I was wondering if anyone has had some experience with an erratic idle to the the point of stalling at times only on cold starts.After 20 secs or so it is back to normal and and no probs till next cold start.cheers..
4.8 rough idle only when cold
Jimmycrackcorn
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Put the pipe away mate, cause it aint doing you much good
I aint going to say heliflyer73 is wrong, because there is NO way in the world I am putting that rot gut through mine, so I will never know
, BUT if these TB48's fall over just because some one puts in premium in the tank, is the FIRST car I have ever heard of in ANY magazine\forum\mechanic that does this in the bloody WORLDI will bet my left AND right nut, there is another reason:bananaro:
Not quite the full 6 pack there B.D.R?
I'm not saying the TB48 wont run on a higher octane than 91, I'm saying that it is tuned to run on 91ron for the Oz market and if you want to run an alternate octane rating then you will need to retune it to suit. Just as you need to retune them, or run a piggyback ecu to run on LPG (106ron)
It's all to do with the information that the ecu is expecting to receive back from all those sensors that these beasts are littered with, you start screwing with that information and computer just says noooooooo.
I'm not saying the TB48 wont run on a higher octane than 91, I'm saying that it is tuned to run on 91ron for the Oz market and if you want to run an alternate octane rating then you will need to retune it to suit. Just as you need to retune them, or run a piggyback ecu to run on LPG (106ron)
It's all to do with the information that the ecu is expecting to receive back from all those sensors that these beasts are littered with, you start screwing with that information and computer just says noooooooo.
Hi mikus,
Your on the right track bud but the only thing that will bugger up your theory is that the 4.8 is a learning/adaptive ecu, you're right about all the sensors and they do have a huge part to play in the way the 4.8 runs, accerlerates, auto changes etc.. But in the case of octane rating in fuel the ecu will sense which octane you are running (by monotoring exhaust gases etched,), the adjust the timing to suit. A lot I'd newer cars do thhd know.. It doesn't always do this well, because I'd condition if sensors etc but that would be relative to what ever octane you run..
Older cars that have no ecu tuning will need to be retuned as you say..
Hope this helps
Jethro
Your on the right track bud but the only thing that will bugger up your theory is that the 4.8 is a learning/adaptive ecu, you're right about all the sensors and they do have a huge part to play in the way the 4.8 runs, accerlerates, auto changes etc.. But in the case of octane rating in fuel the ecu will sense which octane you are running (by monotoring exhaust gases etched,), the adjust the timing to suit. A lot I'd newer cars do thhd know.. It doesn't always do this well, because I'd condition if sensors etc but that would be relative to what ever octane you run..
Older cars that have no ecu tuning will need to be retuned as you say..
Hope this helps
Jethro
I'm no mechanic, ( I know how they work sort of), nor am I a petrochemical engineer, but say you're both right... The 4.8 isn't tuned to run higher octane.. 'Until' it remaps the ECU profile, then runs a treat..
Wouldn't that then mean - it starts rough, then comes good after x seconds?..
Just like mine did on premium.
Heliflyer.
Wouldn't that then mean - it starts rough, then comes good after x seconds?..
Just like mine did on premium.
Heliflyer.
And further to the above, yeah, no other car seems to have this issue if running either standard or premium, but, for my inexperienced knowledge, - when did premium ULP become widely available?.. And how many 4.8's are post Say '03 or 04 that are having issues?..
It's just a logical fault elimination process that I'm following here, and the only variable I have noticed is premium unleaded..
The DAY I put standard in was the day it came good..??
I'd LOVE to hear any other theory or fix that has worked??..
Cheers, Heli.
It's just a logical fault elimination process that I'm following here, and the only variable I have noticed is premium unleaded..
The DAY I put standard in was the day it came good..??
I'd LOVE to hear any other theory or fix that has worked??..
Cheers, Heli.
Hi heliflyer,
It's possible that your not imagining things... A sernario I see for this is as follows..
For a variety of reasons, including octane levels, the ECU will adjust the timeing to get the best balance between clean emissions, power and Econemy as determined my Nissan.. What these parameters are nobody really knows for sure because Nissan don't release that info and as of yet nobody has "cracked" the ecu write etc... The ecu uses all the sensors to decide what to do...
