I bought my pickup about 2 years ago and was running rough and using lots of oil. I replaced the engine recently thinking the missing was due to lack of compression. However, the new engine does the same thing. Both KOEO test and KOER tests all pass. However, I know it is running lean because the spark plugs are white indicating lean (also explaining the rough idle). The following were replaced during the engine replacement:

-Oxygen Sensor
-Injectors
-Spark Plugs and wires
-Distributor, Cap and Rotor
-TFI Module
-Throttle Position Sensor
-Idle Air control Valve
-Fuel Pressure Regulator
-EGR Valve

I have approximately 18 inches of vacuum at idle. I have checked for vacuum leaks and found none. I checked the temperature and intake air sensors…both ok. Also, when I unplug the oxygen sensor and the computer goes into open circuit mode, it runs smooth. Could my PCM be bad?

The extreme lean condition appears to have caused the old engine to fail prematurely (it has 82,000 miles and this appears to be the 3rd engine). I was wondering if anyone had the same issues before I buy a new computer?

 

Is this a MAF engine, or a MAP (speed-density)?

The plugs alone aren't enough to confirm a lean condition. Does it ping/knock/clatter? Does it blow black smoke? Does it run hot? When you goose the throttle, does the noise get louder or quieter? What's the fuel pressure? Has it ever set a lean code?

Where did all these new parts come from, and what brands are they? Did you test any of them before installation? Did you test any of the old ones before removal? Did you save the old ones?

18 is near the low end of the range - where is the ignition timing set? Did you put a new timing gear/chain set in the replacement engine? Have you checked this engine's compression?

Blindly replacing parts is the most expensive & least effective way to fix anything (as you've obviously seen), so I suggest you stop. Don't buy a PCM or anything else until you KNOW what it needs.

 

This is a MAP engine

It doesn’t make any noises, just misses and shakes, most noticeably at idle. When you stomp on it (in park), it coughs before revving up. No black smoke. I have not checked the fuel pressure, but I put a new pressure regulator on it and it runs the same way on both tanks. It has never thrown a lean code, or code of any kind.

Most of the parts came from NAPA, and I did save the old ones.

I set the timing @ 10 degrees BTDC with the spout out, and checked for advance with the spout installed. It’s not the timing chain or compression because it runs great in open circuit mode. Something is going on with a sensor or the computer.

Without any codes, it’s difficult to track what the problem is without replacing parts. I have had it to 3 mechanics…none have been able to find the problem.

 

how much to put ya on the payroll Steve? I mean you are just about the smartest wisest and most knowledged (not to mention you must have the largest hard drive on the market to stock pile all the documents you are able to present to back your side of the conversation) I have yet to of seen in all the threads on this site.... I have some issues I could certainly use a "QUALIFIED" person to assist with!
Black smoke, sputtering, stuttering, hesitation, no throttle responce, tons of pedal and lots of speed but it just takes for ever to get it their! crack manifolds, setting up dual exhaust manifolds, w/inline xpipe, w/trudual flow 40 knockoffs, 60/40 seat interchange , I mean the list just goes on!

So how much an hour?

 

Then it's probably not running lean. Have you checked the EGR? Do you have a Haynes manual?That should be top or your list.Why?Then you're not reading them right. Even an engine with NO faults stores codes. Read this caption:

Good, but they sell cheap parts, too, so what brands are you buying?Codes only tell you where to begin diagnosis, and parts-swapping doesn't track down problems - it usually creates them. Before codes existed, engine problems were diagnosed, so it can be done.Where are you?Don't hijack this thread. Post your own. If I think I have something to add, I'll post in your thread. If I don't, you can e-mail me a link to your thread & I'll review it, but I'll still only reply in that thread if I have something to add to it.
https://www.f150online.com/forums/sh...12#post2840712

 

Steve, addressing your comments:

1. If not lean, then what would cause it to sputter, shake, and ruin motors? And why would the spark plugs be white in color?

2. We replaced the EGR when we put the new motor in. I made sure it is not introducing exhaust into the intake at idle by removing the exhaust pipe that runs to the valve and plugging it. No change.

3. I do have a Haynes and Chilton Manual.

4. I checked the fuel pressure…it is within spec.

5. I thought the fuel pressure regulator was the problem…it wasn’t.

6. What I meant by it not throwing codes is that it throws the “111” (all pass) code during the KOEO and KOER tests.

Getting back to the low intake vacuum (18 inches) for a second….what are the things that can cause that. Intake valves not closing properly? Vacuum leak? Am I missing anything else?

Thanks for your help, any other ideas would be greatly appreciated.

 

Low vacuum can be retarded timing. This can also cause a rough idle and plug issues.

 

1. Lots of things. Too many to list.
2. Why did you replace it? Did you keep the original?
4. What is it?
7. What brands are the parts?
8. Where are you?

Read the links in this caption:

 

Did you ever figure this out? I have the EXACT same situation. Full engine rebuild and replacement of almost every sensor on this thing and it still runs rough and pings as it did post rebuild. I've tried everything except the computer.

 

Considering that this thread died 5 years ago, and the original poster hasn't posted anywhere else in the forum, your odds of getting a response are slim to none.

 

Check fuel pressure. Also, disconnect the battery, and remove the ECM. Pull the lid off of ECM, do you see any damage?

 

Look at this & the NEXT few:

 

Fuel Pressure is great. I got all excited when i realized it could be something visual in the ECM. No dice! It all looks great. When i got this thing it had a new distributor in it. I could still see the finger prints from the mechanic on it. While replacing the hoses i noticed the distributor was loose and i knocked it out of time. So it went to go time it and noticed the spout connector still had the tape on it from the factory! Not bad for a 20 year old motor. when i re-timed it is when i started to notice the ping. However i had only driven it 10 miles so there is a chance it pinged prior to me timing it. I have inspected the distributor to see if the pick-up was loose or anything and found nothing. Literally the only components not replaced on the motor are the distributor, ECM, push rods, rockers, and cam. It has an intermittent rough idle and when cold it seems to surge when i just slightly tip into the throttle.