Idles up and down 2005 Ford Explorer 4.0

[Phillystpete]

When I start the car up the idle jumps from like 800 to 1500 RPM.
she wants to stall when I come to a stop I had two different mechanics tell me two different things one said it was the O2 sensor the other said it was an EGR valve.
It was running fine until we replaced the fuel injectors immediately after that I drove it for about 45 miles and it ran great I shut it off half hour later I went out there and he kept wanting to die and be idle was jumping up and down I would sure appreciate some help thank you

 

[509Explorer]

When I start the car up the idle jumps from like 800 to 1500 RPM.
she wants to stall when I come to a stop I had two different mechanics tell me two different things one said it was the O2 sensor the other said it was an EGR valve.
It was running fine until we replaced the fuel injectors immediately after that I drove it for about 45 miles and it ran great I shut it off half hour later I went out there and he kept wanting to die and be idle was jumping up and down I would sure appreciate some help thank you

I would check for vacuum leaks. Sounds like it to me, but I could be wrong. Just personally have had 3 explorers have that problem. Though only 1 of them was v6

 

[Phillystpete]

I would check for vacuum leaks. Sounds like it to me, but I could be wrong. Just personally have had 3 explorers have that problem. Air idler valve and vacuum leaks each time. Though only 1 of them was v6

 

[swshawaii]

No IAC valve on later build 2004 and newer so can rule that out. Check engine light or trouble codes?

 

[509Explorer]

No IAC valve on later build 2004 and newer so can rule that out. Check engine light or trouble codes?

Thanks, I honestly had no idea. The more you know

 

[swshawaii]

To save time and guessing, scan for trouble codes. Check engine light does NOT have to be on to have stored DTC's in memory. Unless you have disconnected the battery trouble codes will remain until repaired. If you don't have a reader call larger auto parts stores that usually offer scanning for DTC's as a free service.

MANY possibilities.

OBD-II Diagnostic Trouble Codes (DTCs)

I was looking around the Forums and could not find a complete listing of all Ford OBD-II Codes and definitions. I thought something like this would or should be a Sticky but I couldn't find it, so here it is. This whole thing started because I was having a problem with my 98 that was...

www.explorerforum.com

 

[Phillystpete]

To save time and guessing, scan for trouble codes. Check engine light does NOT have to be on to have stored DTC's in memory. Unless you have disconnected the battery trouble codes will remain until repaired. If you don't have a reader call larger auto parts stores that usually offer scanning for DTC's as a free service.

MANY possibilities.

OBD-II Diagnostic Trouble Codes (DTCs)

I was looking around the Forums and could not find a complete listing of all Ford OBD-II Codes and definitions. I thought something like this would or should be a Sticky but I couldn't find it, so here it is. This whole thing started because I was having a problem with my 98 that was...

www.explorerforum.com

In my first post it should have said after the fuel injectors were installed I drove the Explorer 5 to 6 miles and it ran great I shut it off started it up and that's where I had the problem with the idle going up and down and wanting to stall at stop lights.
After my supposably friend / mechanic install the fuel injectors he disappeared on me so I took it to a shop they put it on the scanner he said all kinds of codes went off he cleared the codes took it for a test drive and one code came back I don't remember what it was but he said all Fords have that code. He then suggested to check for manifold leaks which I did there didn't seem to be one ( checked with starting fluid. Another mechanic suggested using water to check it but i haven't tried that yet ) he said if that wasn't it, it would be the O2 sensor.
Then I had a mobile mechanic I found on Facebook who seems to be very thorough and honest and had a good scanner he checked for compression, he check for leaks he checked for wires that might have been loose.
he's the guy who said it would be either the EGR valve or the catalytic converter.
THEN OMG I asked my girlfriends step dad who hasn't turned a wrench in 35 years he however said it's running rich which it is told me to check the exhaust to see if it was blowing out hard which it is he said if it wasn't then it might be the catalytic converter like you guys he was puzzled that it ran fine for a short. Of time so he suggested then the fuel filter which my original Mechanic told me was connected to to the fuel pump inside the gas tank also as long as I'm ranting on I was told by the three different mechanics that is head for catalytic converters her dad said that wasn't true it has to coming off the manifold and the one before the muffler and after the muffler we're resonators.
I'm really sorry to be asking this of you width 250 F in miles but I'm kind of in a rock and a hard place I need to get to work to support my family so if you continue to give me suggestions I would greatly appreciate it thank you guys so much

 

[SyberTiger]

Hard to say exactly what it is based on what you wrote but I'd second the suggestion that you look into manifold leaks. The problem is that even when looking for manifold leaks it might not be obvious because the "air" leaks could be so minor that they are noticeable visually. The reason why manifold and/or vacuum leaks are suggested is because the the engine computer tries to reach a neutral point in the air/fuel mixture. In other words, if you have a small vacuum leak the computer will sense more air in the air/fuel mixture and will then dump more fuel in to meet that neutral point. Of course the idle will increase when there is more air/fuel. Throttle is dictated by the amount of air coming into the engine. Put more air in then the computer will add more fuel. Take air out and the computer will lessen the amount of fuel metered into the system. Read THIS as it might explain it better.

