Low power/boost on Ford TDCi engine
On our last trip to France, our van experienced what appeared to be a major fault, such that it struggled going up hills which is unheard of for these vans! It was as if the turbo wasn’t working properly, or for whatever reason the van was sluggish as pie. We did some basic checks in France and decided it was safe to continue till we got back to UK for further diagnosis. This diagnosis was VERY thorough and as this seems to be a “common” fault I decided to write up all the tests so they could be useful for someone (and me!) should similar happen again.
What I found was that there were many trivial problems that could cause this (or similar) issue.
My “problem” and “fix”
My particular issue was, would you believe, caused by *someone* swapping the EGR and Turbo Actuator Vacuum hoses around (!!!) – and it wasn’t me as until I undertook my research to diagnose the issue I didn’t know what the hoses were for…. And during the time the van was well, to the time we noticed the fault, it was only out of my posession once at a “trusted” garage…… And, of course, they deny all knowledge and accuse me of questioning their integrity and now refusing to speak lol…. Actualy “mate” – no. If I was diagnosing a fault and had an identical van next to it, its par for the course to look at another one and compare. I would, I asked them and a friend to do checks on similar vans for me, and if I had one nearby I’d have asked to do the same! I almost hired an identical van so I could compare! I’d not worry about people using mine. However, on this ocassion, someone put the pipes back on backwards! And actually, for a fact, one of the team there DID compare a van on your site with mine that did involve removing a vacuum pipe – so saying its not something you would do is laughable.
The fix (once found) took 30 seconds to put right, simply by swapping the vacuum hoses back to the right connectors. No harm done, just frustraiting!
In future, I will be photographing the engine before leaving the van anywhere, not just the exterior which I used to do!
Thanks and Credit
This article will hopefully be useful to someone, but beyond typing it I cannot take all the credit. Some friends helped me out for advice, and a number of guys on FordTransit.org forum gave me pointers, accurate information, specific information and tips – one of which identified the swapped pipes. Without these guys, I’d have been lumbered with a huge bill from a garage (possibly the same one mentioned above) for diagnostics and fixes.
I strongly recommend that if you have a transit and an issue, then chat to the guys on FordTransit.org – and search their archives as there is a HUGE amount of information there, and lots of willing people who know a lot (and I mean a LOT) more than me.
I am an IT guru, I am not a mechanic. The information here is specific to my van, a 2005 Mk6 Ford Transit SWB280 FWD 2L TDCi. Whilst I know some information is common between other TDCi variants, the specifics are ONLY for ME AND MY VAN. If you decide to use MY PERSONAL NOTES on your van, please be aware this is entirely at your risk and of course you should not believe anything I say and you should take your van to a trusted garage! Do not attempt to do anything that I have!
Characteristics of fault
Bizzarely, the van drove quite well – on the flat (Wiltshire!) it drove fine, felt maybe slightly down on power, but really nothing to worry about. Of course its a campervan so we don’t thrash it or drive fast. MPG same as normal (mid 30’s), starts first-time every time, and idles fine.
The main way to notice the fault were:-
- At 3200rpm, when static on drive, the van would stutter (as if on a limiter) and smoke before exceeding 3200rpm. When driven, this was fine.
- Going up-hill or on overtakes when power was required, it was flat. It’d still get up the hills but slower and a gear lower (e.g. feeling like an old van)
- No extra smoke or noise.
Note I did NOT have a MIL (engine management) warning light on the dash at first. Only after I paid Ford £90 to update the ECU to the latest software was the fault detected. Once the new software was on, the van entered LHM (Limp Home Mode) so was worse to drive (doh!) – with the error being “p0235 turbocharger boost sensor a malfunction”. At least this helped focus the mind….
(If you have issues starting, or a rough idle, you are likely to have other problems than here)
Possible areas to check
Here is a list of checks I did, each is explained further down the page
- Fuel Pump / Injectors
- F-Super Diagnostics
- MAP Sensor
- MAP Sensor wiring
- MAF Sensor
- MAF Sensor Wiring
- Fuel Filter
- Air Filter
- Turbo (Inlet)
- Turbo boost pipes
- Inlet Manifold
- Vacuum pump
- VNT Actuator
- VNT Vacuum pipework
- VNT Solenoid
- ECU Reset
Tools and stuff to buy
I bought the following tools to help me sort this out, and they were necessary! (the links are to the items on Amazon, if you click and buy, I get 5% sales comission from Amazon. I bought some stuff from Amazon and some elsewhere.)
- Multimeter and Piercing Probes: Essential for wire checking
- If you do continuity tests on wires/sensors, best to have the battery disconnected to save ECU
- Unplugging pipes/sensors as part of the diagnostics may trigger other fault codes (e..g disconnect a sensor, you may get sensor fault; disconnect a pipe you may get airflow fault). f-super deals with this
- Don’t trust Ford entirely – their engineer didn’t find the swapped hoses (despite being told low/no boost; and despite having a computer that could test turbo actuation – which would instantly show it didn’t move when expected which would quickly show the swapped pipe!)
