4.0 sohc falling on it's face for a millisecond...?

[FPGT24]

i have a well cared for 98 explorer with the 4.0 sohc that i got from the original owner who was an old man. bout 3 weeks ago i was making a left hand turn....within a second or so of getting back on the gas, the engine just fell on its face for a split second as if someone had turned the ignition off, but it fired back up almost instantly. a week later, it did it again, again when making a left hand turn and getting back on the gas. the past week however, it has done it 3 times, all of these times were when i was pulling out from a stop. i have no idea what is causing it, but it is a serious cause for concern as today as i was pulling out in front of cars it did this, and worse than ever none the less. the engine again came back on, but this time it had absolutely no power for like two seconds....pretty scary..

my explorer has had some strange electrical gremlin since i got it, the 3rd brake light flickers when the truck is off and just sitting there, but it is steadily lit while the engine is running (not bright as if someones on the brakes, but just enough to see it). and the other strange electrical issue it has is the locks do not automatically lock, except sometimes ill be driving down the interstate and when i put the turn signal stalk to the right, the locks will then lock. i have LED brake lights in the truck, but removing them did not help solve any of these issues.

anyone have any clues as to whats going on? any advice or help is appreciated.

 

[2000StreetRod]

ignition issues?

Very rapid loss and restoration of power is frequently due to ignition issues. Do you have any misfire codes? Have you checked your battery cables and cleaned the terminals to the battery and to the chassis? What does the tachometer do when you lose power? If it drops to zero then clean your camshaft position sensor connector by disconnecting/reconnecting the connector a few times. Check the wiring to the coilpack and the connector.

 

[Mustang Guy]

I had the EXACT same issue with my 2002 4.0 SOHC that I chased around for 6 weeks or so. It ended up being my DPFE sensor. When these start to fail they send bad info to the computer and the computer dumps too much EGR exhaust into the intake and that leans out the mixture for just a moment. For some reason they don't throw a code until they completely fail. Don't mess around with the Chinese junk from the national parts chains. You can get a real Motorcraft from Amazon for $39.00. It takes all of 5 minutes and no tools to change it out.

 

[Flash]

I had the EXACT same issue with my 2002 4.0 SOHC that I chased around for 6 weeks or so. It ended up being my DPFE sensor. When these start to fail they send bad info to the computer and the computer dumps too much EGR exhaust into the intake and that leans out the mixture for just a moment. For some reason they don't throw a code until they completely fail. Don't mess around with the Chinese junk from the national parts chains. You can get a real Motorcraft from Amazon for $39.00. It takes all of 5 minutes and no tools to change it out.

Does a '98 SOHC have this?

 

[Mustang Guy]

Does a '98 SOHC have this?

I'm pretty darn sure it does. The DPFE sensor is a part of the EGR system. If you follow the EGR tube coming off the exhaust manifold you will see two smaller steel tubes coming off of it, usually going straight up. The DPFE sensor is located on the top of these tubes. It just pulls off of the neoprene connecting hoses, no tools required. Be careful unplugging the electrical connector so you don't break it.

 

[2000StreetRod]

Egr

Does a '98 SOHC have this?

I don't know about the export models but the USA models have exhaust gas recirculation (EGR). See this thread: EGR System O&T

 

[Flash]

I'm pretty darn sure it does. The DPFE sensor is a part of the EGR system. If you follow the EGR tube coming off the exhaust manifold you will see two smaller steel tubes coming off of it, usually going straight up. The DPFE sensor is located on the top of these tubes. It just pulls off of the neoprene connecting hoses, no tools required. Be careful unplugging the electrical connector so you don't break it.

I just had a little bit of EGR drama with the pipe coming off at BOTH ends.
The top end burned and melted the plastic pipe that carries evap canister fumes to the intake.
I didn't see the DPFE sensor but then I wasn't looking for it either.

Funny, when the top of the EGR pipe was loose but not off, the noise sounded like a rocker tapping from inside the car, not an exhaust leak.

And there I was trying to fix a leak at the exhaust flange when it was the EGR pipe all along.

 

[Flash]

I don't know about the export models but the USA models have exhaust gas recirculation (EGR). See this thread: EGR System O&T

All of our cars have had EGR since 1978. It was a mess when it was first introduced.

I was just working on my EGR pipe the other day and I didn't see that part but I wasn't looking for it.
I better make sure it still connected properly after jiggering the pipe around.

I had a look on Autozone to see where the DPFE should be and it said only the 3.8 and 4.6 have it.

 

[Mustang Guy]

All of our cars have had EGR since 1978. It was a mess when it was first introduced.

I was just working on my EGR pipe the other day and I didn't see that part but I wasn't looking for it.
I better make sure it still connected properly after jiggering the pipe around.

I had a look on Autozone to see where the DPFE should be and it said only the 3.8 and 4.6 have it.

I just checked Advance Auto and Amazon and they both list a DPFE sensor for a 1998 4.0 SOHC Explorer.

 

[Flash]

I don't know about the export models but the USA models have exhaust gas recirculation (EGR). See this thread: EGR System O&T

I had a look at that thread - well done.
Like you, I've never had an EGR related incident so it's not something I was very knowledgeable about.

