Yungog

Maf brand matter?

Recommended Posts

On 3/22/2018 at 11:29 AM, TomsFocus said:

Fair enough, I've not had an issue with Mister-Auto before either.  I would guess someone's already returned that as faulty/wrong and they've sent it straight to you without checking it...  I've had the same happen with ECP before.

I can't find any close up pics of that Peirburg MAF online but there are other brands of the same MAF which don't have the exposed part on top.  It's different to the later models which used a separate MAF from the plastic tube so can't compare it to my own.  Either way, I reckon send it back and get another.  Make a small mark on somewhere so you'll know if they send you the same one back lol.  

Ye just got the replacement maf yesterday.

Has that same gold mark on top,

Couldn't be my old one as I only sent it to the post office the day before I received this one so must be a new design for them?

On 3/22/2018 at 1:21 PM, Tdci-Peter said:

First step, like Tom says, is get the dodgy MAF replaced or refunded. A good supplier should send you a pre-paid address label in a case like this where the goods are not as described. If it said new, unused, and with no comment about poor packaging, then your unit is SNAD. I had this a couple of times last year. A coupe of good photos is usually enough to convince them.

Airflow problems are a bit of a pig, it is all so inter-dependant. A fall in boost pressure will make the air flow (MAF reading) drop immediately, as less air is going in. A fall in MAF reading (due to a fault), I would not expect to make an immediate fall in boost (MAP). Only if the ECU read the fall from the MAF and deliberately cut the turbo boost, would the MAP fall, so there should be a delay.

I am looking at this on my car a bit, I have been getting the odd P0299 error for ages (Turbo underboost), but it is getting a bit more frequent. So I have been recording MAF & MAP. They normally seem to track quite closely, though RPM will affect MAF in a different way to MAP. Fuel problems can also cause airflow dips, the turbo will give less boost if the exhaust gas cools due to a drop in fuel injection, and this will also be a very rapid change. But you would usually feel the drop in power if this happened.

A bit of my latest Forscan run is below.

(The light blue line in g/sec is MAF, FRT is fuel rail temperature, the green line is fuel rail pressure, APP is accelerator pedal)

 

Log12-1.PNG

Good explanation on it.

They all look in sync with each other so if one reading is off,they all go haywire!

 

 

So I drove 100km yesterday and only noticed a slight drop in boost only once.

But today driving It feels like it was before so new maf didn't fix it!!!

Any ideas lads?

I'm thinking the catalytic converter is blocked. Would this cause these issues do you think?

Share this post


Link to post
Share on other sites
 

4 hours ago, Yungog said:

So I drove 100km yesterday and only noticed a slight drop in boost only once.

But today driving It feels like it was before so new maf didn't fix it!!!

Any ideas lads?

I'm thinking the catalytic converter is blocked. Would this cause these issues do you think?

The original symptoms you gave were:

"Basically what happens is when I the turbo boost kicks in, it boosts for a second around 2k revs then stops then kicks back in from 3k to 4k revs.

I used an obd and torque app and measured the maf reading and the boost reading.

When it works properly the readings increase together.

When the problem happens the maf reading drops from say 80g/s to like 50g/s ,then a second later goes back to normal."

--

I assume there was no light on or stored DTCs after an event.

Blockage in the cat would have a progressive effect, getting worse as RPM increased, as the airflow increased. It does not really sound like that to me. It is likely to give turbo underboost DTCs, as less pressure is available to drive the turbo.

Sudden and unexpected adjustments of the EGR valve could do something like that, when it opens the MAF flow will drop (more re-circ), when it closes MAF will jump up (more fresh air). Turbo actuator problems could do it, MAF problems (as you suspected), or MAP problems.

Does the 2nd new MAF still have a constant reading, or is it more normal now?

Forscan, or maybe Torque, can monitor EGR duty cycle, MAF, MAP and maybe Turbo actuator position. If you can capture an event, then just maybe there would be a clue as to the cause.

Share this post


Link to post
Share on other sites
1 hour ago, Tdci-Peter said:

The original symptoms you gave were:

"Basically what happens is when I the turbo boost kicks in, it boosts for a second around 2k revs then stops then kicks back in from 3k to 4k revs.

