is this a fuel issue? or an air issue? how should i diagnose

bigmoose

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I would log RPM, fuel pressure, maf counts, fpdc, short term fuel trims, coolant temp, voltage. Maybe a few others I'm missing. You need to datalog while drive when everything is good till it goes bad. Note the time so you can corelate to the log. Post it up here afterwards.

Also FYI, when datalogging with the xcal2 your dash gauges will sometimes act funny and sweep or jump around. It's normal.
 

TheOneandOnlyLTstang36

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Check the crank and cam sensors I’ve been a tech for 20+ years and have seen them go bad all the time watch the RPM when it dies also check RPM when it doesn’t start! One more thing is when you turn the key on watch the engine light it should be on for a second and then go off.


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P49Y-CY

fomocomofo
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finally got around to doing a compression test on it. funny thing is in all the years i have been working on cars, i have never actually done one before lol. it is pretty cool and now i'm curious what my other cars' readings will look like. i did this on a cold engine, is that okay? (some videos and instructions say to do it on a warm engine.) i have only done a dry test so far.

#1 - 170 psi (highest reading)
#2 - 150 (-12%)
#3 - 162 (-5%)
#4 - 157 (-8%)
#5 - 147 (-14%)
#6 - 141 (-17%)
#7 - 150 (-12%)
#8 - 165 (-3%)

from what i have read, even cylinder #6 is not completely out of spec even though it is 29 psi less than maximum (83%). i have read that the maximum variance should be no more than 25%. it does looks like #5 and #6 are hurting a little bit though.

i don't think any of this would cause the car to stall like it has. it is 30 minutes or so every time - almost like clockwork! i even loaded the stock back on it but still the same thing. the exhaust smells really rich when it is idling, but all the plugs look fine. i am thinking maybe the bassani cats are clogged and i should put the stock midpipe back on.

i am still practicing datalogging too. the last one i did showed numbers that didn't make any sense at all! for example battery volts were like 0.4375. i think i need to get more familiar with how to do it.
 
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hotcobra03

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finally got around to doing a compression test on it. funny thing is in all the years i have been working on cars, i have never actually done one before lol. it is pretty cool and now i'm curious what my other cars' readings will look like. i did this on a cold engine, is that okay? i have only done a dry test so far.

#1 - 170 psi (highest reading)
#2 - 150 (-12%)
#3 - 162 (-5%)
#4 - 157 (-8%)
#5 - 147 (-14%)
#6 - 141 (-17%)
#7 - 150 (-12%)
#8 - 165 (-3%)

from what i have read, even cylinder #6 is not completely out of spec even though it is 29 psi less than maximum (83%). i have read that the maximum variance should be no more than 25%. it does looks like #5 and #6 are hurting a little bit though.

i don't think any of this would cause the car to stall like it has. it is 30 minutes or so every time - almost like clockwork! i even loaded the stock back on it but still the same thing. the exhaust smells really rich when it is idling, but all the plugs look fine. i am thinking maybe the bassani cats are clogged and i should put the stock midpipe back on.


No 0 good.

Engine warm.
Throttle tied wide open .
Fuel pump fuse pulled .
All plugs out.

Fully charged battery .

I thought 15% of highest.

Dirty valves will also effect readings.

Mine have always been 180 -195

Had 0 twice. Valve
Had low140. Crack in head.
 

P49Y-CY

fomocomofo
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No 0 good.

Engine warm.
Throttle tied wide open .
Fuel pump fuse pulled .
All plugs out.

Fully charged battery .

I thought 15% of highest.

Dirty valves will also effect readings.

Mine have always been 180 -195

Had 0 twice. Valve
Had low140. Crack in head.

