Hi,

I have a 1.6TDCI focus with poor power for a few months now, no lights on dash.

Sometimes the power does come back randomly but when it does there is black smoke from the exhaust especially if accelerating hard, generally the power will only come back for 5 miles then back to low power (sort of feels like a 1L Corsa)

In general the exhaust doesn't smell great like poor combustion but when power is poor there is no smoke.

Any ideas what to check first? (was serviced a month or so ago which was a few months after starting having issues so should rule out filters)

TIA

Any suggestions?

Checked DTC no codes, doesn't idle rough either but when revving and letting go, sometimes needle will drop as low as 400rpm then bounce back up to around 800rpm stable

MAF would be my first thought.

I take it the lack of DTCs was on a generic OBD reader rather than Forscan?

Thanks Tom, generic yes

I did notice the MAF at idle was 10g/s which seem high so I ordered a replacement as they dont cost much/easy to try. The MAF had oily residue all over it. Though when reving the mass air flow goes up perfectly linearly with rpm so almost looks like it does work. 

If MAF is high and its not the sensor then what? I read EGR could cause MAF readings to be out but I would have thought if EGR is always shut closed then I wouldn't have performance issues, if MAF was stuck open I'd assume MAF would drop

Thanks

Not the answer you want but really the next step is to get Forscan on it.  That'll generally pick up fault codes that generic OBD can't see.

It does sound like your MAF is working ok.  Really just suggested as they don't often throw codes and most people won't check the flow rates on diags before posting on here.  You're absolutely correct in that EGR opening reduces the flow through the MAF.

Which 1.6 is it?  16v or 8v?  90/110/115bhp?  Reason I ask is there are different turbo's, different EGR valves, some have DPFs, some don't, etc.  At the moment there are too many variables to just start throwing parts at it.

5 hours ago, TomsFocus said:

Not the answer you want but really the next step is to get Forscan on it.  That'll generally pick up fault codes that generic OBD can't see.

It does sound like your MAF is working ok.  Really just suggested as they don't often throw codes and most people won't check the flow rates on diags before posting on here.  You're absolutely correct in that EGR opening reduces the flow through the MAF.

Which 1.6 is it?  16v or 8v?  90/110/115bhp?  Reason I ask is there are different turbo's, different EGR valves, some have DPFs, some don't, etc.  At the moment there are too many variables to just start throwing parts at it.

109HP 16V (in MK2 focus)

If its not the MAF then any idea why would it be reading 10g/s at idle, everywhere I read online says 2-7g/s at idle is normal? EGR error at idle is 50% give or take which further concludes were in the right sort of area, I'd believe the EGR error is calculated using MAF in these older engines

If the engine thinks it's getting more air than it should then fuel mix ratio will end up being wrong/bad performance/smoking/rich exhaust?

10g/s doesn't sound unreasonable for this engine.  2g/s would be far too low, that's probably a petrol value.  Sure I'll be corrected if wrong.

EGR Error is misleading at idle.  Should get a more accurate figure while cruising.

Thanks, just read up more I think you're right.

Just stuck with what to try next 😩

10 minutes ago, Ionise said:

Just stuck with what to try next 

Forscan...

Luckily after an hour of searching for my old f super obd (a bit better than genetic one) I connected quick and read DTC. I have no idea what these mean, a garage who fixed my alternator about a month ago reset my DTCs so these are something present

Thanks.  Although that raises more questions than it answers!

There aren't any lambda sensors on these, so nothing to determine cat efficiency.  I guess it could be used for a clogged DPF, but that really is just a guess at this point.

There are a couple of throttle bodies.  One partially closes the intake when the EGR opens.  The other is an intercooler bypass valve, that removes the intercooler from the system for a quicker engine warm up.  If the intake one is stuck open, that could cause issues when the EGR opens.  That would be my first check personally.

 

Thanks, really appreciate your input but I think I may leave this to the garage now and their better diagnostics tools etc

Would be nice and easy if I could test air throttle like the old ones without taking stuff apart but this has siemens actuator attached.

Regarding DPF this was cancelled about a year ago, would like to think that not causing me issues

Turns out the garage not sure either as no codes 😔 my reader reading duff obviously.

Looking at the data, I don't seem to be getting any boost as MAP is barely increasing as I rev, it actually even dips as I initially put my foot on the pedal.

I think the MAP sensor reading right at idle (ambient), when revving I assume it should increase a lot more than 100mbar at 4500rpm. Could be turbo/actuator/wastegate?

Turbo wastegate actuator is extended when engine is off (as normal), and at no point during startup, idle or accelerating does the actuator retract (how exactly should this operate?)

It is vacuum but I don't know where the pipe goes it looks like I'll have to remove a lot to get to it. I can move the actuator in and out relatively easy, and if I plug the vac port with my finger and actuate it a pressure is built against my finger and it holds, if I put my finger over vac port and let it extend it pulls and holds a vacuum against my finger so sort of proves actuator itself is okay. I can't really test the suction on the vac pipe when engine is running because its all under the rubber air intake

Do you mean accelerating or just revving?  It doesn't move much while revving stationary, needs to be under load to get it moving.

