Spyder Boost Cut or Fuel Cut?

[spyderdrifter]

I got my Spyder back to being drivable today. Previously I had an issue with my OBD port, which I assume is still there, but that's not the issue for this post.

While driving, if driving casually, everything seems fine. When driving a bit harder, once I hit around 4500rpms, the power cuts, regardless of gear or speed. This first got noticed while turning, so I initially thought fuel cut. But I'm not sure, maybe a boost cut issue. How can I figure out which one it is?

I've managed to repeat this while driving straight on a level road multiple times. So it can't be fuel not being sucked into the pump, plus this was all on a full tank anyway. The reason I'm considering a boost cut potentially, is I have a Greddy boost controller, but don't think it's wired up properly. Therefore I reinstalled the OEM control solenoid. But I have my reservations on that even being hooked up properly. To make the boost idea more interesting, is I have an HKS BOV. Not a BOV that's exactly quiet, however I don't hear it very much. I have that system recirculation, but I've had the same setup in the past and it was audible.

Any suggestions would be helpful. Thanks.

 

[steve]

What are you tuning with? I don't see anything listed in your profile.

 

[pauleyman]

You're describing fuel cut as if its a mechanical thing, hence the description of happening while turning. Thats not what it is at all. Fuel cut is based on ecu programming and the need to shut things down. You exceed a certain airflow (on a stock ecu) and ecu will yank fuel. Not via fuel pump, by shutting injectors off. Its hard and violent when it happens.
Concerning boost, ecu has no control over boost other than to shut solenoid on and off. All the solenoid does it allow a few more pounds. Shut it off and it lowers boost a few pounds. Thats it. Sounds like you have a misfire. Any codes?

You also list 3 different spyders in your profile. Which one is it?

 

[Tyeler18]

If you have a way to log, log the MAF HZ and see what it's doing. My 4g swapped summit would intermittently hit fuel cut at very specific load (without boost), at first I didn't realize it was fuel cut but while logging one day I watched the MAF hz spike as it was doing it. Something in the MAF was acting up, it was a very specific HZ that would cause it to go crazy. You could drive normal and not do it and you could floor it and not have an issue, a brisk acceleration into traffic was enough to get it to do it though.

 

[spyderdrifter]

This issue is on the white spyder.

No logging ability yet.

I haven't noticed any misfires, but that isn't to say it isn't possible. The boost cut/ fuel cut ideas were only that, and the only way I could describe the issue.

As far as codes, that is currently not an option. I have an on-going issue with the under dash harness where I can connect my code reader and it turns on, but won't communicate with the car.

 

[pauleyman]

Let's start with what maintenance you've done?

 

[spyderdrifter]

All maintenance. This engine has only recently been dropped into the car and maybe has 15 miles on it at most. Everything was replaced, and the engine is upgraded. I haven't done much with it due to trying to fix the OBD issue.

 

[pauleyman]

describe the power cut. Fast and sharp? Stutters? Dies then recovers? What is it doing exactly. Regardless that it's new....what have you checked? Plugs? wires? Are they fully seated? Gapped correctly? Fuel pressure good? This sounds like a fresh build so there could be 100 things.

 

[spyderdrifter]

describe the power cut. Fast and sharp? Stutters? Dies then recovers? What is it doing exactly. Regardless that it's new....what have you checked? Plugs? wires? Are they fully seated? Gapped correctly? Fuel pressure good? This sounds like a fresh build so there could be 100 things.

The cut is a bit fast, once it hits, rpms drop but recover. So far it hasn't stalled form this. The power just hits a wall, drops, and recovers. I have checked through everything, and everything does seem fine. Plugs are properly gapped, seated, and connected to the wires. All 4 cylinders are getting spark and fuel.

 

[pauleyman]

The cut is a bit fast, once it hits, rpms drop but recover. So far it hasn't stalled form this. The power just hits a wall, drops, and recovers. I have checked through everything, and everything does seem fine. Plugs are properly gapped, seated, and connected to the wires. All 4 cylinders are getting spark and fuel.

