Random rough running and black smoke

Reply Subscribe

Thread Tools

Search this Thread

Jan 5, 2017 | 11:16 PM

Ford_Six

Thread Starter

Hotshot

Joined: Oct 2002

Posts: 18,488

Likes: 22

From: The Big, Oregon

Random rough running and black smoke

I am working on a 2000 Expedition with a 5.4 and some interesting issues. It will randomly start running rough, have very low power and blow black smoke, but then be just fine once shut down and restarted. It had the MAF replaced last year, before this started, and had it replaced again a couple weeks ago with a new Delphi unit with no change. I was playing around with it a little bit today and watched MAF voltage on my scanner and directly backprobing the harness side of the connector, and found an almost .2v difference. I'm not seeing where this loss could be coming from, is it possible that the PCM is failing?

Jan 6, 2017 | 08:30 AM

alloro

Fleet Owner

Joined: Apr 2008

Posts: 24,316

Likes: 5,127

From: 0,0,1

It's all guess work unless you connect a scan tool that can read live data. My first though is the rubber boots on the COPs are starting to fail and spark is jumping to ground.

Jan 6, 2017 | 11:33 AM

Ford_Six

Thread Starter

Hotshot

Joined: Oct 2002

Posts: 18,488

Likes: 22

From: The Big, Oregon

I've watched live data, I have a Ford emulator program on my scanner that I can graph with. I'll have to find out when it's last tune-up was, but the issue comes and goes.

Jan 6, 2017 | 01:44 PM

pdqford

Logistics Pro

Joined: Jan 2001

Posts: 3,740

Likes: 37

From: Central NYS

Quote:

Originally Posted by Ford_Six

If it's belching black smoke, the ignition is prolly okay.
But it is running rich.
Look at the short term fuel trims when it starts running rich.
If both STFTs are adjusting for a rich condition,
it is prollY something that affects both banks.
Check the fuel pressure regulator for fuel in the FPR vacuum line.
Put a fuel pressure gauge on it and verify the fuel pressure when it runs rough.

If the fuel trims indicate only one bank is rich,
An amp clamp and scope might indicate a sticky injector pintle on the rich bank.

What does the MAF sensor data show when it runs rough?

All these issues and no codes?

Jan 6, 2017 | 07:26 PM

Ford_Six

Thread Starter

Hotshot

Joined: Oct 2002

Posts: 18,488

Likes: 22

From: The Big, Oregon

It's been hard to catch it with the scanner when it's running rough, but there is no fuel in the vacuum line, and MAF reading will occasionally drop very low (like .8 grams per second, not even a realistic number). I did have a gauge on it previously and the pressure was within specs, 40ish if I remember correctly.

Jan 7, 2017 | 08:39 AM

pdqford

Logistics Pro

Joined: Jan 2001

Posts: 3,740

Likes: 37

From: Central NYS

Where are the fuel trims?

Not even a pending code?

Jan 7, 2017 | 11:48 AM

Ford_Six

Thread Starter

Hotshot

Joined: Oct 2002

Posts: 18,488

Likes: 22

From: The Big, Oregon

I'll check it again today, I don't recall what the trims are. The check engine light was on with a 171/ bank 1 lean the other day that had not popped up before, but it was not acting up.

Trending Topics

BREAKING: Ford Drops 6.8L V8 and Standard 6.7L Power Stroke from 2027...

131

9.8k
FX4 Real-World Use

28

643
Reverse Lights Not Working

27

415
New F-250 owner, coming from GMC/thoughts

24

914
Pedal Monster 7.3

27

882

Oct 21, 2021 | 06:46 PM

James427

Trailering

Joined: Jul 2021

Posts: 22

Likes: 4

UPDATE: I think I finally got this thing sorted out. I pulled the tank and Master Pro fuel pump I bought at O'Reilly's. I compared it to the Bosch replacement I bought. HUGE differences in quality of construction and materials. Ran it for a 20 mile test and fuel rail gauge under the wiper arm showed 32psi at idle and 43-45psi under WOT just like it was supposed to be. Car ran strong, pulled hard and fuel pressure never dropped. There is a little burble and unevenness at idle, but I can sort that out later.

When I first put the Master Pro in I had pulled the tank out, emptied it, literally pressure washed the inside very well, cleaned it out, dried it and put it back in. However, when I pulled it out again to remove the pump, there was sediment in the bottom of the tank and around the magnet I had put into the tank to catch rust particles. I had used two bottles of injector cleaner and the only thing I can think of is that the cleaner may have dissolved some of the hardened residue on the sides and bottom of the tank and released the particles that were trapped in the hardened gunk that the pressure washer did not get out. However, I do not think that this had any major impact on the low fuel pressure issue. The low fuel pressure issue existed as soon as I fired it up with the Master Pro pump in it. This time, I wired brushed it and coated it top and bottom with a layer of tank sealer.

So, after three months of pulling my hair out, replacing just about every part under the hood and fighting with this bitch every way I knew how, the lesson to take away is DO NOT BUY CHEAP CHINESE PARTS! This vehicle sat for about a year and had bad gas in it. So, you figure pull the tank, clean it out, new filters and pump and you should be good to go. When that didn't make it run right, I went with new (Chinese) injectors. So, after replacing BOTH the pump AND the injectors and still having the issue, your THINK those two are no longer the problem, but BOTH the injectors AND the Chinese Master Pro fuel pump were pieces of crap that did not function as advertised. That set me on a course of unnecessary repairs and parts until I circled back around to the pump and injectors again.

If anything else goes wrong, I will fill you guys in. But I wanted to let others know what my problems were and what I did to correct them. I put in Chinese parts and paid dearly for those temporary savings.