Rough idle

[Brad2296]

Hey guys, I'm new to the site, and really trying to get some help.

Just got a 98 explorer XLT "x'' motor, 210,x.. miles. Girlfriends brother was the previous owner, and never had a single problem with it. Just a couple days before I bought it, it picked up a really bad idle, out of no where! It seems like it's misfiring, or firing the wrong order, or has a horrible vacuum leak. It runs perfect when it's cold, then when it starts to slightly warm up is when the idle problem happens. Under acceleration, there is absolutely no hesitation what so ever. Did new plugs and wires, that didn't help. Got 3 MAF's from a pick and pull, cleaned them all, tried them all, still didn't help. Cleaned the IAC, didn't help. When you unplug the MAF, it runs perfect..... Did a vacuum test, it has 17 in Hg at good and bad idle. Checked all vacuum lines, they are good. PCV is good. Used a fog machine through the intake, no leaks. Sprayed carb cleaner around EVERYTHING, didn't react to it at all. CEL came on and it gave a P0455 "EVAP Gross Leak". The gas cap is good. Got told to check the canister purge valve (under the battery). Both hoses and 1 vacuum line are good. Unplugged them and capped them off, and it still didn't get better.

I'm completely stuck now. Could the cam sensor have anything to do with this? The truck is also getting absolutely horrible gas mileage. I'm not sure if it has anything to do with the idle problem, or if the 210,x.. miles plays factor to it.

I don't have access to any type of live data logging or scanning unless I take it to a shop.

Looking for ANY help here guys, I appreciate it in advance!

-Brad

 

[Brad2296]

Anyone at all got any advice? Please...

 

[Brad2296]

I guess no one at all knows a thing about this then?

 

[Reddawg]

???

I have a 04 and its had a rough idle and bad gas mileage for the last 6 months. If I nail it no problem in acceleration. Mine only has 110,000. tried alot of the same things as you have. So I am looking myself, if you figure it out please let me know.. Do you have the 4.0 SOC. Mine is flex fuel also.

 

[Jordan86]

Have you tried cleaning the EGR valve? It will give it a rough idle if the valve isn't opening and closing properly, keep me posted

 

[Brad2296]

I have a 04 and its had a rough idle and bad gas mileage for the last 6 months. If I nail it no problem in acceleration. Mine only has 110,000. tried alot of the same things as you have. So I am looking myself, if you figure it out please let me know.. Do you have the 4.0 SOC. Mine is flex fuel also.

Acceleration is not a problem at all for the car. It's just when it's at idle once the truck has warmed up. And my motor is the 4.0 OHV.

Have you tried cleaning the EGR valve? It will give it a rough idle if the valve isn't opening and closing properly, keep me posted

No, i've not tried cleaning the EGR. Hasn't really crossed my mind to try that. Like I originally posted, it only starts to idle rough after it starts to BARELY warm up. Also when I first start it up in the morning, it will idle bad for only like 2 seconds, then it picks up the RMS to about 1300, and it's fine again....up until it starts to warm up a little bit.

 

[Jordan86]

Is it throwing any check engine codes? I'm in the process of changing out a bad EGR valve myself. My explorer is idling rough once it gets warm also and it likes to stall out when coming to stop signs.

 

[Brad2296]

Is it throwing any check engine codes? I'm in the process of changing out a bad EGR valve myself. My explorer is idling rough once it gets warm also and it likes to stall out when coming to stop signs.

The only code I get is a P0455 EVAP Gross Leak.

 

[Brad2296]

Is it throwing any check engine codes? I'm in the process of changing out a bad EGR valve myself. My explorer is idling rough once it gets warm also and it likes to stall out when coming to stop signs.

Did changing your EGR fix your problem?

 

[Jordan86]

I replaced the EGR valve but we also found a vacuum leak around the O ring where the EGR tube hooks into the intake manifold, spray a bit of starting fluid around there and if your idle picks up then you got a vacuum around it. Hope that helps a bit

 

[Brad2296]

Well I'm almost 100% that I've narrowed down the problem.....It's the EGR valve. Here is why I think it is the problem, please tell me if I'm wrong. I took off the vacuum line from the EGR pressure sensor and sprayed carb cleaner in it, and the motor stalled out....which tells me that the EGR is stuck open, therefore making a BIG vacuum leak.

Does this seem correct?

My problem now is getting the courage to remove the EGR and replace it. It is the same one from 1998, and has 210,000 miles on it.....needless to say, it is VERY rusty. and I'm using VERY, lightly.

 

[beco2326]

Same problem

Thank god , after a while of searching i think i found something just like my problem. I got a code p0455, and the problem seems only at idle. I have looked everywhere for the problem. I need to fix it it's getting really bad and its the only thing i have to get to work with. and being pretty broke im stuck to doing this myself. i have a 99 explorer sport, and it also has. close to 175,00 miles.. the lady had it sitting for a year but it was 500 bucks and its all i could do. anyway, im gonna try out these steps you took tonight and see if i get the same. did changing the egr help?

 

[05explorerXLT]

Did anybody find out if the EGR was the culprit?