Unusual boost issues

[foxdie]

Hi all, story time

Ever since I got the silver Galoon late last year its felt like it was running on wastegate spring levels of boost. About a month ago I temporarily fit a 7202, put Kens 2.0 ROM on it and tried upping the boost (also wanted CEL-on-knock). The car was unresponsive to boost changes and there was mild knock too. Nothing dialling back a couple of degrees of timing in certain areas didn't fix.

When the engines under load at WOT, there is a hissing noise. I tried tightening up the pipework, replacing the boost solenoid and using soapy water on the pipework to try and find any leaks. Nada.

I took the car to a local garage and they pointed out there's an exhaust leak by the rear turbo, the mechanic said he thinks the boost leak could also be coming from there too. I need to get a proper boost leak test.

I didn't bother to put the stock ROM back on the ECU, I kept it as it was with a relatively high boost target thinking there was no point changing it back. There's been no change in weeks.

That all changed this evening. Whilst stuck in stop-start traffic on the motorway, the car spluttered a little when idling twice (once when idling, then when trying to move away), this went away pretty much immediately.

Towards the end of my journey, I had to pull out into fast moving traffic and floored it, expecting the usual wastegate spring levels of performance (still more than enough to get up to speed safely) but the car rocketed forward like suddenly it decided it wanted to finally boost. Shocked me at first. Once I got clear of traffic on a clear road, I tried flooring it again and sure enough, wheeeeee powahhhh!!

I'll try it again in the morning, but I really am confused why it would start working now (3 months and nearly 5000 miles later) after a few days since I last tried anything?

[Davezj]

a car that fixes itself nice.

did you have a boost gauge fitted, if not why notyo bad lad, very cheap diagnostic tool, all turbo cars should have one.
It would have given you all the answers you needed to all the questions you had.
it will still help tell you what is going on now with the boost pressure

[foxdie]

Evening Dave

The problem is I have a set budget to spend on this Galant as it's part of a rally in September, it'd be nice to have but can't justify the cost

I'll probably run it with EvoScan tomorrow on the way to work to see what the ECU load reports in as (wasn't going above 140 last time I checked, target was 180).

[Davezj]

yep that is good plan.
if you need a boost gauge for testing i am sure i have a spare one somewhere, if i can find it i can post it out to you so you can use it to keep an eye on wha is going on with the boost then once you anre satisfied it is fixed you can send it back to me.

are you doing one of the £500 car rallys down to north africa for a charity run?
mate of mine at work did one a couple of years ago and said it was a great laugh.

[Grid]

The issues you are describing all sound like the issues I was having, apart from the miraculous fix. In the case of my Legnum I had a broken boost control solenoid and a leaking dump valve. After replacing the dump valve with a metal Evo one and fitting a MBC to bypass the borked solenoid I am back in business. Even hitting fuel cut sometimes, MBCs aren't ideal, but for simple traffic lights grand prix it works well enough.

[foxdie]

And back to the usual wastegate spring boost levels this morning

yep that is good plan.
if you need a boost gauge for testing i am sure i have a spare one somewhere, if i can find it i can post it out to you so you can use it to keep an eye on wha is going on with the boost then once you anre satisfied it is fixed you can send it back to me.

are you doing one of the £500 car rallys down to north africa for a charity run?
mate of mine at work did one a couple of years ago and said it was a great laugh.

Hi bud, yeah I think I might need to get one, may be able to get a cheap one soon.

And yeah, £600 scumball challenge, gotta get it to the ring, do a couple of laps, then get it home again

The issues you are describing all sound like the issues I was having, apart from the miraculous fix. In the case of my Legnum I had a broken boost control solenoid and a leaking dump valve. After replacing the dump valve with a metal Evo one and fitting a MBC to bypass the borked solenoid I am back in business. Even hitting fuel cut sometimes, MBCs aren't ideal, but for simple traffic lights grand prix it works well enough.

I've already tried replacing the boost solenoid but it could be the second was knackered too. I'm not sure my BOV is leaking as it's the stock recirc one.

Will see if I can get hold of an MBC too. Would help rule out some stuff.

[Confused]

Sounds very much like boost solenoid - my Anglia is much better now I've put another solenoid on it (getting about 13 PSI)

If you removed the pipe into the solenoid that goes to the wastegates, and give it a quick try, then you should find it's an animal (but there will be no boost control, so it'll climb and climb and climb) - but it will at least rule out the solenoid as being at fault.

[Davezj]

good advice form gary there, remove the boost pressure feed to the waste gates and you to can have 1.5 bar or pressure upto about 4000rpmthen it will tail off to about 1.1 at the red line.
but you need a boost gauge for testing or monitor with evoscan on 2Byteload.

if ou do find it is the boost solenoid i might have a spare somewhere. let me know about the boost gauge option and i will have a look for it.
mind you a boost gauge can be had for £10 ish from ebay and then you can sell it afterwards if you want.

