Diesel Fuel Injection System Help Desk

[RustyXIII]

What are the possible reasons when a diesel engine loses top speed? May arangkada pero bumaba ang rekta. I can still reach 100KpH without problems but that's it. Used to reach 120KpH, even 140KpH once when I really floor it. It's as if the last 1/4 of the accelerator pedal travel does not give any additional speed.

No black smoke, one-click start in the morning, fuel consumption is still the same, no weird noises/rattles, clutch is not slipping. Just a lower top speed.

Vehicle is a 2006 Mitsubishi Adventure. 4D56NA.

[Dieseldude]

What are the possible reasons when a diesel engine loses top speed? May arangkada pero bumaba ang rekta. I can still reach 100KpH without problems but that's it. Used to reach 120KpH, even 140KpH once when I really floor it. It's as if the last 1/4 of the accelerator pedal travel does not give any additional speed.

No black smoke, one-click start in the morning, fuel consumption is still the same, no weird noises/rattles, clutch is not slipping. Just a lower top speed.

Vehicle is a 2006 Mitsubishi Adventure. 4D56NA.

1) Blocked fuel filter.

2) Check accelerator pedal travel and cable adjustment.

[asher25]

dieseldude, dami ko pong tanong.... we replaced the timing belt our trooper 4jx1 is having an abrnormal engine vibration "parang alog2x"shaking ba ang tawag at hindi siya stabilized during idle....

we brought the unit to the casa for scan and diagnosed the problem they said injector daw..so did replaced the fuel injector but the problem still exist.. diangosed again rpcv naman ang sira so palit naman ng rpcv pero ganun parin at lumala pa pag shifting gear na like nasa 1500 to 1700 rpm black smoke is coming out everyitme hit the pedal pero saglit lang yung usok..so he did blocked the vacuum to egrvalve para mawala ang itim na usok pero bitin yung power during acceralation..

hindi naman po hardstarting or matakaw sa oil...
may mis aligned kaya na ngipin sa timing ng engine? need to adjust yung timing ng injection pump or calibrate the the injection pump?
kapag loose compression po? causes din ba ng strong vibration?
anu po ang dapat na gawin?

thanks sa magrereply...

asher.....

[Dieseldude]

dieseldude, dami ko pong tanong.... we replaced the timing belt our trooper 4jx1 is having an abrnormal engine vibration "parang alog2x"shaking ba ang tawag at hindi siya stabilized during idle.... Kelan nag simula ang abnormal vibration, before or after timing best was replaced? Nag iimprove ba ang performance pag mainit na ang engine?

we brought the unit to the casa for scan and diagnosed the problem they said injector daw..so did replaced the fuel injector but the problem still exist.. Did casa install new injectors and code these to the ECU?

diangosed again rpcv naman ang sira so palit naman ng rpcv pero ganun parin at lumala pa pag shifting gear na like nasa 1500 to 1700 rpm black smoke is coming out everyitme hit the pedal pero saglit lang yung usok..so he did blocked the vacuum to egrvalve para mawala ang itim na usok pero bitin yung power during acceralation..
hindi naman po hardstarting or matakaw sa oil...
may mis aligned kaya na ngipin sa timing ng engine? This is possible. Did casa check timing?
need to adjust yung timing ng injection pump or calibrate the the injection pump? 4JX1 does not have an injection pump.....so walang kelangan icalibrate.
kapag loose compression po? causes din ba ng strong vibration? Possible yan. Did casa do a compression test before replacing the injectors and rpcv?

anu po ang dapat na gawin? Mahirap sagutin dahil naniniwala akong marunong ang casa. Nagtataka lang ako kung bakit hindi ginawa yung basic checks bago pumunta sa maraming palit ng pyesa. Back to basics sana ang approach.
1) Did they check/replace oil and filters? Correct oil type is critical on these engines.
2) Was your timing belt installation rechecked by casa?
3) Was compression test performed before replacing any major parts.

thanks sa magrereply... Asher, sa palagay ko, dapat magbigay ng tamang sagot ang casa sayo sa laki na nang ginastos mo. Meron pa bang check engine light after all these repairs have been done?

Good luck......and keep us posted

asher.....

[r_delro]

I will PM you.

This is how repairs are often done:
1) Do a scan and perform repair on any detected fault/s. Fyi, Scan tools can only detect electronically related faults. Most mechanical problems cannot be seen by a scan tool.
2) If no fault/s are detected, it is very possible that the problem is mechanical in nature. This is the more difficult part as the mechanic has no fault code to guide him. He will have to check all possibilities. This takes a lot of time and effort.

The hard part is locating the problem. Once the faulty part is identified, it is now just a matter of doing the corrective action. Your problem could more difficult to diagnose/repair as Toyota has twice worked on your car with no success.

Thanks sir dieseldude for the response. Ipon muna ako siguro ng budget at pag maluwag na. Also received your pm. Thanks.

