Dibilas CAI maf issue.

[-pseudonymous-]

Hey guys. I recently took delivery of my new Dbilas cai for my cupra. I am fairly impressed with the quality of the kit however my only real issue is that the MAF appears to sit too deep in the filter pipe whereas when fitted to the original airbox it sits dead central in the line of airflow.
Anyhow after i finished installing it i was intrigued to see if my airflow readings had increased (previously maxing out at 221g/s) but to my surprise i was seeing no more than 209 g/s. While i was out logging i had a quick look at my long term fuel trims which have since risen from -3.2% to +7% multiplicative which suggests the car is now running lean. Now my question is could this be due to the fuel pump maxing out or could it be down to the position that the MAF sensor is now seated not allowing it to get a true airflow reading?

Has anyone come accross this problem before after fitting a filter? Or any suggestions as to what else could be causing it?

 

[wild willy]

Good to see your actually logging to see any gains rather than just assuming it improves performance.
I recon it needs to be center of the tube to compare apples with apples.
I would measure the internal diameter of the new maff housing to check if the csa has increased. If it has the maff reading will become diluted but could still be making more power than before.

 

[Al]

Hey guys. I recently took delivery of my new Dbilas cai for my cupra. I am fairly impressed with the quality of the kit however my only real issue is that the MAF appears to sit too deep in the filter pipe whereas when fitted to the original airbox it sits dead central in the line of airflow.
Anyhow after i finished installing it i was intrigued to see if my airflow readings had increased (previously maxing out at of 221g/s) but to my surprise i was seeing no more than 209 g/s. While i was out logging i had a quick look at my long term fuel trims which have since risen from -3.2% to +7% multiplicative which suggests the car is now running lean. Now my question is could this be due to the fuel pump maxing out or could it be down to the position that the MAF sensor is now seated not allowing it to get a true airflow reading?

Has anyone come accross this problem before after fitting a filter? Or any suggestions as to what else could be causing it?

Fairly simple explanation. As standard, the TFSi engine runs a little leaner than other engines when tested on a rolling road going by the results I have seen. Your car must be fairly standard at 209g/s (approx 260bhp) When you increase the air flow, it will only serve to lean out the mix unless you do something to counteract it like add aftermarket software. Adding in an uprated fuel pump will probably not make that much of a difference on standard code, but I have not seen this confirmed.

It is not likely the MAF is located that much differently in the Dbilas to the OEM intake in the engine cover. I can check mine and see however if it helps you.

 

[wild willy]

Fairly simple explanation. As standard, the TFSi engine runs a little leaner than other engines when tested on a rolling road going by the results I have seen. Your car must be fairly standard at 209g/s (approx 260bhp) When you increase the air flow, it will only serve to lean out the mix unless you do something to counteract it like add aftermarket software. Adding in an uprated fuel pump will probably not make that much of a difference on standard code, but I have not seen this confirmed.

It is not likely the MAF is located that much differently in the Dbilas to the OEM intake in the engine cover. I can check mine and see however if it helps you.

All other things being equal, if it flows better the g/sec should increase.
Software will make the most of it but it should increase not decrease.

 

[-pseudonymous-]

Thanks for your input guys. Yeah as you said horace the airflow reading of 209g/s seems fairly standard which is what im a little concerned about as im running Revo stage 1. I dont think there is much difference in the size between the two tubes although i did notice that the standard tube is oval shaped whereas the Dbilas pipe is round. My maf seems to sit near the back wall of the maf tube on the Dbilas but it sat dead central on the standard tube. I think the only thing i could do to rectify this is to make a spacer to re-postion the maf more centrally.

Are there any blocks on vag com you would suggest logging?

 

[Al]

Looks like I never read the post properly - I thought 221 was the figure after fitting the intake, not before

I wonder if when moving the MAF that it was touched by hand as this could cause problems.

 

[-pseudonymous-]

lol no mate the readings dropped after fitting the Dbilas. I handled the maf with care when changing knowing how delicate they can be.

