In another post i had a problem where my 850 was stuttering and dying where warm. After replacing the hose to the throttle body and tightening the loose intake manifold bolts seems to have fixed the stuttering and dying problem my 850 was having.
i hope that starting this new thread was the correct way of handling this other questions.
Over the past couple of weeks i have tried to get the reset the ecu to clear the stored long term fuel trims.
I tried to accomplish this by disconnecting the battery cables, taping the cables together, stepping on the brake pedal and turning the key to start.
The second time i left the cables off for an hour. Then I taped the cables together for another hour finally stepping on the brake pedal and
Each time upon starting the car i had the same results on my hand held scanner:
1) First the long term fuel trim showed as positive 21 instead of resetting itself to 0.
2) The short term trim showed as 0 without movement.
3) The car was running in open loop.
4) The o2 sensor readings seemed to be off as the movement was now over a very narrow range.
I found out that it takes time maybe a very long time on the 96,97, 850s for the systems to finally read as ready on the scanner. by systems i mean CAT, Evap, etc. infact after the first reset i drove a couple of hundred miles without much luck.
prior to the resets the:
1) ltft was around -5
2) the short term fuel trim was fluctuating between - 10 and +10
3) the o2 sensor was in working fine
4) the fuel system showed it was running in Closed loop mostly closed loop fault
So Im wondering if others have had the same problems when trying to reset the ecu.
1) if my systems dont show as ready will my car get out of open loop.
2) shouldnt the ltft been 0 after the reset.
3) why after the reset to the o2 sensors readings change? with very little fluctuation?
4) do i wait it out?
5 i tried to get the systems in the ready mode by doing the proper drive cycles but its difficult if not impossible in the area i live to perform them.
Also my maf readings seemed high and my idle was a little rough so i called bosch to see what they should be. the tech support person thought the readings at idle should be 3 grams per second. and i either had a boost leak or a maf that wasnt functioning properly. mine was reading 5.5 at idle. i also read somewhere that as a car gets more miles on it the maf readings at idle could be closer to 4 grams per second.
I put a new/used sensor in (dont yell but i only had the sensor from another 96 turbo not the housing) the sensor itself appears to have been made in 2004. after putting the sensor in my idle seemed smoother and the readings at idle were 4.1.
any thougts on my ecu reset issue.
1996 850R resetting ecu doesn't clear fuel trims
1996 850R resetting ecu doesn't clear fuel trims
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
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jblackburn
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- Year and Model: 1998 S70 T5
- Location: Alexandria, VA
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I think it may start off at some default pre-programmed value for LTFT and "learn" from there.
If you're experiecing rough idle or dipping idle when slowing to a stop that then smooths out over 1-2 drive cycles, your car did reset and is learning exactly like it should.
And yes, the monitors take FOREVER to show ready. There is a proper sequence to get them to show, but it's complicated and sometimes doesn't work. If you don't have an inspection coming up in the next month, don't worry about the drive cycle.
If you're experiecing rough idle or dipping idle when slowing to a stop that then smooths out over 1-2 drive cycles, your car did reset and is learning exactly like it should.
And yes, the monitors take FOREVER to show ready. There is a proper sequence to get them to show, but it's complicated and sometimes doesn't work. If you don't have an inspection coming up in the next month, don't worry about the drive cycle.
'98 S70 T5
2016 Chevy Cruze Premier
A learning experience is one of those things that says, "You know that thing you just did? Don't do that."
mercuic: Long live the tractor motor!
2016 Chevy Cruze Premier
A learning experience is one of those things that says, "You know that thing you just did? Don't do that."
mercuic: Long live the tractor motor!
jblackburn thank you for your reply. Can you tell me a couple of things.
1) why upon reset is the longterm fuel trims showing as Positive 21 vs starting at 0.
2) upon reset no short term fuel trim readings.well actually it has had a brief reading three times. This morning when i first hooked up the gauge and the car wasnt fully warm. it briefly read +29. and the other night on the freeway the same.
2) upon upon reset is the 02 sensor reading different. when the car is warm it fluctuates between .19 and .195 at idle. If i blip the throttle it fluctuates between 0.005 and 0.2. this is different than before the reset
Before reset
1) after i fixed one of the leaks the ltft was hovering around -5 and stft would fluctuate between -8 to +9
2) o2 sensor behaved differntly (i lost my paper with notes) but i believe when warm if I blipped the throttle it would fluctuate between .1 and .9
no inspectioin until late march.
