HELP! Explorer rough idle, can't figure it out!

[offspeed]

Ford has a TSB that deals with a rough Idle condition which involves reflashing the PCM.

[lianalet]

OK, guys. My 1997 Sport has 174K miles on it and has been running a bit rough for the last 30K miles, But a few weeks ago during a road trip he started running noticeably rougher. It progressively got worse and now its not drivable. In the last year I have replaced the crankshaft and throttle positions sensors, the thermostat, starter and solenoid. I took it to a shop where he mechanic said no codes came up on the reader . After reading this blog I ran it for a while and sprayed carb cleaner around the vac lines with no change in idle. When I removed various vac hoses there was no change in the motor. I'm guessing that means there is a vacuum leak I couldn't detect with the first test. I decided i should clean the throttle body and it was such a mess that I continued on to at least get the upper manifold gasket replaced. Wow, what a trip! So many devices, each with its different connectors and quirks.

I finally got almost everything off the upper manifold, but I cant get the EGR tube out of the manifold. How does it come apart? Is the voltage regulator supposed to come off with the upper manifold? Should I drain the coolant before I get to the lower manifold? There is much talk about o-rings. Where are those located and should I replace them all? My manual doesn't bother telling me how to disconnect the various connectors! I dint want to quit before I replace the lower gasket. Are there any other obstacles I'll be running up against that your experience and wisdom can foresee? Any guidance would be greatly appreciated.

[okhedher]

hi
1-check the ignition coil(distributer).if o.k
2-your engine vaulves stucked,you should open engine check core and change the vaulves.
good luck
omar,ford lover

[shorod]

I certainly wouldn't jump to stuck/bad valves based on the symptoms. Definitely before tearing in to the engine, check the compression on the cylinders to see if there is on that is noticeably lower. If there is a problem with the valves it would shop up as a compression issue.

-Rod

[joborosco]

i have done the following:

1. cleaned IAC
2. new plugs and wire
3. replaced 4 o2 sensors..chek engine lite was on
4. injector flush
5. cheked fuel pressure

and in the process of this my mechanic says that engine' runs cool' and wants to replace thermostat

thing is the problem i took it to him for was not resolved. it still idles rough before warmup and sometimes idles down to stall. it also sometimes has to be started twice.

is the 'cool' running engine the culprit?

i don't know...but he didn't fix it. and i am talking about a grand here.

is there something fundamental to this ford 4 l OHC engine that we don't know about?

[shorod]

Welcome to the forum!

What model year is your V6 Explorer? What diagnostic codes did it have that lead to the replacement of the 4 oxygen sensors? Did that cause the CEL to go out?

Depending on the particular 4.0L engine and model year, intake manifold gaskets and PCV elbow are known sources of vacuum leaks that can cause rough idle. Likewise, DPFE sensors have been known to cause issues as well.

-Rod

[joborosco]

gents ...bear with as i describe my problem...if we solve mine i think we solve everyone's

99 ford x 4l -6cyl SOHC with 164k miles

over past year the problem of starting and rough idle developed. i would occaisonally have to start the car twice as it wouldn't catch first try. this was intermitent. as time progressed it got to where this was the case every time. in addition once it started it surged at idle and died out. other than that it never ran poorly. about 6 months ago, recognizing a problem i did the IAC/MAF cleaning . it did nothing. over the the last 6 months problem progressed to nearly never starting first crank, surging at idle and dying. if i applied gas on cranking this would not happen. aslo in last 3 months CEL came on and stayed on.

so this last week i took it in and had the mechanic guy do the following:

chek any exhaust leak...none detected
chek fuel pump pressure......fine
complete tune up.......
new fuel filter
all new 02 sensors. there are 4.
fuel injector flush.
cheked vacum leaks....he didn't say

he said the engine ran 'cool' and wanted to replace thermostat. i held off on that


results
CEL off
starting....while regularity of problem has abated, that is, mostly it starts first time, about 15% of time it does not. it still surges but doesn't die after surge. nearly but not all the way to stalling.

in other words all the repairs seemed to only have only partially fixed the problem.

i have had these problems last week when temps around here were in 7-0's and 80's , for those of you thinking about the gasket warm up/seating issue. i love the idea but would ambient temps render moot that problem? or maybe ambient temperture not significant influence on gasket performance.

so i tried all the fixes described in this thread except gaskets.
where do we go from here?

[AJGumper]

I know an old topic, but I think I have figured out my problem after literally MONTHS of monkeying around.

There were two holes, yes holes about the size of dimes in the intake manifold.

Truck died and lots of stuff looked at, and it was finally found. Replaced that and she is running pretty good now. Maybe check that... maybe you are just at the 'crack' phase now... you don't want to get to where I was at.

We think it started off as a small 'crack' and after a cat converter went bad, replacement, and then another cat going bad and car losing total power, this was found out... previous to this replaced vac hoses, egr's, O2 sensors, on and on....

I have 2003 Explorer XLT, 97,500 miles 4.0 V6
Good luck

[daves1965]

After reading through these posts I figured my problem is similar. Rough idle when cold and gets better as it warms up, first start rpms up high then back down to stalling. Using starter fluid found a subtle vacuum leak in lower manifold gasket area. All the orings were pretty flattened out. Replaced and BAM problem gone completely!

[koerb00]

I've had the same problem with my 97 4.0 L V6 EFI that's grown worse and worse over the last year. Now just this afternoon my truck won't start. It turns over idles rough and dies. Same codes P0171/P0174. It seems like the most consistent fix is the o-rings on the plastic intake or the upper and lower gaskets on the intake manifold. Any suggestions? Can this be fixed at home?

[daves1965]

Originally Posted by koerb00

I've had the same problem with my 97 4.0 L V6 EFI that's grown worse and worse over the last year. Now just this afternoon my truck won't start. It turns over idles rough and dies. Same codes P0171/P0174. It seems like the most consistent fix is the o-rings on the plastic intake or the upper and lower gaskets on the intake manifold. Any suggestions? Can this be fixed at home?

During idle, spray the manifold area with starter fluid or some other really volatile spray. If the idle changes (better or worse) consistently if you spray in one spot, there's a vacuum leak. The intake manifold gaskets, both upper and lower, get flat over time. I paid about 5$ for the starter fluid and $10 for a gasket (upper and lower)set. Fixed my idle problem right away. Easy garage job took about an hour.

[97explorer5.0]

my 97 5.0 has rough idle; changed plugs; wires; cleaned throttle body; cleaned mass air flow sensor........Code said EGR Valve but there isn't any vacuum at EGR Valve so i was told it was ok........ help

[shorod]

What was the specific code number?

-Rod

[97explorer5.0]

they didn't give me a code # just said also number 7 cylinder

[shorod]

Did changing the spark plugs and spark plug wires improve the way the engine runs? Do you have a parts store in your area? If so, many of them offer a service to connect the diagnostic tool to your vehicle and read active diagnostic codes as no charge. You want to get the actual code number though versus the salesperson's interpretation of the diagnostic code. There's no such thing as a code that says the EGR sensor is bad, only codes that indicate an issue has been identified in that system. The EGR may be the issue, but not necessarily.

On many older Fords issues with the Differential Pressure Feedback EGR (DPFE) sensor would cause rough idle, lack of power, and even stalling.

-Rod