Rough idle. | Ford Explorer - Ford Ranger Forums - Serious Explorations

  • Register Today It's free! This box and some ads will disappear once registered!

Rough idle.

scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
Hey everyone! I have 1991 Explorer XLT 4.0 M/T 4x4, and i've got something of a rough idle, i've replaced quite a few things including...MAF sensor, ECT sensor, O2 sensor, FPR, cats have been replaced, air temp sensor. I'm kind of at a loss. its not a very rough idle but its definatly their, like just a little shake here and there, and the exhaust has a very light pop to it, possible exhaust leak? I know my water pump is leaking which i will be replacing today, do you think that could cause it to idle weird? or possibly vaccum leak? my cruise control surges when its on and can't keep a steady speed (+/- 5mph) possibly the canister is bad? i dont know, any help would be great. Thanks!
 
<

Join the Elite Explorers $20 Gets rid of the ads!

Elite Explorer members see no advertisements, no banner ads, no double underlined links, can add their own profile photo, upload photo attachments in all forums, and Media Gallery, create and save more private conversations, and more. Join Today. Your support is greatly appreciated.




BrooklynBay

Moderator & long time member.
Staff member
Moderator
Elite Explorer
Joined
November 11, 2005
Messages
55,303
Reaction score
736
City, State
Brooklyn, NY
Year, Model & Trim Level
88 89 93 95 96 Aerostars
<



scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
Thanks, yeah i replaced the coil pack, plugs and cables too. its not a very rough idle almost not even there but still noticable and annoying, its still starts and drives fine.
 
<



BrooklynBay

Moderator & long time member.
Staff member
Moderator
Elite Explorer
Joined
November 11, 2005
Messages
55,303
Reaction score
736
City, State
Brooklyn, NY
Year, Model & Trim Level
88 89 93 95 96 Aerostars
<



scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
I've got a set of 6 new fuel injectors and am going to do this one myself. anybody got a write up on how to replace them? i've watched it done before but some written help with a few pictures would be nice. Thanks! 1991 explorer 4.0
 
<



FIND

Explorer Addict
Joined
December 27, 2009
Messages
3,862
Reaction score
12
City, State
Vermillion, SD
Year, Model & Trim Level
99 XLT V8 AWD
They aren't hard to replace. Just take off the UIM then the fuel rail. Make sure to replace all the o-rings, put a little Vaseline on the o-rings when you install the injectors so they seat properly. If you are having trouble figuring out any of the stuff, just ask, but for the most part, it is pretty straight forward. On some of them, the studs are outside torx, on others you just need a small wrench..... 7mm maybe? I can't remember Anyways, good luck with it.
 
<



scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
so my rough idle i had i thought would be fixed by replacing the fuel injectors and i replaced them but now my rough idle has seemed to have gotten worse. i've replaced the fuel pressure regulator, injectors upper intake gaskets, fuel filter, but the idle has almost gotten worse now. I'm beginning to suspect the fuel pump...possible the old injectors were clogged and now the fuel pump can't keep up with the new ones? i'm also dealing with an exhaust leak. let me know if anyone has any ideas. thanks!
 
<



huntman58

Well-Known Member
Joined
February 13, 2007
Messages
722
Reaction score
4
City, State
Fremont calif.
Year, Model & Trim Level
2013 Dodge Advenger
Recheck the UIM for leaks and that they are properly tightened down both the nuts and the studs. Also did you check the lower Intake to make sure it was tight when you did the gaskets and injectors?
 
<



scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
yeah the upper intake was torqued down, i did not check the lower intake, i'll go ahead and do that as well. here's an idea of what happening... engine starts and runs just fine...push down on clutch shift into gear, as I'm coming off the clutch the motor damn near stalls, and motor shakes and runs poorly, and if I'm cruising along say in 3rd gear, if i stomp on the pedal nothing happens, it accelerate very slowly and rpms hardly climb. at idle the motor runs good but idle is rough, and as soon as its under load it sounds like crap. again the idle was already choppy with the old injectors and after replacing them these symptoms have seemed to have gotten worse. I'm just hung up on wondering if my fuel pump is possibly failing and cant keep up the pressure in the system. I've done the whole injector job twice now and the second time I did it, I went to depressurize the system at the fuel rail and there was hardly any. Any thoughts on fuel pump or exhaust leak as possible culprits?
 
<



huntman58

Well-Known Member
Joined
February 13, 2007
Messages
722
Reaction score
4
City, State
Fremont calif.
Year, Model & Trim Level
2013 Dodge Advenger
I do not believe an exhaust leak would do this and you said you replaced the pump so let go that it’s good for now.

Some thing you did not say and so I wonder if you did them
Test Fuel pressure static, running and holding?
Changed fuel filter?
Could you possibly have cut an O ring on the injectors when putting the new ones in as that would be one reason for it to become worse after new injectors then before?
Did you test all the injectors before installing them to make sure they were all working? New or not you can still get a bad part now and then.
Did you forget to plug on or two in (injectors) or maybe had one or two pull lose?
Did you disconnect the battery after each new job to reset the computer for the new parts and possible settings?
Have you pulled or checked for any codes both KOEO and KOER?

Just some thoughts.
 
<



walterd140

Well-Known Member
Joined
August 9, 2003
Messages
355
Reaction score
1
City, State
Ludlow, Massachusetts
Year, Model & Trim Level
'94 Sport
Vacuum leak? Check the tree on the driver side of the engine
 
<



scottb12486

New Member
Joined
August 31, 2010
Messages
6
Reaction score
0
City, State
Andover MN
Year, Model & Trim Level
1991 Explorer XLT 4.0 M/T
yeah i tested the injectors and everything on install went great, battery cables were taken off each time i haven't pulled any codes yet will do though, thanks. as for vacuum leaks, i'm going to replace all hoses coming off that tree on th intake manifold. i was told by a guy once that the lower intake manifold gasket could have a leak at one of the coolant passages and letting coolant into one or more of the cylinders, i do get quite a bit of steam and dripping from the tailpipe, i've had the heads tested and i'm not loosing any compression, they told me that the heads and the gaskets should be fine. this was awhile ago, i have notice slight coolant loss so i'm going to take my lower intake off and replace its gasket. any special tricks or problems with doing this job i should know about? do i need to pull the valve covers off? Thanks for all the help guys its greatly appreciated!
 
<



huntman58

Well-Known Member
Joined
February 13, 2007
Messages
722
Reaction score
4
City, State
Fremont calif.
Year, Model & Trim Level
2013 Dodge Advenger
Yuppers you gots to pull the valve covers all right as they over hang the lower intake some and with out pulling them you can not get the intake to come out as they hold it in.

Make sure you fallow the directions for sealing the joint were the heads block and intake all come together also. That is the area you use the sealer both before you lay down the intake gaskets and again after you do. Also do not forget to use some sealer on the valve cover gaskets were they seal to the cover only.
 
<



Top