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Ask Matt Your Own Question

Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20378
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I've got a 2006 new shape sprinter that is really down on power,

Customer Question

I've got a 2006 new shape sprinter that is really down on power, even local mechaics are stumped as to what's going on with it! Diagnostic bringing up four codes, MAF sensor voltage too high and not in range or something? boost regulator and something else! Sorry cant remember more exactly what it said. The AA were out the other day and another code it brough up was a blocked DPF even though it wasn't showing on the dash, I've cleaned the DPF and it's not bringing the code up now but still no power! I'm losing the will to live here and no one seems to have a clue what they're doing! HELP ME PLEASE!
Submitted: 6 months ago.
Category: Car
Customer: replied 6 months ago.
I've also changed the air and fuel filter along the way, both of which weren't in that bad of condition to be honest. The steering was really heavy when I got the van so I've changed the power steering pump and fan belt and it was no better so I've now also changed the rack as well and it's fine!
Customer: replied 6 months ago.
Ok so I was expecting an answer by now, has this message even been viewed by any mechanics or have I just wasted more money on this van??? Or is the site just making me wait for my answer so I buy into the faster response time and pay more again? Sorry if I sound sceptic it's just I've been stung by a lot of sites in the past, promising lots and delivering nothing unless you keep paying and paying after you've already paid everything you thought you'd have to pay! Won't even let me post unless I remove the amount I've paid, starting to question what I've signed up for here!
Expert:  Matt replied 6 months ago.
HelloThis could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running. Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.Work your way through each possible joint one at a time and you should find it. I use a slightly flattenedpiece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements. It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.if the engine condition is the same then chances are the meter or the connection to it is faultyAir leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them. This leads them to be quite intermittent in the case of mild leaksits also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue On no account touch the sensor wires with anything physical as they are extremely fragile
Customer: replied 6 months ago.
Ok, thank you so much for your help. The engine sounds sweet and isn't running lumpy at all, it just has no power when driving. I'll have a good look over all the pipes tomorrow and use your method for discovering leaks and report back. What if I find no leaks? What then? Thanks, Mark.
Expert:  Matt replied 6 months ago.
Hello I'd also check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost. If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issuesAlso have a feel around with your bare hands with the engine running to see if you can feel any escaping gas under your touch. Another method is to use a soap and water solution sprayed onto any suspect areas - if there's a leak it'll bubble up with the engine running Also check that the vacuum hose running to the dump / turbo bypass valve is intact with no leaks as if the dump valve is opening prematurely you'll be losing all your boost If this is OK then remove the high pressure intake hose after the turbo and have a feel of the turbine wheel - there should be no play radially at all - but a little bit of axial / end to end float is normal one other possibility is that the wastegate actuator spring has gone soft so allowing the wastegate to open prematurely - if your actuator has a threaded end you can increase the preload on it to see if this improves things otherwise these units are quite cheap compared to a new turbo so it may be worth trying a replacement
Customer: replied 6 months ago.
Ok thanks, I'll work through all that tomorrow. I've just fitted a brand new genuine Mercedes boost control solenoid as this was showing as a fault on the diagnostic (this could of come up due to my friend bypassing it but I replaced it just incase) I know both the pipes and waste gate are fine with no leaks as when I pulled the pipes apart the next morning after bypassing the solenoid the pipes hissed and the bar moved back to its resting position so that system is 100% air tight. The waste gate has no adjustment on the bar but I have had the turbo off and checked it over, all seems fine and I applied high temp grease to the bar on the waste gate to ensure it was free to move. Will check everything you've said and come back to you tomorrow, thanks again, Mark.
Expert:  Matt replied 6 months ago.
Customer: replied 6 months ago.
I've also got a new genuine MAF sensor on order which will be with me Thursday as this is showing up on the diagnostic. Thanks Matt, chat soon.
Expert:  Matt replied 6 months ago.
no problem
Customer: replied 5 months ago.
Ok so I've checked all the pipes/hoses etc and no leaks anywhere. The intercooler is also fine. Mark.
Expert:  Matt replied 5 months ago.
hello Mark in that case it might be worth doing a compression test across all cylinder to check that they are all within 10-15 psi of each other

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