Isuzu 3.1D Autoshifting problem

[ltx]

Sir Galactus,

Thank you sa info. mo sarap ng pakiramdam pag madaming tumutulong ... sana ganito lahat ng Pinoy ..anyway back to topic.

hindi naman siguro lahat ng mekaniko, pero meron nga ilan dyan na sasamantlahin ka. thanks po ulit


Will keep you updated Guys, para meron tayong reference

[nap123]

Galactus thanks for your input. I suggest nga kay ITx to clean muna all the wirings kasi sabi niya bago nangyari yung problem nag pa underwash sya tapos binugahan ng kerosene ang ilalim. Ganun pa man pa check parin sa ibang mekaniko na may experience sa Auto Trans. Its a good reference for AUTO TRANS Problem here kahit hindi bighorn ang car mo.

Bro, I don't own a Bighorn, but we share the same problem. In my Accord's case, naayos na.

Hindi rin kasi nag-autoshift ang Accord ko. Nagbi-blink yung D4 indicator light, meaning may possible problem sa AT. I used to start off at 2 or L, tapos pag 50-60 kmh na ako, then shift sa D3 or D4. Pag akyatan, hindi ako umaandar pag D3 or D4, kahit mataas na yung rev ko, kailangan talaga nasa 2 or L. It's annoying, kasi parang hindi tuloy matic.

So I went to Baltak and AT Master (Visayas Ave). They made a cursory examination and testing, less than 5 minutes, tapos ang recommendation agad, overhaul, and quoted me a whopping 32k. Yung surplus sa Baltak, 20k plus 3.5k ata for labor.

Eh wala pa akong pera, so pinabayaan ko muna. Nung nagka-problema starter solenoid ko, pinaayos ko sa talyer malapit sa work. Sa Accord kasi, masikip ang engine bay, and for you to access the starter assembly, marami kang babaklasin. Nung binalik nila, aba, hindi na nagbi-blink yung D4. Ok na, nag-auto shift na siya. So tinanong ko yung mekaniko kung ano ginawa niya. Sabi nya wala naman daw, binalik nya lang yung mga piyesa at hinigpitan yung mga wires.

Baka may TCM (Throttle Control Module) yung Bighorn, and you can jump the connectors para magbato ng error code. Or try mo ulit check yung sockets ng wiring, disconnect and reconnect mo ulit. Ok pa naman kasi hatak kamo, hindi rin lang nag-aautoshift.

My experience kasi really made me distrust yung mga shops na gusto agad palitan or overhaul. I saved a lot of money, until now OK pa rin tranny ko.

Sensya na, mahaba, pero baka makatulong.

[ltx]

Thanks for the input good fellows of tsikot.com.... My plans for this coming week/s.. feel free to add or comment



Additional Information:

1. Isuzu service center
>>> Trans overhaul [kit replacement] = P30,000
plus labor = P10,300
additioanal payment for solenoid if found shot
possible total cost = P50,000.00


2. Baltac Banaue [Thanks to Yourman for providing the detailed location of Baltac]
>>> Trans replacement [surplus form Japan] = around P30,000 plus
including labor


3. WALCO shop
>>> TPS = P5,800.00 [Am not sure if the throttle body is included]
>>> Solenoid Valve = P3,500 each . X3 = P10,500


**** My plan for this coming Two weeks *****


1. Recheck Fuse, Relays,Diode
2. Recheck ulit wiring, will try to replace connectors if needed
3. Recheck TPS assembly [voltage reading], will replace if found defective

4. If step 1-3 were found to be good, then will seek help from Baltac mech.

Note: I'll try to check the solenoids of Trans, using portable 12 DC power supply [negative pole of car bat. should be disconnected]. dapat mag engage ang solenoid kapag may 12DC [I set ko lang sa 8V-10V para safe]supply.


... That's all for now mga Sir, update po ulit ako maybe after two weeks


Thanks to 4jgtootsie, Nap123, Sir Joseph, Yourman, Jarhead, Galactus, Bluebimmer...


Best regards and more power to all.

[Hyakushiki]

Good luck bro.ltx! please do update us... meron din akong bighorn AT din.

[rion]

based from your description " it will only start to move * 2000 rpm"

and IF the line pressure test is really true, it is highy possible it's the tranny...
btw, did they say no pressure? then how did you reach the shop for testing your ride?

you could still run the vehicle without TPS, and it will still move and upshift. though the movement and shift is questionable.

Tanong lang if you don't mind guys...

where's the TPS power source comes from? how come some vehicles with same engine and model have different constant voltages? ex. there is the 5Volts constant on a vehicle, while the other same vehicle has 4Volts constant only. is there a resistor or some kind of 12V to 5V converter that needs to be adjusted here?