So if its getting a reading of +29 then is that what the ecu has decided to run the car at until the systems are ready? Shouldn't it have started out at 0 with the reset?
For the heck of it i hooked the scanner to our 2005 xc90. it is amazing how much information it reads compared to a 96 car.
1) why upon reset is the longterm fuel trims showing as Positive 21 vs starting at 0.
2) upon reset no short term fuel trim readings.well actually it has had a brief reading three times. This morning when i first hooked up the gauge and the car wasnt fully warm. it briefly read +29. and the other night on the freeway the same.
2) upon upon reset is the 02 sensor reading different. when the car is warm it fluctuates between .19 and .195 at idle. If i blip the throttle it fluctuates between 0.005 and 0.2. this is different than before the reset
Before reset
1) after i fixed one of the leaks the ltft was hovering around -5 and stft would fluctuate between -8 to +9
2) o2 sensor behaved differntly (i lost my paper with notes) but i believe when warm if I blipped the throttle it would fluctuate between .1 and .9
no inspectioin until late march.
So if its getting a reading of +29 then is that what the ecu has decided to run the car at until the systems are ready? Shouldn't it have started out at 0 with the reset?
For the heck of it i hooked the scanner to our 2005 xc90. it is amazing how much information it reads compared to a 96 car.
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
Ok well yesterday I had a dead battery. I parked shut the car off. Left the lights on Had the key in the on position cell phone plugged into the cigarette lighter adapter. Made a few phone calls. Not sure how long I was in the car I think it was 20 minutes maybe half an hour. And bingo Dead battery At least I think it was a dead battery. My brother-in-law had a portable power 300 A he brought it to me but it didn't turn the car over at all. I want to cross the street to it Jiffy Lube and somebody there had a 500 amp version and that jumped the car fine.
I disconnected the battery and when I got home and put on a portable charger overnight So I think the 21.1 Long term fuel trim number may be a preset number as blackburn Suggested may be a preset number for the feel trims. Because that's what it came on ass one more time.
Couple things My maf sensor readings may be a little Hyatt Idol it's about four or 4.2 g per second which I think puts it up around 15 kg per hour I was told that the correct reading it Idalyn park or neutral with the car warmed up it's probably closer to 3 Grams per second.
I too good for a few runs today including one that lasted about an hour During that time the short-term fuel trim readings showed up 30% of the time they were high 29 21 etc
There were glimpses of the front O2 sensor getting up momentarily into the higher numbers
I disconnected the battery and when I got home and put on a portable charger overnight So I think the 21.1 Long term fuel trim number may be a preset number as blackburn Suggested may be a preset number for the feel trims. Because that's what it came on ass one more time.
Couple things My maf sensor readings may be a little Hyatt Idol it's about four or 4.2 g per second which I think puts it up around 15 kg per hour I was told that the correct reading it Idalyn park or neutral with the car warmed up it's probably closer to 3 Grams per second.
I too good for a few runs today including one that lasted about an hour During that time the short-term fuel trim readings showed up 30% of the time they were high 29 21 etc
There were glimpses of the front O2 sensor getting up momentarily into the higher numbers
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
good progress maybe issues solved. please read question about charging system at the end.
on friday i pulled over to make a couple of cell phone calls. I shut the motor off, mistakenly left the lights on, and with my cell phone plugged into the cig lighter made some calls. I think about 20 minutes maybe 30 went by when I tried to start the car and found the battery had died.
i jumped the car to start it using a portable charger i borrowed from the jiffy lube that was accross the street. drove home disconnected the battery and charged it over night.
The next afternoon i drove the car for about an hour solid and noticed that on the live data from the obd scanner that the o2 sensor looked like it was showing some life. with it briefly going up into .08 .06 etc and getting a few readings on the stft. the readings werent great as the ltft was still around 21 and the stft would briefly come. it was very high also around 21 even 29.
on monday my kids briefly drove the car. and then today when i got in the car and hooked up the code reader prior to starting the car i noticed that there was the long term fuel trim from the previous day was -.8 progress
drove the car several today total of about 20 miles durning this time the ltft was anywhere between -1.6 to positive 0.8. With it mostly being around -.8
the stft were fluctuating between -3 to pos 3
Maf readings were about 3.6 at idle in park.
