EJ22T With Robtune 550 hitting fuel cut in hard acceleration

[subiedoutlegacy]

Hey everyone just a little confused at this point on what could be causing this issue.
My car has as follows just to give and idea,
Stock ej22t motor
td05 16g
550 injectors
Jegs Maf
dw200 fuel pump
ej20 Robtune 550 ecu


IMG_1jj461 by Stephanie Apgar, on Flickr

I have gone back an fourth with issues with the car, one being that launch control was stuck on at any speed. I then concluded with rob that it must be the ecu so he sent another without it. Upon installing the new ecu without launch control I took it for a test drive. Everything worked great car accelerated and boosted fine. I then decided to turn up the boost from 10 to 15 as I thought I could finally really push the car. This was a mistake unfortunately.

When accelerating smoothly I can boost the car to 15 no issue yet when I downshift or really hard accelerate the car bucks and hits fuel cut. At this time I am not even at where boost cut would be stock (12.7). At the same time the CEL comes on and when I check it is code 33 (vehicle speed sensor). My speedo works perfectly and I am puzzled on how this code has a correlation and how to fix the issue. I have even tried swapping in another speedo and came up with the same issue.

Let me know what you guys think! I currently have my car sign up for track days the end of August and want all these bugs gone before then.

[mike-tracy]

What about your spark plug gap.

[subiedoutlegacy]

What about your spark plug gap.

Already tried that, they are currently gapped to .030. I thought that was the issue myself.

[mike-tracy]

Did you try gappimg them to the mid to low 20s? That was the only way i could hit 18psi on my setup.

[subiedoutlegacy]

Did you try gappimg them to the mid to low 20s? That was the only way i could hit 18psi on my setup.

Problem is that I can hit 15 pounds no problem if I ease into it. It is only when I downshift or more aggressively accelerate on the gas the car then looses it and bucks all over hitting fuel cut. I re-created it a few times and every time it never even went into 10 pounds of boost.

[subiedoutlegacy]

I could try gapping more but I don't fully know if that is the issue especially with the code being thrown.

[subiedoutlegacy]

I am also being told that possibly a nick in the wiring to the vss in the harness could be causing my issue. It is strange because it is an intermittent issue.

[robertpaige]

Check your map sensor and pressure exchange solenoid. It's the brown and black sensors on the passenger strut tower. Make sure that wiring looks good and make sure the vacuum line going from the PES into the MAP sensor looks good without any splits. I had similar issues related to MAP sensor.

The VSS code is interesting..

[SILINC3R]

make sure your wiring from the robtune is in good order as well as grounds

[rob]

Hi,

Just to be clear the reason for launch control stuck on was because of error code 33. LC is only disabled after the ECU sees a speed reading above 2MPH. Without a speed reading (or a speed reading fault) LC is always active. As I mentioned in our email exchanges, as with LC, I think the abnormal boost cut behavior is directly related to the code 33 (vss) CEL. Figuring out this error should be your first focus. Now that we have tried two different ECUs and they both show the exact same behavior, we can assume that it isn't an ecu problem.

With the cable driven speedos, the cluster is responsible for generating the VSS signal that is sent to the ECU and to the cruise control computer. What I found interesting is that you said cruise control has never worked on your car which probably means you have had this problem for a while. Why the stock ej22t ECUs didn't throw a code is a bit perplexing.

My first thought is that something is wrong with your cluster, but you did mention that you had tried a replacement. It wasn't clear to me that after you switched clusters, if you had reset the ECU to clear CEL? If not then the replacement cluster might have fixed the problem, but the ECU was still reporting the old error.

If it isn't the cluster, then it has to be a harness issue somewhere. Do you know if the under dash wiring was removed at some point? It might be as easy as a missed connector. The wiring diagrams are not entirely clear on how this signal traverses the harness. But what I did find is the trouble shooting guide from the legacy FSM for code 33. It is different than the one I sent to you in email as that one was for the EDM model WRX with the VSS sensor in the tranny.

Have a go through these steps and report back.

-Rob

[wtdash]

Although it's stated the Speedo works, Code 33 can also be a bad cable to the trans.

Have you checked the connector on the transmission? It's common for the mechanical blade to break off.
This THrEAD should give you some info.

GL,
Td

[Legacy777]

Stephanie,

Did you ever get this resolved?

Any chance you or someone near by can run Vikash's scan tool to read the ECU?

http://surrealmirage.com/vrg3/b10scan/

This will tell you what the ECU is seeing for a speed signal. I agree with Rob that if the cluster did not change things, then the problem is the wiring between the cluster and ECU. If that's the case I would first check to see if you have a short on that wire. You can check that wire at the ECU and check for continuity between it and ground. If there is none and you can't find anything obviously wrong with the wiring harness, I would run a new wire spliced in just after the connector at the gauge cluster down to the ECU. This would bypass the stock harness and give a new run directly from the cluster to ECU.

[subiedoutlegacy]

UPDATE!
Finally resolved the fuel cut, it was the MAF, was not working at its prime, replaced it and now running 15lbs no problem!! Wahoo!

[rob]

Yay! Good news. Thanks for the update. I love the problems that are not my fault

-Rob

[jessman1942]

ha ha i bet i just like reading through a thread on here and get to see how it was resloved

[Legacy777]

Yes, thank you for posting the resolution it's extremely helpful for people searching in the future