[foxdie]

So I couldn't easily get to the solenoid on my lunch break so I just removed the waste gate pipe from the intake manifold for a quick test..

OMFG POOWAA.. er KNOOOCK

Think we've found our culprit gentlemen, much appreciated

[Confused]

Awesome These solenoids are getting old now, so I'm not too surprised that even a 2nd hand one is not working properly all the time.

The part number for this is MR212636 (they're called an "Emission solenoid valve"), and I have just called my local Mitsubishi dealer, they are £46.27 + VAT (£55.53)

[Davezj]

i have a spare standard boost solenoid, i am not 100% sure of how well it works. but you are more than welcome to try it to see if it fixes the issue. and if so then we can come to some arrangement on the price.

i think it would be a good idea if you buzz out the wiring to the solenoid, it might just be a bad connection considering you already replaced the solenoid once.
i think you should be able to put a DVM across the boost solenoid wires on the loom and see if you get a voltage that changes when boost pressure changes and the ecu tries to control the boost.
i am not sure if the solenoid is powered to keep it shut to get max boost or powered to open it to bleed off the boost. the action will determine if you max +ve volts at zero pressure idle or max +ve volts as the solenoid bleeds off the max boost . it also depends on if the valve is positively or negatively switch.

[Davezj]

I have just checked the UK spec galant wiring manual which is linked on here via a link to an off site location,
http://www.clubvr4.com/forum/showthr...l=1#post744608

It seems that all the solenoid valves are Negatively switched so i do not see why the boost solenoid would be any different. on the boost valve wireing you should see 12V pin and floating/GND pin.
so measure each pin to chassis to see which is the 12V power and then pin to pin to see if you get a short to 12V across the pins or a floating signal this will tell you if the solenoid is power shut at idle or if it will be powered open as the boost is controled.

if there is no 12V then the wiring is faulty. wiggle the wire around to see if the fault is at the solenoid end or if it else where

[Confused]

The solenoid defaults to powered off, and closed. This means that when the electrical system fails, it defaults to the safest possible scenario - wastegate spring pressure.

It has a common 12v ignition feed, shared with many other components on the engine (obviously it does split off to run to the solenoid individually). The Ground runs straight back to the ECU, and defaults to floating.


The ECU pulses the ground connection to activate and open the solenoid as per the required duty cycle.


I had a solenoid that was stuck solidly closed - I opened it up, gave it a clean up and tested it on the bench, and it started clicking when power was applied. Put it into the car, and it locked up again almost immediately. So I just pulled the un-used one out of the Legnum, and hooked it up to the Anglia.


So - as @Davezj said, check the wiring - ensure you've got that 12v feed, and check continuity from the solenoid to the ECU.

[Grid]

There's two of these solenoids on the schematics though... What does the other do?

12421T VALVE,EMISSION SOLENOID MR212636
12421S VALVE,EMISSION SOLENOID MD320313

Screenshot from 2016-02-11 17:12:56.png

[Confused]

The other one is for the fuel pressure regulator.

It's 12421T that you need.

[foxdie]

Thanks Gary, I'll get one ordered tomorrow.

Incidentally, has anyone tried to use the fuel one as a wastegate solenoid?

[Confused]

They have different connectors on them (so you can't accidentally plug them in incorrectly) but they might well be mostly similar on the insides.

[Grid]

The 12421T/MR212636 is cheap - it's 26GBP + taxes + shipping from Japan (Amayama). However it seems to be a weak part, a common source of failure. I am planning to just replace it with a industrial 3-port MAC valve (and block off the middle port of the valve). In fact all the companies like Greddy, Grimspeed use the exact MAC valves, just with a nice big sticker covering the MAC logo. I'm sure it's been done before in our VR-4s.

[Confused]

The "issue" with that is that the ECU is tuned based on reaction speed and flow of the standard boost solenoid, as well as the internal resistance of the coil, which can all affect how it works and how it produces boost.

I have a nice GM 3 port solenoid which I was looking at using - after some research, it seems that to use that one instead, the ECU needs to be adjusted to take into account the better reaction time, and you actually need to *reduce* the duty cycle to get similar levels of boost!!

http://www.evolutionm.net/forums/ecu...-solenoid.html


(I've now got myself a nice OpenPort 1.3u cable so I can flash my ECU, but when I was installing it, I didn't, so I didn't install it, and instead stole the OEM one from the Legnum!)

[foxdie]

Well, had a quick crack on my lunch break, I can see battery voltage on one pin and pulses with the oscilloscope when put on both wires and the throttle blipped. It's most likely another faulty solenoid.

I've found them pretty cheap on Part Box here: OEM Mitsubishi Mitsubishi OEM Cylinder Assy, Clutch [MR212636]