These use a VNT turbo, so that's a VNT actuator, not a wastegate.

The vac pipe goes to an electronic solenoid that I believe is bolted to a bracket on the bulkhead but memory is hazy on that now.

 

Not sure if you're familiar with VNT.  But basically it uses adjustable vanes to make the turbo hotside larger or smaller internally.  These vanes are moved between open & closed by the actuator.  They default to open with the engine off, and during normal running for minimal boost pressure. When you want maximum acceleration from low RPM the vanes are quickly closed, which makes the internal space smaller, forcing the same amount of exhaust gas through a smaller space increases the speed at which the turbine rotates, creating more boost in the intake at low RPM than an old 'fixed' turbo with a wastegate.  Reduces lag and gives a much wider powerband.

Also, what program were you using before?  I assumed F Super was just a lead to be used with Forscan but looking at the picture again, that doesn't look like Forscan?  I really would recommend getting Forscan on it, will be much better than any generic garage scanner.

I meant revving, I thought the actuator should move atleast a bit when revving hard from idle.

Thanks for the explanation, I find it hard finding whats fitted to what and how what works vs a different type

The program the screen shots are from car scanner app on phone using a wifi OBD (just to take sensor information), the OBD used the other day was f super connected to laptop, I'm not sure if it will work with forscan but could give it a try.

What should the MAP pressure be at idle, vs revving? is that indicative of turbo / turbo actuator issue? 

 

Yeah, I would expect a small amount of movement when revving hard, but not much.  

MAP should be around 100kPa at idle iirc.  But it's difficult to estimate when revving.  Would generally just compare the MAF & MAP graphs, rather than looking for specific figures.

I don't have any experience with F Super, looks like it's not compatible with Forscan though.  Need an ELM327 adapter for that.  Can buy wired adapters for a laptop or wireless for a phone.  Phone app costs a few quid and has limitations on programming, so I've always used the laptop version myself.

ELM327 (fwscart.com)

Well this is where it gets confusing, this morning the power came back, I quickly pulled over and put on car scanner, idle MAP was about 700mbar (it was 1000 yesterday when I had no power), but when I rev (stationary) the MAP went up to 1500mbar. After getting the graph, I got straight back on the road and power still there, all the way for a 20minute drive. 

Now this afternoon, no power again 😑 

Hmm, that is confusing.  I wonder if your fiddling with the actuator caused it to work briefly.  Might be worth having another look at that now.

Hi, I sort of gave a break on this as its only just some lack of power but this morning the power came back.

I plugged in OBD scanner and seen the throttle position reading 1.57% at idle (and increases when revving), previously it always read 14.51% regardless of revving or not but I could never be 100% that this was supposed to change as some cars don't have the feedback etc and I expected if it was supposed to be working I should have had a DTC, however, I now know that's not the case and the issue must be the position feedback from the throttle actuator. When the ECU isn't getting the throttle position it must start working off using some other value instead such as MAF, as a result it doesn't quite run right hence poor acceleration.

My question now though is, when the throttle position feedback is working (like now) there is some black smoke when accelerating, exhaust doesn't smell great at idle, and when I press the clutch and the rev needle is falling from say 2500rpm, it will shoot as low as 500rpm and bounce back up to 850rpm, could this be because the PCM needs to relearn the throttle position? I don't see an option on forscan for learning the throttle position (but on my bluetooth OBD scanner I can see relative and absolute throttle which would suggest the PCM does learn this position).

PS. obviously I know the throttle position feedback will most likely stop working again and there is an actual issue with the throttle or wiring so needs fixing/replacing, but just need a heads up RE the throttle position learning if needed etc?

There's no throttle as such on these.  The throttle plate is only used for EGR dosing & anti-shudder on shutdown.  

The pedal position is used to calculate the fuelling, but that must be working to some extent otherwise you wouldn't get any revs.  (There's no physical cable).

Do you know if the throttle position reading is coming from the pedal or the EGR doser?

The pedal TPS uses two variable resistors which it uses as 'belt & braces' (in case one failed to wide-open throttle) but it can still work with just one, albeit in a limited failsafe mode.

The pedal is very easy to change if that is at fault.  It's literally a few bolts and an electrical plug.

I believe the throttle position is the intake air throttle (which is what I referred to/meant when saying throttle). The accelerator pedal is called pedal position which seems to work fine

The EGR doser 'throttle' plate shouldn't be moving when revving in the way you describe.  It should remain fully open for the majority of the time, only closing slightly when the EGR opens or quickly when you switch the engine off.

I think we are talking about the same valve but I always called it intake air throttle (throttle valve) and I'm fairly sure the "throttle position" on OBD would be that. Picture attached of the valve I refer to.

The valve I refer to, could this be the problem, or could something else cause this to stay in fixed position 14.51%. When revving/accelerating I'm sure this valve should open more to allow the increased air flow required. When power was back, idle throttle position read 1.5% and increased to 4 or 5% when revving a bit, but when engine power is poor it reads 14.51% and nothing else not even 14.52%