pulsing boost at transition to secondairy turbo
 

Car is running simplified sequential off a haltech. What would cause the boost to pulse rapidly after the second turbo comes online. datalog of map looks like the teeth of a saw.

Also the pulsing starts just after the transition, and continues getting worst as the rpm go up.

It did this when stock (stock computer, stock turbo controll setup).

Could this be a bad turbo contoll actuator?

Have you done anything to the precontrol hose? Replaced it? Removed the pill? Installed a boost controller?

What boost gauge do you have?

My car had a blitz boost gauge in it and i didnt have this problem. Now i do, but ive since had the car remapped with a decat and a few other bits and installed a defi boost gauge.

ive bene told that the defi gauges are very sensitve and are supposed to come with a little dampener thing that stops this from happening?

I think your onto something, so the precontroll could be causing this problem.

Let me guess, if the second turbo isn't spooled when the y pipe valve and TC bring both turbo's online the boost will flow to the other turbo, and somehow the y pipe valve is fluttering after that point as a result.

This has nothing to do with what boost gauge I have...

Another guy found that this problem was a clogged cat.

What exactly does pulsing boost mean?

I'm having abit of problem usually on 3rd gear after about 5k rpm with the car cutting out slightly as I approach red line. Like the car stutters and cuts out for a slight second so is this pulsing or just purely fuel cut? Better yet how do I fix this?

Could be, but you didn't answer my questions.

Well to answer your question, I am controlling the pre control with a haltech, but I set it to return the pre control actuator to closed at the transition point.

Here's an overview of the system:

http://www.autosportracetech.com/RX-...erOverview.htm

Just make sure you are emulating something similar.

Thanks for the link, I could potentially set it up exactly like that.

So I think I need to move the control solenoids to between the wastegate and pre control actuators rather than have them in the stock locations.

And acording to this link the pre controll stays open after the changeover.

Also I am controling the CCV and CRV with the same output (they seem to have the same paramaters, so why not) it seems to me mazda didn't do it because it has the tendancy to make honking noises in some ranges depending on what the pre controll is set at.

I suggest that you reinstall an OEM precontrol line (with a pill in it), and only use the haltech to control boost on the wastegate.

Even with the oem pil, I don't have an OEM computer installed to controll the pre-controll solenoid. what I have on the haltech is a 3d map that gives duty cycle based on boost and rpm.

I may set it up just as you are suggesting, I might experiment some. The haltech with a trim module and easy dataloging makes it very easy to experiment.