So did my recharging of the battery help things along? the battery is only 2 years old. and if so does that mean i have a charging problem that affects the running of the car.
the only ready light that is still blinking on the code ready is CAT converter light. the rest are on.
on friday i pulled over to make a couple of cell phone calls. I shut the motor off, mistakenly left the lights on, and with my cell phone plugged into the cig lighter made some calls. I think about 20 minutes maybe 30 went by when I tried to start the car and found the battery had died.
i jumped the car to start it using a portable charger i borrowed from the jiffy lube that was accross the street. drove home disconnected the battery and charged it over night.
The next afternoon i drove the car for about an hour solid and noticed that on the live data from the obd scanner that the o2 sensor looked like it was showing some life. with it briefly going up into .08 .06 etc and getting a few readings on the stft. the readings werent great as the ltft was still around 21 and the stft would briefly come. it was very high also around 21 even 29.
on monday my kids briefly drove the car. and then today when i got in the car and hooked up the code reader prior to starting the car i noticed that there was the long term fuel trim from the previous day was -.8 progress
drove the car several today total of about 20 miles durning this time the ltft was anywhere between -1.6 to positive 0.8. With it mostly being around -.8
the stft were fluctuating between -3 to pos 3
Maf readings were about 3.6 at idle in park.
So did my recharging of the battery help things along? the battery is only 2 years old. and if so does that mean i have a charging problem that affects the running of the car.
the only ready light that is still blinking on the code ready is CAT converter light. the rest are on.
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
good progress maybe issues solved. please read question about charging system at the end.
on friday i pulled over to make a couple of cell phone calls. I shut the motor off, mistakenly left the lights on, and with my cell phone plugged into the cig lighter made some calls. I think about 20 minutes maybe 30 went by when I tried to start the car and found the battery had died.
i jumped the car to start it using a portable charger i borrowed from the jiffy lube that was accross the street. drove home disconnected the battery and charged it over night.
The next afternoon i drove the car for about an hour solid and noticed that on the live data from the obd scanner that the o2 sensor looked like it was showing some life. with it briefly going up into .08 .06 etc and getting a few readings on the stft. the readings werent great as the ltft was still around 21 and the stft would briefly come. it was very high also around 21 even 29.
on monday my kids briefly drove the car. and then today when i got in the car and hooked up the code reader prior to starting the car i noticed that there was the long term fuel trim from the previous day was -.8 progress
drove the car several today total of about 20 miles durning this time the ltft was anywhere between -1.6 to positive 0.8. With it mostly being around -.8
the stft were fluctuating between -3 to pos 3
Maf readings were about 3.6 at idle in park.
So did my recharging of the battery help things along? the battery is only 2 years old. and if so does that mean i have a charging problem that affects the running of the car.
the only ready light that is still blinking on the code ready is CAT converter light. the rest are on.
on friday i pulled over to make a couple of cell phone calls. I shut the motor off, mistakenly left the lights on, and with my cell phone plugged into the cig lighter made some calls. I think about 20 minutes maybe 30 went by when I tried to start the car and found the battery had died.
i jumped the car to start it using a portable charger i borrowed from the jiffy lube that was accross the street. drove home disconnected the battery and charged it over night.
The next afternoon i drove the car for about an hour solid and noticed that on the live data from the obd scanner that the o2 sensor looked like it was showing some life. with it briefly going up into .08 .06 etc and getting a few readings on the stft. the readings werent great as the ltft was still around 21 and the stft would briefly come. it was very high also around 21 even 29.
on monday my kids briefly drove the car. and then today when i got in the car and hooked up the code reader prior to starting the car i noticed that there was the long term fuel trim from the previous day was -.8 progress
drove the car several today total of about 20 miles durning this time the ltft was anywhere between -1.6 to positive 0.8. With it mostly being around -.8
the stft were fluctuating between -3 to pos 3
Maf readings were about 3.6 at idle in park.
So did my recharging of the battery help things along? the battery is only 2 years old. and if so does that mean i have a charging problem that affects the running of the car.
the only ready light that is still blinking on the code ready is CAT converter light. the rest are on.