[asher25]

[QUOTE=Dieseldude;1836133]dieseldude, dami ko pong tanong.... afterwe replaced the timing belt our trooper 4jx1 is having an abrnormal engine vibration "parang alog2x"shaking ba ang tawag at hindi siya stabilized during idle that i did'nt noticed before.... Kelan nag simula ang abnormal vibration, before or after timing best was replaced? Nag iimprove ba ang performance pag mainit na ang engine?after we replaced timing belt... ok namn ang performance pag miinit ang engine..

we brought the unit to the casa for scan and diagnosed the problem they said injector daw..so did replaced the fuel injector but the problem still exist.. Did casa install new injectors and code these to the ECU?i think nope and not sure... i'm coming back ask them

diangosed again rpcv naman ang sira so palit naman ng rpcv pero ganun parin at lumala pa pag shifting gear na like nasa 1500 to 1700 rpm black smoke is coming out everyitme hit the pedal pero saglit lang yung usok..so he did blocked the vacuum to egrvalve para mawala ang itim na usok pero bitin yung power during acceralation..
hindi naman po hardstarting or matakaw sa oil...
may mis aligned kaya na ngipin sa timing ng engine? This is possible. Did casa check timing? nope
need to adjust yung timing ng injection pump or calibrate the the injection pump? 4JX1 does not have an injection pump.....so walang kelangan icalibrate.okeykapag loose compression po? causes din ba ng strong vibration? Possible yan. Did casa do a compression test before replacing the injectors and rpcv?nope thye only scan it with tech2

anu po ang dapat na gawin? Mahirap sagutin dahil naniniwala akong marunong ang casa. Nagtataka lang ako kung bakit hindi ginawa yung basic checks bago pumunta sa maraming palit ng pyesa. Back to basics sana ang approach.
1) Did they check/replace oil and filters? Correct oil type is critical on these engines.about top change oil na rin po..2) Was your timing belt installation rechecked by casa?nope3) Was compression test performed before replacing any major parts.nope
thanks sa magrereply... Asher, sa palagay ko, dapat magbigay ng tamang sagot ang casa sayo sa laki na nang ginastos mo. Meron pa bang check engine light after all these repairs have been done?walapa naman po QUOTE]
Good luck......and keep us posted

asher..
i'm coming bukas sa casa and i will ask them and perform those things..thank you po

[Dieseldude]

Asher, scanning and diagnostics are two different things.

Scan tools don't have complete capability to check all engine faults. It can only read electronically related faults which are detected by the car's ecu. It will immediately see a faulty sensor or circuit.

Poor quality oil, restricted filters, wrong valve clearances, worn engine bearings are just a few examples of mechanical problems which cannot be detected by the ecu and/or scan tool. The mechanic will still have to use his skills training to fully diagnose a problematic vehicle.

Scanning is easy.....takes only a few minutes. Replacing the failed part is also easy. The most difficult part is diagnosing to know which part is faulty and needs to be replaced. It may take even a couple of days to do a thorough diagnostics.

Keep us posted on the situation of your car. This will be a big help to other 4JX1 owners.

Your car may have a mechanical problem as your check engine light is off.

[cokezero]

i have a isuzu ls 1994 model.. normal lang ba na kada startup (morning) ng pickup ko lalabas yung oil & batter indicator tapos kelangan ko pa mag antay until mawala yun (siguro 15-20min) bago magamit yung pickup.. *btw nawawala agad pareho pag ni-revolution ko agad

[Dieseldude]

dieseldude, dami ko pong tanong.... afterwe replaced the timing belt our trooper 4jx1 is having an abrnormal engine vibration "parang alog2x"shaking ba ang tawag at hindi siya stabilized during idle that i did'nt noticed before.... Kelan nag simula ang abnormal vibration, before or after timing best was replaced? Nag iimprove ba ang performance pag mainit na ang engine?after we replaced timing belt... ok namn ang performance pag miinit ang engine..
Since abnormal vibration started after timing belt replacement, it is very possible that the engine is out of time. I suggest that engine timing be rechecked.

i'm coming bukas sa casa and i will ask them and perform those things..thank you po
You're welcome... Please keep us posted.

[Dieseldude]

I have a isuzu ls 1994 model.. normal lang ba na kada startup (morning) ng pickup ko lalabas yung oil & batter indicator tapos kelangan ko pa mag antay until mawala yun (siguro 15-20min) bago magamit yung pickup.. *btw nawawala agad pareho pag ni-revolution ko agad.

Oil light on indicates low oil pressure
Battery light on = alternator not charging enough.

Your idle speed might be too low at morning starts:
1) Low engine rpm = low oil pump speed = low oil pressure
2) Low engine rpm = low alternator speed = low charging current

Sana ganito lang ka-simple ang problem......1994 model = 17 year old engine, may have other related problems....