Boost advise please

[waynepixel]

Hi All.

I have a 1.8T AUM and I seem to be having a boost problem between 3000-4000-Rpm. It just seem to lose all it pull and then slowly the turbo comes back to life. I have done a scan with VAG COM but no errors are coming back, I have checked all the pipe work around the Forge DV and N75 Valve and they all seem to be fine. This boost problem only happens when the engine is warmed up and is Intermittent. Could someone take a look at my logs and give me a second opinion please. I have log Blocks 115 02 32.

The car has a stage one remap Revo and I have a Forge TIP and Forge DV valve installed running K03S Turbo.

 

[james walker]

maf looks low for ko3s.... that could be your problem, should be looking at 175/185 g/s with good cai and stage 1 map

big maf g/s spike at 4k did you floor it from 2800 to redline?

what intake are you running?

try unplugging the maf then running...

 

[waynepixel]

Hi

Do you know what mate I have never manage to get 175/185 g/s, in the summer time, and in the winter when it was very cold I just got 169 g/s, it always been like that and that was with a new MAF 4 years ago. I am running standard OEM air box with OEM air filter.

Good call about the maf g/s spike at 4k, The first log was a second gear run, and the last log was a Third Gear run.

With standard OEM air box with OEM air filter should I be getting more then 160 g/s then?

 

[TRUMPY]

Hi

Do you know what mate I have never manage to get 175/185 g/s, in the summer time, and in the winter when it was very cold I just got 169 g/s, it always been like that and that was with a new MAF 4 years ago. I am running standard OEM air box with OEM air filter.

Good call about the maf g/s spike at 4k, The first log was a second gear run, and the last log was a Third Gear run.

With standard OEM air box with OEM air filter should I be getting more then 160 g/s then?

logged mine today two runs peaked at 176 g/s at 6200 rpm

 

[waynepixel]

big maf g/s spike at 4k did you floor it from 2800 to redline?

what intake are you running?

try unplugging the maf then running...

Do you think the spike might be the N75 valve I am running, It's a H valve from the Audi TT and it's a bit more aggressive acceleration then the standard J valve?

 

[james walker]

theres no boost spike there, just maf... but if you logged in 2nd, could be why tbh. boost looks ok to me.

try open cone induction, or drill the oem box to get more airflow.. low for stage 1 map.

could do with some more logging, try to log fuelling and timing pull.

blocks 031,020 for fuelling and timing pull

 

[Cupra Ross]

theres no boost spike there, just maf... but if you logged in 2nd, could be why tbh. boost looks ok to me.

try open cone induction, or drill the oem box to get more airflow.. low for stage 1 map.

could do with some more logging, try to log fuelling and timing pull.

blocks 031,020 for fuelling and timing pull

It depends on how much the map makes from timing as opposed to out and out boost although, I'd expect to see a bit more flow from a REVO map, they are quite boost heavy.

Really need to see better logs, I'm assuming its a Golf/Bora/A3 if it has the AUM engine. Its identical to AUQ with the exception of the standard ECU map. Try logging block 002 and 115 in 3rd gear (5 speed box) with full throttle from 2000rpm to the redline.

 

[wayne lcr]

could also a problem with dv valve as well not opening and shutting propley how old is it the dv?

 

[Cupra Ross]

Highly unlikely to be DV related as the car is hitting it's requested boost target. It's hard to see what's happening as the logs don't look like they are full throttle from start to finish. The long term fuel trims look like the car has been running very rich. Usually indicative of a boost leak or a duff coolant temp sensor.

 

[waynepixel]

theres no boost spike there, just maf... but if you logged in 2nd, could be why tbh. boost looks ok to me.

try open cone induction, or drill the oem box to get more airflow.. low for stage 1 map.

could do with some more logging, try to log fuelling and timing pull.

blocks 031,020 for fuelling and timing pull

I will try and do some more logs today on block 031, 020. Should I also log block 02.