I used an obd and torque app and measured the maf reading and the boost reading.

When it works properly the readings increase together.

When the problem happens the maf reading drops from say 80g/s to like 50g/s ,then a second later goes back to normal."

--

I assume there was no light on or stored DTCs after an event.

Blockage in the cat would have a progressive effect, getting worse as RPM increased, as the airflow increased. It does not really sound like that to me. It is likely to give turbo underboost DTCs, as less pressure is available to drive the turbo.

Sudden and unexpected adjustments of the EGR valve could do something like that, when it opens the MAF flow will drop (more re-circ), when it closes MAF will jump up (more fresh air). Turbo actuator problems could do it, MAF problems (as you suspected), or MAP problems.

Does the 2nd new MAF still have a constant reading, or is it more normal now?

Forscan, or maybe Torque, can monitor EGR duty cycle, MAF, MAP and maybe Turbo actuator position. If you can capture an event, then just maybe there would be a clue as to the cause.

As far I can remember there wasn't any under/over boost codes when I checked with forscan. I'll have to check again to make sure.

The egr is blanked off so I'm guessing it wouldn't matter what the egr is doing??

The new maf has a normal reading now(increasing with rpm).

The actuator was moving as the car is revved ,tho not sure of its movement when the car is actually driving.

Im unable to monitor driving with forscan as my ancient laptop needs to be on charge all the time!!!!

I'll fiddle with torque and see if I can monitor and record data.

Another thing I've recently is this only seems to happen when I put the pedal to floor,but if I have the pedal down say 75-80% of the way I haven't noticed it happening.

Maybe throttle position sensor?

Share this post


Link to post
Share on other sites
2 hours ago, Yungog said:

The egr is blanked off so I'm guessing it wouldn't matter what the egr is doing??

The new maf has a normal reading now(increasing with rpm).

The actuator was moving as the car is revved ,tho not sure of its movement when the car is actually driving.

Im unable to monitor driving with forscan as my ancient laptop needs to be on charge all the time!!!!

My laptop battery lasts just a few minutes, so I bought a car charger for it. Dead cheap now, just plugs in to the cigar lighter. And mine is a Dell that needed the 3 pin charger with the "secret" Dell chip in it.

Good to hear the MAF shows signs of life now. If that critical MAF reading drop still happens, then we can rule out the sensor itself. Can't rule out the car wiring, or the other bits, but one suspect is down!

I half guessed EGR may be blanked, but it still remains on the edge of the suspect list. My ECU knows when the EGR is blanked, the air flows do not respond as they should, and the valve ramps either full open, or full closed. The ECU seems to ignore the anomaly, but I suspect its behavior does alter a bit, the turbo seems to start to ramp up a bit earlier, maybe to try to get the EGR flow it wants. So some sort of ECU response to a dodgy EGR is possible, but unlikely.

Forscan can certainly monitor the APP (accelerator pedal position), and should quite quickly show any problems there. On mine, the engine does not need to be running to test the APP.

There is a throttle on a 1.6TDCI, but it is not used much in normal running. Not like in a petrol engine. It can be used to restrict the intake airflow a bit to boost EGR flow. It is usually called an anti-shudder valve, as it is also used at engine off to shut it down quickly. It can also be monitored, I forget what it is called, maybe EGR-TV or something. In a diesel, the air intake is normally free, regardless of power and fuel. My 1.8 has no throttle at all. A throttle wastes energy, but is essential on a standard petrol engine where a strict ratio of air to fuel has to be maintained. (GDI engines like the 1l Ecoboost can run lean like a diesel, with the throttle valve full open and just use the fuel injections to control the power.)

With the EGR blanked, the ECU may be making more use of the throttle valve to try to obtain the wanted EGR flow. Then above about 2500 rpm, the EGR is not used (on my car at least), and the throttle would open fully since no EGR flow is wanted. So a sticking throttle valve might just cause the problem you describe. (This would not apply if the EGR has actually been mapped out of the ECU, but this is expensive, and not often done.)

