View Full Version : open loop/closed loop...what is it?
can someone explain open/closed loop to me?
ami right in thinking that open loop is when the ECU is giverning fuelling,ignition etc by information picked up from the sensors in real time rather than the pre-learned info?
If the ECU gets the closed loop/open loop signal from the Lambda, and the lambda is nackered.. is it possible for the ECU to stay in open loop mode continously?
can someone explain open/closed loop to me?
ami right in thinking that open loop is when the ECU is giverning fuelling,ignition etc by information picked up from the sensors in real time rather than the pre-learned info?
If the ECU gets the closed loop/open loop signal from the Lambda, and the lambda is nackered.. is it possible for the ECU to stay in open loop mode continously?
Open loop = internal maps, when cold starting, idling and WOT.
Closed loop = governed by O2 sensor, etc, up to about 75% throttle I think.
If the O2 sensor wasn't working and the ECU knew about it then I guess it would have to go into open loop or a form of safe mode. If the ECU didn't know about it then it would be in closed loop with not very good tuning. It requires more than a working O2 sensor to go into closed loop.
cheers .. :D so i got it the wrong way round..
hmm.. i'm not counting chickens yet.. but i have poor/rubbish idling when cold, hunting when idling at warm, and poor performance over 75% throttle... oh and poor consumption (50 miles fron £20 on occasions).
oh roll on new lambda.. even if it doesnt make any difference it'd bound to do something for my abysmal petrol consumption.
either that or it'll blow my engine up as its not a direct replacement and is 'universal' .. but i checked the specs out and it should be okay.
Tony Donovan
09-08-04, 08:31 PM
AFM, maybe? Would surely give abysmal fuel consumption and indifferent running if it's shot?
AFM, maybe? Would surely give abysmal fuel consumption and indifferent running if it's shot?
AFAIK no AFM on 1jz... MAP system (manifold absolute pressure) ...
If the o2 sensor was duff then wouldn't the ecu report it as a fault? (guessing!)
cheers .. :D so i got it the wrong way round..
hmm.. i'm not counting chickens yet.. but i have poor/rubbish idling when cold, hunting when idling at warm, and poor performance over 75% throttle... oh and poor consumption (50 miles fron £20 on occasions).
oh roll on new lambda.. even if it doesnt make any difference it'd bound to do something for my abysmal petrol consumption.
either that or it'll blow my engine up as its not a direct replacement and is 'universal' .. but i checked the specs out and it should be okay.
Ignition and cam timing okay?
Also, check for intake leaks.
Also reset the ecu.
yep, map system..ignition is a possibility.. although it was checked by toyota (yes i know, but at the time i dint know any different) and it was fine.. that was about two years ago.
Air/vacuum leak is a possibility... anyway i'll fit the new lambda and see what happens. yes, the ECU would report a fault if the lambda was open circuit or giving readings which were WAY out, but if it was just giving false readings it wouldnt pick up on it.
cheers
adi
oh and poor consumption (50 miles fron £20 on occasions).
Christ! It can't be USING all of that fuel. That's about 9MPG!
If it was, at the right air/fuel ratio, it would be developing about 500BHP.
If the A/F ratio was running THAT rich, the engine would just drown and stall wouldn't it?
I know you've probably checked but it's not a leak is it? Maybe not a constant drip, you'd smell that when you came back after parking, but a leak under pressure or something. So it's only leaking on the road. I heard about a mate, years ago, who had a fuel leak and it was dripping onto something hot (not the 'zorst :no: ) but only when the pump was running. The fuel was evaporating so there was very little smell. It took him weeks to track it down.
it doesnt use that much all the time.. only when i floor it.. on a motorway trip i get about 100 miles from £20.
Def no leaks etc.. i think its just overfuelling badly.. theres a lot of carbon in the exhuast.
TurboChick
10-08-04, 10:55 AM
Have you checked for any error codes or tried resetting the ECU?
Does sound like either O2 sensor or AFM. You can use a multimeter to check that they are both reading as they should do, though my attempt on my car proved pointless as I couldn't work the damn thing! :)
yep no error codes.. and the ECU gets reset every so often so not that either. I was going to test the O2 sensor but i felt better just putting a new one in.. at least then you know its 100%.
It should be fitted by tomorrow so i'l now more then.
Have you checked for any error codes or tried resetting the ECU?
