Rough Idle... High Hydrocarbons

[sicknickclassics33]

UPDATE: Inspected the intake pipe (airbox to throttle body)... no leaks. Also swapped out the fuel filter... no difference. Left battery unplugged for an hr to reset as well.

Any more ideas?

Im down to thinking it may be dirty fuel injectors... being that the truck sat for 8 years. Is anyone familiar with the symptoms of dirty injectors? Or, the most affordable correction?

 

[~X~]

Firing order

3 5 2 6 1 4 is this the correct firing order? I replaced my wires not long ago, 4.0 OHV 93 explorer that's the firing order labeled on my wires

www.explorerforum.com

 

[sicknickclassics33]

Firing order

3 5 2 6 1 4 is this the correct firing order? I replaced my wires not long ago, 4.0 OHV 93 explorer that's the firing order labeled on my wires

www.explorerforum.com

Thank you for the response. Ill triple check the order. But the thing is, it runs really good while driving. Its just the idle thats rough. If I hold it at let's say 3k rpm, the needle still dances though. So it seems to be trying to correct the mixture in a cycle. He seemed to conclude that the injectors may be the issue as well, but never followed up with results. I left message on thread as to whether it resolved his issue...

 

[~X~]

I was just throwing it out there. By saying high hydrocarbons, makes me think of unburnt fuel.

I read that you ran Seafoam. Good idea but still no guarantees that it had a positive effect on the injectors. You said it sat for 8 years then it was rebuilt? That's what had me thinking about firing order. Was the block separated from the bell housing?

 

[sicknickclassics33]

I was just throwing it out there. By saying high hydrocarbons, makes me think of unburnt fuel.

I read that you ran Seafoam. Good idea but still no guarantees that it had a positive effect on the injectors. You said it sat for 8 years then it was rebuilt? That's what had me thinking about firing order. Was the block separated from the bell housing?

The 4 wheel drive and the entire front axle/suspension system was removed, for a 3" lift, and left in pieces in a garage for 8 years. The engine was left intact. Of course, I had to change all the fluids and run through basic maintenance/tune up stuff and prep for start up. Replaced items mentioned above. What was left in the tank and fuel lines looked blackish green. After fogging the cylinders and hand turning the crank... it started right up. It was garaged and maintained regularly, since purchased, by a grandmother. Everything is in real nice order. All suspension components and exhaust system was also upgraded... aside from cat. No one is sure if its 27k or 127k original miles. All is why I'm suspecting injectors.

 

[1sicbronconut]

If you had the plug wires off the coil it's fairly common for people to the new ones on in the wrong order.

 

[sicknickclassics33]

If you had the plug wires off the coil it's fairly common for people to the new ones on in the wrong order. View attachment 436394

Agreed. That was me a few days ago... that's how I know I got them right now

 

[mitch1204]

Trust your computer. You have an EGR, 4.0 right? All cars from 1986 have them, its mandatory. The parts store list it. It's on the driver's side towards the front of the exhaust manifold mounted right in front of the oil dipstick. Unplug the vacuum hose on top of it and plug it with your finger temporarily. Does the engine smooth out? Yes, the EGR control valve is stuck open. Next with the vacuum hose off the EGR, add your own scrap hose to it and suck on it hard. The engine should almost quit if it's a good EGR. Usually it's the Control Valve or the DPFE sensor. Both are hard to find and your best bet is ebay.

 

[mitch1204]

If you find it's the EGR control valve reply back and I'll tell you a possible fix where you don't have to buy one.

 

[Mark the mechanic]

So, rebuilt a friends 92 V6 XLT... 127k mi. Sat garaged for 8yrs.

Drives good. Its had a rough irregular idle, and I notice the misfire situation at all RPMs. Checked for all possible vacuume leaks, replaced plugs, wires and coil packs. Replaced fuel pump, PCV valve, fresh gas with Seafoam injector cleaner. Aside from swapping out the fuel filter next, im at a loss. Would this be the cause? Was considering the capacitor at the coil pack as well, but read it only prevents radio interference and has no other function.

I took it to see if it might pass smog anyways, the guy did a pre-reading at idle and said the hydrocarbons were high and to address this issue first before an official test... so no additional emissions reading to go off at this time. When I swapped the plugs which had run recently for about 80 miles, they were clean with a yellow tinge.

Im looking to rule out full injectors or exhaust valve seating issues. Being all the plugs are the same, it doesn't seen to be an individual cylinder issue. Any ideas guys?

Thank you in advance!

A slight bend in the distributor shaft will throw it off like that.

 

[sicknickclassics33]

Trust your computer. You have an EGR, 4.0 right? All cars from 1986 have them, its mandatory. The parts store list it. It's on the driver's side towards the front of the exhaust manifold mounted right in front of the oil dipstick. Unplug the vacuum hose on top of it and plug it with your finger temporarily. Does the engine smooth out? Yes, the EGR control valve is stuck open. Next with the vacuum hose off the EGR, add your own scrap hose to it and suck on it hard. The engine should almost quit if it's a good EGR. Usually it's the Control Valve or the DPFE sensor. Both are hard to find and your best bet is ebay.

The 92 Explorer 4.0 dosent actually have an EGR valve. Its usually one of the first things I check with symptoms like this. I've been able to verify this throughout various forums. Im not sure why part stores offer it.

 

[sicknickclassics33]

A slight bend in the distributor shaft will throw it off like that.

There isn't a distributor on this engine. There is however, a crank position sensor which is on my list as a possibility. No codes though.