 

[wild willy]

Log 118 before and after fitting the intake, when air flow increases the turbo pressure will either increase a little or the duty cycle will decrease a little as it has less work to do.

 

[wild willy]

A very small increase in diameter has a big increase in CSA which will proportionally decrease your maff reading whilst actually improving flow. Get your tape out.

 

[-pseudonymous-]

Log 118 before and after fitting the intake, when air flow increases the turbo pressure will either increase a little or the duty cycle will decrease a little as it has less work to do.

I have a log of 118 from last week and will try and get another tonight with the Dbilas fitted. Not the best comparison i know but it a bit of mission to sway the two intakes over, not like the good'ol 1.8 20vt's!

Will try and get some measurements later also. Cheers Willy!

 

[-pseudonymous-]

Ok so i removed the Dbilas intake this morning to compare it against the stock intake. As i said previously the OEM intake is oval shaped and measures 3" x 2" id whereas the Dbilas pipe measures 3" round id. As you can see from the pictures below the MAF sits alot deeper in the Dbilas pipe which is making me think the airflow readings may be inaccurate.

I've had a little browse of the web this morning and came accross the following info: http://www.golfmkv.com/forums/showthread.php?t=84314

It seems this could well be the reason for my lean long term fuel trims as i suspected. I might machine a little spacer to bring the maf more central in the tube to see if that helps. What do you guys think?

Standard intake:

Dbilas intake:

 

[stuartsjg]

If the sensor is closer to the walls of the tube then it will measure slower air flow. Remember that fluid in a pipe flows fastest in the middle and slowest at the edges (infact, there is a molecular level which is stationary is it is in contact with the tube walls!)

Shows the flow rate distribution in a tube

I imagine the MAF's are designed to measure the centre mass flow then will apply a flow curve which factors in the size and possible geometry of the tube.

If the speed sensor is at the tip then it will be distorted by being so close to the walls.

I'm wondering if the round/oval thing have any effects?
Perhaps the original is oval inorder to compensate for the presence of the sensor itsself(?)

Stuart

 

[Al]

Interesting. I have my dbilas sat in front of me and will look at it this afternoon.

 

[-pseudonymous-]

This is what i suspected Stu. Good explanation there! I guess the only way to tell is to modify the maf bracket and do a few more logs with vag-com. Will be interesting to see if the airflow readings increase.

Yeah Horace have a look and see what you reckon. Am i right in thinking the Dbilas intakes were originally designed for the Ko3s based models? Do you know if their maf sensors are the same length as ours on the k04 based cars?

 

[Al]

This is what i suspected Stu. Good explanation there! I guess the only way to tell is to modify the maf bracket and do a few more logs with vag-com. Will be interesting to see if the airflow readings increase.

Yeah Horace have a look and see what you reckon. Am i right in thinking the Dbilas intakes were originally designed for the Ko3s based models? Do you know if their maf sensors are the same length as ours on the k04 based cars?

The K04 kits are modified from the K03s kits by Regal. Regarding the MAF, I am not sure if these are shared between the K03s TFSi and K04 TFSi cars.

 

[ares]

The length of the MAFs is the same in K04 and K03. My MAF (Cupra) and my friend's MAF (GTI) are visually identical having the same length and same size.

 

[-pseudonymous-]

The length of the MAFs is the same in K04 and K03. My MAF (Cupra) and my friend's MAF (GTI) are visually identical having the same length and same size.

In that case you would assume that the maf being off centre does not cause any problems or read inaccurately if all the TSFI maf's sit this deep on the Dbilas kits. I wonder if any other CAI kits are designed the same way or if the maf is more central?

 

[DanGB]

Check this thread out here for the same issues:

http://www.golfmkv.com/forums/showthread.php?t=80189&highlight=ltft

Interesting reading. Being an american forum, take it how you will....

 

[Al]

What i find hard to understand is Chinese writing. Also why my MAF readings and all other logs were good with the Dbilas fitted.

 

[DanGB]

What i find hard to understand is Chinese writing.

Were you reading better or worse with the Dblias Al?