Does sound like either O2 sensor or AFM. You can use a multimeter to check that they are both reading as they should do, though my attempt on my car proved pointless as I couldn't work the damn thing! :)
AFM. :no: Checking a failing O2 sensor with a multimeter is not going to give a meaningful result unless you can run a known working O2 sensor simultaneously as a reference. Just getting a reading does not prove that it is correct. If the O2 sensor has failed completely then you should get a code, just like if you unplugged it.
buttmunch
10-08-04, 11:57 AM
If the O2 sensor has failed completely then you should get a code, just like if you unplugged it.
How long does it take for a code to appear if you unplug your O2 sensor?? Does it put the check engine light on?? I know my O2 sensor is dead because I checked it with a Lambda sensor checker and it just didn't respond. Unpluggin my O2 sensor makes no differance to the way my car runs and I don't get a check engine light on either. But curiously I still get about 25+mpg out of the car with a bit of mixed driving :confused:
:D reinforcing the fact that we could all have nackered O2's and not even know it ... they reckon they only last about 60,000 miles tops.
How long does it take for a code to appear if you unplug your O2 sensor??
The TRSM doesn't give a specific time it just says "after a certain period." I guess you should check your codes and see what has showed up.
If you believe that your O2 sensor is completely dead then this can be confirmed, as Turbochick suggested, by monitoring the outputs of the sensor and the heater with a multimeter. If the heater has failed then the sensor output becomes pretty meaningless on a GTE.
buttmunch
10-08-04, 03:25 PM
I guess you should check your codes and see what has showed up.
So you can have fault codes witout the check engine light coming on??? I thought the idea of the light was to inform you that there was a problem. I could have been driving for ages and have loads of faults I don't even know about :banghead:
the light stays on for a while, and then doesnt bother showing up anymore.. its gets bored of you not responding.
So you can have fault codes witout the check engine light coming on???
Only potentially serious faults cause the warning light to come on.
For example, error code 51 (which I have on both my cars) seems to be caused by the air-con and therefore not classed as serious and likely to cause damage to the engine; hence the warning light does not come on, although the code is stored and can be recovered by shorting E1 and TE1 on the diagnostic soocket.
Nodalmighty
10-08-04, 07:44 PM
Only potentially serious faults cause the warning light to come on.
For example, error code 51 (which I have on both my cars) seems to be caused by the air-con and therefore not classed as serious and likely to cause damage to the engine; hence the warning light does not come on, although the code is stored and can be recovered by shorting E1 and TE1 on the diagnostic soocket.
You can soon trace a bad O2 or an air leak by doing the voltage test on the VF(or VF1) and E1 in the diagnostics port. 0v = dead O2, 5.0v = air leak in the inlet somewhere. It should be between 2.0v and 4.0v on a normal car.
Nod.
well... i fitted the new lambda today ... and....
I dunno.. it certainly feels better.. but maybe its my imagination :D My power still tails off after about 5000 though...
well... i fitted the new lambda today ... and....
I dunno.. it certainly feels better.. but maybe its my imagination :D My power still tails off after about 5000 though...
How much boost are you running? If the car seriously is running out of steam after 5000 rpm then maybe you need to look at the timing of the cams and ignition.
Also...fuel pump and/or fuel filter could be a cause to your problem.
its not short of boost.. running 1bar.
The car is a bit weird to drive.. its lifeless below 3500 (but then again its got bigger turbos), absolutely flies up to 6000, and then seems like it cant be bothered (redlines at 7100). 6000-7000 theres just nothing there. If i'm in 3rd (auto) then the power just seems empty above 5500. I'm not sure if this is a characteristic of the engine though...
heres some vids... but looking at them maybe its just me.. i always think theres something wrong with it :D but you can see how long it takes to get to 30 !! it seems like forever !! (its mph by the way and not kmh as indicated)..
www.mkiiisupra.net/pics/DASH1.wmv (http://www.mkiiisupra.net/pics/DASH1.wmv) (0-80)
www.mkiiisupra.net/pics/DASH2.wmv (http://www.mkiiisupra.net/pics/DASH2.wmv) (rollling start from 50)
TurboChick
12-08-04, 12:11 PM
You can soon trace a bad O2 or an air leak by doing the voltage test on the VF(or VF1) and E1 in the diagnostics port. 0v = dead O2, 5.0v = air leak in the inlet somewhere. It should be between 2.0v and 4.0v on a normal car.