Capturing an event would be good. I am not sure what the sampling rate of Torque on a phone is, I suspect it may be quite a bit lower than Forscan on a laptop. To be able to distinguish cause from effect can need some quite fine time resolution. On some of my runs, Forscan managed a 20ms (50 samples/sec) rate.

One benefit is this sounds like an annoying but livable problem at the moment, and time spent monitoring symptoms and doing various tests might save money compared to the other (garage) approach of changing increasingly expensive bits until the problem is cured!

 

 

Share this post


Link to post
Share on other sites
On 3/30/2018 at 11:51 PM, Tdci-Peter said:

My laptop battery lasts just a few minutes, so I bought a car charger for it. Dead cheap now, just plugs in to the cigar lighter. And mine is a Dell that needed the 3 pin charger with the "secret" Dell chip in it.

Good to hear the MAF shows signs of life now. If that critical MAF reading drop still happens, then we can rule out the sensor itself. Can't rule out the car wiring, or the other bits, but one suspect is down!

I half guessed EGR may be blanked, but it still remains on the edge of the suspect list. My ECU knows when the EGR is blanked, the air flows do not respond as they should, and the valve ramps either full open, or full closed. The ECU seems to ignore the anomaly, but I suspect its behavior does alter a bit, the turbo seems to start to ramp up a bit earlier, maybe to try to get the EGR flow it wants. So some sort of ECU response to a dodgy EGR is possible, but unlikely.

Forscan can certainly monitor the APP (accelerator pedal position), and should quite quickly show any problems there. On mine, the engine does not need to be running to test the APP.

There is a throttle on a 1.6TDCI, but it is not used much in normal running. Not like in a petrol engine. It can be used to restrict the intake airflow a bit to boost EGR flow. It is usually called an anti-shudder valve, as it is also used at engine off to shut it down quickly. It can also be monitored, I forget what it is called, maybe EGR-TV or something. In a diesel, the air intake is normally free, regardless of power and fuel. My 1.8 has no throttle at all. A throttle wastes energy, but is essential on a standard petrol engine where a strict ratio of air to fuel has to be maintained. (GDI engines like the 1l Ecoboost can run lean like a diesel, with the throttle valve full open and just use the fuel injections to control the power.)

With the EGR blanked, the ECU may be making more use of the throttle valve to try to obtain the wanted EGR flow. Then above about 2500 rpm, the EGR is not used (on my car at least), and the throttle would open fully since no EGR flow is wanted. So a sticking throttle valve might just cause the problem you describe. (This would not apply if the EGR has actually been mapped out of the ECU, but this is expensive, and not often done.)

Capturing an event would be good. I am not sure what the sampling rate of Torque on a phone is, I suspect it may be quite a bit lower than Forscan on a laptop. To be able to distinguish cause from effect can need some quite fine time resolution. On some of my runs, Forscan managed a 20ms (50 samples/sec) rate.

One benefit is this sounds like an annoying but livable problem at the moment, and time spent monitoring symptoms and doing various tests might save money compared to the other (garage) approach of changing increasingly expensive bits until the problem is cured!

 

 

Sorry only getting back now.

Need to get me one of those laptop car chargers .

Did a few bits on the car.

Changed the map sensor , 3 of the glow plugs weren't working so changed all 4 plugs.

Fixed exhaust leak.

Issue still there.

So today ran forscan

Got these

 

IMG_20180405_132449.jpg

P138b I thought was the glow plugs but must be the relay.

The turbo one I seem to think its the pressure converter.

I only changed it about a year or 2 ago.

Anyway to check it before I buy another one?

Share this post


Link to post
Share on other sites

20 minutes ago, Yungog said:

P138b I thought was the glow plugs but must be the relay.

The turbo one I seem to think its the pressure converter.

I only changed it about a year or 2 ago.

Anyway to check it before I buy another one?

P0404 - Exhaust Gas Recirculation Circuit Range/Performance.

P138b glow plug control module system voltage

P0238 Turbocharger Boost Sensor A Circuit High

Not a very helpful mix! But that is all to often the case.