- These are MY NOTES – they may be useful for Transit or Mondeo TDCi engines or other engines, but don’t take them as gospel!
After my ECU update and the newer software detecting a fault, the van then moaned about P0235 – “turbocharger boost sensor A malfunction”. What this really means is “the data I am getting from the
Silly as it sounds, check all 4 corners and ensure your brakes aren’t sticking/binding. If they are, this can give the impression of lack of power.
2.Fuel Pump / Injectors
Fortunately I didn’t need to examine these, but these can be a cause of low power. However, from my research a fault with either of these would typically flag a DTC identifying them, or you would have other symptoms – like poor starting or idle. This subsystem is quite complex, and almost certinly left to an expert.
3.F-Super DiagnosticsIt also allows you to read (and clear) DTCs as necessary. As not all codes flag up a MIL light, it is worth checking anyway.
The interface port is under the steering wheel.
A point to note, my late Mk6 didn’t flag any error codes, but after a trip to Ford and £90 later, they updated the ECU software and the newer software did indeed flag a code (and put the van into limp mode 🙁 ) – however this did help me diagnose where to focus my attention even if Ford read the code and insisted the MAP sensor was faulty (even though I didn’t think it was).
With f-super, some key bit of information:-
- BARO is air pressure, and is out by a factor of 10. So 100 is roughly 1000mb. (MAP sensor). Should be roughtly 99-101 depending on the weather and altitude. Note on images mine is 88 – thats because I was up in the Alps!
- MAP is manifold absolute pressure, and is in effect boost pressure. It is in effect a factor of 100 out! (see MAP sensor). On idle, it should match BARO (x10), and on revving to 2-3000 revs should read up to 14. (Boost pressure in PSI = (( 10xMAP ) – BARO ) x 0.145. So, if BARO = 100, and MAP = 14, then PSI = ( (10 x 14) -100 ) x 0.145 = (140 – 100) x 0.145 = 40 x 0.145 = 5.8 psi boost
- IAT is inlet air temperature (from MAP sensor which is actually a T-MAP sensor)
- APP1-3 is throttle position
- FRP = fuel rail pressure
- MFdes is metered fuel
The rest of the readings are obvious, so look at what they are. The temperatures should all be logically correct.
I’ve included some images of f-super on my van which may be useful to compare – the only thing to rememeber is these were taken in the Alps when the turbo wasn’t connected properly, so MAP (aka “boost”) will be a lot lower than it should be.
Ford, in their £90 diagnostic session where they failed to test the turbo actuator or notice the vacuum pipes were wrong, simply saw the P0235 error and said it was a faultly MAP sensor. After trying to charge me £380 for a new sensor and intercooler I bought just the sensor from a parts place opposite, fitted it in 2 mins, proved it wasn’t it – and then was told “tough – come back another time to continue diagnostics”….
Anyway, the MAP sensor is a TMAP sensor which reads boost pressure, air temperature, and also atmospheric pressure. Absolutely no idea how it does the latter….
This is located on the off-site pipe at the bottom of the intercooler. It comes off simply with 2 star-shape (torx) screws. The electrical connector unplugs. On other vans this is near the EGR and hence gets gunked up – so if its dirty, clean it gently – it should be spotless (mine was). Also clean and check the electical connectors. Mine looked all fine and actually gave correct readings in f-super – so why Ford said it was faulty….. ARGH! lol!
Anyway, using the
You can also directly check voltages (thanks to Dan @ FordTransit.org)
The map sensor loom has 4 pins;
1. MAP reading
2. 5v reference
3. IAT reading
So… With ignition on pin 2 should read 5v and pin 1 should read 1.5v
At engine idle pin 1 should still read 1.5v, with a little throttle the voltages will increase to about 3.9v roughly.
Pin 4 should earth with no resistance (0 ohm)
Discount pin 3 as it works the iat sensor.
5.MAP Sensor wiring
On the forums, and a friends experience, the wiring to the MAP sensor can corrode or wear through. If you clean the sensor wires you can see they are colour marked – make note of these. Note each wire has a PRIMARY colour and then a thinner SECONDARY stripe. This is important – white with green stripe looks similar to, but is different to green with white stripe!
The wires go into a loom and cover, up near the radiator, under the AC pipes, behind the air-filter housing, across the windscreen to the ECU on the near-side top part of the engine above the coolant bottle.
- Check the wiring to the plug
- Open and check the loom from the MAP sensor up – reports of corossion up to 10cm away from plug
- Check wiring behind air-filter housing (a bitch to get to if you have AC and after market cruise control!) – a friends had worn through here due to bad fitting at Ford.
