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I am a technician, and work in a shop......

Let me rephrase my statement... Maybe you should bring it to a shop who employs people with a clue.


Go Micheal! :)



why would I put my foot in my mouth? If you cant diag a lean problem, what kind of tech can you really be?

Must do mostly quick-lube.


Have you verified voltage to or from the sensors? Have you done any voltage backprobing at all?
 
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Wow, do me a favor and remove yourself from my post. I didn't come to this forum to have some a ss decide he somehow thinks he if f ucking better than me. I was a lead tech for Firestone Complete Auto Care for 5 years. I am the diagnostic tech for Savannah Tire. I hold 7 current ASE Certs, of which include engine repair and engine performance. I fully understand rich and lean, short and long term fuel trims, mass air grams and voltages. 02 sensor voltages and how they switch, and when switching what that actually means to a computer. Do me a favor, with out going to google, can you tell me what a P0401 is, maybe a P0420, how about a P0442, or maybe a P0456 and how to diagnose any of them. Hell, heres an easy one, what is a P0301.
I came here to get assistance from people whom have dealt with these cars longer than I. At 30 years old, kinda missed the old school systems by a few years. So I diagnose OBD II with PIDS and Modules that give me real time data so I can pinpoint sensor faults so that I can diagnose them and determine the failure and why.
I have checked everything that could create a lean condition, yet one still remains. I have done voltage checks and resistance checks. Checked spark and fuel. I did how ever notice that the ported intake that I received doesn't have the injector seats in them any more. I can't get the car to act up at idle, but while I am driving it always feels like it is hesitating. And this damn cold start and dying thing. Maybe I need to bring my car to your addermk2, think you can figure it out.
 
Infact, I know I could.

Owner and operator of 64bit Tuning Concepts, ASE certified technician, Nissan Certified, Toyota Certified, Ford Certified, SCT certified, and Moates trained.


As I said before... If you had a Quarterhorse, you'd be able to diagnose your problem quickly.
 
Now that we have both p issed, is there another constructive approach to this. As I said earlier, I noticed the ported intake has the injector seats drilled out. I was grabbing some parts for a vehicle I am flipping and was looking at another explorer lower. Noticed the injector seats were there. Given the fact that there is a lot of vacuum created there, THAT could be my issue. Im gonna clean this one up and install it. I did a resistance/voltage check on my mass air, act (replaced had a code) Baro (replaced had a code) ect, coil, injectors, replaced distributor and tfi (because I have another) timing, wires are less than a month old, plugs are 4 month old NGK's (gt40p heads). Everything is checking out. Replaced the O2's because ofthe 41/91 (it was recomended, no I did not test them, one was fused into the exhaust.) Valve lash is good.
 
Began retesting everything, and the one thing I didn't test was fuel pressure at RPM. I was messing with my fuel pressure, and Mitchell ProDemand has a fuel pressure range of 30-45. It doesn't specify if this is with or with out vacuum. Be that as it is, I set it to 45 vacuum removed. Reattached the vacuum and fuel pressure drops to 39. Rev the motor to about 2000 rpms and the fuel pressure drops to 32-33. This is with un regulated FP at 45. Drop is 6 psi to be at the factory 39 and I am running less than 30 psi at rpms. Hey, that will make you run lean!! Guess I need to find out what the warranty is from Walbro.
 
Good work, I am glad you found the culprit.
I am fond of saying that "Persistence is often of greater value than genius".

It was definitely something a Motes Quarterhorse would not have found. . :)
 
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Good work, I am glad you found the culprit.
I am fond of saying that "Persistence is often of greater value than genius".

It was definitely something a Motes Quarterhorse would not have found. . :)

actually, it would have told him WHEN he was going lean... which would have brought him around to what he just guessed at.


Although his post isnt clear, I'm going to assume you tested your fuel pressure with the vac line disconnected, then ran the RPM's up? Because doing such a test with the vac line still on the regulator can give you false results.
 
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I tested it both ways, and testing it with the vacuum line on is a real world test. It's the pressure the vehicle would actually see. When I accelerate and the vacuum drops, the pressure should increase. Not by a lot, but should increase. It shouldn't drop 6-8 psi. Anything that had the ability to datalog would have told me when I was going lean, which would have led me to where I am a lot sooner. My intention is to get a Motes set up here in the next couple of weeks (tied money up in a vehicle I am flipping)

All that aside, how is it this became some sort of pissing contest? Your ability vs mine? Had I had access to data on this thing, I would have figured this out a while ago. I, unfortunately, don't have several hundred bucks to toss at a Motes considering I have spent the last year fixing the previous owners massive amounts of screw up.
 
Some more on the subject of fuel pressure...

How the fuel pressure regulator works

Revised 29-Aug-2013 to make the pressure/vacuum relationship clearer.