It will then adjust the timeing by rotating the cam slightly this advancing the timing, I don't think it adjusts the distributor ...
What if due to wear of timing chain, cams valves etched. The ecu isn't able to get enough adjustment to get the timing it wants in certain scenarios, like high octane..
This could be be hole dependent due to different cars condition..
There is a good thread on hear, (it might even be this one without going back through pages), on how to advance this mechanisim and the advantage that is gained by this..
Of course, there is also the chance that one of thes my sensors may be sending slightly false info to the ecu buggering up the ecu calcs... Poor air supply, Maf, oxygen, TPS sensors are but a few of the inputs that can be troublesome .. She's and interesting be hike the 4.8...
If you want do a trial of this (cam timing afjustment) and post the results.. I would be very interested on your results..
J
It's possible that your not imagining things... A sernario I see for this is as follows..
For a variety of reasons, including octane levels, the ECU will adjust the timeing to get the best balance between clean emissions, power and Econemy as determined my Nissan.. What these parameters are nobody really knows for sure because Nissan don't release that info and as of yet nobody has "cracked" the ecu write etc... The ecu uses all the sensors to decide what to do...
It will then adjust the timeing by rotating the cam slightly this advancing the timing, I don't think it adjusts the distributor ...
What if due to wear of timing chain, cams valves etched. The ecu isn't able to get enough adjustment to get the timing it wants in certain scenarios, like high octane..
This could be be hole dependent due to different cars condition..
There is a good thread on hear, (it might even be this one without going back through pages), on how to advance this mechanisim and the advantage that is gained by this..
Of course, there is also the chance that one of thes my sensors may be sending slightly false info to the ecu buggering up the ecu calcs... Poor air supply, Maf, oxygen, TPS sensors are but a few of the inputs that can be troublesome .. She's and interesting be hike the 4.8...
If you want do a trial of this (cam timing afjustment) and post the results.. I would be very interested on your results..
J
Mine just takes quite a few turns to start when cold, occasionally it runs rough when it starts and practically stalls, so I turn it off restart and all good, seems to have started since I fixed my starter motor 2 yrs ago, on Gas tho as far as tuning, I've got a injected system which hasn't been touched in 2 yrs, due for a filter change and check but otherwise runs 100%
Mate I want to try all the learning procedures on ya truck to see if thats the issue.Mine just takes quite a few turns to start when cold, occasionally it runs rough when it starts and practically stalls, so I turn it off restart and all good, seems to have started since I fixed my starter motor 2 yrs ago, on Gas tho as far as tuning, I've got a injected system which hasn't been touched in 2 yrs, due for a filter change and check but otherwise runs 100%
After doing to mine ive relised how important the throttle valve closed position,idle air volume learning and accelarator pedal release position learning procedures to the ECU.
Just gone back through this thread and no one has performed this.
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Someone mentioned way back in this thread that they replaced the coolant temp sensor, and fixed the drama. A few of you guys have thought about it but apparently carnt afford the $90 for one, and are looking for petrochemical, astrophysical, anatomical reasons for the problem.
My 4.8 started doing this the day after I had extractors and exhaust fitted. Found I had
One fault 02 sensor. Replaced both, no change to start. I'm going to try the coolant temp sensor next and see what happens. I too tried the 91 octane thing, as I always run mine on 98, and I don't have gas. No change. Its not the fuel. I did do the pva shortly before the exhaust, so if the coolant temp sensor don't work, putting the pva back to standard.
My 4.8 started doing this the day after I had extractors and exhaust fitted. Found I had
One fault 02 sensor. Replaced both, no change to start. I'm going to try the coolant temp sensor next and see what happens. I too tried the 91 octane thing, as I always run mine on 98, and I don't have gas. No change. Its not the fuel. I did do the pva shortly before the exhaust, so if the coolant temp sensor don't work, putting the pva back to standard.
Try the learn procedures as outline in the service manual, costs nothing,just download from here somewhere and takes 5-10mins.
I see your exhaust as another link to idel rpm change that the ECU can not configure, or they may have unpluged any of the connectors around the throttle body which then requires all learning procedures to be carried out.
I see your exhaust as another link to idel rpm change that the ECU can not configure, or they may have unpluged any of the connectors around the throttle body which then requires all learning procedures to be carried out.
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What is the learning procedure? I tried a search, but didn't find anything specific.