- I personally openned the loom near the ECU (tape unwraps), found each of the 4x MAP wires, and with BATTERY DISCONNECTED I checked continuity between here and the plug (using automotive piercing probes), also I checked for shorts to ground, all whilst wrigging the cable along its entire route.
So its essential that there is 100% continuity at all times, and there are no shorts to earth. The exception is Pin 4 which should be earth and 100% continuity to earth at both ends.
The MAF sensor measures air flow being sucked in via the air filter housing. The ECU uses this to determine how much air is in the system and how much fuel it can lob in. So a duff sensor can mean very poor power.
This is simply held in with 2 torx screws. Once removed be gentle as the element is very very fragile.
If you think you have a faulty MAF, the “internet says” to simply disconnect it! The ECU will revert to a safe program assuming safe settings for what the MAF should be. If the van drives the same/better, then the MAF is faulty. If it drives worse – it isn’t!
You can clean the element – gently – with a cotton bud and electrical cleaner.
You can test the voltages on the sensor and you should get, roughly:-
- Pin 2 (to earth): 12v (12-14v)
- Pin 5 to earth, on idle, 1.7v
- Pin 5 to earth @ 3000rpm 3,4v
In other words, Pin 5 voltage should vary smoothly depending on RPM.
7.MAF Sensor Wiring
Similar to the MAP sensor wiring, I would treat this the same. I checked all the way back to the ECU loom. See MAP sensor wiring.
The vans appear very fussy on fuel filters as the fuel filter is particular to the TDCi engine as it is a finer filter than the TDDi. So, ensure you have a new and GENUINE and TDCi fuel filter. If you did a DIY change, ensure you did it properly to avoid air in the fuel lines – remember the TDCi does not have a fuel lift pump!
If you haven’t got a genuine TDCi filter – put one on.
If at any time you’ve had a non genuine or a TDDi filter on, then you may have fuel pump/injector issues…
A dull possibility, but check your air filter! If its clogged it will starve the engine of air and hence power. I’d take this further and check the airbox and the inlet pipe to the grill – you don’t know if a bird is nesting/rotting in there! Check the pipes to the air resvoire and ensure they are all spotlessly clean.
Check all pipes are in good condition and not split
Simple, but worth checking
Remove the pipe from the air resovoire to the turbo inlet. Its a bit awkward to get at the turbo side, but do this and ensure the pipe is clean. It is also linked to the crankcase breather, so ensure there isn’t gunk there.
Once the pipe is removed you can actually stick a finger in the turbo and touch the compressor rotor. Spin this manually and ensure it spins easily and freely, and ensure there is no play in/out or side/side if there is, then you have a turbo issues of some sort. It should not move much beyond rotating freely.
Once that is clear, reassemble and I would suggest removing a “Boost pipe”, maybe the first one (from turbo to intercooler) as its easy to get to. Then start the engine, and at 2000rpm air should be blown out. If no air is blown out at all, then your turbo isn’t working or the pipes are blocked.
See sections on boost pipe & VNT actuator for futher tests.
11.Turbo boost pipes
Post turbo, the pipes will be (or should be) under pressure when the engine is being revved or driven. As such the pipes will be under pressure and leaks may become apparent. The problem is, at idle, there isn’t always enough pressure to show leaks.
I took off and manually checked every pipe from the turbo to the inlet manifold. There are rubber pipes to inspect for signs of wear on joins, or splits, or any form of damage. There is also the EGR pipe which is metal where someone on the internet has had a pipe split and needed it welding. So check everything.
Pipes are fairly easy to get off with the exeption of the ones connected to the turbo boost outlet! There, there is a short flexible bit of rubber, linked to a plastic thingie, then to a rubber pipe. All mine were in perfect condition but it was easy to see how pipes could split and not be evident from a visual test.
Any leak would give lack of power, so check carefully, and reassemble well!
The inlet manifold sits under a few bits, so see HERE for instructions on how to remove it. This is worth checking as if you haven’t blocked your EGR valve, all the exhaust crap will be going into the inlet manifold and blocking it up. I’ve seen pictures with 30% gunk! Mine (with blank EGR) was 99.9% clear 🙂
But worth taking off, checking and cleaning.
Also, inspect for damage and cracks, again someone on the internet has had a cracked inlet manifold which would vastly reduce boost pressure. Definately inspect carefully.
Bearing in mind the turbo pipework is connected to the crank breather pipe, and the EGR is linked, then any gunk/oil in the air will accumalate in the lowest possible point – which is the intercooler. Many people have blocked intercoolers which will restrict the flow of air and thus boost pressure.
