91 EB---STILL very poor running

[radjcw]

Well, I've replaced the Throttle Position Sensor, the Mass Airflow Sensor, and the Ignition Module, and the doggone Explorer STILL is running poorly. (Thought: If this was a carbureted vehicle, I would think the float was stuck in the bottom position, not letting enough fuel into the system.) The car runs, then doesn't - not enough to die, just enough to cause severe jerking under acceleration. Sounds like an electronic problem or a fuel system problem, right? BUT, the thing runs like a scalded cat over 3500 RPM at full throttle. What happens at full throttle that doesn't happen at other throttle settings? So, I'm now looking at the fuel system: new filter, maybe new injector, fuel pump (groan-Why did they put it in the fuel tank??!!) Any suggestions?

 

[Boman01]

I have a similar problem with mine. Mine stays running just fine, but has almost a miss in it . under light acceleration, ecspeacially around 45-55 in O.D., it has a heavy shudder to it. I have basically checked out all the things you have and i am left with one option that the mechanics told me it could be, the injectors. Just havent got around to doin that. Keep us posted if you figure it out and good luck!

 

[S. Allen]

checked the IAC module yet?

I don't know if your year Explorer has one (the wife's 95 4.0 XLT does and I'll bet yours does too), but cleaning the IAC (idle air contol) Module really works wonders for our vehicles.

These being the mentioned 95 Explorer with 130K miles and my 91 3.0L Ranger with 175K miles on the original engine.

The IAC Module is located on the throttle body and comes off with two screws removed and the wire unplugged from the back. I take STP Throttle Body Cleaner spray and a few Q-tips and clean all of the gunk out of the unit on both of my vehicles about twice a year after I found out about this little trick.

Our 95 Explorer had a rough idle, seemed like it was missing and ran really rough for a long time and I could not kill the problem. After the first cleaning, the rough idle smoothed out ALOT and the missing sensation went away.

My 91 Ranger had a rough cold start idle and the RPMs went up and down while sitting still at idle. I too replaced the coolant temp. sensor, like you did and still had the rough idle. The IAC cleaning cleared the troubles up in a hurry...it was totally filthy and clogged with black goo...not good.

The whole IAC cleaning bit takes about 30 minutes or so...maybe a bit longer on the first time, but is not a hard procedure. STP Throttle Body Cleaner is sold at at any CarQuest or decent auto parts store and is not expensive. Make sure it SAYS it is for throttle bodies...not just carbs and be sure to clean the butterfly valve on the throttle body while you're at it (its probably filthy as well!).

If you live in a big city, where they use re-formulated gas that leaves tons of deposits (like I do), the IAC cleaning might help.

...worth a try, eh?

...good luck with it!

-SA

 

[oceanworker]

I would have bet a six pack that it was a bad ignition module. Have you performed any type of fuel pressure test yet. Hook up a fuelpressure gauge on the schrader valve on the fuel rail (passenger side). It should read about 39-45 psi with key on-engine off. After cranking your engine it should read about 34-35psi. Does the engine miss occur when revving at idle or do you need to be underway? If this is the case, borrow a test gauge and rig it up w/ fittings to a tee and longer hose so you can read it snaked under the hood by your wipers. And read it while underway.
Good luck. Let us know what happens.
When you installed the new module did you clean the contacts in the plug w/ electrical contact cleaner? Mine where corroded from a lot of water splashing up there etc.

 

[914x4sport]

i had the same prob as boman ...replaced the plug wires and that did it for me...just my .02

 

[S. Allen]

duh...should've mentioned that too!

914x4Sport is right,

..be sure to replace your plug wires if they're more than 3 years old or have 5oK miles on them. Its not that expensive and easy to do as well.

With both my 91 Ranger and 95 4x4 Explorer, about 50-60K miles is about all I get out of the plug wires.

Yank those old wires and clean your IAC Module/throttle body real well, like I mentioned above and you'll be amazed at how well your Explorer runs.

good luck,

-SA

 

[asp84]

I would replace your plug wires first. After replacing the spark plug wires on my 94 4.0L, I accidently hooked up the 5 and 6 cyclinder wires wrong. It caused the surging you are describing. After looking at the Chiltons manual,and looking at the correct spark plug wire diagram, I easily found my problem, and hooked the wires up correctly. ( I felt stupid actually)

 

[stroud13]

Have you checked your vacuum lines?

I had a similar problem. The solution in my case turned out to be clogged vacuum lines once and a cap and a hose that had blown off the second time. It ran poorly for a couple of weeks so I ended up changing the plugs too. I also ran a can of BG44K through it to clean up any carbon build-up because of the poor running.

The vacuum tree sits on the driver's side manifold, back near the fire wall. Several vacuum tubes and caps should be in place. If you hear a hissing noise you've got a problem. Put your hand over each exposed hole and you can tell the difference it makes at idle.

Hope that helps.

 

[rustytr]

Whew, just from hearing about those problems I hope mine never encounters them. Good luck.