The fuel pressure regulator in 5.0 pushrod Mustangs is a shunt regulator that works in parallel with the fuel injection system. The regulator bypasses fuel back to the tank to maintain a constant 39 PSI to the injector tips. A constant pressure insures that the computer will always have the same flow rate to base its calculations on.

The 39 PSI pressure is measured at 29.92 inches of atmospheric pressure to get the proper flow rate. But the pressure inside the intake manifold may be higher or lower than the atmospheric pressure outside the intake manifold. These differences would cause the flow rate to change and mess up the computer’s air/fuel calculations.

As the vacuum inside the intake manifold increases, the effective pressure at the injector tips increases. Conversely, as vacuum inside the manifold decreases, the effective pressure at the injector tip decreases.

Some math to illustrate the effect:
39 PSI at 20” of vacuum inside the manifold works out to be 49 PSI,
since the 20 “ vacuum/2 = 10 PSI that you add to the base fuel pressure.
That gives you 49 PSI at the injector tip.

39 PSI at 5” of vacuum inside the manifold works out to be 41.5 PSI,
Since 5” vacuum/2 = 2.5 PSI that you add to the base fuel pressure
That gives you 41.5 PSI at the injector tip

39 PSI with 10 lbs of boost inside the manifold works out to be 29 PSI.
That gives you 29 PSI at the injector tip

That reduces the flow rate and explains the need for higher pressures on engines with pressurized induction.

Since intake manifold vacuum and pressure plays havoc with the pressure at the injector tips, what has to be done to get it back in the magic 39 PSI range? That’s where vacuum applied to the back side of the fuel pressure regulator comes in. Remember this: unless you have some really poorly designed or trick plumbing, vacuum is the same throughout the engine’s vacuum system.

Apply 20” of vacuum to the back of the regulator and the 49 PSI pump pressure with 20” of vacuum at the injector tips drops to 39 PSI.

Apply 5” of vacuum to the back of the regulator and the 41.5 PSI pump pressure with 5” of vacuum at the injector tips drops to 39 PSI.

Here’s another side effect: apply 10 PSI boost pressure to the back of the regulator and the normal 39 PSI at the injector tips increases to 49 PSI. That overcomes the 10 PSI in the intake manifold to give you 39 PSI at the injector tips. Pretty clever of these engineers to use intake manifold vacuum and pressure that way.

Simply stated, intake manifold vacuum adds to the effective fuel pressure at the injector tips. Apply the same vacuum to the back side of the fuel pressure regulator, and everything balances out. Add pressure to the intake manifold and the effective fuel pressure at the injector tip decreases. Apply the same pressure to the back side of the fuel pressure regulator, and everything balances out.

Now you know why to disconnect the vacuum when making fuel pressure measurements.
 
I tested it both ways, and testing it with the vacuum line on is a real world test. It's the pressure the vehicle would actually see. When I accelerate and the vacuum drops, the pressure should increase. Not by a lot, but should increase. It shouldn't drop 6-8 psi. Anything that had the ability to datalog would have told me when I was going lean, which would have led me to where I am a lot sooner. My intention is to get a Motes set up here in the next couple of weeks (tied money up in a vehicle I am flipping)

All that aside, how is it this became some sort of ****ing contest? Your ability vs mine? Had I had access to data on this thing, I would have figured this out a while ago. I, unfortunately, don't have several hundred bucks to toss at a Motes considering I have spent the last year fixing the previous owners massive amounts of screw up.
Accelerating with a load, and simply running the RPMs up at a stand still are two completely different things. So TBH, unless you were holding a manifold vac reference gauge next to your FP gauge while doing said test... you may have seen skewed results.

Taking the vac off completely and THEN running up the RPMs is the only real sure fire way to make sure that is your problem... unless, you could see the FP gauge from inside the car while driving.
 
At idle I have 14 inhg vacuum. When I pull the RPM's up to 3000, I have 11 inhg. The drop in pressure should result in an increase in fuel pressure, regardless of driving or not. In my case it does not. I lose fuel pressure. I lose fuel presure with vacuum attached and un attached. I can rule out the regulator because it set FP to 45 with no vacuum and it drops to 38 with vacuum attached. The only thing having a load on it will do is modify the injector pulse width and spark curve. Fuel pressure is only effected by fuel pump, filter and regulator. So fuel pressure at 2500 rpm's is fuel pressure at 2500 rpm's regardless of driving or sitting still. Oh wait, what's that, your going to come back and tell me the injectors effect it to. If one was clogged or leaking? Well I would have a noticeable and consistent misfire, it would fail an cylinder balance test or it would make me read rich because of the leaking injector.
 
Glad you figured it out. I was leaning towards it being the PIP. I hate it when I think I fixed something and it still doesn't run correctly. Nothing more frustrating to me. I know plenty of people who love those "mysterys". I'm not one of those people. I have no patience with that crap. Good job on the perseverance:nice: