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Long Term ,will learn lean condition over time, A quick current draw and oscillation check with a scope pattern can tell you a lot with out getting the fuel all over the place.
LT ST is like the old GM block learn and integrator
you can do the current draw at the inertia switch,
voltage drop the ground toojust to be sure
I don't have a scope to perform the oscillation test. I have a digital volt meter and OBD Fusion on my iPhone.
I believe that I have a bad MAF according to all the tests and eliminations that I have done.
I ran the volumetric efficiency test with the OBD scanner connected to the iPhone. I did 4 separate tests at WOT for approximately 4 seconds. My starting speed was approximately 20 MPH for each test. I logged intake air temperature, RPM, and MAF flow rate using an online volumetric efficiency calculator. I performed the test on a flat road. It's not like this is real science.
I had a feeling that the MAF was bad because there were no vacuum leaks, the fuel delivered seemed normal, and both banks 1 & 2 had high long term fuel trims greater than 22%.
Rather than swap out parts, I did my best to eliminate what was not causing the problem. I have a new Ford MAF that I will install tomorrow. Even with high LTFT, the engine has not thrown a code in 200 miles driving. I am doing everything I can to make the engine throw a code. Not even a pending code was thrown.
I installed the new MAF and immediately felt the difference driving. I connected OBD Fusion to my iPhone and noticed that the Long Term Fuels trims never go much higher than 12% even when driving WOT up a grade. I drove the van 13 miles and am pleased with the performance. Feels like a new van again!
It took me 1 month of testing and studying using fuel trims for diagnosing problems.
The calculate volumetric efficiency driving up the steep grade was over 80%.
After owning the 5.4 for nearly 3 months, I feel more confident diagnosing problems than I did on owning the 6.0 PSD for 4 years.
The van drove beautiful after replacing the MAF. Even though I tested the MAF with a voltmeter and it passed, the engine ran horribly. It feels like I have a custom tune on the engine for increased horsepower and throttle response!
Big thank you to JWA! I have been on the FTE forum for 7 years and he has helped walk me through the process of troubleshooting mechanical problems on my own. JWA makes you work and think like an engineer. His testing methods are methodical and easy to understand.
The engine runs almost like a new 5.4. I replaced the 8th plug this morning. My 19-year-old son has small hands and a long reach. I "tipped" him $25 for putting the 7mm COP bolts back in. I replaced 4 out of 8 COPS. 2 failed for misfiring. Rather than fool around on the last 2 plug replacements, I installed 2 new COPs. $30 each. I spent 1 hour per plug. New COPs are money well spent. I kept 2 old ones for spares.
The van drove beautiful after replacing the MAF. Even though I tested the MAF with a voltmeter and it passed, the engine ran horribly. It feels like I have a custom tune on the engine for increased horsepower and throttle response!
Big thank you to JWA! I have been on the FTE forum for 7 years and he has helped walk me through the process of troubleshooting mechanical problems on my own. JWA makes you work and think like an engineer. His testing methods are methodical and easy to understand.
Too many sensors will pass a continuity test yet still not interact as designed with the PCM. Apart from simple switches continuity usually doesn't tell us too much. OTOH good on ya for solving your situation to the faulty MAF sensor. Since that's basically the first device in the ignition/intake path it makes sense it could greatly affect engine performance.
Also good to keep parts you know were working before being replaced, carried as spares just in case they're needed while on a road trip. I too have another growing pile of OEM COP's I'll hang on to for a while. Plugs and boots get recycled, new good quality replacement parts are cheap enough its not a budget breaker keeping a few of those around too. Prices on OEM plugs, boots and COP's have come down so drastically lately its easy enough to have the good stuff on hand.
And I greatly appreciate the compliments on whatever minor help I provide here Coolfeet---at best I'm a rank amateur when compared to others here and in the V10 forums too. I dare say anything I do contribute is mostly lessons learned with the help of others here on FTE-----& SMB a lot too.
And don't dismiss or discount your own involvement with finding your problem---I'm impressed you went to the lengths you did solving your issue. Too many stumble into these forums looking for a one-answer immediate and permanent solution without any willingness to dig into it past changing a fuse or other simple repair. You know them immediately---they'll have one or two total posts.
As you've observed the gasoline Modular Motors have longevity with the proper maintenance, aren't overly difficult to work on when needed.
07-18-2019, 10:29 AM
