94 Explorer not running right...please help

[CTroxtell]

I have a 94 EB 4wd 4dr auto daily driver with almost 245k miles, check engine light comes on and it needs help. I pulled the codes off it the other day and it listed 123 - Throttle Position Sensor above maximum voltage (I replaced the TPS and it still gives this), 186 - Injector Pulse-width higher than expected, and I believe it was 335 - EGR Sensor voltage out-of-range. Has a rattle under acceleration, holding your foot steady on the accelerator you can feel the truck gain power then loose power...also at times I will be driving along and the engine I think cuts off for a split second then fires back up, when it does this you can hear the rear end clunk I guess because of this.

 

[MrShorty]

When dealing with multiple codes, a couple of things to do first:

1) Identify which codes are KOEO codes (before separator pulse during KOEO test) and which are CM codes (after separator pulse). Usually you want to start by diagnosing and resolving the KOEO codes.

2) Clear CM, test drive, and pull codes again to see which ones come back. This way you won't be chasing down any "ghosts"

3) Review instructions and perform KOER test. Often, after KOEO codes are resolved, you will want to work on the KOER codes before going on to the CM codes.

Based on the code descriptions in my code list, I expect this means you'll end up starting with the KOEO 335, which will mean testing the DPFE sensor circuit.

 

[CTroxtell]

Okay, code 335 was resolved by installing a new DPFE Sensor. I did a KOEO test and got a 111 so that all passed, then a KOER test and I only get a 332 which is a EGR valve opening not detected I believe. EVP sensor is getting 12+ volts from the battery with the key on, testing resistance of EVP sensor was kinda wacky got 40 ohms then it hit into the megaohms and then back to 36 ohms. Connected a vacuum hose and pulled a vacuum on the egr valve itself, seem to hold the vacuum and you could hear the plunger. What would you recommend now? Thanks again

EDIT: Well it appears that I "finished" breaking my metal egr hose that bolts to the manifold, it was broke about halfway around, guess the heat ate away at it. I have sprayed it with PBlaster and that nut on the manifold is seized ridiculously tight. Hopefully it'll break loose tomorrow...anyone have ideas on how to break it loose? Might try a socket since it broke off right at that nut.

 

[CTroxtell]

Well just an update, upon trying to remove that nut the entire egr tube to manifold adapter came out pretty much stripped so I'm off to the dealer to see if they have it in stock and I will probably have to run a tap in it so it'll screw back into the manifold.

 

[CTroxtell]

Another update, finally found a special tool company that let me borrow their tap to clean manifold threads out, was a M22 x 1.5 tap. I finally found out my egr port was stopped up on my throttle body, used air compressor, carb cleaner, and an assortment of allen wrenches. Cleared code and drove it and got a code 186, what does this lean toward?

 

[MrShorty]

CM186 is an air/fuel mixture code. The computer thinks the engine is running lean and can't open the injectors enough to correct it. 1st question: from other symptoms (exhaust condition, spark plug condition) would you say that the engine is running lean, or is it really running rich? If the computer is incorrectly seeing a lean condition, that would suggest a fault in the O2 sensor circuit. If the computer is correctly seeing a lean condition, that would suggest a fault in fuel delivery or a vacuum leak or something.

 

[CTroxtell]

I think its running rich, when I start the engine up I can watch the engine and it will run smoothly for a second and then it shakes and you can tell its not running right and then back to running right and it just keeps doing this while idling. When its idling if I press tap on the gas it bogs down then revs up. I have replaced the TPS, I have no idea if the O2 sensors were ever replaced and its got 245k miles on it. Any idea what it sounds like?

EDIT 1: I'm wondering about the O2 sensors since when parked and idling I think I can smell excessive gas fumes. But from what I've read the O2 sensors aren't active until the engine is hot, so at idle this shouldn't play a part in it not running right when started while cold correct? (On a side note would it run like this because the computer has this information stored in its memory since its been running badly like this for a while?) From what I remember the spark plugs were black and wet last time I pulled them so I think that's a rich sign. Is the IAC supposed to close 100%? My IAC valve does not close 100%, the motor on the IAC pushes the valve open slightly when attached to the valve itself. The tube from the MAF to the throttle body don't make the best seal so I'm guessing its sucking in some air in but the gas fumes coming out the tailpipe are strong.

EDIT 2: Well driving it today to work was fun to say the least, running 60MPH down the highway with cruise set the speed would drop to about 55MPH, you could tell its missing its power. I was at an intersection and got on the gas to get across traffic from a stop and it was like it bogged down and about died, had to let off of it to get it to go. Been hearing a rattling noise while engine is accelerating, sounds like the noise I hear when I pull the PCV valve out of the engine and shake it. Just wondering if I might have a bad injector after this many miles or what it is. Waiting patiently for MrShorty...