[4JGtootsie]

The ECU is responsible for most of the power supply of sensors.
Never interfere with the electricals of an ECU a slight change in voltage will render its computation invalid and inaccurate. Worst is it will destroy it.
What it usually do is send voltage to a sensor and reads the return voltage and makes the necessary adjustments by sending signals to actuators.

[rion]

but if your ECU is giving lesser voltage. like what I said. two same vehicles, Static voltage should be 5Volts Terminal-A and 1Volt Terminal-B . the fist vehicle has excactly 5volts, while the other has only 4Volts. but both has same 1Volt on Terminal B.

that will make your TPS send wrong voltage range. since you cannot adjust the vehicle 2 TPS because the terminal-B is giving exact voltage.

on ltx's case kasi, I think it's possible his TPS could be fine, it's the power supply that has a problem. no connection or bad power supply output perhaps.

though like I said, A vehicle could still run questionably without a TPS.

[4JGtootsie]

What is the normal voltage output of the ECU 5v or 4v?
It is possible that a lower voltage sent the same reading as the higher because it fell on the same range in the variable resistor.
Its also possible that 1 volt is the lowest voltage based on air volume entry.
Did you try measuring 5v and 4v at full throttle if it will still give 1volt?

[ltx]

[SIZE=3]

based from your description " it will only start to move * 2000 rpm"

[/SIZE]
[SIZE=3][/SIZE]
[SIZE=3]and IF the line pressure test is really true, it is highy possible it's the tranny...[/SIZE]
[SIZE=3]btw, did they say no pressure? then how did you reach the shop for testing your ride? [/SIZE]
[SIZE=3][/SIZE]
[SIZE=3]you could still run the vehicle without TPS, and it will still move and upshift. though the movement and shift is questionable.[/SIZE]
[SIZE=3][/SIZE]
[SIZE=3]Tanong lang if you don't mind guys...[/SIZE]
[SIZE=3][/SIZE]
[SIZE=3]where's the TPS power source comes from? how come some vehicles with same engine and model have different constant voltages? ex. there is the 5Volts constant on a vehicle, while the other same vehicle has 4Volts constant only. is there a resistor or some kind of 12V to 5V converter that needs to be adjusted here?

[/SIZE]


[SIZE=3]Correct Sir, my ride will start to crawl at 2000rpm [gearstick at “D”] [/SIZE]

[SIZE=3]=====[/SIZE]
[SIZE=3]TPS vs RPM [TPS measurement done using digital Volt meter][/SIZE]

[SIZE=3]0rpm = 0.05V TPS[/SIZE]
[SIZE=3]1000rpm = 0.25V TPS[/SIZE]
[SIZE=3]1500rpm = 0.35V TPS[/SIZE]
[SIZE=3]1750rpm ~2000rpm = 0.45V TPS , Bhorn will start to move[/SIZE]
[SIZE=3]====[/SIZE]
[SIZE=3]As per advice by mekaniko of Isuzu Service center; the result of line pressure test is “ NO PRESSURE”, ….eerrhh!! pero bakit umaandar pa din ang Bhorn kung pressure ang problem? .. e father ko pa nag drive papunta sa Isuzu cervice center, ok naman ang takbo.. nakaka overtake pa nga e [ basta I shift muna sa “2”, tapak accelerator, then shift to “D”.. ayun naka overtake pa. pero ang nakakapagtaka dito Sir, sabi ng mekaniko papalitan daw nila lahat ng o-ring, seal, ..etc .. pero pwede din daw ang solenoid ang problema … meaning hindi sila sure kung pressure nga talaga ang problema..[/SIZE]


[SIZE=3]With regards to TPS. TPS is a variable resistor, it has Three terminals; Ground, +V [depende sa PCM model] supply, and Signal terminal.[/SIZE]

[SIZE=3]The output voltage from Signal terminal of TPS usually varies depend on the resistance of TPS, this resistance varies depend on how heavy you step on the accelerator or opening of throttle window.[/SIZE]

[SIZE=3]The supply volatge of TPS comes from PCM .. [/SIZE]

[SIZE=3]Based on Isuzu standard TPS reading [signal terminal], specs from Isuzu manual[/SIZE]

[SIZE=3]Idling = 0.44 to 0.87[/SIZE]
[SIZE=3]Throttle wide open = 3.7V to 4.6V[/SIZE]


[SIZE=3]According to Isuzu Manual:[/SIZE]
[SIZE=3]Circuit Description[/SIZE]
The throttle position (TP) sensor circuit provides a voltage
signal that changes relative to throttle blade angle. The
signal voltage will vary from about 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is used by the powertrain control module
(PCM) for fuel control and many of the PCM-controlled
outputs. The PCM monitors throttle position and
compares actual throttle position from the TP sensor to a
predicted TP value calculated from engine speed.