Oh so it should be up above 180?! damn i guess then it is pretty jacked up then
 

P49Y-CY

fomocomofo
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No. You'll get lower numbers cold and it's only a reference. Your numbers seem fine. It's not your issue. Get a chance to datalog yet?

yes i did it once in the driveway jon (only idling) with the parameters you mentioned in post #61. but i'm thinking i need to try it again because all of the numbers seemed waaayy off. none of it made any sense to me. but if i can somehow post it up here i will

for example, these were the average numbers over about a 10 minute period:

- battery volts: 0.429
- coolant head temp: -18667.4 (negative value!)
- coolant temp: -3.405 (negative)
- maf ad counts: 509.353
- pressure drop fuel injector: 114.436
- rpm: 3538.939 (i didn't rev the car over 2200 the whole time?)
- returnless fuel pump duty cycle: 0.849
- short term fuel trim bank 1: 0.487
- short term fuel trim bank 2: 0.343
 

01yellercobra

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Sounds like you selected the wrong PIDS. There's usually two versions. One is capital letters and they other is lower case. I can't remember which ones I selected, but I'm pretty sure it was all capital. Although if there's an issue in the fuel system it could read that high at idle.

I should have my laptop with me on Sunday at the show. If you make it down bring a thumb drive. I'll give you a couple configurations I usually go with when I datalog.

I still say it's a power problem. It acts like my car did when the alternator started acting up.
 

P49Y-CY

fomocomofo
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Sounds like you selected the wrong PIDS. There's usually two versions. One is capital letters and they other is lower case. I can't remember which ones I selected, but I'm pretty sure it was all capital. Although if there's an issue in the fuel system it could read that high at idle.

I should have my laptop with me on Sunday at the show. If you make it down bring a thumb drive. I'll give you a couple configurations I usually go with when I datalog.

I still say it's a power problem. It acts like my car did when the alternator started acting up.

okay that sounds good bob, thanks alot. yeah i think i must have done something wrong on this one, but gonna keep trying
 

P49Y-CY

fomocomofo
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so it's been about a month and i haven't exactly fixed the car, but i actually have been driving it a lot lately, if only local.

i'd been doing a lot of testing for a while (went through more than half a tank of gas just idling in my garage lol), and the car is very consistent about stalling at between 27 and 35 minutes. like every time. then, it would start up again within 10 minutes. after i started it up again, sometimes it would run for over an hour before stalling, and sometimes i'd even have to shut it off myself.

my attempts at datalogging were inconclusive because none of the parameters that i was able to get to work seemed to give any me any useful information. like for example the egr duty cycle which i think would change after the first few mintues just stayed at 1.844 the whole time and the dpfe stayed at 8.500. short term fuel trim bank 2 was steady, but stft bank 1 was jumping all over the place. the fuel pump duty cycle was steady at about 0.23. but most of the parameters seemed to be jumping all over the place most of the time.

so, that's good enough for me for now, but like i say i have been driving it - and it gets into boost and seems to drive just fine. it's a blast. i just make sure i stay real local like only to the grocery store or the bank - places that are not further than about 15 minutes away, lol.

anyway one of these days i will probably start to dig back into it again... thanks again for all of you guys' help.
 

01yellercobra

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so it's been about a month and i haven't exactly fixed the car, but i actually have been driving it a lot lately, if only local.

i'd been doing a lot of testing for a while (went through more than half a tank of gas just idling in my garage lol), and the car is very consistent about stalling at between 27 and 35 minutes. like every time. then, it would start up again within 10 minutes. after i started it up again, sometimes it would run for over an hour before stalling, and sometimes i'd even have to shut it off myself.

my attempts at datalogging were inconclusive because none of the parameters that i was able to get to work seemed to give any me any useful information. like for example the egr duty cycle which i think would change after the first few mintues just stayed at 1.844 the whole time and the dpfe stayed at 8.500. short term fuel trim bank 2 was steady, but stft bank 1 was jumping all over the place. the fuel pump duty cycle was steady at about 0.23. but most of the parameters seemed to be jumping all over the place most of the time.

so, that's good enough for me for now, but like i say i have been driving it - and it gets into boost and seems to drive just fine. it's a blast. i just make sure i stay real local like only to the grocery store or the bank - places that are not further than about 15 minutes away, lol.

anyway one of these days i will probably start to dig back into it again... thanks again for all of you guys' help.
We'll have to set up a time to meet in the middle. We can go over the datalogs and see if anything pops out.
 