EDIT 3: Well I thought I'd check the engine codes today after driving it to work yesterday and was I in for a surprise, on the stored memory I got these codes. 122, 157, 158, 175, 176, 177, 186, 189. I got some security torx and pulled the MAF sensor out of the truck and cleaned it with CRC Electronic Cleaner.

 

[CTroxtell]

I thought I had figured it out finally. After I cleaned the MAF sensor I reset the codes and my CEL didn't come back on, the truck just has no power. I popped the hood, threw the e brake on and gave it gas in reverse and drive and I can hear the engine popping while under acceleration but it don't do it if in Park.

 

[MrShorty]

Let's see what changing the motor mounts does.

At this point, I would suspect the O2 sensors/circuits are not quite right, where it seems to be running rich but the PCM reports lean. Many would replace the O2 sensors as a maintenance item if you can't say when (if ever) they were last changed.

"By the book" one would check fuel pressure, too. I might put a fuel pressure gauge on it and make sure fuel delivery is running up to par.

 

[CTroxtell]

I checked fuel pressure about a month ago and it was where the Haynes book said it needed to be. Just crawled under it and found the bracket that mounts to the engine that the motor mount mounts to was coming loose, one bolt was almost all the way out and the other was trying to come out. Okay I found out the rattling noise wasn't the motor mount. I can put the e brake on, put it in reverse/drive and give it gas and you can hear a really loud pop coming from somewhere in the engine. Could a O2 sensor cause the cylinders to have too much gas therefor causing an explosion so to speak inside the engine? The tailpipe has a nice black soot ring around the end of it.

 

[CTroxtell]

Some more info...pulled coil pack and tested it, all 3 of them were about 13.5K ohms which is above the 11.5 max. I then decided to pull some plugs, pulled 5 of the 6 plugs, cylinder 5 was black and wet, the other 4 were dry. Going to try to do a compression test when I get a chance.

 

[MrShorty]

Could a O2 sensor cause the cylinders to have too much gas therefor causing an explosion so to speak inside the engine?

O2 sensors can definitely cause the engine to run rich. I don't usually associate noises like that to a rich condition. Spark knock or ping is usually associated with a lean condition, which leads coincidentally to:

cylinder 5 was black and wet, the other 4 were dry.

One of the common causes of engine ping on this engine is when the lower intake manifold bolts come loose. Coincidentally, when those bolts come loose, they also frequently create oil/coolant fouling problems for the number 5 cylinder. Whenever I see someone with this kind of problem on the number 5 cylinder, I suggest that they tighten those bolts (there's a thread somewhere here, I think it is in the useful threads forum). Usually they have just come loose, though occasionally the gasket needs attention.

 

[CTroxtell]

I will try to get around and check those bolts. That and the gasket should be fine though, the gasket just got replaced a few months back because it was leaking coolant because the gasket had got weak and was leaking coolant. I don't know what's going on but I can't even hardly go up any inclines, if I start up a hill at 55MPH I have to floor it and make the rpms jump to well over 4k to not slow down jurastically. It went straight downhill after I fixed the egr, and I lost 50 miles per tank of gas it seems.

 

[CTroxtell]

Confused

Okay I went to work yesterday, driving all around because I'm a satellite technician, when I got in the truck and started it to head home for the day the truck was running totally different...it seemed to be driving and running perfectly fine. Going to check this morning to see how it runs going to work to make sure I wasn't just thinking it was running better, but it was idling smoothly, accelerating fine...was like a change between night and day. Any idea how this is possible?

 

[bchapman]

Someone please help!!!

I have a 94 explorer limited that I bought acouple weeks ago and the guy I bought it from told me that in order to start it has to be jumped everytime. Well I said ok its just the battery or alternator. I pulled them both off went and had them both tested and of course they were bad so got new ones got home put them in and oh qrap its still doing the same thing for some reason the battery wont hold a charge. No after about a week of jumping it all the time the darn thin doesn't want to start at all when I go to jump it. The battery holds alittle charge but when I go to fire it up I get nothing. I sounds like it wants to but just doesnt have enough juice to do it. Any ideas on what could be causing this???

 

[CTroxtell]

Okay well today I went out and pulled stuff off the engine and checked and re-tightened the lower intake manifold bolts. Most all of them were already at 192 in. lb of torque, was only 1 or 2 in the middle that just need about a 90 degree turn. Upon looking at the front of the engine I can see what appears to be a coolant leak on the passenger side of the intake manifold where the rtv sealant gets placed at, appears to be an extremely small leak as my coolant level hasn't changed. If I look under the vehicle I can see a small drop of coolant on the driver side dimple of the oil pan. I wouldn't imagine that the gasket is bad, it was just put on less then 6 months ago I think it was. Is there any way to check the gasket without having to pull all this off.