 

[mitch1204]

The 92 Explorer 4.0 dosent actually have an EGR valve. Its usually one of the first things I check with symptoms like this. I've been able to verify this throughout various forums. Im not sure why part stores offer it.

I did some checking and 1992 was a change over year. I think it has the air injection pump driven by the fan belt. You should have about a 1" pipe going to the exhaust manifold. Locate it. Off of the pipe you'll see a 1/4" pipe. Attached to it is a rubber hose. It might be covered with a white kevlar heat shield. Follow it and it will lead to a DPF pressure sensor behind the driver side valve cover area. That's your code 33 problem. Inspect the rubber hose for cracks.

 

[1sicbronconut]

Could be injectors, ethanol plays havoc on fuel systems if it's left in them and not run, rebuilt injectors are fairly cheap on Ebay.

 

[Turdle]

Check fuel pressure regulator. You may get even find raw fuel in the vacuum line to regulator.

 

[AtariJeff001]

So, rebuilt a friends 92 V6 XLT... 127k mi. Sat garaged for 8yrs.

Drives good. Its had a rough irregular idle, and I notice the misfire situation at all RPMs. Checked for all possible vacuume leaks, replaced plugs, wires and coil packs. Replaced fuel pump, PCV valve, fresh gas with Seafoam injector cleaner. Aside from swapping out the fuel filter next, im at a loss. Would this be the cause? Was considering the capacitor at the coil pack as well, but read it only prevents radio interference and has no other function.

I took it to see if it might pass smog anyways, the guy did a pre-reading at idle and said the hydrocarbons were high and to address this issue first before an official test... so no additional emissions reading to go off at this time. When I swapped the plugs which had run recently for about 80 miles, they were clean with a yellow tinge.

Im looking to rule out full injectors or exhaust valve seating issues. Being all the plugs are the same, it doesn't seen to be an individual cylinder issue. Any ideas guys?

Thank you in advance!

 

[AtariJeff001]

I have a 93 Explorer which had one of the 6 fuel injectors stuck closed. Because pre-94 Explorers do not have true sequential injection, the injectors are "batch fired" in groups of three. This made diagnosis somewhat more difficult. Once i removed the upper intake, then the fuel rails, it was easy to check them.

I've got several first-gen explorers, and another issue they have is worn pushrods and rockers due to the factory oiling being marginal. This will exhibit as ticking that comes and goes, or never goes away. I don't believe you described anything like that.

My best bet would be the injector. I had a hell of a time diagnosing my 93, tried everything you tried. All the injector cleaner didnt do anything. I had to remove the injectors and thats when i found the stuck one. I hope this helps.

Atari Jeff

 

[sicknickclassics33]

I did some checking and 1992 was a change over year. I think it has the air injection pump driven by the fan belt. You should have about a 1" pipe going to the exhaust manifold. Locate it. Off of the pipe you'll see a 1/4" pipe. Attached to it is a rubber hose. It might be covered with a white kevlar heat shield. Follow it and it will lead to a DPF pressure sensor behind the driver side valve cover area. That's your code 33 problem. Inspect the rubber hose for cracks.

Thanx! I'll check into that tomorrow.

 

[Richard Alexander]

So, rebuilt a friends 92 V6 XLT... 127k mi. Sat garaged for 8yrs.

Drives good. Its had a rough irregular idle, and I notice the misfire situation at all RPMs. Checked for all possible vacuume leaks, replaced plugs, wires and coil packs. Replaced fuel pump, PCV valve, fresh gas with Seafoam injector cleaner. Aside from swapping out the fuel filter next, im at a loss. Would this be the cause? Was considering the capacitor at the coil pack as well, but read it only prevents radio interference and has no other function.

I took it to see if it might pass smog anyways, the guy did a pre-reading at idle and said the hydrocarbons were high and to address this issue first before an official test... so no additional emissions reading to go off at this time. When I swapped the plugs which had run recently for about 80 miles, they were clean with a yellow tinge.

Im looking to rule out full injectors or exhaust valve seating issues. Being all the plugs are the same, it doesn't seen to be an individual cylinder issue. Any ideas guys?

Thank you in advance!

Clean or replace the fuel injectors, thats what cured mine.

 

[sicknickclassics33]

I have a 93 Explorer which had one of the 6 fuel injectors stuck closed. Because pre-94 Explorers do not have true sequential injection, the injectors are "batch fired" in groups of three. This made diagnosis somewhat more difficult. Once i removed the upper intake, then the fuel rails, it was easy to check them.

I've got several first-gen explorers, and another issue they have is worn pushrods and rockers due to the factory oiling being marginal. This will exhibit as ticking that comes and goes, or never goes away.

I have a 93 Explorer which had one of the 6 fuel injectors stuck closed. Because pre-94 Explorers do not have true sequential injection, the injectors are "batch fired" in groups of three. This made diagnosis somewhat more difficult. Once i removed the upper intake, then the fuel rails, it was easy to check them.

I've got several first-gen explorers, and another issue they have is worn pushrods and rockers due to the factory oiling being marginal. This will exhibit as ticking that comes and goes, or never goes away. I don't believe you described anything like that.

My best bet would be the injector. I had a hell of a time diagnosing my 93, tried everything you tried. All the injector cleaner didnt do anything. I had to remove the injectors and thats when i found the stuck one. I hope this helps.

Atari Jeff

No ticking.

Are they 24lb injectors? I found a set of Accels for $350 that claim OEM replacement.