Do I have a grounding issue? 07 Ford Freestyle 3.0-V6 w/ 198000 miles

wfsdno

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@billr I will look at reader to get MAP and MAF units this afternoon. I do not have KNK readings on my reader(that i know of) or Injector readings. It does read fuel pressure, I'll watch that next time it shudders. I do NOT hear hissing when taking off gas cap.
I will go to 3/4 tank of fuel and leave cap off and see what happens. if nothing, might go full tank and try that.

Dont worry about guessing! Thats the point I am at. Over the last year, I have replaced most sensors (cam, crank, fuel pressure regulator) out of frustration (not to say one of those isn't bad already) Someone suggested crankshaft sensor because of the shuddering, etc. but did not help.

I did see a round black sensor mounted on the back side (bank 1) side of the engine, Don't know what it is, it is mounted in the area of the pistons? Just throwing stuff out there!

Thanks!
 

wfsdno

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So.... put some more fuel in the tank in town, now at 3/4 full, left gas cap loose. Died 4 times on way home (about 10 miles), when either coming to a stop or slowing down below 30mph. Needless to say I put the cap back on when I got home.

Spark Advance: readings look like an EKG reading. The last dip was when it died. Had phone camera ready and snapped pic. I was a on a small county road and no one around me (safety!).

I went back and updated the map/maf units of a previous post.
 

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billr

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Going back to reply #29, the MAF looks too low; you might want to try cleaning that (if possible). From the rpm and MAP, I calculate that MAF should be more like 5 #/min. This kind of "data disagree" could also be caused by a faulty reading of rpm or MAP, but it is not likely the engine would run with improper rpm detection, and the MAP sensor is a far more simple/rugged/reliable device; so I am suspecting the MAF. Oh, IAT could also be a problem, so check that to see if it makes sense; but IAT has much less influence in the calculation, so actual IAT would have to be way high to make the MAF that low (also not likely). I'm surprised a MAF code hasn't been set.

PS: That spark curve is interesting, looks realistic, but of no real use without simultaneous curves for rpm and MAP. Even taking the "snapshot" values of 22 deg and 11 mph means nothing, since I don't have any clue what 11 mph relates to in rpm.
 

wfsdno

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Thanks billr. Let me verify next time I head to work. I will watch RPM's and MAF readings.

I will also clean the MAF sensor after work and see if get different readings on the way home.

Thanks
 

wfsdno

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Ok, on way to work this morning with still more than half a tank, it stumbled several times. By the time I got close to work it started to drop to half a tank and stumbling started to disappear (minimal studdering verses when more fuel in tank. The Ford Freestyle has 2 sending units in the tank. One is side is the fuel pump with what appears to be a sending unit and other side of tank has 'dedicated'? sending unit. Why it has 2 I don't know.

On a flat section of road with cruise set at 62mph , rpm about 1650 and MAF reading was about 3.0 lb/min. MAF would decrease when going down hill and increase going up hill.

I was able to test the Evap Purge Valve. It held a vacuum and the electiric solenoid inside worked when hooked up to power and release the vacuum. It held a vacuum for sevearl minutes.


Thanks!
 

billr

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You haven't tried cleaning the MAF sensor yet, have you? You didn't give MAP in the post above, but the MAF/rpm/speed data look like they could be realistic. Note that the recent rpm is lower than the minimum in reply #29 and MAF is up at maximum. MAP calculated is 13.4 "Hg (16.5 "Hg vacuum), about reasonable for 62 mph on a level road. Another "sanity check": that MAF (3) would give you 31 mpg at 62 mph. That also seems realistic.

Fun with numbers, but doesn't help much for solving your problem! I'll have to go re-read the thread.
 

wfsdno

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I was wrong in post #29 on RPM. I will go back and change it for correctness! Fuel mileage on this car at 60 will get 27mpg(never seen 31...) at 60 you get runover on the interstate here in Missouri!

I have not cleaned the MAF sensor, will today before I head home. The MAF sensor was replaced about a year ago but will clean anyway!

IIRC ... The MAP was running about 16-17 in/Hg at 62mph,1650 rpms, level ground.
 
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billr

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I didn't run the calcs again for the new/revised data in reply #29, but they look like they may correlate good enough now. I wouldn't bother fussing with the MAF sensor unless it is really easy to do. I can only use data and calcs from them to look for gross discrepancies. There are way too many other variables involved for me to do much more than an educated guess.

So, I am focused back on that weird symptom of the fuel tank level being critical. I would try blocking any-and-all lines from the intake manifold to the EVAP system, testing for the possibility that fuel is getting sucked directly from the tank into the manifold.
 

wfsdno

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I cleaned the MAF sensor and numbers changed a small amount at same speed/rpm as last time, maybe down from 3 to 2.5.

@billr -- I disconnected the purge valve and the lower return port had some fuel on it (wet but not dripping) The car had been setting for several hours if that matters. Is it safe to blow air into the evap system and fuel lines/return lines?

This weekend I am going to drop the canister and see if it is clogged.
 

billr

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How much air pressure? I think the usual 90 psig "shop air" or 30 psig "OSHA safe" would be OK.

Understand, I am not suggesting that you fuss with any of that EVAP stuff just yet. I am only suggesting that you disconnect it from the intake manifold, so there is no chance of the engine slurping fuel directly from the tank through any possible malfunction of the EVAP. See if it runs OK that way with the tank fairly full and cap off/loose
 

wfsdno

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Ok, I understand now. I can try that! Reporting back in a day or so.

Thanks
 

grcauto

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Raw fuel at the purge valve you need a new canister for sure. Do you stop fueling as soon as the pump stops or do you top it off?
 

wfsdno

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I am one of those people that always 'top it off'. But... I have not done that to this car in a long time.... of course maybe the damage is done???
 

grcauto

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Once the canister gets that raw fuel from topping it off things start happening that are not so nice.
 

wfsdno

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Been topping off that car for 130,000 miles! Guess it is time to quit!! Should i look into a replacement?
 
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