But just recently I had the EGR pipe on the Explorer come off at both ends and I found out how it affects general performance.

There was a Diesel Touareg for a pretty good price that I didn't buy because it had an EGR code. I got scared and ran away but I think I could tackle it now.

 

[Flash]

I just checked Advance Auto and Amazon and they both list a DPFE sensor for a 1998 4.0 SOHC Explorer.

Yeah, I saw on Amazon it was listed, part number egr151 i think and 153 fits as well.
But Autozone said.....

2000StreetRod's thread EGR System O&T shows it quite clearly on the cam cover right near the oil dip stick, I'm almost sure I remember seeing it there.

I'm going to check to make sure everything's still connected properly when it's light.

 

[Mustang Guy]

I had a look at that thread - well done.
Like you, I've never had an EGR related incident so it's not something I was very knowledgeable about.

But just recently I had the EGR pipe on the Explorer come off at both ends and I found out how it affects general performance.

There was a Diesel Touareg for a pretty good price that I didn't buy because it had an EGR code. I got scared and ran away but I think I could tackle it now.

Honestly, the EGR system is basically pretty simple and easy to repair (the parts aren't expensive either).

 

[Flash]

Honestly, the EGR system is basically pretty simple and easy to repair (the parts aren't expensive either).

A bit more complicated (and expensive) on a common rail diesel.
There's electronically controlled flaps and parts into the $300s.

I wasn't keen on dropping $11k on a car showing codes.

 

[FPGT24]

Very rapid loss and restoration of power is frequently due to ignition issues. Do you have any misfire codes? Have you checked your battery cables and cleaned the terminals to the battery and to the chassis? What does the tachometer do when you lose power? If it drops to zero then clean your camshaft position sensor connector by disconnecting/reconnecting the connector a few times. Check the wiring to the coilpack and the connector.

My scanner says no codes, stored or active. I'm very **** about checking under the hood often, the battery and cables are in good order. I'm not sure about the tach, i think the last time it dropped all the way down but like i said "i think"...i can't remember because it happened so fast.

 

[FPGT24]

I had the EXACT same issue with my 2002 4.0 SOHC that I chased around for 6 weeks or so. It ended up being my DPFE sensor.

I'll try replacing that, but it appears that the DPFE that is on there currently isn't too old....i'd say maybe a few years old. But like you said that may be a cheapass one. Is there any way i can tell if its a Motorcraft part or cheap garbage? It looks pretty cheap.

 

[FPGT24]

Honestly, the EGR system is basically pretty simple and easy to repair (the parts aren't expensive either).

Yeah, on the SOHC it is. Not on the OHV 4.0....thats an expensive and difficult job from what I have heard and seen.

 

[Mustang Guy]

I'll try replacing that, but it appears that the DPFE that is on there currently isn't too old....i'd say maybe a few years old. But like you said that may be a cheapass one. Is there any way i can tell if its a Motorcraft part or cheap garbage? It looks pretty cheap.

All I can say is your symptoms are the exactly the same as I had and it never threw a code. From the research I've done, the DPFE sensors are a weak link and often fail in the 30,000 - 50,000 miles range. You just could try unplugging the electrical connection and leave the DPFE in place and see what happens with your symptoms. It will likely throw a code but if the cutting out goes away you have your answer.

 

[2000StreetRod]

disable EGR

You can also just disconnect the vacuum hose to the EGR valve and plug the hose. Without vacuum the EGR valve will stay closed (as it should during idle and WOT).

 

[koda2000]

i have a well cared for 98 explorer with the 4.0 sohc that i got from the original owner who was an old man. bout 3 weeks ago i was making a left hand turn....within a second or so of getting back on the gas, the engine just fell on its face for a split second as if someone had turned the ignition off, but it fired back up almost instantly. a week later, it did it again, again when making a left hand turn and getting back on the gas. the past week however, it has done it 3 times, all of these times were when i was pulling out from a stop. i have no idea what is causing it, but it is a serious cause for concern as today as i was pulling out in front of cars it did this, and worse than ever none the less. the engine again came back on, but this time it had absolutely no power for like two seconds....pretty scary..

my explorer has had some strange electrical gremlin since i got it, the 3rd brake light flickers when the truck is off and just sitting there, but it is steadily lit while the engine is running (not bright as if someones on the brakes, but just enough to see it). and the other strange electrical issue it has is the locks do not automatically lock, except sometimes ill be driving down the interstate and when i put the turn signal stalk to the right, the locks will then lock. i have LED brake lights in the truck, but removing them did not help solve any of these issues.

anyone have any clues as to whats going on? any advice or help is appreciated.

I recall reading several threads on the engine cutting out briefly while turning. I do not remember the resolution (assuming there was one posted) but it seems to me it was somehow fuel tank related. It was several years ago and my memory isn't as good as it used to be, but try searching the forum, or search via Google, as the search feature on the forum sucks.

Of course that doesn't explain your electrical Gremlins, but the weird electrical problems are often ground or alternator related.

 

[murkinstock]

I have the same problem with my '92, it only happens when I'm low on gas and make a hard left turn. So I think that's your issue. Are you getting low on gas? Try filling it up and see how it goes.