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Discussion Starter · #1 ·
Originally posted 8-08-2011 on FJ

So I've owned my SVT for 2.5 yrs now. This has been going on for a while, however, it only happens after 3-3.5 hours of consistent highway driving. Basically, and long periods of crusing with CC (like 3 hrs on the highway at 75-80ish) the car starts to bog with added load from going up an overpass. Within 2 overpasses the car will be trying to accelerate, but bogging so hard Im slowing down (like to 60). I've found shutting the car off and restarting it by releasing the clutch remedies the problem, for maybe another .5-1 hour. If I resart the car with the starter/ignition, it shuts back off. This has been occuring since before I had Toms tune. BUT I forget to bring the predator with me on the trips incase this happens I can log it.

Was talking at a g2g with a Ford Tech this weekend and he suggested the cam position sensor.

NO CODES WHAT SO EVER.

So if anyone has any insight, thatd be awesome. And since I infrequently drive 3.5-4 hrs on the highway any longer, it doesn't bother me until it happens (like this weekend when I went to Gainesville from Miami) and I'd like to solve the riddle.

Thanks!

Rolled 102k this weekend, only mods are k&n panel filter, LBD, STS, poly inserts in stock mount, MSD coil/ wires (on car when purchased) and Toms tune

Posted 10-16-2011 on FJ

UPDATE:

so this past weekend i drove up to gainesville to hang out with my brother and attend a conference. On the way up fri, temps were in the 60s the whole way. No bogging.

However, on the way home! it happened again. Temps increased and were in the high 70s when I left gainesville at 4pm. by 7/730 pm, it did it, not as intensely as it happened in Aug, but it would do it all the same. This time I remembered my predator!!!!!!! I did log...however, I'll need to get a cable to transfer the file(s) to a computer to send.... I'm in miami if anyone local can help with that....

The things I noticed while doing this:

Timing went from 34* cruising at 78 mph dropped to 28* upon going WOT. As the bogging intensified, timing did drop to 17*

FRP (Fuel rail pressure I assume) 51 psi at cruising speed, DROPPED TO (went down to) 2-3 PSI WHEN BOGGING.

Any new thoughts, opinions? Next time I do a trip of this length (with warm temps), I'll remove the tune and see if that solves it....
 

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Originally posted 8-08-2011 on FJ

So I've owned my SVT for 2.5 yrs now. This has been going on for a while, however, it only happens after 3-3.5 hours of consistent highway driving. Basically, and long periods of crusing with CC (like 3 hrs on the highway at 75-80ish) the car starts to bog with added load from going up an overpass. Within 2 overpasses the car will be trying to accelerate, but bogging so hard Im slowing down (like to 60). I've found shutting the car off and restarting it by releasing the clutch remedies the problem, for maybe another .5-1 hour. If I resart the car with the starter/ignition, it shuts back off. This has been occuring since before I had Toms tune. BUT I forget to bring the predator with me on the trips incase this happens I can log it.

Was talking at a g2g with a Ford Tech this weekend and he suggested the cam position sensor.

NO CODES WHAT SO EVER.

So if anyone has any insight, thatd be awesome. And since I infrequently drive 3.5-4 hrs on the highway any longer, it doesn't bother me until it happens (like this weekend when I went to Gainesville from Miami) and I'd like to solve the riddle.

Thanks!

Rolled 102k this weekend, only mods are k&n panel filter, LBD, STS, poly inserts in stock mount, MSD coil/ wires (on car when purchased) and Toms tune

Posted 10-16-2011 on FJ

UPDATE:

so this past weekend i drove up to gainesville to hang out with my brother and attend a conference. On the way up fri, temps were in the 60s the whole way. No bogging.

However, on the way home! it happened again. Temps increased and were in the high 70s when I left gainesville at 4pm. by 7/730 pm, it did it, not as intensely as it happened in Aug, but it would do it all the same. This time I remembered my predator!!!!!!! I did log...however, I'll need to get a cable to transfer the file(s) to a computer to send.... I'm in miami if anyone local can help with that....

The things I noticed while doing this:

Timing went from 34* cruising at 78 mph dropped to 28* upon going WOT. As the bogging intensified, timing did drop to 17*

FRP (Fuel rail pressure I assume) 51 psi at cruising speed, DROPPED TO (went down to) 2-3 PSI WHEN BOGGING.

Any new thoughts, opinions? Next time I do a trip of this length (with warm temps), I'll remove the tune and see if that solves it....
Before I read the entire post I was thinking a bad fuel pump. Your datalog confirms this. Could be a driver module issue because I've seen them crap out too....but usually they take the pump out with them OR the pump takes out the driver module. I'd get a new pump in it and go from there. How many miles?
 

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what it be like
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could be something so simple like the plug wires...look at everything really carefully I doubt its actually the fuel pump but look at all the easys first like the fuel filter and vaccum leaks
 

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FF PHOTOG ENTHUSIAST
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This actually recently happened to me ... about a month ago or so.

Car would all of a sudden lose power ... like chocking.