Nod.
This is what I was saying but got told wont show anything!
This is what I was saying but got told wont show anything!
Turbochick If you are referring to my reply then what I said was "Checking a failing O2 sensor with a multimeter is not going to give a meaningful result." My point was that a "failing" O2 sensor might not throw a fault code, but also may not give a correct A/F signal to the ECU and a second point of reference would be required in order to confirm that the device was working CORRECTLY. Checking a FAILED O2 sensor with a multimeter, as I agreed with you in a later post, is a good idea. The first part of my post regarding the AFM was just pointing out that Adi's car does not have an AFM.
Sorry if you have taken offence at my comments, but I was just trying to point out that there is a state between working 100% and completely broken that needs to be taken into account when dealing with such a precise device. I wasn't disagreeing with you just expanding on your comment.
TurboChick
12-08-04, 12:57 PM
No offence taken Lofty! Maybe I should've added some smilies :duck:
It's just, I know that you can test to see how much of a resistance there is going through these things and, as somebody else said, it should give you an idea of whether the part is on its way out or working fine etc.
I always know what I'm saying but maybe not everyone else does :)
TurboChick
12-08-04, 01:00 PM
...........oh and I agree with the rest of what you said......just in case you think I missed your point, lol.
its not short of boost.. running 1bar.
The car is a bit weird to drive.. its lifeless below 3500 (but then again its got bigger turbos), absolutely flies up to 6000, and then seems like it cant be bothered (redlines at 7100). 6000-7000 theres just nothing there. If i'm in 3rd (auto) then the power just seems empty above 5500. I'm not sure if this is a characteristic of the engine though...
heres some vids... but looking at them maybe its just me.. i always think theres something wrong with it :D but you can see how long it takes to get to 30 !! it seems like forever !! (its mph by the way and not kmh as indicated)..
www.mkiiisupra.net/pics/DASH1.wmv (http://www.mkiiisupra.net/pics/DASH1.wmv) (0-80)
www.mkiiisupra.net/pics/DASH2.wmv (http://www.mkiiisupra.net/pics/DASH2.wmv) (rollling start from 50)
Interesting vids, are you sure you launched the car agressively enough? It appears you just launched the car on idle rather than say 2500 - 3000 RPM.
I still think the fuel filter and pump are worth checking out (ie upgrading/replacing). Remember the more boost you add, the LESS fuel a fuel pump can deliver.
its an auto so when i did the vids it was just a foot back job. I cant powerlaunch as my turbos wont spool below the stall point of the auto.. again perhaps pointing to an ignition problem? If i put the foot on the brake and try and raise the revs the boost shows exactly 0psi at about 2500... it wont produce ANY positive boost until about 2600-2700.. hence crappy launches (but this has been discussed a zillion times before :D )
how'd you mean the more fuel you add the less the fuel pump can deliver?
its an auto so when i did the vids it was just a foot back job. I cant powerlaunch as my turbos wont spool below the stall point of the auto.. again perhaps pointing to an ignition problem? If i put the foot on the brake and try and raise the revs the boost shows exactly 0psi at about 2500... it wont produce ANY positive boost until about 2600-2700.. hence crappy launches (but this has been discussed a zillion times before :D )
how'd you mean the more fuel you add the less the fuel pump can deliver?
The more boost you have the less fuel is delivered by the fuel pump. Boost adds pressure in the manifold, which in turn raises fuel pressure in the fuel rail, the more pressure there is in the rail the more difficult it is for the pump to deliver fuel as it has more pressure supply fuel against. A high performance Walbro fuel pump delivers similar amount of fuel to a stock pump at low PSI but as the boost climbs up, the stock pump becomes far less efficient than a Walbro. And also, older stock pumps (say 100k miles of use) become even worse.
What condition are your plugs and leads in?
if there is a problem in that area it would give you a rough idle poor fuel consumption and poor response and would give you no fault code
no leads.. the coils sit directly on top of the plugs..
Plugs are okay i think as they were only changed about 3000 miles ago.. toyota plats.
OK 100% not the leads then right how about fuel pressure reg not opening creating excess fuel pressure making the injectors dribble just a thought as it is not throwing up a fault code it must be somthing thats not controled by the ECU :bigeyes:
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