[ltx]

TPS supply voltage [+5V] comes from PCM




At wide open throttle the reading from TPS signal terminal will be equal to supply voltage.

Therefore if the TPS supply voltage that coming from PCM is less than +5V... ex 1V lang ... at wide open throttle the voltage at signal terminal will only be ~1V ..

[rion]

What is the normal voltage output of the ECU 5v or 4v?
It is possible that a lower voltage sent the same reading as the higher because it fell on the same range in the variable resistor.
Its also possible that 1 volt is the lowest voltage based on air volume entry.
Did you try measuring 5v and 4v at full throttle if it will still give 1volt?

the normal is 5Volts.

tried it with plugged TPS, at full throttle, the vehicle A is almost hitting at 5V, while Vehicle B is almost hitting 4V.

also measured unplugging the TPS. to make accurate reading from the supply itself. Vehicle A is static 5V while Vehicle B is static 4V. but both have same less than 1 volt in the other terminal.

*ltx, have you tried measuring it while unplugging the TPS?

[4JGtootsie]

Is there any significant difference in performance between those with 4v and 5v?
Hindi kaya na program sa ECU na 4v lang ang ibigay?
Try ninyo pagpalit ang computer box to confirm.

[baker123]

Is there any significant difference in performance between those with 4v and 5v?
Hindi kaya na program sa ECU na 4v lang ang ibigay?
Try ninyo pagpalit ang computer box to confirm.

well sir. based on gas engines with TPS. yes meron difference. idle and gas consumption usually differs. pag wala sa tamang voltage or position. tumatakaw yung car. and usually. when engine braking. pumuputok yung exhaust.

could be the same with diesel engines too. both are running on computers. its always best when all are factory specs.

[4JGtootsie]

Now I think I know why 4v lang ang binabato.
At full throttle 4v lang ang babalik sa ecu therefore ang injectors will be releasing fuel good only for a 4v openning and not for 5v. Economy mode?
Send 3v and mas titipid pero mahina ang response.

[baker123]

Now I think I know why 4v lang ang binabato.
At full throttle 4v lang ang babalik sa ecu therefore ang injectors will be releasing fuel good only for a 4v openning and not for 5v. Economy mode?
Send 3v and mas titipid pero mahina ang response.

yes sir. but, this is not good with the engine. as the fuel injectors doesnt open much. but there are (full throttle) lots of air coming in the combustion. meaning "lean" condition na. so, engine knock. then ecu would retard timing if engine knock is detected. and if the engine is equipped with a knock sensor. kung wala mas bad nanaman. etc.

overall. the engine would not run efficiently. and may be disastrous in the long run. due to lean burn. must not forget. diesel engines are like 15:1 sa compression ratio or more. and this is turbocharged (4gj2) pa. so high comp. tapos lean burn. very hot running combustion chamber.

so economy mode? well dun tayo sa tip top condition para mas tipid. heheh magastos ang repair e.

[4JGtootsie]

I understand.
So going back to the question of Rion. Why are two identical vehicles sending two different voltages. Defective ECU or Set to do so?

[rion]

thats a good question 4J. the 4 volts has lesser response actualy.

and thats good idea, thanks for the tip, I will try to exchange the box...

underfueled diesel is not as bad as underfueled gasoline, I hear that there's no such thing as lean- diesels are always "lean-burn", and running rich/ overfueled increases power and temperatures.

however, the engine could be much more hotter if the fuel is very low, forcing you higher revs because of low power than before. and lesser power means longer upshift points...

[baker123]

I understand.
So going back to the question of Rion. Why are two identical vehicles sending two different voltages. Defective ECU or Set to do so?

ah yes. sorry sa tthreadstarter naging tps yung topic.

well 4jgtotsie. the TPS can be adjusted. just loosen the bolts that attaches it. put a voltmeter or multi-tester. move it and see the meter go up or down. then set to desired voltage. when close its 0.5V when WOT its 4.5V.

[baker123]

underfueled diesel is not as bad as underfueled gasoline, I hear that there's no such thing as lean- diesels are always "lean-burn", and running rich/ overfueled increases power and temperatures.

however, the engine could be much more hotter if the fuel is very low, forcing you higher revs because of low power than before. and lesser power means longer upshift points...

haha what i meant was leaner than what is desired by the engine. and yes they can go lean. lack of fuel delivery is the reason.

but, nevertheless, its bad for the engine in the long run.

[4JGtootsie]

ah yes. sorry sa tthreadstarter naging tps yung topic.

well 4jgtotsie. the TPS can be adjusted. just loosen the bolts that attaches it. put a voltmeter or multi-tester. move it and see the meter go up or down. then set to desired voltage. when close its 0.5V when WOT its 4.5V.

It can be adjusted, but what good will it do if the ECU is sending an in accurate voltage.