Well, come to find out my MAF wasn't reading correctly, and last month it just plain died then a code popped up. ... So a friend let me borrow his spare MAF and the car runs fine again.

But agree ... start at looking for a Vacuum leak then the plug wires.

-Ray-
 

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( o Y o )
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Discussion Starter · #5 ·
wouldnt the maf reading incorrectly totally screw my daily driving up?! This only happens after 3-3.5 hours of highway driving.....

fuel filter will be changed during my next oil change (3-4 weeks). I'll also clean the maf (i havent ever done it).

I'll also look for vac leaks during that same time.
 

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Forget whateverthehell the other people are saying. YOUR FUEL PRESSURE IS DROPPING. If it where simply the sensor indicating a false low pressure reading, the pump duty cycle would increase and your pressure would actually go up.... this would not result in a performance issue like this.

A vacuum leak wouldn't cause your FRP to be 40psi too low

Plug wires? Seriously?

A clogged fuel filter would not be temperature dependent and it wouldn't be intermittent.

On the other hand, loosing fuel pressure under load especially when everything is nice and warm is a TEXTBOOK example of a weak fuel pump.

Granted nobody can tell you exactly what the causal part is.....I'm just guessing it's the pump. But you need to track down why you are losing fuel pressure; it explains your symptom.
 

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Discussion Starter · #7 ·
^i agree. If it is the fuel pump, my laid back mechanic friend down the street is getting a call in a few weeks after schools out.

Is this scenario even possible? My dad was thinking that maybe my fuel tank vent isn't venting properly on these long drives and the pump is trying to suck gas from a vacuum (kinda the opposite of what happened to GM pumps/tanks years back, they over inflated the tank)
 

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^i agree. If it is the fuel pump, my laid back mechanic friend down the street is getting a call in a few weeks after schools out.

Is this scenario even possible? My dad was thinking that maybe my fuel tank vent isn't venting properly on these long drives and the pump is trying to suck gas from a vacuum (kinda the opposite of what happened to GM pumps/tanks years back, they over inflated the tank)
Doubt it. But, if that's the case run out and remove your filler cap when it happens. Besides, your tank is under a vacuum quite often...it's how the computer tests the system for vapor leaks....
 

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If you have 51 psi and only loose 2-3 psi then IT IS NOT your fuel pump , it is VERY NORMAL to see a small psi drop under load anything above 35psi and the SVT runs perfect , the factory fuel psi target is only 39psi

I would like to see a datalog and see what your VCT is doing among other things , let me know if you need any help with the datalog

Tom
 

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If you have 51 psi and only loose 2-3 psi then IT IS NOT your fuel pump , it is VERY NORMAL to see a small psi drop under load anything above 35psi and the SVT runs perfect , the factory fuel psi target is only 39psi

I would like to see a datalog and see what your VCT is doing among other things , let me know if you need any help with the datalog

Tom
Tom the way i understand it is that his fuel pressure was actually at 2-3 psi when it bogged.

i would also say fuel pump
 

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If it is actualy at 2-3 psi then i agree with fuel pump, but dropping 2-3 then that is not the issue.
 

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Discussion Starter · #12 ·
the FRP code/diagnostic label went fron 51 psi at cruising to 2-3 psi when bogging, meaning it DROPPED 48-49 psi of pressure.

Could this be more of a sensor issue? Why only after 3-3.5 hours of cruising, why not around town? I frequently drive ~1hr to my parents or a research site and it doesnt happen then, same speeds and all sorts of temps.

there are a couple of logs on the Predator, if all saved and each one didnt override the last. Would you want to see the advanced WOT, fuel, or iginition log (the predator didnt "have enough memory" to record all paramaters at once, i assume the critical stuff is recorded under advanced WOT). But, I'll need a cable to retrieve the logs as I currently do not possess the serial/usb cord to do so.
 

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the FRP code/diagnostic label went fron 51 psi at cruising to 2-3 psi when bogging, meaning it DROPPED 48-49 psi of pressure.

Could this be more of a sensor issue? Why only after 3-3.5 hours of cruising, why not around town? I frequently drive ~1hr to my parents or a research site and it doesnt happen then, same speeds and all sorts of temps.

there are a couple of logs on the Predator, if all saved and each one didnt override the last. Would you want to see the advanced WOT, fuel, or iginition log (the predator didnt "have enough memory" to record all paramaters at once, i assume the critical stuff is recorded under advanced WOT). But, I'll need a cable to retrieve the logs as I currently do not possess the serial/usb cord to do so.
Ok I misunderstood and stand corrected , If your psi is dropping to 2-3psi your car shouldnt even be running

I would first check fuel filter , then sock on the fuel pump then fuel pump it self , its very rare for the fuel rail psi sensor or the fuel pump driver to do bad

Tom
 

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My car had a similar issue.....Pickup filter on the fuel pump was clogging after long drives. Mine was not temp sensitive though......
 

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replace the filter and try it they are like 20 bucks tops if that dont fix it put in a fuel pump
 
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