To Hi-HP MPI CARS! ~ PSA

[Twist1]

So we have started tuning this new build in the last week. The TBB v2 was on for a couple weeks and then 980cc cts mpi and 525 lpfp was enabled and we got to tuning. After some LPFP weirdness all was well and we got to ripping.

Then all of a sudden we start pushing power to the left and we get ALL this knock. Tried to soften, more knock, more knock, more knock. It's knocking with less timing and HIGHER octane than it was before.

Something is going on...

One of my close buddies just did the same build to his s3 and left these plates pictured out on accident. He mentioned he thought they were impacting the way mpi injectors flowed into the cylinder. So I asked a couple on here that have made 500+ in oem motors and both left theirs in, so I figured they probably were fine to leave in and helped with stabilizing airflow coming into the cylinder.

WRONG.

I left mine in and the injectors were literally spraying straight on them. Pull out the mpi and look down the holes. They are literally spraying directly onto them and then splattering everywhere.

It's clean beneath 500~whp, as more fuel is more fuel and our DI still does a lot. However once we really started to get above 500 the spray was just not getting into the cylinder.

This is after MPI enabled for one week. There was blowby nearly all up the injector and gas all the way up to the seals. Does anyone k ow more about this? What do euro cars look like in the head?

To also help fix this I took my injector clips off so they could be seated all the way down. I'm sure those chickens will come home to roost but for now, all's well.

 

[TrueGTI]

Doesn't look like you mentioned trying a pull with those dividers out? I have recently just became aware of those from a clean out. I think 1st we should find out what they are exactly for. All older motors have nothing like that. Possible it is a MPI only item, which would mean Euro use only. So without MPI not needed? Now if they are an MPI item it would lead to the belief that there would have to be some type of precise injector control through the RPM range. How??

 

[El_bigote_AJ]

Doesn't look like you mentioned trying a pull with those dividers out? I have recently just became aware of those from a clean out. I think 1st we should find out what they are exactly for. All older motors have nothing like that. Possible it is a MPI only item, which would mean Euro use only. So without MPI not needed? Now if they are an MPI item it would lead to the belief that there would have to be some type of precise injector control through the RPM range. How??

Mk6 with the previous gen tsi, do have those dividers (non mpi car). Also to clarify the OP has a factory NON mpi car that has added mpi.

 

[Diggs24]

This is probably why PR didn't use those injectors. Spray pattern is wrong.

 

[Wastegate13]

This is probably why PR didn't use those injectors. Spray pattern is wrong.

Are you speaking specifically about the cts mpi kit?

 

[Twist1]

This is probably why PR didn't use those injectors. Spray pattern is wrong.

They are the same injectors lol. A couple said they are both flow matched Bosch just different claims.
Take your rail off diggs and shine a light through the injector hole in the manifold.

No spray pattern in world could avoid that plate. Not even in the movie wanted lol. It's literally straight in the way no matter what angle you look at it.

Why haven't more had issues? Well same reason I didn't until above 11*30psi. More fuel is more fuel even if it's being splattered the DI is still doing most of the heavy lifting. Then above 530whp people are just gonna assume it's knock from spark/octane imho. Which is what I did. But this would've definitely ended badly. They're heat sinks and Dan said the 1300cc injectors will literally warp them from heat and splatter even on PR injectors!

 

[Twist1]

What I really wanna see is a euro tech or owner that's walnut blasted chime in with pictures of the plates found in euro MPI cars. But then again the injectors could be so tiny that finding air carries it good enough anyway.

 

[Diggs24]

Are they? CTS claims a 980cc injector. PR claims 925cc and mine flow around 950cc. Don't think you can sell a 980cc injector that only flows 950cc witout someone causing a stink.

 

[El_bigote_AJ]

Are they? CTS claims a 980cc injector. PR claims 925cc and mine flow around 950cc. Don't think you can sell a 980cc injector that only flows 950cc witout someone causing a stink.

The local guy I got the hybrid from just switched to UM flex, and is using the apr kit with the 980cc’s and he’s doing over 35 psi on E75 right now said the car feels faster than when it was on the eqt dual maps, I wonder if they kept those plates in cause one the eqt tune he was at 600 ish numbers.

 

[Twist1]

I bet you almost all of the BIG power guys (600whp) have taken these plates out. I'd love to hear from more people about this for sure.

Very very interesting that this has never been mentioned online. It seemed to be a dirty little secret between tuners and turbo suppliers cough cough lmao

 

[Diggs24]

https://www.golfmk7.com/forums/inde...-ihx475-turbo-kit.348728/page-80#post-7093969

 

[Diggs24]

I bet you almost all of the BIG power guys (600whp) have taken these plates out. I'd love to hear from more people about this for sure.

Very very interesting that this has never been mentioned online. It seemed to be a dirty little secret between tuners and turbo suppliers cough cough lmao

Lots of liars and unhelpful people on the net. Like ones who claim their IS20 can run 9s 60-130 with some nitrous. Well, it can't.

 

[PowerDemon]

Lots of liars and unhelpful people on the net. Like ones who claim their IS20 can run 9s 60-130 with some nitrous. Well, it can't.

zing

 

[Twist1]

FB says my injectors are facked. I thought the CTS kit was good to go..

A guy said the spray pattern is jacked up on the cts kit and hits the walls of the plenum. Also is wider everywhere like you said Diggs

If I have to switch to PR injectors IMA kermit myself.

But couldn't I just buy those injectors separate and put into my cts kit? Ugh so many variables.

 

[Diggs24]

Should be same EV1 connector and same size. Don't see why not.

Did I mention I hate CTS before?

"Like 20 times Diggs."

Well, here's 21. Suck a fatty. ECS too.