 

[waynepixel]

could also a problem with dv valve as well not opening and shutting propley how old is it the dv?

I have checked the DV and it's fine, there are no rubber seals broken.

 

[waynepixel]

Highly unlikely to be DV related as the car is hitting it's requested boost target. It's hard to see what's happening as the logs don't look like they are full throttle from start to finish. The long term fuel trims look like the car has been running very rich. Usually indicative of a boost leak or a duff coolant temp sensor.

Hi mate

The log where taken flat out trust me on this. It is hard doing a third gear run sometimes because you get into some high numbers if you know what I mean

I did change the coolant temp sensor when I first got my Golf about 4 years ago now for the new green coolant sensor. Would you say that -6.3 is to high, it does seem to be within the 10% limit?

 

[Cupra Ross]

Hi mate

The log where taken flat out trust me on this. It is hard doing a third gear run sometimes because you get into some high numbers if you know what I mean

I did change the coolant temp sensor when I first got my Golf about 4 years ago now for the new green coolant sensor. Would you say that -6.3 is to high, it does seem to be within the 10% limit?

The Air Fuel Ratio at the pre-cat lambda is being reported as richer than what the car is expecting over the long term but block 32 is not much use in pinpointing shorter term fueling problems.

I have the same engine as you, albeit with slightly different mods. Your car is not requesting any boost until over 3000rpm, thats just not right. I'm betting its because the MAF is not reporting much airflow until this point. If the car genuinely is running rich, I'd say that either your MAF is under-reading at low revs or your TIP is not correctly seated.

Try driving it with the MAF disconnected, if this is the problem you'll feel the difference instantly.

I had a similar problem to you recently, no power between 3k and 4.5k rpm. Mine turned out to be a dying fuel pump but it read lean on the fueling tables.

Log block 002 and 115 together and then do another one with 031 (this will show the Lambda values) and 115 to see what effect the Lambda value is having on requested boost, if any. Do try to do them in 3rd as you will get a better view of the symptoms when the car is under more load. If 2nd is all you can do, thats fine. Don't log more than 2 blocks at a time, you don't get a high enough sample rate to show much if you do this, especially if its in a low gear.

 

[waynepixel]

The Air Fuel Ratio at the pre-cat lambda is being reported as richer than what the car is expecting over the long term but block 32 is not much use in pinpointing shorter term fueling problems.

I have the same engine as you, albeit with slightly different mods. Your car is not requesting any boost until over 3000rpm, thats just not right. I'm betting its because the MAF is not reporting much airflow until this point. If the car genuinely is running rich, I'd say that either your MAF is under-reading at low revs or your TIP is not correctly seated.

Try driving it with the MAF disconnected, if this is the problem you'll feel the difference instantly.

I had a similar problem to you recently, no power between 3k and 4.5k rpm. Mine turned out to be a dying fuel pump but it read lean on the fueling tables.

Log block 002 and 115 together and then do another one with 031 (this will show the Lambda values) and 115 to see what effect the Lambda value is having on requested boost, if any. Do try to do them in 3rd as you will get a better view of the symptoms when the car is under more load. If 2nd is all you can do, thats fine. Don't log more than 2 blocks at a time, you don't get a high enough sample rate to show much if you do this, especially if its in a low gear.

Hi mate

I will do a log today and get back to you with them numbers.

 

[waynepixel]

So I managed to get the logs done today, Block 002 115 where done in Forth Gear because I though I was in Third Gear, sorry about that. And I managed to get a good Second Gear pull.

I did unplug the MAF today and I was surprised with the rev range, it seemed mush more progressive in the First and Second gears, so it might be the MAF.

 

[Cupra Ross]

If you felt a positive difference with the MAF unplugged, that would be the first thing to change. I personally think that its under reading slightly at lower revs. Fueling looks not too bad. You are pretty much hitting the ECU's expected air/fuel ratios.

I think you also have a small boost leak as your real time AFRs are just a tad rich. Check all of the hoses (by feel, not just visually) coming off of the intake manifold including the two larger pcv hoses on the underside centre of the manifold.

