04 hilux petrol runs rough

[Peeved]

Have an 04 hilux SR5 3.4l with 170,000 km on the clock that has been a dream until it developed a problem recently. Runs ok when first started, then starts to run rough after warmed up or turned off and restarted.Then it starts to shudder especially at idle, and lacks power,particularly on hills. Have just had plugs and leads replaced,Ignition coils checked and okayed. Cylinder pressures all good,and injectors cleaned [2 were borderline].After this work was done [$750.00 worth] it ran fine for a few days and then back to square one. It is actually a bit worse now in that it used to come and go, meaning after a while on a long trip it would suddenly come good. Now it runs for 5 mins. and the problem comes on and remains until turned off for a length of time. There are no warning lights on at any stage. Not prepared to go to Toyota re.this problem until I win tattslotto due to previous experience, and none of the mechs. I have talked to have a clue, just a matter of elimination and wallet reduction.Hoping for some help please.

[trentmeyer23]

Has anything else been checked on the fuel system?

[Manxman]

Prob bad fuel pressure--bad pump(S), regulator, blocked filter. MUST measure fuel pressure on common rail. pour one bottle of metho into 1/2 a tank of fuel. it will absorb all water and allow it to be burnt. otherwise thermal fault -bad sensor or electronics-need can of refrigerant to spray on things to observe changes..

bad injectors aren't helping. are they blocked or not sealing?

Edited March 7, 2015 by Manxman

[Manxman]

Were injectors tested on or off the car-pref off the car so the result is independent of faults in the car.

EFI is a pain in the neck. Most mechanics don't know enough to diagnose properly, and it's expensive and long term unreliable. It's only good feature is it is better metering than a carburettor, which I'd rather have because then I can fix it.

Edited March 7, 2015 by Manxman

[Manxman]

It's apparent to me that few mechanics understand how EFI is supposed to work as a concept. All they are capable of is module replacement, until it's fixed. They are unable to diagnose what's likely to be wrong. It may be lack of experience, but I think it's lack of understanding. Most systems operate with the same sorts of sensors, which generally measure similar magnitudes, and whilst the individual cars are different physically, they are all electrically and combustionally similar. We've had EFI for 20 yrs. there's no longer an excuse for ignorance. It's not terribly difficult to learn how it operates. It's reasonably predictable in operation and when certain faults will occur. It's just wilful incompetence that people cannot or will not do what their job entails. There's nothing to be afraid of, it won't hurt you or self destruct if you follow a few precautions, and most problems are simple fixes. It only requires a modicum of intelligence. My skills are almost all self taught, by virtue of necessity. I'm certain proffesional instruction can do better.

[Peeved]

The first thing I tried was draining fuel tank to remove possible contaminates,no result. I have checked manual to see if filter is servicable , not sure if it has ever been replaced.Wondered if a crack or loose fitting in fuel line was to blame due to the fault occuring when engine is warm but there are no obvious leaks of any kind near motor. Injectors were checked when taken off engine.I do not think the CO levels have been looked at but it does not blow any smoke.Diagnostic results indicated faults with air intake sensor and this was tested with a new one for no result. Thanks all for your replies and ideas.

[TiAg]

On 3/7/2015 at 6:35 PM, Peeved said:

Have an 04 hilux SR5 3.4l with 170,000 km on the clock that has been a dream until it developed a problem recently. Runs ok when first started, then starts to run rough after warmed up or turned off and restarted.Then it starts to shudder especially at idle, and lacks power,particularly on hills. Have just had plugs and leads replaced,Ignition coils checked and okayed. Cylinder pressures all good,and injectors cleaned [2 were borderline].After this work was done [$750.00 worth] it ran fine for a few days and then back to square one. It is actually a bit worse now in that it used to come and go, meaning after a while on a long trip it would suddenly come good. Now it runs for 5 mins. and the problem comes on and remains until turned off for a length of time. There are no warning lights on at any stage. Not prepared to go to Toyota re.this problem until I win tattslotto due to previous experience, and none of the mechs. I have talked to have a clue, just a matter of elimination and wallet reduction.Hoping for some help please.

Sorry for bumping an old thread. I have exact same issue as described done some of the same work plugs,Leads,Coils, Fuel filter.

Almost seems like it shuts an injector off.  For a test when its running good i pulled one injector plug while it was running and i acted sounds the exact same as when i plays up.

Edited March 5 by TiAg

[TiAg]

Just to add we narrowed it down to no.6 cylinder. Spark is good when it decides to play up. and compression is a perfect 180psi.

So it's gotta be fuel injector or related to what drives it, ECM?. Or something else is telling cylinder 6 not to inject fuel. Crankshaft sensor? 

 

Edited March 6 by TiAg

[TiAg]

Update. It was the injector! Ended up replacing all 6 though. no problems since.