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Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by 800artfreed »

After fixing the P0455 code due to a split vacuum line my LTFT went from +20% down to around 10%. I have done a vacuum test with a guage and the 1999 S70-GLT 2.5L turbo engine pulls 20Lbs of vacuum. I would assess that there are no major vacuum leaks. I also cleaned the MAF and also exchanged the MAF with another from the PnP yard.

LTFT & STFT should be close to 0 %. Older engines can run at + or - 5% to 10%. Does anyone know what there LTFT is for this GLT turbo? It only shows 70K miles on the odometer.

Thanks.
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1998 S70-T5 200K+
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by bronco »

My 98 V70 turbo is at -4.7% and has never really budged off that. I have a 0455 code that I ignore because I don't have to pass emissions. Not sure if they are related
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by kallekula »

Do a smoke test to check for leaks. But, i mean 10% yeah i guess maybe high? A few here and there are normal i guess. What kind of mpg do u get?

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800artfreed
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by 800artfreed »

I built a home made smoke machine. It did not show any leaks when run through the center vacuum port on the intake manifold. When I introduced the smoke from the intake pipe after the MAF a small amount was visible near the turbo but I could not see the actual location. Mileage varies by driving type. Mileage has been as high as 30mpg on a long constant highway trip. Local stop and go driving is as low as 18mpg. Engine performance is good. Causes of high LTFT are low fuel pressure (I tested it at 55psi), clogged injectors (running lucas injection cleaner now) a bad MAF (I just exchanged it with one from the PnP), a failing O2 sensor that I have not swapped. There is really no difference as of yet.
I am going to run more smoke tests with the turbo shield removed and see if I can find the source of the wisp of smoke I saw before.
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by bronco »

800artfreed wrote: Fri Sep 20, 2019 6:47 pm I built a home made smoke machine. It did not show any leaks when run through the center vacuum port on the intake manifold. When I introduced the smoke from the intake pipe after the MAF a small amount was visible near the turbo but I could not see the actual location. Mileage varies by driving type. Mileage has been as high as 30mpg on a long constant highway trip. Local stop and go driving is as low as 18mpg. Engine performance is good. Causes of high LTFT are low fuel pressure (I tested it at 55psi), clogged injectors (running lucas injection cleaner now) a bad MAF (I just exchanged it with one from the PnP), a failing O2 sensor that I have not swapped. There is really no difference as of yet.
I am going to run more smoke tests with the turbo shield removed and see if I can find the source of the wisp of smoke I saw before.
I had a ford explorer to fix last month that was at +49% on long term , both banks! :shock: It was a fuel pump issue , kind of a tricky one , initial pressure was ok but it would pump less fuel after it ran a bit. Pressure would erractically drop , it was a volume problem really. In 2003 the explorer had a returnless fuel system with an in tank regulator. I never found out if it was the regulator or the pump but replacing it fixed the issue. It was actually tough to pick up on with a pressure gauge at first but I decided to change the fuel filter and it was off and someone bumped the key and hardly any fuel came out of the line . So I hooked up a clear line and shorted the relay , put the line in a large glass jar and you could see the fuel volume start strong then slow to a trickle. After 10 minutes it did not fill a gallon jar . I was getting codes for all sorts of random things that were extraneous but changing the pump made them all go away.

The high +% fuel trim numbers were the computer trying to correct a lean condition when the called for injector pulses were not providing enough fuel. That year explorer does not have a fuel pressure sensor so there was no code being thrown
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by abscate »

Typically out of range codes are thrown at about 20% in my limited experience, so I will guess 10% is in the normal operating range for an older car.

I'll try grab some data from mine
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by kallekula »

800artfreed wrote: Fri Sep 20, 2019 6:47 pm I built a home made smoke machine. It did not show any leaks when run through the center vacuum port on the intake manifold. When I introduced the smoke from the intake pipe after the MAF a small amount was visible near the turbo but I could not see the actual location. Mileage varies by driving type. Mileage has been as high as 30mpg on a long constant highway trip. Local stop and go driving is as low as 18mpg. Engine performance is good. Causes of high LTFT are low fuel pressure (I tested it at 55psi), clogged injectors (running lucas injection cleaner now) a bad MAF (I just exchanged it with one from the PnP), a failing O2 sensor that I have not swapped. There is really no difference as of yet.
I am going to run more smoke tests with the turbo shield removed and see if I can find the source of the wisp of smoke I saw before.
30 MPG???? If you get that, stop all work immediately. Dont touch anything and just be happy with your car! 👍

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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by Goupil »

abscate wrote: Sat Sep 21, 2019 3:50 am Typically out of range codes are thrown at about 20% in my limited experience, so I will guess 10% is in the normal operating range for an older car.

I'll try grab some data from mine
Mine is around 20/21% because E85, and doesn't even throw a code :lol:
1998 Volvo V70 B5254T M56
1993 Volvo 940 D24TIC M46
800artfreed
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by 800artfreed »

......I ran additional smoke test using my home brew machine. Smoke appeared from the intake pipe down near the PTC valve just after the nipple. As it is a PITA to remove and replace. I tried the propane gas trick to see if when the engine ran it would suck in propane and change the fuel trims. There was no difference. I then used the propane to feed propane around the intake manifold and other intake location. No differenc. I will try the smoke test on my other two 1998 S/V 70-T5. They have the same intake piping. BTW I am making the same trip up to Canada this October. Hopefully I won't need the A/C like the last time. I do NOT expect to get 30MPG again. :-(

Some pictures of the test machine. I have a mp4 video but don't see how I can upload it.
Attachments
smoke machine
smoke machine
interface to the down pipe
interface to the down pipe
VolvoVoyeur
1998 S70-T5 200K+
1998 V70-T5 200k+
1999 S70-GLT 80k+
800artfreed
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Re: Long Term Fuel Trim at 10% What is typical for a 1999 S70-GLT

Post by 800artfreed »

Here is a link to the Youtube video of my smoke test.

VolvoVoyeur
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1998 V70-T5 200k+
1999 S70-GLT 80k+
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