I would take off the in/out boost pipes of the intercooler, and clean up one of the sides. Then simply blow through it. You should get fairly free-flowing and unrestricted air going through. If it is excessively dirty or restricted then you will need to clean it out or use a new intercooler. (You can’t bypass the intercooler as the MAP sensor would then not get a boost reading and you would cause a boost error DTC!
The EGR is a valve that sends dirty exhaust gasses back into the engine for a second burning. This is entirely for emisssions control, but the side effect is all the crap in the exhaust goes back through the valve, back into the inlet manifold and makes a mess.
On the Mk6 van the EGR is vacuum operated and does NOT have any sensor on it – so this means you can block it and stop it sending the dirt into the engine! This means the engine gets cleaner air and there are no side effects.
On my van, the EGR failed (due to getting covered in soot) which is common, so I disabled it. See HERE for detaild of EGR fixing.
The vaccum pump is bolted to the engine, and how it works is beyond this scope. However, what it does, is provide a constant vacuum to the devices that need it – namely the brakes and the VNT/EGR solenoids.
All we care about here, is to ensure there is enough vaccum being sent to the VNT/EGR solenoids.
There are 3 vacuum pipes that run across the engine next to the oil filler – one goes to EGR, one goes to VNT, and one goes up to the top of the engine, then left towards the brake servo. This is the one we want to test as it is this that provides the vacuum needed to operate the turbo.
Locate this pipe and pull it apart on the 90′ elbow.
With engine off, using the
With engine running, connect to the side of the pipe connecting towards the vacuum pump – and this should suck > 70 kpa and be constant. Any less, check pipes and ensure vacuum pump is OK
The VNT actuator is basically a vacuum operated lever which controls the variable veins inside the turbo, and hence the amount of boost. The ECU should adjust this constantly based on boost demand and RPM.
- With engine not hot, feel behind where the arrow is and find the actuator. This feels like an old throttle cable type setup.
- With engine off, the actuator should be relaxed (back), and you should be able to pull it forward with one finger. Let go, it should spring back. If not, your VNT is probablu crudded up with carbon and will need clearning.
- Assuming it is smooth and moves freely, continue tests….
The way it should work is:-
- On engine off, relaxed
- On ide, pulled in
- On revving from idle to 3000rpm fairly gentle, the lever show go back slowly
If so, it is behaving
If not check:-
- Actuator should move at least 10mm between “on” and “relaxed”
- When vacuum applied to actuator, it should remain. If it leaks you’ve got a broken vacuum diaphragm.
To check to ensure the VNT is moving, remove the 90′ intercooler elbow and start the engine.
- On idle, with vacuum off (and turbo relaxed) there will be only a very very small blow
- On idle, with vacuum on (and turbo in) there will be a gentle blow
If this is the case, turbo is working!
17.VNT Vacuum pipework
If the turbo is working by manually applying vacuum but not always automatically, check the pipework. Trace the VNT vacuum pipe back back to the solenoid, and it should be connected on the top (see next section). Disconnect from solenoid and apply vacuum to that pipe. 65kpa should move the actuator fully and the vacuum should hold. If not, you have a leak.
Note – my issue was someone swapped the VNT pipe to the EGR pipe on the 90′ elbow to the right of the oil filler – so check carefully that it goes back to the correct solenoid.
The VNT solenoid is basically an electronic valve that applies vacuum based on input voltage – thus the ECU controlls this valve to control VNT position by varying voltage. This is on the off-side part of the engine attached to the bottom of the air-filter box. (removing the air intake pipe makes access easier)
It has an input from the vacuum pump, and outlet to the air filter which are shared between the EGR and VNT solenoids. And the top solenoid (green plug) controls the VNT actuator the bottom solenoid (black plug) controlls the EGR.
- With engine running, unplug the pipe coming from the vacuum pump – check you get >70kpa vacuum
- With engine running, check that at least 65kpa is being sucked in on the VNT pipe
- Check the green plug is in correctly, and when engine idling, it has 12-14v on one pin, and 10+v on the other pin. (between pin and earth).
In my tests, on idle, the green plug is powered and vacuum is demanded and actuates the VNT; then unplug the green plug and vacuum is released and turbo relaxed. Ensure the green plug/top pipe is to VNT!!!!!
Last resort that did nothing for me, but as the ECU “learns” how the vehicle behaves it tunes itself accordingly. Disconnecting battery for 48 hours resets all these parameters…. As I said, last resort….
It was mentioned that blocked/failed CAT or exhaust could restrict air flow out, so something worth considering if you feel this is the case. I “tapped” the entire length to see if anything sounded solid, but beyond that I assumed it was OK. To be fair, it “felt” and “sounded” okay. But, cats fail and block the exhaust so don’t rule it out.
Do note, TDCi VNT engines do not like being de-catted! TDDi engines are, apparently, ok, but don’t do it on a TDCi without research!