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
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jimmy57
- Posts: 6694
- Joined: 12 November 2010
- Year and Model: 2004 V70R GT, et al
- Location: Ponder Texas
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If you have a weak battery the voltage drop during cranking from starter load will affect the FT's. THE voltage can go lower long enough that the caps in the ECM will not be able to support RAM function on the earlier control units (99 and later were revised in this area). The LTFT may be most anything in that situation. With FT fouled up the IAC gets more flow to give correct idle speed to an engine running with less than optimal air fuel ratio and that ups the MAF value.
weak batteries and poor grounds have been the cause of hundreds of thousands, maybe millions of repair dollars.
weak batteries and poor grounds have been the cause of hundreds of thousands, maybe millions of repair dollars.
Jimmy thank you for your reply. Since your reply the short term fuel trims are no longer reading. the o2 sensor has stopped fluctuating as much and the ltft froze again at 21.1
Very annoying. so perhaps it wasn't a coincidence that the three readings above started coming to life after i charged the battery with my home charger.
my battery readings i think are border line. 12.65 with the off after running it for about 15 minutes. car was fairly warm at the time.
13.8 at the battery with the lights off
13.65 at the battery with lights on
13.92 at the alternator running with lights off
13.85 at alt with lights on.
Very annoying. so perhaps it wasn't a coincidence that the three readings above started coming to life after i charged the battery with my home charger.
my battery readings i think are border line. 12.65 with the off after running it for about 15 minutes. car was fairly warm at the time.
13.8 at the battery with the lights off
13.65 at the battery with lights on
13.92 at the alternator running with lights off
13.85 at alt with lights on.
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
Friday night I took the battery out and charged it overnight for about 7 hours on a portable charger at the 10 amp setting.
the next morning after unplugging the charger the volt meter said there was 12.8 volts between pos and neg terminals. after installing the battery back into the car the voltage reading was 12.6. Does anyone know if this should have happened.
after taking the car for two short rides of 10 minutes each the car sat for about 2 hours. i hooked up the code reader and in liver mode the o2 sensor seemed to be functioning properly moving up and down between .9 and .3 maybe .2. and the ltft was -4.7, the short term trim was starting to function again and the maf readings were better.
So now i need to see if i have a charging problem, a draw problem, or a bad battery.
1) When i checked the voltage output at the charger with the car warm it was 13.8 which was higher than the voltage at the battery. I think the difference was .2 or .3. i can run a new cable from the alt to the battery. i read one post where the person left the old wire and added a new 0 guage wire. is this ok?
2) When i felt the cable from the battery to the starter it felt warm, not hot but warm, i will check it again tomorrow. can the cable be at all warm and be ok?
3) When I reinstalled the battery and the voltage dropped by .2 does that mean i had a draw. or is it normal?
the next morning after unplugging the charger the volt meter said there was 12.8 volts between pos and neg terminals. after installing the battery back into the car the voltage reading was 12.6. Does anyone know if this should have happened.
after taking the car for two short rides of 10 minutes each the car sat for about 2 hours. i hooked up the code reader and in liver mode the o2 sensor seemed to be functioning properly moving up and down between .9 and .3 maybe .2. and the ltft was -4.7, the short term trim was starting to function again and the maf readings were better.
So now i need to see if i have a charging problem, a draw problem, or a bad battery.
1) When i checked the voltage output at the charger with the car warm it was 13.8 which was higher than the voltage at the battery. I think the difference was .2 or .3. i can run a new cable from the alt to the battery. i read one post where the person left the old wire and added a new 0 guage wire. is this ok?
2) When i felt the cable from the battery to the starter it felt warm, not hot but warm, i will check it again tomorrow. can the cable be at all warm and be ok?
3) When I reinstalled the battery and the voltage dropped by .2 does that mean i had a draw. or is it normal?
1996 850R
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
2005 xc90
1994 850 turbo totaled
1966 p1800 purchased 1975 sold 76
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abscate
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Disconnecting the battery (negative terminal) and confirm the .2V drop, then do it again in morning.
If you do have a 0.2V drop I would say that's worth investigating by isolating the circuit in question..pull fuses one by one until you see the drop go away.
If you do have a 0.2V drop I would say that's worth investigating by isolating the circuit in question..pull fuses one by one until you see the drop go away.
Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 XC90-in-Red
Link to Maintenance record thread
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 XC90-in-Red
Link to Maintenance record thread
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