Is your mod list correct? 68hta but stock injectors and stock ecu?

 

[chrysler kid]

Since my post was a bit snarky and deleted:

You need to verify your boost pressure, it could be surging to over 12psi and causing fuel cut

You need to verify fuel pressure.

The stock maf sensor will only let you run a certain amount of boost and if it senses the turbo sucking by more air than acceptable the stock ecu will cut fuel.

Verify boost with a boost gauge. If you don’t have one then run the boost signal line directly to the watergate, a td05 framed turbo should only run 8psi where as the boost solenoid tries to run 12 which may be too much especially if it is a 68hta.

You could also have a boost leak and the watergate can’t regulate boost because your turbo is throwing a lot more pressure out than the car is actually receiving, which you would verify with a boost leak test or a boost gauge

You’re not new here this is all common stuff and we need to know your setup on this car.

Stock turbo?
Stock injectors?
Stock ecu?

 

[spyderdrifter]

Is your mod list correct? 68hta but stock injectors and stock ecu?

Yes, my mod list is updated. Those parts are accurate. I have done this setup before with no issues, this exact turbo even. It's not ideal, but it's what I have at the moment. I haven't added more mods as I want to get ECMLink before adding more.

Since my post was a bit snarky and deleted:

You need to verify your boost pressure, it could be surging to over 12psi and causing fuel cut

You need to verify fuel pressure.

The stock maf sensor will only let you run a certain amount of boost and if it senses the turbo sucking by more air than acceptable the stock ecu will cut fuel.

Verify boost with a boost gauge. If you don’t have one then run the boost signal line directly to the watergate, a td05 framed turbo should only run 8psi where as the boost solenoid tries to run 12 which may be too much especially if it is a 68hta.

You could also have a boost leak and the watergate can’t regulate boost because your turbo is throwing a lot more pressure out than the car is actually receiving, which you would verify with a boost leak test or a boost gauge

You’re not new here this is all common stuff and we need to know your setup on this car.

Stock turbo?
Stock injectors?
Stock ecu?

I'm the one that deleted your last post, as it was outright disrespectful, and I refuse to tolerate it. Espcially when I said nothing to deserve it.

But since your new post is way more of a help than the last, yes, I do have a boost gauge installed, and what you said does make sense. It's been a couple years since I've had to deal with these cars as I gave them up, and then for whatever reason decided to come back. My mod list has been updated since I got the car and started throwing parts on.

 

[pauleyman]

Yes, my mod list is updated. Those parts are accurate. I have done this setup before with no issues, this exact turbo even. It's not ideal, but it's what I have at the moment. I haven't added more mods as I want to get ECMLink before adding more.


I'm the one that deleted your last post, as it was outright disrespectful, and I refuse to tolerate it. Espcially when I said nothing to deserve it.

But since your new post is way more of a help than the last, yes, I do have a boost gauge installed, and what you said does make sense. It's been a couple years since I've had to deal with these cars as I gave them up, and then for whatever reason decided to come back. My mod list has been updated since I got the car and started throwing parts on.

Even if you've ran than before I'm going to concur this is probably fuel cut and you're better off running wastegate pressure only. At least try it and see what happens.

 

[spyderdrifter]

I'll give a shot. I appreciate your patience.

 

[chrysler kid]

I'm the one that deleted your last post, as it was outright disrespectful, and I refuse to tolerate it. Espcially when I said nothing to deserve it.

I can help you rebuild a motor over a keyboard if that’s the information you want, but the more information you give us is better

A boost leak test is for sure the best diagnostic tool you can use on these cars. For all you know the shop that put the motor in forgot to connect a vacuum line and the boost gauge is showing 10 psi because the other 15 psi is leaking out into the engine bay.

I’ll start it over, I’ve seen so many engine bays that it would really help me out if you could upload an engine bay picture so we could see anything possibly unhooked or looped wrong with the vacuum lines. Small stuff can get missed on a big job especially if you had them put a new motor in