P49Y-CY

fomocomofo
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that sounds good buddy! i look forward to checking out that awesome whippled mystichrome of yours
 

P49Y-CY

fomocomofo
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got some info on what this was (and still is) lol.

to answer my original question, it is def a fuel issue. the car was driving for a while, but for the past month or so it won't even start anymore.

so i bought the wiring manual, and started to take the car apart so that i could check out every wiring harness on the car, if need be. and i did check, and all the wiring is good. there is continuity on every single wire related to fuel delivery in the car.

when i jumper the fpdm connector to bypass the pcm, the car starts right up and idles.

so, since it is getting good power, and i have swapped out the fpdm from my other car (known good), my conclusion is that the pcm is not sending its duty-cycle signal to drive the pumps, and i need to figure out how i am going to change out this pcm. that is one part i don't think i can swap out myself because of all the pats and gem module software changes needed.

this is by far the longest my car has been down since i bought it. but it definitely has been a learning experience
 

hotcobra03

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This thread got long.

Dumb question since I recently had issues on this item.

Does car have an added ford alarm?
 

P49Y-CY

fomocomofo
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This thread got long.

Dumb question since I recently had issues on this item.

Does car have an added ford alarm?

you know it's funny you should mention that. like I said, I pretty much disassembled the entire car and went through each wiring harness...

and much to my amazement, there was indeed a bunch of hacked up wiring for a dealer-added alarm in the driver's footwell. I remember my dealer pushing it when I bought the car, but I told them I didn't want it. i didn't know that they already hacked into the wiring. They probably do that automatically to all cars on the lot, but then only plug the actual alarm in if they can sell it.

when I bought my coupe from my buddy that he bought new, I ended up having to remove the dealer-added alarm that he told me they forced him to buy (to get a certain price).

Here the last thing I expected was for my ford dealer to have mutilated my brand new car's wiring lol.

What kind of issue are you having with it @hotcobra03?
 
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hotcobra03

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you know it's funny you should mention that. like I said, I pretty much disassembled the entire car and went through each wiring harness...

and much to my amazement, there was indeed a bunch of hacked up wiring for a dealer-added alarm in the driver's footwell. I remember my dealer pushing it when I bought the car, but I told them I didn't want it. i didn't know that they already hacked into the wiring. They probably do that automatically to all cars on the lot, but then only plug the actual alarm in if they can sell it.

when I bought my coupe from my buddy that he bought new, I ended up having to remove the dealer-added alarm that he told me they forced him to buy (to get a certain price).

Here the last thing I expected was for my ford dealer to have mutilated my brand new car's wiring lol.

What kind of issue are you having with it @hotcobra03?
Mine just crapped out and caused a no start.

My thoughts now is it may be an interruption of a signal to pcm ?

Just food for thought.

Side note. I would have never known where to look for alarm if it wasn’t for the clicking noise it gave out
 

P49Y-CY

fomocomofo
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allright this should be my final post in this very long running thread because the car is finally back up and running again, and i wanted to say what the fix was in case it might help anyone in the future.

but i am still very confused about it because it doesn't make any sense to me. it was the fuel pumps.

what makes no sense is that six months ago when i first started this thread, the fuel tank from my coupe was one of the very first items that i swapped out. the car still stalled out after 30 minutes (like it had been doing with every other part i tested). so how in the hell could replacing the fuel pump assembly now make any difference at all? i don't get it! also, remember that the pumps primed with key on, and also ran when full power was applied to them... so i really thought i was correct ruling out the pumps.

but this week i threw in the towel on my diy attempts and brought it to my tuner. (after all it was coming up on being broken for six months and i had just renewed the registration on the car right before it crapped out lol) anyway he hooked up the gauge, asked me to start it, and immediately said fuel pumps. i told him the history but he still said we at least needed to start there. i was thinking okay, give it a try, but i doubt it will fix it. i couldn't believe it when he called the next day to say the car is running good and that he double checked the a/f on his dyno and it even made a little more power than when i first got it tuned years ago! today i drove it home and it is running fine - almost like nothing ever happened...

so even though i am scratching my head about it, i'm real happy that the car is fixed. and many, many thanks to all you folks who offered all your good help and advice.

cheers -
 

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