 

[waynepixel]

If you felt a positive difference with the MAF unplugged, that would be the first thing to change. I personally think that its under reading slightly at lower revs. Fueling looks not too bad. You are pretty much hitting the ECU's expected air/fuel ratios.

I think you also have a small boost leak as your real time AFRs are just a tad rich. Check all of the hoses (by feel, not just visually) coming off of the intake manifold including the two larger pcv hoses on the underside centre of the manifold.

I think your right about the MAF might need changing, Quick Question, how to you work out the AFR when looking at the these log numbers because I am still learning VAG COM. I will have a look for boast leak over the weekend.

The real annoying thing about these MAFs is if you took my car into VW to check the MAF, which I have done, they would say everything is fine because VW only check the MAF at engine tick over and if it reads above 2.2g/s it's working correctly according to VW, but this is not always the case is it.

 

[james walker]

figure under load x 14.7

 

[Cupra Ross]

I think your right about the MAF might need changing, Quick Question, how to you work out the AFR when looking at the these log numbers because I am still learning VAG COM. I will have a look for boast leak over the weekend.

The real annoying thing about these MAFs is if you took my car into VW to check the MAF, which I have done, they would say everything is fine because VW only check the MAF at engine tick over and if it reads above 2.2g/s it's working correctly according to VW, but this is not always the case is it.

I was a bit baffled by the two numbers until Damoegan enlightened me. Its the opposite to block 115. The first number is the Actual Lambda factor as reported by the front Lambda sensor (wideband on the AUQ/AUM). The second number is the one that the ECU is expecting/attempting to achieve.

As james says, you multiply the first number by 14.7 to work out the volume of air vs fuel in the mixture. An engine that is running 14.7 parts air to 1 part fuel is said to be in perfect Lambda. 14.7 to 1 is the perfect Stoichiometric ratio. Its the ratio at which all oxygen is burned and all fuel is expended in the burn process. This or higher is fine at idle and at low revs/part throttle. At higher revs you want that mixture to be a bit richer (less parts of air to fuel) and as a consequence, you should get a number of less than 1 in the first reading of Block 31. Somewhere around 0.75 to 0.825 is ideal on the 1.8T at high revs.

In this respect, your fueling is good. It is a tad richer than what the ECU is trying to achieve, this is what makes me think you have a small boost leak. Some of the metered air is getting out and the mixture is a tiny bit richer than specified because of this. If there is a leak there, its a small one. I suspect its the MAF thats causing you problems.

 

[waynepixel]

I was a bit baffled by the two numbers until Damoegan enlightened me. Its the opposite to block 115. The first number is the Actual Lambda factor as reported by the front Lambda sensor (wideband on the AUQ/AUM). The second number is the one that the ECU is expecting/attempting to achieve.

As james says, you multiply the first number by 14.7 to work out the volume of air vs fuel in the mixture. An engine that is running 14.7 parts air to 1 part fuel is said to be in perfect Lambda. 14.7 to 1 is the perfect Stoichiometric ratio. Its the ratio at which all oxygen is burned and all fuel is expended in the burn process. This or higher is fine at idle and at low revs/part throttle. At higher revs you want that mixture to be a bit richer (less parts of air to fuel) and as a consequence, you should get a number of less than 1 in the first reading of Block 31. Somewhere around 0.75 to 0.825 is ideal on the 1.8T at high revs.

In this respect, your fueling is good. It is a tad richer than what the ECU is trying to achieve, this is what makes me think you have a small boost leak. Some of the metered air is getting out and the mixture is a tiny bit richer than specified because of this. If there is a leak there, its a small one. I suspect its the MAF thats causing you problems.

Well thanks allot for your help, you and James have been more then helpful and if I can return the favour let me know, Any ideas where the best place to get a new MAF might be, I'm not to sure if I want to pay VW dealer prices again, and I'm not to sure about getting one off Ebay.