351 with 2000 explorer efi will run for 1 second

[ba123]

ok, well, score on the successful test and ruling that out as the major issue.

One thought on startup vs running. Maybe someone knows the answer…does the explorer start on wasted spark and then shift to full sequential once it gets a signal from the cam sync? Maybe the cam sync is bad or not properly adjusted? Just a thought. Although not sure why the mag unplugged would keep it running unless for some reason that maintains wasted spark…

Just thinking out loud, maybe it’ll help.

 

[Broncobowsher]

Explorer is always a wasted spark. The coil fires both posts every time the coil fires.

 

[ba123]

Explorer is always a wasted spark. The coil fires both posts every time the coil fires.

Crank trigger plus cam sync…why would it have both and be wasted spark? Really?

 

[ba123]

Holy crap…I think I just found the info and that’s lame! Cam sync is for sequential injectors but why the heck not make it sequential ignition along with it.,.all the hardware is there!

Ok, scratch that theory.

Thanks for the enlightenment @Broncobowsher

 

[Viperwolf1]

Holy crap…I think I just found the info and that’s lame! Cam sync is for sequential injectors but why the heck not make it sequential ignition along with it.,.all the hardware is there!

Ok, scratch that theory.

Thanks for the enlightenment @Broncobowsher

Ignition is sequential. That's where the firing order comes into play. ECM counts pulses from crankshaft position sensor to determine when to fire ignition coils. Cam sensor only provides 1 pulse for every 2 crankshaft revolutions. Not enough resolution for spark timing but plenty to determine which half of the ignition firing order the engine is in.

 

[ba123]

Ignition is sequential. That's where the firing order comes into play. ECM counts pulses from crankshaft position sensor to determine when to fire ignition coils. Cam sensor only provides 1 pulse for every 2 crankshaft revolutions. Not enough resolution for spark timing but plenty to determine which half of the ignition firing order the engine is in.

That’s what I was saying but Broncobowsher said it’s not and I looked it up…at least what I could find on it. If it’s EDIS-8 it doesn’t use the cam sensor.

CPS is only used for sequential injectors. Makes no sense to me either.

Also, I searched some more @rjrobin2002 and I found that MAF unplugged puts it into limp mode bypassing other sensors.

You have a bad sensor somewhere or a bad reading for some other reason like a look hose (could be air intake) most likely and that's causing your issue. You just need to figure out which one it is.

Could be air and maf, could be cps, most likely not crank trigger...I'm not sure what sensors

Could be a simple ground maybe as well...

 

[73azbronco]

Ohm check your sensors.

 

[EFI Guy]

I'll chime in to confirm some stuff.
The Explorer system is wasted spark always, and also performs MSD in some cases. The ignition signal is based on the crank sensor only. The cam sensor is used for injector firing only. It only tells the PCM if the engine is on the compression stroke or not so that it knows when to fire the injectors in relation to the crank sensor. If the cam sensor signal is missing or faulty the computer will default to batch-firing the injectors. It will still run, just not sequentially.

I give the spec of 65psi for the returnless system based on some engineering documents I have and some references to 65 in the internal tables in the software. I have service manuals that spec at both 60 and 65. I'd rather leave you with a computer that pulls a little fuel out on fuel trims than one that tries to add it. Having said that, there have been local people using the Corvette filter that regulates to 58 that have no issues with it. They typically only run a couple of percent high on long-term fuel trims. Well within the computer's ability to adjust.

The part on the fuel rail that looks like a regulator on the returnless system is both a dampener and an accumulator. It is used to smooth out the spikes in fuel pressure when an injector closes. The engineers refer to this as the "Hydro-Hammer-Effect". Also when you crack the throttle and the vacuum drops it allows the diaphragm in it to lower and push accumulated fuel back into the rail to lessen any sudden drops in pressure. This is all necessary because the actual regulator is back in the tank. The computer calculates manifold pressure on its own and adjusts the firing time of the injector to compensate rather than having a regulator adjust fuel pressure in reference to vacuum.

