1994 ford explorer running terrible after tuneup.

[Kofire]

Ok so I did a large amount of proactive parts replacing because I use my vehicles off road in often rural places with no service and need them to be reliable. I purchased my explorer this spring and it has ran great up until this point. It is now at the point where it barely runs. This has been a slow decline in its performance and I have also been battling failing parts from local parts stores. I am running out of ideas.

At the moment it runs like it has a cam in it. It’s running very rich and will DeFinetely not stay running if I were to drive it.
I have ran through almost all of the suggestions I have seen that can usually fix problems like this but I am getting nowhere.

My next step is to replace all injectors and associated gaskets but I’m trying to avoid that if it’s not necessary.

I have replaced the following-
MAF ( replaced twice)
TPS
PCM (50 state with egr)
IAT
eCT sensor
TPS
EGR, DPFE, Vacuum solenoid
FPR
Coil pack , oreillys brand lasted two weeks then failed so I switched to motorcraft.
Spark plug wires and spark plugs. Ngk double platinum iridium.
New Delphi fuel pump and motorcraft filter
CKP and improved the wiring so it’s protected

New High output alternator , thermostat, water pump, three core radiator, severe duty fan clutch etc.

The engine has no apparent vacuum leaks. It has been smoke tested. Pulling the IAT will kill the motor.

It ran great for a week after everything was done. Then one morning everything changed.

It has fuel pressure.
The cats are not plugged.
Grounds are good
Battery is charged and good.
There is no evidence of a blown head gasket or a cracked head.


It sometimes will blow blue smoke then switch to black smoke then die. I do believe however this was the failing ignition coil.

It idles extremely rough and is not currently drivable.

It will sometimes blow the DPFE hose off of the tubes. It is also backfiring with any application of the throttle. Any ideas? Suggestions? Path moving forward?

 

[Kofire]

My bad I just realized I posted in the wrong place can somebody move this to the 4.0 section ? Thanks.

 

[Uncle Gump]

What are your fuel pressure numbers?

Have you checked the pressure regulator?

Hopefully you didn't pitch the good working factory sensors... many of the aftermarket parts are not good these days.

I'm also a stickler for using Motorcraft spark plugs. What plugs did you take out?

 

[ekrampitzjr]

Check your plug wires carefully to make sure the right wire is on the right plug. Getting them mixed up at the coil pack is amazingly easy to do.

 

[Kofire]

What are your fuel pressure numbers?

Have you checked the pressure regulator?

Its new how would I check it?

Hopefully you didn't pitch the good working factory sensors... many of the aftermarket parts are not good these days.

I’m learning this and wow what a joke. I’m not used to older vehicles.

I'm also a stickler for using Motorcraft spark plugs. What plugs did you take out?

Motorcraft plugs that looked original.

 

[Kofire]

Check your plug wires carefully to make sure the right wire is on the right plug. Getting them mixed up at the coil pack is amazingly easy to do.

I followed the order on the new coil. Thanks.

 

[Uncle Gump]

Forgot to mention... I did move your post to the 4.0L forum.

 

[Uncle Gump]

I don't trust any plugs in my Ford except Motorcraft. Not saying it's your issue but I've seen many driveability issues created from other plugs.

So... you say fuel your pressure is good... yet you don't give me a pressure value. Fuel pressure should be the first thing you check when diagnosing driveability concerns. The entire fuel strategy depends on fuel pressure being within spec.

Simple test for pressure regulator... pull the vacuum hose and see if fuel is entering the hose. If there is fuel in the hose the regulator diaphragm is bad. Next test would be to monitor fuel pressure while running and stab the throttle. That will create an absence of manifold vacuum and the fuel pressure should go up.

I know you said it ran OK for a minute after the tune up... then went to hell. It's absolutely worth double checking the firing order and ensure the wire are connected securely.

I would pull a couple plugs and have a look at them. If they're black and fouled... put the proper Motorcraft plugs back in it and see if it helps your condition.

 

[Kofire]

I don't trust any plugs in my Ford except Motorcraft. Not saying it's your issue but I've seen many driveability issues created from other plugs.

So... you say fuel your pressure is good... yet you don't give me a pressure value. Fuel pressure should be the first thing you check when diagnosing driveability concerns. The entire fuel strategy depends on fuel pressure being within spec.

Simple test for pressure regulator... pull the vacuum hose and see if fuel is entering the hose. If there is fuel in the hose the regulator diaphragm is bad. Next test would be to monitor fuel pressure while running and stab the throttle. That will create an absence of manifold vacuum and the fuel pressure should go up.

Ok I’ll recheck it.

I know you said it ran OK for a minute after the tune up... then went to hell. It's absolutely worth double checking the firing order and ensure the wire are connected securely.

Ok that’s done.

I would pull a couple plugs and have a look at them. If they're black and fouled... put the proper Motorcraft plugs back in it and see if it helps your condition.

Ok I will do that today. Yes they are black and fouled. The motorcraft I pulled out were carboned up as well. Thanks.

 

[Shran]

^^^ that, there are two wires that are not in the place you'd expect them to be on the coil pack (out of numerical order.)

I'd have your injectors cleaned or replace them. Cleaning is more expensive than remans but a good shop will give you a flow report and tell you if you had any stuck open. If it's running rich enough to smoke, my guess is you have one or more stuck open.

 

[Kofire]

^^^ that, there are two wires that are not in the place you'd expect them to be on the coil pack (out of numerical order.)

I'd have your injectors cleaned or replace them. Cleaning is more expensive than remans but a good shop will give you a flow report and tell you if you had any stuck open. If it's running rich enough to smoke, my guess is you have one or more stuck open.

I’ve got that part figured out. (Coil pack) Thank you. The motorcraft coil has them labeled.

 

[Kofire]

Ok compression checks out
150 across all cylinders besides one that is 160.

 

[Kofire]

Ok compression is good
Fuel pressure is good
I changed out a vacuum line that looked iffy on the FPR.
Changed out to motorcraft platinum plugs
Said a prayer and turned the key. At the moment it is running fantastic. However it has done this to me before.
. It’s a night and day difference from last night but it’s done this to me before.

 

[Uncle Gump]

Just put some easy miles on it and see how it goes.

A sketchy vacuum hose on the FPR could have given you a couple problems. Leaking vacuum and higher fuel pressure.

That would cause an erratic/high idle and blowing black smoke.

Think positive!