it's dirty and try to clean it and if that don't fix it IL either delete them or just buy new ones will see if that fixes it thank you tho I am really liking this forum so far

 

[Harpua216]

good luck. spark, fuel, air, first on the 1st Gens.

and i would be lost without this place too its awesome!

 

[acschilling]

So I'm pretty sure I figured the problem did sparkplug and wires couple days go no cracks that I could see and my oxygen sensor is think my system is running lean so my engine is throwing more fuel into it then what is need wich is cause high idle I will see if it's dirty and try to clean it and if that don't fix it IL either delete them or just buy new ones will see if that fixes it thank you tho I am really liking this forum so far

Been having the same feeling too. I have put a new 02 sensor in mine, cleaned MAF, Seafoam all around, new PCV, fuel filter, pump relay, air filter, cleaned the hall effect part of the crank sensor, spark plugs. It'll idle normal @ 650 when it's warming up but once in the throttle idle goes between 850-1000.

Hope you come up with something!

 

[Reballion]

Well hopefully this fixes it cause if it dont then I'm gonna be pissed hahaha

 

[Reballion]

Soo I'm pissed and confused ugh. I do not have a egr in mine yay I guess. But there is a egr looking thing on the passenger side of engine it has a metal hose that goes to the driver side of engine into intake and one vaccum line that I could see but I have used a can of carb cleaner all over engine to see if it will change idle and nothing but! Even if I unplug a vac line and spray it it won't change unless I flood the vac line with the cleaner and the line as good suckling power haha. So I need to know what all controls the idle air to fuel ratio and back do what cause I seriously don't know what the thing does it looks slightly like a egr valve but the only thing I have coming off my exhaust is a big hose that runs towards the air filter box (what's that for?) Please any ideas would definitely help a lot cause I seriously have no idea still

 

[Harpua216]

but the only thing I have coming off my exhaust is a big hose that runs towards the air filter box (what's that for?) Please any ideas would definitely help a lot cause I seriously have no idea still

what part of the exhaust is this? do you have a picture? or are you talking about the intake manifold?

Have you checked compression on all cylinders yet? lean codes can mean too much air. if one of your rings is starting to go, it might (most likely) pop a code like that.

I cant remember if you said you replaced the Intake Manifold gaskets or not, but have you ever had any leakage in the engine compartment? ie antifreeze, oils etc.,.,? problem with a leaky water pump? its only takes a bit to foul up those IM gaskets and once the start breaking down, you get more air and lean codes (with rough idle)

two ideas you are probably trying to stay away from. like i mentioned, lots fo issues on these blocks between the 5 & 6 heads.

 

[Reballion]

Well the largest hose coming from the exhaust is on the passenger side towards the front of engine and that egr looking thing(I know it's not an egr valve tho cause there are no other hose going to the exhaust is also on the passenger side on top of the first front cylinders injector and other than that I have sprayed **** all around the intake manifold to find a bad gasket or a Crack and still nothing. And now as long as my vehicle is moving the rpms will stay at 1300 to 1700 with clutch in but once I let off they jump between 1100 to 1500 and this will all suddenly stop once I go less then 10 mph maybe? There is no coolant loss and the damn thing runs like a dream with lots of power my step dad has a 2nd Gen with the 4.0 to and his is gutless compared to mine and he has 260k miles on it. I will use a fuel pressure reader when I get the chance to see if the pressure is to high or low.

 

[acschilling]

what part of the exhaust is this? do you have a picture? or are you talking about the intake manifold?

Have you checked compression on all cylinders yet? lean codes can mean too much air. if one of your rings is starting to go, it might (most likely) pop a code like that.

I cant remember if you said you replaced the Intake Manifold gaskets or not, but have you ever had any leakage in the engine compartment? ie antifreeze, oils etc.,.,? problem with a leaky water pump? its only takes a bit to foul up those IM gaskets and once the start breaking down, you get more air and lean codes (with rough idle)

two ideas you are probably trying to stay away from. like i mentioned, lots fo issues on these blocks between the 5 & 6 heads.

I think the hose being referred to is the air inlet that splits and one part goes to the air box and the other should connect to a heat shield that cools the passenger side exhaust manifold.

With mine I'm noticing the fuel gauge fluctuating by about an 1/8 of a tank between decelerating and accelerating when approaching and taking off from a stop light for example. I have premium in the tank right now with a can of Seafoam. I'll get pinging at about half throttle when things get really warmed up, but if I go WOT the pinging will stop. Might be extra gas getting pumped in that needs more air to burn.