1995 explorer new iac valve did not fix idle

[Tugboat Jim]

My 1995 Explorer has 210,000 miles, and runs great except that recently it has been rough idling if re-started anywhere from 10-30 minutes after shutdown. It does this consistently -- 5 times in a row yesterday alone. Garage put in new Echlin IAC valve, and the problem got worse (I also had a major tuneup 4 weeks ago, including new EGR, but that did not seem to have a bearing on this new problem). Garage cannot seem to replicate the problem. BTW, the old IAC valve was the original from the factory in 1995. Suggestions?

 

[chefduane]

Any codes?

 

[Tugboat Jim]

I have no idea. Will ask mechanic tomorrow. Thanks very much for the idea. I know he has had some kind of diagnostic computer hooked to it for most of the day today.

 

[swshawaii]

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

*** This should work on 1st Gen 91-94 Explorers and also 95 2nd Gen. The 95 got a face lift but uses the same 1st Gen brain. From what I read if you have a 96+ you HAVE to have a code reader.****

EEC-IV 2 and 3 digit trouble codes
http://www.explorerforum.com/forums/showthread.php?t=160035

 

[lobo411]

Mine used to do that--drive it, park it hot, and restart it 10 mins later = rough idle.

Replaced the DPFE sensor and it never came back. This was 5 years ago.

 

[Explodr94]

I changed an IAC once and had a rough idle after replacing it. I went on these boards and there was thread where several others had experienced that. The suggestion that worked was unhook the battery and let the ECM reset. Might be worth a try.

 

[chefduane]

How does she start up when cold? Hard start or does it fire right up? I'm thinking fatigued upper/lower manifold gaskets maybe?

 

[gmanpaint]

Sounds like a bad Temp sensor to me. I would replace the sensor with the cone end.

This is a common problem with these Explorers. The ECM is being told the wrong temp info, and is mixing the air to fuel ratio based on temp data being sent to it. You will only have a bad idle, run rough symptom after it warms up and a restart is done.

 

[Tedybear]

Sounds like a bad Temp sensor to me. I would replace the sensor with the cone end.

This is a common problem with these Explorers. The ECM is being told the wrong temp info, and is mixing the air to fuel ratio based on temp data being sent to it. You will only have a bad idle, run rough symptom after it warms up and a restart is done.

If this is indeed the problem, as it gets worse you'll notice a very large increase in RPM when restarting the truck when warmed up. Or the reverse. On cold start it will be extremely hard to start and not want to stay running. Depends on which way the sensor has failed.

It's a cheap enough part usually. And not hard to change out. I'd change it just for peace of mind.

S-

 

[manimal]

Mine had the same long-standing issue as yours. Recently replaced the spark plugs, and in the process found that almost all of the spark plug wires were rotting and falling apart. Looked fine from the outside, fell apart when pulling them. Replaced with Bosch set. Also cleaned IAC (though you went one step further). Reset PCM. Problem went away and has not returned.

I also replaced the ECT sensor but this alone did NOT resolve the issue, but is possible that fuel tables really need to be reset once this sensor is replaced.

 

[Tugboat Jim]

1995 Explorer New IAC Valve Did Not Fix Rough Idle

Thanks to all of you who responded. Lots of ideas. My mechanic noticed that fuel pressure was at 28 psi when idling, suggested that is the problem, since new IAC did not fix the rough idle.

Service Advisor at the local Ford store told me fuel pressure on this '95 Explorer (4.0L V6 fuel-injected) should be not less than 45 psi!!

New complete fuel pump installed by favorite mechanic/garage (not Ford), and fuel pressure with new pump, at idle, is 32 pounds. I gained 4 psi of fuel pressure with the new pump! Mechanic says his professional sources say fuel pressure should run between 28 and 32 psi, not the 45 psi Ford told me. Mechanic is going to check fuel regulator next. Have put on 3 new fuel filters in the last month, nothing changes (I only paid for one of the three).

Thoughts, ideas? Thanks

 

[gmanpaint]

Fuel PSI changes with RPM's. Lots of posts here about that, and you will find your mechanic is more right then the Ford person you talked to.

I mentioned the temp sensor, because I went through a similar issue, and found that a $8 part fixed my issue... AFTER I spent a bunch on parts I didn't need.

 

[Tugboat Jim]

1995 Explorer New IAC Valve Did Not Fix Rough Idle

Thanks for the confirmation, and the info. Can you tell me what the temp sensor is, and where it is located, please? Possible I've wasted the money on the new fuel pump??!!

 

[gmanpaint]

Price has gone up a bit since I last bought one, but this little deal has a huge impact on fuel/air mixture. This sensor has a Cone end to it.

http://www.oreillyauto.com/site/c/d...0_4419&keyword=temp+sensor&pt=01392&ppt=C2177

It is to the right of the T-stat on the OHV. There is also a temp sender, that is not what you want, as that just controls the dash gauge, nothing to do with the fuel mix.

 

[Tugboat Jim]

1995 Explorer New IAC Valve Did Not Fix Rough Idle

Thanks again. Will discuss with my mechanic ASAP. I appreciate the help.

TJ