Unplugging the MAF makes it run in a limp mode where it uses TPS vs RPM to calculate fuel based on a failure table. When it will run this way but not with the MAF plugged in then it is usually a sign of a bad MAF or a massive vacuum leak. In the OP's case, I believe it's a sign that the PCV system is not plumbed correctly. I do not see a hose between the MAF and throttle body that runs to the valve cover. That hose is the fresh air side of the PCV system. Without it, the air being sucked out of the crankcase by the PCV is not measured by the MAF. This would give the same symptom as a massive vacuum leak.

Correct that and if you still have issues grab an OBDlinkMX+, or a Vgate Vlinker FS, and a Windows laptop and give me a call. I'd be happy to remote in and give it a look-see.

 

[rjrobin2002]

Only sensor not new is crank position, and throttle body/throttle position sensor

 

[rjrobin2002]

I'll chime in to confirm some stuff.
The Explorer system is wasted spark always, and also performs MSD in some cases. The ignition signal is based on the crank sensor only. The cam sensor is used for injector firing only. It only tells the PCM if the engine is on the compression stroke or not so that it knows when to fire the injectors in relation to the crank sensor. If the cam sensor signal is missing or faulty the computer will default to batch-firing the injectors. It will still run, just not sequentially.

I give the spec of 65psi for the returnless system based on some engineering documents I have and some references to 65 in the internal tables in the software. I have service manuals that spec at both 60 and 65. I'd rather leave you with a computer that pulls a little fuel out on fuel trims than one that tries to add it. Having said that, there have been local people using the Corvette filter that regulates to 58 that have no issues with it. They typically only run a couple of percent high on long-term fuel trims. Well within the computer's ability to adjust.

The part on the fuel rail that looks like a regulator on the returnless system is both a dampener and an accumulator. It is used to smooth out the spikes in fuel pressure when an injector closes. The engineers refer to this as the "Hydro-Hammer-Effect". Also when you crack the throttle and the vacuum drops it allows the diaphragm in it to lower and push accumulated fuel back into the rail to lessen any sudden drops in pressure. This is all necessary because the actual regulator is back in the tank. The computer calculates manifold pressure on its own and adjusts the firing time of the injector to compensate rather than having a regulator adjust fuel pressure in reference to vacuum.

Unplugging the MAF makes it run in a limp mode where it uses TPS vs RPM to calculate fuel based on a failure table. When it will run this way but not with the MAF plugged in then it is usually a sign of a bad MAF or a massive vacuum leak. In the OP's case, I believe it's a sign that the PCV system is not plumbed correctly. I do not see a hose between the MAF and throttle body that runs to the valve cover. That hose is the fresh air side of the PCV system. Without it, the air being sucked out of the crankcase by the PCV is not measured by the MAF. This would give the same symptom as a massive vacuum leak.

Correct that and if you still have issues grab an OBDlinkMX+, or a Vgate Vlinker FS, and a Windows laptop and give me a call. I'd be happy to remote in and give it a look-see.

Thanks, I will check that out.

I know your a busy man and I was trying to brainstorm here before I emailed you.

 

[rjrobin2002]

I dont have a hose between the MAF and throttle body that runs to the valve cover.

I must of missed that need when I switched to aftermarket valve covers and intake tube, LOL. OOPS.

Now I need to rig it up somehow.

 

[ba123]

Here ya go...I posted my solution a while back:

5.0 EFI PCV System solution.

I spent too much time figuring out what would work for my own Pcv setup. The BXR manifold gives you zero clearance and wants you to put a lame s hose on the stock cover and I came up with this instead. I don’t think I even have the stock covers anymore. The possibilities are endless with...

classicbroncos.com

Maybe it'll help you.

 

[DirtDonk]

Speaking of aftermarket valve covers and the PCV, we’re talking about a 5.8 L lower intake. Correct?
The 5.0 L had a large port in the back of the lower intake to accommodate a PCV valve. But wasn’t the 5.8 blank of that fitting and they put the actual valve back in the valve cover like in the old days?
if this is the case, do you even have a PCV valve plumbed into the system?
If not, you will need both ends of that system. The PCV valve connected to full upper intake manifold vacuum, and the clean air return connected somewhere between the throttle-body and MAF, and connected (most likely) to the other valve cover.