The first thing I would do is save the log file with those codes, then clear them. Some may be quite old, and can be caused by servicing & maintenance.

One possible common link is the battery voltage, which is controlled while running, by the alternator, but battery condition can have a big effect too. If the battery has gone a bit high impedance, there can be ripple and noise on the system. Bad earth wires from battery to body & to engine could also cause this. Either a full alternator & battery test, or monitoring the battery voltage with the engine running would give some clues here. battery voltage should stabilise at 14.2v to 14.6v, and hardly change with loads like headlights on & off.

The Turbo error relates to the feedback signal from the turbo. However, a faulty solenoid valve (pressure convertor) could be the cause, as the ECU does not really know which one would be the problem.

Forscan can initiate a PCM (ECU) self test. It is not often useful, but worth doing. It should activate the turbo and egr during the test. The egr can be monitored on the driveway. If yours is blanked, I would expect it to be fully open most of the time, but close on over-run, ie rev the engine a bit, & release the throttle quickly. The reading should ramp repeatedly between two values.

Turbo is a bit harder, it will only be fully used under power. I think Forscan can force the turbo to open, though that bit does not seem to work on my car. I seem to recall that vacuum is needed to open the vanes / wastegate, if so disconnecting the vacuum pipe to the solenoid valve or actuator should close the vanes. This can be monitored also.

Share this post


Link to post
Share on other sites
On 4/5/2018 at 8:10 PM, Tdci-Peter said:

P0404 - Exhaust Gas Recirculation Circuit Range/Performance.

P138b glow plug control module system voltage

P0238 Turbocharger Boost Sensor A Circuit High

Not a very helpful mix! But that is all to often the case.

The first thing I would do is save the log file with those codes, then clear them. Some may be quite old, and can be caused by servicing & maintenance.

One possible common link is the battery voltage, which is controlled while running, by the alternator, but battery condition can have a big effect too. If the battery has gone a bit high impedance, there can be ripple and noise on the system. Bad earth wires from battery to body & to engine could also cause this. Either a full alternator & battery test, or monitoring the battery voltage with the engine running would give some clues here. battery voltage should stabilise at 14.2v to 14.6v, and hardly change with loads like headlights on & off.

The Turbo error relates to the feedback signal from the turbo. However, a faulty solenoid valve (pressure convertor) could be the cause, as the ECU does not really know which one would be the problem.

Forscan can initiate a PCM (ECU) self test. It is not often useful, but worth doing. It should activate the turbo and egr during the test. The egr can be monitored on the driveway. If yours is blanked, I would expect it to be fully open most of the time, but close on over-run, ie rev the engine a bit, & release the throttle quickly. The reading should ramp repeatedly between two values.

Turbo is a bit harder, it will only be fully used under power. I think Forscan can force the turbo to open, though that bit does not seem to work on my car. I seem to recall that vacuum is needed to open the vanes / wastegate, if so disconnecting the vacuum pipe to the solenoid valve or actuator should close the vanes. This can be monitored also.

Hi

battery and alternator all good.

Ye I've cleared these codes numerous times and the only one that disappears is the egr one and only comes up every now and again but that is because the egr is blanked.

I've ordered the pressure converter and is due to be here next week :)

Couldn't seem to find those tests on forscan. I'm still fairly new to forscan so probably just couldn't see it :p

Hopefully changing this will fix the turbo issue as it wasn't too bad before as in if I kept my foot from going the whole way down it wouldn't happen but now its happening and happening more frequently, very scary when overtaking or going up/down a sliproad or junction.!!

Share this post


Link to post
Share on other sites

Update:

Part arrived today.

Threw it in

Car sounded smoother and not as loud.

Drove for about 20km and no boost issue. Drove in 2nd and 3rd gear and floored it a few times and no issue.

Seems to drive and pull smoother.

Although all this could be a placebo effect! :p

Hopefully its sorted.

Will update after a few hundred km .

Share this post


Link to post
Share on other sites

Right back to square one .

Issue still remains.

I've 

Blanked egr

Turbo itself only has about 27,000 miles

New maf

New map

New pressure converter

Can't find any cracks or leaks

Any other ideas?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now