 

[Phillystpete]

Hard to say exactly what it is based on what you wrote but I'd second the suggestion that you look into manifold leaks. The problem is that even when looking for manifold leaks it might not be obvious because the "air" leaks could be so minor that they are noticeable visually. The reason why manifold and/or vacuum leaks are suggested is because the the engine computer tries to reach a neutral point in the air/fuel mixture. In other words, if you have a small vacuum leak the computer will sense more air in the air/fuel mixture and will then dump more fuel in to meet that neutral point. Of course the idle will increase when there is more air/fuel. Throttle is dictated by the amount of air coming into the engine. Put more air in then the computer will add more fuel. Take air out and the computer will lessen the amount of fuel metered into the system. Read THIS as it might explain it better.

I really appreciate your insight here's where I'm at right now I I've replaced the EGR valve I replace the manifold intake gaskets it's still giving me the code p 21.96 stuck rich it ran fine if I get usually does for a little bit and then started doing the same thing surging at idle the only thing I checked for I checked for any other leaks broken hoses all that the only thing left is the O2 sensors so I'm going to try that if that doesn't do it I don't know what to do if you can give me any more advice I greatly appreciate it thank you

 

[SyberTiger]

You have a different year and engine but you can read THIS thread to see if your engine has a similar issue.

 

[donalds]

Anyone do a smoke test yet?

 

[RetiredFordTech]

When I start the car up the idle jumps from like 800 to 1500 RPM.
she wants to stall when I come to a stop I had two different mechanics tell me two different things one said it was the O2 sensor the other said it was an EGR valve.
It was running fine until we replaced the fuel injectors immediately after that I drove it for about 45 miles and it ran great I shut it off half hour later I went out there and he kept wanting to die and be idle was jumping up and down I would sure appreciate some help thank you

 

[RetiredFordTech]

When I start the car up the idle jumps from like 800 to 1500 RPM.
she wants to stall when I come to a stop I had two different mechanics tell me two different things one said it was the O2 sensor the other said it was an EGR valve.
It was running fine until we replaced the fuel injectors immediately after that I drove it for about 45 miles and it ran great I shut it off half hour later I went out there and he kept wanting to die and be idle was jumping up and down I would sure

 

[RetiredFordTech]

I swapped engine on my 04 with 05 had to swap induction system. Had same kind of problem. Was oring on injector not seated promptly Found it listening around in injectors. Was setting lean code and definitely running rich.

 

[Lobo316]

I had same with my 2000 expo sport n it was throttle sensor

 

[Phillystpete]

You have a different year and engine but you can read THIS thread to see if your engine has a similar issue.

Okay my friend here's what I did yesterday I took the manifold off replaced the gaskets and replace number 3 fuel injector because I was getting a code that said it was missing misfiring put it back together it was running fine cleared the codes at AutoZone 10 minutes later same problems

I had same with my 2000 expo sport n it was throttle sensor

Thanks for your Insight I'm about to try the O2 sensors my codes are telling me I'm running rich if that doesn't work I'll give your suggestion a try thanks

 

[Lobo316]

I also had same on my 03 sport 4.0l v6 i cleaned fuel injectors n throttle body n changed maf sensor n air filter also upper o2 sensors egr n egr solenoid spark plugs n wires n it was the dam fuel pressure regulator the whole time now runs like new an got lil bit better mpg n horse power

 

[Phillystpete]

I also had same on my 03 sport 4.0l v6 i cleaned fuel injectors n throttle body n changed maf sensor n air filter also upper o2 sensors egr n egr solenoid spark plugs n wires n it was the dam fuel pressure regulator the whole time now runs like new an got lil bit better mpg n horse power

OMG bro where were you a month ago and $1,000 ago


but I'm glad you came through.
I've done all the same things, even replaced all the fuel injectors and gaskets and I'm about to put on the O2 sensors but I'm going right for what you've done thank you so much I hope it works if it don't I guess $2.85 will fix it well that and a match

 

[Phillystpete]

OMG bro where were you a month ago and $1,000 ago


but I'm glad you came through.
I've done all the same things, even replaced all the fuel injectors and gaskets and I'm about to put on the O2 sensors but I'm going right for what you've done thank you so much I hope it works if it don't I guess $2.85 will fix it well that and a match

Hey bro can you please tell me what is it the fuel pressure regulator and the sensor or just a sensor or just the fuel pressure regulator and what did you pay for it if you don't mind me asking thanks