Chas:
Is it possible for the exhaust brake to stick on?
Absolutely.
Been having intermittent problems with a lack of power that I can’t quite fathom. Trucks been in the shop several times but to be honest, I have little faith in their diagnostic skills.
For no apparent reason the truck loses a lot of its power for acceleration, I’ve tried everything, every combination that could possibly affect it, yet I cannot induce it or replicate it on demand.
If the exhaust brake was stuck on when you pressed the accelerator you’d see a cloud of soot.
Occasionally, usually when I need it most, the bugger won’t rev through the range as normal.
IT IS NOT ENGINE MANAGEMENT & IT IS NOT DODGY DIESEL. The laptop diagnostics bring up 0 errors & the whole fuelling system has had manufacturer level mechanics look into it.
Some days it happens several times & some days it doesn’t happen at all !
Today was a bad day, & it’s doing my effin head in.
Throttle pedals are no longer connected to the engine by a cable but use a potentiometer so its electronic. You could have a faulty one of those or faulty connection or broken wire.
Sadly what most fitters know about vehicle electrics and electronics can fit on the head of a pin with room to spare.
If you can get the garage to hook up the diagnostic tool then go for a drive around the block while looking at live data readings on the map sensor and the common rail fuel pressure , does your truck use the ad blu system if so when the sensor starts to fail on them it causes strange power loss problems
What engine if its a 25 tonner it wont have that crap 220 (ha) horse 4 cylinder crap donkey in it.Is it the 240 or 290. (Is it a 2524 or a 2529)
Some engines dont use a flap valve(which are bloody useless anyway) but as the fuel shuts down compressed air is fed in to the cylinders so the engine turns into a compressor.If its a 2 position brake there are 3 solenoids that control this air supply 2 for the brake and one for the stop control under the drivers step and sometimes they stick,
As for “fitters” knowing bugger all about electrics,potentiometers etc Im sure "connor "could explain to us all how a throttle potentiometer with push pull wiper and track works.Go on lets have a laugh.
Check cam and crank position sensors are not full of dust or crap.Also check turbo charger actuation rod.Stupid bloody variabe geometry type.If the vanes stick you will get no boost and no black smoke because boost sensor will signal ECU to reduce fuel supply.
Merc engines are simple enough.Just old unit pump crap.Had one a while ago where the ecu shut down half the engine 4,5 and 6 intermittently.They have 2 ecus in one housing only cure is new ECU.
You sure its not a rigid Axor?
I’m having the same problem with my MAN TGX at the moment; lack of power and a bit of black smoke when it’s really struggling at 44t. No dash warnings, nothing showing up on diagnostics. It’s got our fitters perplexed and I suspect they think I’m just making it up. A couple of other people have suggested it might be the exhaust brake sticking on.
It’s relatively easy to physically check that an exhaust brake is not stuck on. As previously mentioned, it’s a case of removing the operating piston from the butterfly valve and making sure the valve operates and isn’t seizing. If this is ok then it could be the air cylinder at fault or a switch or even a broken wire. By process of elimination it should be very easy to locate the fault.
As for intercooler pipes drawing in air this won’t happen. The intercooler pipes are always at atmospheric pressure or pressurised by the turbo so if there was a hole/split you’d have air escaping from them, not being drawn in. The only pipe that could collapse is the one from the air filter to the turbo as the impellers draw or ■■■■ the air through. If this was the case then it would be a blockage in the air cleaner.
If it’s not the exhaust brake then it sounds like a mechanical issue rather than electrical. Some people are all too quick to plug a laptop in nowadays, find no faults and send the vehicle on its way. Sounds like this is a case where someone needs to get their hands dirty and get involved.
Chas:
Is it possible for the exhaust brake to stick on?
Absolutely.
Been having intermittent problems with a lack of power that I can’t quite fathom. Trucks been in the shop several times but to be honest, I have little faith in their diagnostic skills.
For no apparent reason the truck loses a lot of its power for acceleration, I’ve tried everything, every combination that could possibly affect it, yet I cannot induce it or replicate it on demand.
If the exhaust brake was stuck on when you pressed the accelerator you’d see a cloud of soot.
Occasionally, usually when I need it most, the bugger won’t rev through the range as normal.
IT IS NOT ENGINE MANAGEMENT & IT IS NOT DODGY DIESEL. The laptop diagnostics bring up 0 errors & the whole fuelling system has had manufacturer level mechanics look into it.
Some days it happens several times & some days it doesn’t happen at all !
Today was a bad day, & it’s doing my effin head in.
Throttle pedals are no longer connected to the engine by a cable but use a potentiometer so its electronic. You could have a faulty one of those or faulty connection or broken wire.
Sadly what most fitters know about vehicle electrics and electronics can fit on the head of a pin with room to spare.
How dare you? you cheeky SOB.Anytime you feel that you can tell me how trucks work please feel free to come to my house and I will pay for your beer and digs.
Then you can tell me how it works.
I been repairing this crap 35 years and I really need some steering wheel attendant to tell me my job.