'96 XLT rough warm idle

[Tbars4]

....With your last MAF disconnection your computer will be looking to see what the problem is ...You might want to disconnect the battery again...

...It is also common for that brake booster to leak at that bushing and that hose...You also need to spray around the edge of the intake manifold...A leaky gasket could also be sucking air...

...For your P0401 code...
http://www.explorerforum.com/forums/showpost.php?p=2034042&postcount=9

 

[CrownRoyalRacing]

Why would I need to disconnect the battery if the computer is not seeing a code? I looked at it a few different times with the reader and cleared it after connecting and disconnecting the connector. As for the brake booster, it only leaked when i was moving the hose around at the booster. Wouldn't the fact that it was holding pressure reassure that there's not a vacuume leak? Honest questions......not trying to be sarcastic at all. After driving home, I performed I/M monitor with the code reader.....which output the following:
Misfire monitor OK
Fuel System monitor OK
Comp Component OK
Catalyst Mon INC
Htd Catalyst N/A
Evap System Mon OK
Sec Air System N/A
A/C Refrig Mon N/A
Oxygen Sens Mon OK
Oxygen Sens Htr OK
EGR System Mon OK

Why are there "N/A's"? I did read that if there are incompletes that I didn't drive enough for the computer to run the test. But for the NA's??

 

[Tbars4]

...N/A's are "Not Applicable" or you do not have these items so they don't apply...

...Whenever I have had a rough idle, I usually find it related to vacuum leak first, a bad wire or plug, or an electronic sensor that is having a problem...

...Maybe someone else can chime in and better assist with your problem...

 

[CrownRoyalRacing]

Thanks for the help.....You're probably right and I just have found the leak yet. I'll keep looking.

 

[CrownRoyalRacing]

Well I think I'm gonna change the intake plenum gasket this weekend. I've read on here that it's been a problem and it's only $4.99 at the local AZ. Can't hurt to try!

 

[alohamonte]

I've been chasing a very similar problem with low/rough idle when engine is warm.

So far I've...
- Replaced Spark Plugs
- Replaced IAC
- Replaced Fuel Filter
- Replaced Air Filter
- Cleaned MAF, Throttle Body, Injector Cleaner (fuel tank), Carbon Cleaner (PCV)
- Replaced PCV and PCV hose/elbow


No help. I can hear the IAC cycle on when the idle gets very low, preventing the stall out. Even so, my idle regularly dips to 500 rpm, when warm, stopped, and in drive. It will dip below 500 rpm under hard breaking or hard (full lock) turning.

New spark plug wires and EGR solenoid (shot in the dark) are on order and will go in this weekend. Might help, likely wont.

I think the OP and myself are dancing around the same issue, some vac leak that we haven't able to locate or some other issue with the air/fuel mixture.

Note: No CEL and scan tool reads all normal.

EDIT: I read some posts on this site saying that Autolite Iridium Plugs can cause issues with the low octane, low reving, slug of a OHV. The Iridium plugs went in last summer. I will change this out to Autolite Single Platinums this weekend when the new wires get there.

 

[CrownRoyalRacing]

Well now I have a new development. I live in South Florida and it's been raining for about 18 hours straight. I was driving thru a parking lot and what turned out to look like a small puddle, ended up being a rather deep one! It was about 3.5 ft or so and as I dipped down into it, my car stalled. (I was moving about 10 mph) At the same time, I lost complete power to the X. (radio stations reset) Power came back immediatly but I wasn't able to start the thing. (i was out of the monster puddle) After about 5 minutes, I got it started (giving it plenty of gas) and pulled it in a parking spot. It was running extrememly crappy and blowing a lot of white smoke. I thought the head gasket blew Well I got it started again and pulled out on the road. It started bogging down again and about stalled so I pulled into a gas station and popped the hood. There was water everywhere! I pulled the dipstick to check for water in the oil and it was clean. (what a relief!!) I got it started again and pulled back out on the road. It ran like crap all the way back to work but I made it. Towards the end it starting running better. I think maybe I sucked some water into the intake somehow?? What do you guys think?? If I have a vacuum leak, maybe this just proved it??

 

[alohamonte]

sounds like you sucked in some water (white smoke = steam) through the intake. check to see if the air filter is wet.

 

[CrownRoyalRacing]

Lol.....Just got back from doing that.......As i opened the strap, water was pouring out. The filter is SOAKED!! I guess the pulled was a lil deeper than I thought. At least it's not a big problem!!

 

[CrownRoyalRacing]

Ok....bought a compression tester today and these are the results:
1-170
2-165
3-115
4-150
5-135
6-120
Numbers aren't the best....but what I've heard, not terribly bad either. I suspect I have the infamous head gasket leak on near the #3 cylinder. Also got a new code on the way home. (P0133 o2 Sensor CKT Slow Response (bank 1 Sensor1). That's a new code. Not sure if it's a fluke, but something to consider. I really really don't want to change my head gasket, put it all back together, and have the same idle issues!! So.............what do you guys think??

PS......I checked the Vacuum and it was 18.......from what I've read on here.....that's about normal?!?

 

[CrownRoyalRacing]

I installed a new Upstream Bank 1 O2 sensor (forward passenger side before the CAT) and that took care of the rough pulsing idle when the X warmed up. The idle still isn't as smooth as I would like it, but not near as bad as it was. I think I'm gonna replace the upstream bank 2 O2 sensor just because the one I took out of the R/H side was in pretty bad shape. I really wish the computer would have thrown an O2 sensor code earlier......would have saved me quite a bit of money!!

 

[alohamonte]

Nice!

I had similar luck this morning. I replaced the EGR control solenoid and the DPFE hoses and it fixed the low idle issue. From Wiki: "EGR is typically not employed at high loads because it would reduce peak power output. This is because it reduces the intake charge density. EGR is also omitted at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle."

I cut the DPTE hoses in half and discovered they were completely obstructed by this white crust junk.

From Wiki: "In almost all cases, a disabled EGR system will cause the car to fail an emissions test, and may cause the EGR passages in the cylinder head and intake manifold to become blocked with carbon deposits, necessitating extensive engine disassembly for cleaning." After the repair, the X smoked for about 2-3 minutes, which to me means it was burning off the carbon build-up.

Replacing the solenoid and hoses was a shot in the dark effort to fix a EVAP leak code that triggered a CEL. It fixed the EVAP leak and stumbling idle issue. A great 2-for-1 for $30.

 

[CrownRoyalRacing]

Well, it still runs a little rough when it warms up but it doesn't seem to pulse back and forth anymore. When it's idling rough the exhaust smells strange.....nothing like any exhaust I've ever smelled before. I went to buy the other upstream o2 sensor but the AA I went to was out of them. I was on a lunch break and didn't really want to drive across town to another store so I'll pick one up later. Still no CEL light when it idles rough.