Also probably not the majority of your problem. But installing it sure isn’t gonna hurt anything!

 

[rjrobin2002]

Speaking of aftermarket valve covers and the PCV, we’re talking about a 5.8 L lower intake. Correct?
The 5.0 L had a large port in the back of the lower intake to accommodate a PCV valve. But wasn’t the 5.8 blank of that fitting and they put the actual valve back in the valve cover like in the old days?
if this is the case, do you even have a PCV valve plumbed into the system?
If not, you will need both ends of that system. The PCV valve connected to full upper intake manifold vacuum, and the clean air return connected somewhere between the throttle-body and MAF, and connected (most likely) to the other valve cover.

Also probably not the majority of your problem. But installing it sure isn’t gonna hurt anything!

My lightning lower had a hole and grommet for PCV valve in the back center just like the explorer 5.0 lower had.

 

[Timmy390]

Speaking of aftermarket valve covers and the PCV, we’re talking about a 5.8 L lower intake. Correct?
The 5.0 L had a large port in the back of the lower intake to accommodate a PCV valve. But wasn’t the 5.8 blank of that fitting and they put the actual valve back in the valve cover like in the old days?
if this is the case, do you even have a PCV valve plumbed into the system?
If not, you will need both ends of that system. The PCV valve connected to full upper intake manifold vacuum, and the clean air return connected somewhere between the throttle-body and MAF, and connected (most likely) to the other valve cover.

Also probably not the majority of your problem. But installing it sure isn’t gonna hurt anything!

Yes the lightning lower and even the marine application 5.8L lowers had a PCV port in the rear of the intake. Most do not use it due to the "where did my oil go" question. I abandoned using it when I was using more oil than gas it seemed. My intake had the baffle and the screen yet was still sucking oil. Lots of info on the issue over on the "stang" boards.

I moved my PCV to the valve cover and no more oil loss.

Tim

 

[DirtDonk]

OK thanks. I just remembered that most of the 351s I had seen had the valve in the driver side valve cover.
Couldn’t remember if there was a fitting/hole in the back still or not.
What did Ford do when they used the valve in the cover? Rubber plug?
Or did the regular truck 5.8’s eliminate the hole in the intake and the Lightning kept the valve back there in the lower?

 

[rjrobin2002]

I just welded a filler neck on both aluminum valve covers.

Gonna pipe thread tap the passenger for a hose barb I guess.

I need to go look at a stock Explorer and refresh my mind on the plumbing. I need pictures to comprehend or remember anything.

 

[Timmy390]

OK thanks. I just remembered that most of the 351s I had seen had the valve in the driver side valve cover.
Couldn’t remember if there was a fitting/hole in the back still or not.
What did Ford do when they used the valve in the cover? Rubber plug?
Or did the regular truck 5.8’s eliminate the hole in the intake and the Lightning kept the valve back there in the lower?

All the non lighting 5.8's I've seen including vans used the PCV in the valve cover. I'm using a van valve cover on my setup.

Tim

 

[bigmuddy]

Only sensor not new is crank position, and throttle body/throttle position sensor

So, I have had something similar happen on two different explorers. One on the six cylinder and one of the eight.
Both times, mechanics couldn't find what the issue was as it would stay running and then once I moved it to there shop by low boy it started working again. Fought this for a very long time. Eventually, I spent the small amount of money and bought a new CPS and bam never had the issue again..

I would bet its the CPS

 

[bigmuddy]

Yes the lightning lower and even the marine application 5.8L lowers had a PCV port in the rear of the intake. Most do not use it due to the "where did my oil go" question. I abandoned using it when I was using more oil than gas it seemed. My intake had the baffle and the screen yet was still sucking oil. Lots of info on the issue over on the "stang" boards.

I moved my PCV to the valve cover and no more oil loss.

Tim

How did you plug the hole in the rear of the intake?