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Is it in the factory owners manual, or a Gregory?
I can't believe you Muppets are still playing around with this, charge your battery with a decent 3 stage charger, take it off charge in the morning and start. I guarantee you it will start fine.
Then work out why your battery is not charged. i.e. rooted, or Redarc or similar device draining voltage overnight.
Then work out why your battery is not charged. i.e. rooted, or Redarc or similar device draining voltage overnight.
Ha ha tried that mate and even brand new battery, just takes a few turns in the morning to start, I got no 2nd battery either lol
Mate just waiting for you to drop by one afo, even got plenty of beer here for you lol,
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You have no idea on what different RON does do you:idiot: , you will NOT over fuel a ULP, ECU controlled car running a 98 instead of 91, and if you think Gas is tuned the same as petrol but a higher octane rating:doh:
Jeff, I did change the battery to a BRAND new one I pillaged from work for a trial....it made no difference
, although in the batteries defence, my problem is not rough starting so much as surging.Well I am getting the PC program\cable to hook up to this thing next week, so I will check for faults, and do the all the relearns it lets
Here's a link to a copy of the service manual, not sure if its the same as mine but should have the 4.8 supplemented version's.
The learning procedure is in the file marked EC for engine control system.
http://db.tt/8jzSfGix
The learning procedure is in the file marked EC for engine control system.
http://db.tt/8jzSfGix
This be easier, its the one I used and worked great. Need to follow it to the letter and time.
Accelerator Pedal Released Position
Learning
DESCRIPTION
“Accelerator Pedal Released Position Learning” is an operation to learn the fully released position of the
accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed
each time harness connector of accelerator pedal position sensor or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.
Throttle Valve Closed Position Learning
DESCRIPTION
“Throttle Valve Closed Position Learning” is an operation to learn the fully closed position of the throttle valve
by monitoring the throttle position sensor output signal. It must be performed each time harness connector
of electric throttle control actuator or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON”.
3. Turn ignition switch “OFF” wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume Learning
DESCRIPTION
“Idle Air Volume Learning” is an operation to learn the idle air volume that keeps each engine within the
specific range. It must be performed under any of the following conditions:
+ Each time electric throttle control actuator or ECM is replaced.
+ Idle speed or ignition timing is out of specification.
PREPARATION
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
+ Battery voltage: More than 12.9V (At idle)
+ Engine coolant temperature: 70 - 95°C (158 - 203°F)
+ PNP switch: ON
+ Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light
only small lamps.
+ Steering wheel: Neutral (Straight-ahead position)
+ Vehicle speed: Stopped
+ Transmission: Warmed-up
For models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/T”
system indicates less than 0.9V.
For A/T models without CONSULT-II, drive vehicle for 10 minutes.
BASIC SERVICE
PROCEDURE TB48DE A/T (WITH EURO-OBD)
EC-31
Accelerator Pedal Released Position
Learning
DESCRIPTION
“Accelerator Pedal Released Position Learning” is an operation to learn the fully released position of the
accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed
each time harness connector of accelerator pedal position sensor or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.
Throttle Valve Closed Position Learning
DESCRIPTION
“Throttle Valve Closed Position Learning” is an operation to learn the fully closed position of the throttle valve
by monitoring the throttle position sensor output signal. It must be performed each time harness connector
of electric throttle control actuator or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON”.
3. Turn ignition switch “OFF” wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume Learning
DESCRIPTION
“Idle Air Volume Learning” is an operation to learn the idle air volume that keeps each engine within the
specific range. It must be performed under any of the following conditions:
+ Each time electric throttle control actuator or ECM is replaced.
+ Idle speed or ignition timing is out of specification.
PREPARATION
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
+ Battery voltage: More than 12.9V (At idle)
+ Engine coolant temperature: 70 - 95°C (158 - 203°F)
+ PNP switch: ON
+ Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light
only small lamps.
+ Steering wheel: Neutral (Straight-ahead position)
+ Vehicle speed: Stopped
+ Transmission: Warmed-up
For models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/T”
system indicates less than 0.9V.
For A/T models without CONSULT-II, drive vehicle for 10 minutes.
BASIC SERVICE
PROCEDURE TB48DE A/T (WITH EURO-OBD)
EC-31
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