Electronic boost gauge

[Heaveho]

I'm having all kinds of aggro with my Evo 9 engined Evo8 hitting target boost. It's mapped for 1.8 bar, runs and drives as though nothing's wrong right through to the redline, but will only hit 1.4 bar and drops off afterwards.

I've changed the 3 port boost solenoid as I've had bother with one before, and checked the preload on the actuator, to no avail. The car feels fine, to the point where I'm starting to wonder if the gauge is on the fritz.

I don't think it's a boost leak, the delivery is spot on.

What next?

[GreenV8S]

A mechanical boost gauge would prove that either way very cheaply and easily. Make sure you're measuring true manifold pressure and don't have anything else in the way of the gauge. You should also be able to see the boost level from the ECU.

If the gauge is pegged at that boost level I'd be looking at the range of the sensor and gauge. If it's showing a figure that varies sensibly with load and revs then it's more likely it's showing real pressure, but there's a chance it is not calibrated accurately.

[stevieturbo]

Heaveho said:

I'm having all kinds of aggro with my Evo 9 engined Evo8 hitting target boost. It's mapped for 1.8 bar, runs and drives as though nothing's wrong right through to the redline, but will only hit 1.4 bar and drops off afterwards.

I've changed the 3 port boost solenoid as I've had bother with one before, and checked the preload on the actuator, to no avail. The car feels fine, to the point where I'm starting to wonder if the gauge is on the fritz.

I don't think it's a boost leak, the delivery is spot on.

What next?

Next ?

First step would be datalog what the ecu is seeing.

[Heaveho]

Cheers, I'm limited to what I can do at home. I've been trying to find an old mechanical boost gauge I think I've still got, no luck so far.

I'm also trying to remember how the current electronic gauge works. I fitted it 12 years ago, it's in a home made pod on the door mirror triangle, and obviously there is only a small wiring loom coming from the back of it. There's a vac pipe from the inlet coming into the car through the bulkhead, but I can't see where or how it terminates. I'd like to check it to make sure there isn't a leak, but it's buried in there somewhere.

The last time I drove the car before having to put it away for 2 years was a trip to have a major service. The gauge stopped working on the way there, and they re-vac piped it. I'm wondering now if there's a connection to that.

[stevieturbo]

I wouldn't care what a separate gauge says just yet.

Datalog the ecu and see what it is seeing.

Does the car feel or behave any different ?

[Jazoli]

You can get info on boost pressure from apps like Torque Pro and use a 10 quid ELM dongle through the OBD port, there should be no need to plug a mechanical gauge in at all

[Heaveho]

stevieturbo said:

I wouldn't care what a separate gauge says just yet.

Datalog the ecu and see what it is seeing.

Does the car feel or behave any different ?

I've got a scangauge, and typically I've managed to get readouts for everything but boost pressure, despite multiple attempts to get it to connect.

Although I've owned the car for 20 years, I rarely get to drive it. There was a long period between me knowing it was making full boost and doing what it's doing now, and tbh, it still feels properly quick even if it isn't right, but I just can't remember if it's any slower than usual or not. In all other respects, it drives absolutely faultlessly. I think it'll be going to it's second home ( Evotune ) next week for someone with the gear to have a better look.

[stevieturbo]

Heaveho said:

I've got a scangauge, and typically I've managed to get readouts for everything but boost pressure, despite multiple attempts to get it to connect.

Although I've owned the car for 20 years, I rarely get to drive it. There was a long period between me knowing it was making full boost and doing what it's doing now, and tbh, it still feels properly quick even if it isn't right, but I just can't remember if it's any slower than usual or not. In all other respects, it drives absolutely faultlessly. I think it'll be going to it's second home ( Evotune ) next week for someone with the gear to have a better look.

Mmmmm...never really worked at Evos. Some oddball cars run MAF, and do not have a map sensor for manifold pressure. It might be one ?
I'm sure I've come across them before, but just cannot recall what cars where like that

Tactrix cable and Evoscan would let you see and datalog all ecu info.

[Heaveho]

It's got a MAP sensor, the car's mapped to run Speed Density through that rather than the MAF. It wouldn't have had one originally, but when I fitted the E9 inlet manifold with all the rest of it, they come as standard with it. I don't know if something else already taking a reading from the MAP would prevent it from providing boost pressure readouts?

Thanks for the input. I'd like to find the fix myself, partly just out of curiosity , but also the fact that I had a £900 bill for a mega service at Evotune less than 200 miles ago, so there's also that to consider!

Edited by Heaveho on Saturday 23 September 17:35

Edited by Heaveho on Saturday 23 September 17:38

[stevieturbo]

Then you absolutely should be able to get boost readings from it.

I assume it is on a standard ecu that the scan tools will read ?

get the Evoscan and a Tactrix cable

https://evoscan.com/product/mitsubishi-subaru-obdi...

Although a mechanical boost gauge is simple and cheap for a test, but always better to have data recorded for proper analysis and future reference.

[Heaveho]

Cheers, I'm clearly doing something wrong. I've been into Scangauge .com. but there's nothing specifically for my car. The car has a standard Evo 9 ecu.

Thanks for the link.

Someone posted up about Torque app earlier, I've got that, but again, I can't get it to connect.

[stevieturbo]

App yes, but what plug in reader are you using ?

Tactrix is proven

[Heaveho]

stevieturbo said:

App yes, but what plug in reader are you using ?

Tactrix is proven

Is Tactrix generic, or car specific?

[stevieturbo]

Heaveho said:

Is Tactrix generic, or car specific?

Did you even look at the link I gave you ?

It first came about for diag and reflash for Evo's and then Subarus. But pretty sure the hardware can be used for other stuff too.

[Heaveho]

stevieturbo said:

Did you even look at the link I gave you ?

It first came about for diag and reflash for Evo's and then Subarus. But pretty sure the hardware can be used for other stuff too.

Er yes, but I went straight into the tables and completely ignored the name and picture of the Evo at the top!

I get so absorbed in trying to find a solution, I don't always see what's right in front of me. I went into looking for specific models without realising you'd already done that. Thanks for your help.

[Heaveho]

Ok, this appears sorted now. Probs my fault, bad memory about the high boost configuration. It made 410 / 400 when tested this morning, on the same dyno it was mapped on 4 years ago, up the from 391 / 380 it made on that day, with no changes other than a new like for like 3 port boost solenoid, so I've done something right. Probably.

It's right on the edge of where I want it to be at that, so I'll have it knocked back to what it was to save the rods and 4th gear from unnecessary unpleasantness stress wise. Torque at 400 is about all they can cope with as a rule.