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5.0 diagnosis needed! 

 

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 Post subject: 5.0 diagnosis needed!
Posted: Wed Oct 17, 2007 10:48 pm 
Getting Side Ways
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Age: 48

Posts: 419

Joined: 16th Jan 2005

Ride: EF Ghia 5.0

Location: Adelaide
SA, Australia

Your suggestions are welcome on this problem!

My Windsor (stockish- mild cam, E7's, HO) starts up OK, but a few hundred metres down the road begins to stumble and drop power like it's running out of fuel. A little throttle and it instantly comes to life again and no more power loss. UNTIL I turn it off for a while, get back in and drive away, when the problem repeats itself. This happens hot OR cold in exactly the same manner. There is no hesitation or backfiring through the airbox which would suggest to me a lean fuel mixture.

Car has new fuel pump and in-tank connector, fuel filter, plugs. leads etc. MAF hotwire has been cleaned. I think it's a fuel pressure issue, like the system is dropping pressure when parked, but that should happen anyway right?

Suggestions: fuel regulator, oxy sensor, injectors, dizzy module.....?

Anyone else experienced this? Otherwise the car drives normally after it has cleared itself for the rest of the drive and apart from a 5 year old crappy idle (ChipTorque modded ECU) runs nicely on 98.

Cheers, Mike

 

_________________

EF Ghia 5.0 - XR8 in a tuxedo....classy, low and loud

Bordeaux Purple, Tickford kit, slammed, 18" BA XR8's, EL Ghia chrome, full leather, Pioneer audio, C&C, ABS, LSD, Crane cam, GT40P heads, high flow cats, Genie extractors, lots of woodgrain, chrome and interior lights!

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Posted: Thu Oct 18, 2007 1:20 am 
EFI Guru
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Age: 52

Posts: 4289

Joined: 5th Nov 2004

Gallery: 28 images

Ride: 351 Vogue,XH 5.0,'17 5.0 Stang

Location: Perth
WA, Australia

Could be a number of things.
First...unplug the chip.
Run the car through the problem minus the chip.
Do a self test.
The MAF may still be faulty.
Fuel pressure should stay up for some time...at least ten minutes.
You may have dribbling injectors which could explain the clearing of the problem.
Your TPS may be faulty.
ECT sensor may be faulty.
The self test may pick up some of these faults.
I await your results.

Pete.
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Posted: Thu Oct 18, 2007 7:24 pm 
Getting Side Ways
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Age: 48

Posts: 419

Joined: 16th Jan 2005

Ride: EF Ghia 5.0

Location: Adelaide
SA, Australia

Thanks for the reply!

The ECU doesn't have an external chip- Lachlan must have re-flashed the computer after I had endless trouble with the plug in chip. My car was an early guinea pig for ChipTorque's Ford V8 tuning. It has always run fairly rough, but OK power.

Self test? I have tried to put it into this mode several times over the years but it just won't do it. I suspect the modded ECU is the culprit.

ECT sensor- what is that? :)

I'll try another TPS as see how it goes.

I am suspecting injectors though. They have 345,000km on 'em! I'm considering a GT40P and Explorer upgrade. Can I upgrade to bigger injectors at this stage or will the ECU be a problem?

Oxy sensor not a possibility?

Mike

 

_________________

EF Ghia 5.0 - XR8 in a tuxedo....classy, low and loud

Bordeaux Purple, Tickford kit, slammed, 18" BA XR8's, EL Ghia chrome, full leather, Pioneer audio, C&C, ABS, LSD, Crane cam, GT40P heads, high flow cats, Genie extractors, lots of woodgrain, chrome and interior lights!

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Posted: Fri Oct 19, 2007 5:02 pm 
EFI Guru
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Age: 52

Posts: 4289

Joined: 5th Nov 2004

Gallery: 28 images

Ride: 351 Vogue,XH 5.0,'17 5.0 Stang

Location: Perth
WA, Australia

What model car is it?
ECT = Engine Coolant Temp
If Self test doesn't work and it doesn't have anything on the J3 the EEC maybe toast or the calibration is screwy.
The TPS you can test by backprobing the connector and check for smooth changes in resistance as you slowly open the throttle.
Only use bigger injectors if you need them. If you run your car up on a dyno you should be able to get them to check your injector duty cycle at full noise/load. If it's under 90% you don't need bigger injectors unless you do somethingt to make more power.
O2 is likely only a problem if you have another problem causing a lean adaptation. This will set a fault code if the adaptive lean limit is reached but you'd probably have to give more than a little throttle(of course I don't exactly know how much throttle you're using?) to notice it drop out of closed loop.
If you have another unmodded EEC plug that in an run it up then do a self test.

Pete.
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Posted: Sun Oct 21, 2007 7:11 pm 
Getting Side Ways
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Age: 48

Posts: 419

Joined: 16th Jan 2005

Ride: EF Ghia 5.0

Location: Adelaide
SA, Australia

Well, I made some progress today. I ended up changing the O2 sensors as they were around 245,000km overdue. :) I've noticed an immediate difference- instant start-up, more power down low and a little less grumpy. Still not sure if it will fire and then hold idle on it's own yet, but that will wait for the morning from dead cold. It's definitely a happier car now.

I did swap the ECT about a year ago, no difference. I reset TPS voltage a while back, but only at closed position. I didn't know to check resistance while opening at the time. Pretty sure MAF is OK at this point.

I'll try and check the other items you listed Pete (thanks) when I have some more time. It would be interesting to plug in another ECU to see how she runs, but don't have access to one.

Mike

 

_________________

EF Ghia 5.0 - XR8 in a tuxedo....classy, low and loud

Bordeaux Purple, Tickford kit, slammed, 18" BA XR8's, EL Ghia chrome, full leather, Pioneer audio, C&C, ABS, LSD, Crane cam, GT40P heads, high flow cats, Genie extractors, lots of woodgrain, chrome and interior lights!

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