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Discussion Starter · #1 ·
Hi all,

Just need to confirm the correct operation of the wastegate boost control vavle (solenoid), not 100% on proper name as there several different references ive found.

I've received P0243 which is advising an issue with it, I've removed it from the car and if apply a vacuum on the line that gets plugged into the brake booster line it doesnt hold vacuum, will take 2-3 seconds to release the vacuum. If I apply 12v to the solenoid it clicks and immediate allows air to flow through, but on release sometimes it holds vacuum for longer or not at all or slowly increase the resistance when vacuum is apply. Its abililty to hold vacuum varies allot.

I'm assuming given its style it should hold vacuum 100% when no power is applied or does the ECU/ECM do something else fancy with this device?

Cheers,

Nic
 

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It should be sealed no power applied. ECM applies a pwm signal to it to vary its opening to control boost
P0234 is the genetic "open or short circuit " detected.
While the solenoid seems suspect from a sealing point of view, you may also have a wiring problem. Id replace the solenoid as its not functioning correctly and should hold a vacuum when unplugged.
 

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Discussion Starter · #3 ·
Great thanks for the info, I’ve ordered a replacement and should be there here in a few days. Given its source is PWM from ECU would the voltage vary when measured by a multi meter? When I have the solenoid unplugged and I have the car with ignition turned im
Measuring 9.6volts across the two pins. Is this normal?
 

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I haven't measured one in ages but a pwm signal will show a varying voltage on a multimeter, only way to really look at it is via a scope
 

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Discussion Starter · #6 ·
since its a PWM, i'll i'll put the boost control valve back, get the multmeter hooked up which driving and monitor the voltage, see if it adjusts at all. Can does sometimes feel normal but then it drops boost and limp mode appears. On long drives limp mode disappears mostly, the behaviour feels similar to how the vacuum sometimes hold and sometimes doesnt.
 

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Discussion Starter · #7 ·
Just did a couple of tests, both pins going into the boost control valve report around 12-13voltage after the car has been driven and in limp mode.

Interestinly, while driving in limp mode, PIN2 reports 13-14.4 voltages based on engine RPM, so assuming alternator charging/battery voltage.
PIN1 reports much more interesting stuff.

In Limp Mode - Testing with PIN1 and ground to engine chassis
1. At idle it reports 4.23volts approx
2. While parked and reving to 3,000rpm it goes up to 7-9volts
3. When driving and in gear, say 2nd or 3rd and on a flat stretch of road and I slowly get it to 3,000RPM it gets up to around 4.5v approx.
4. If rolling down a hill while in gear and it gets to 3,000RPM the voltage reads 8-9volts, if I slightly touch the accelerator pedal it drops down to 4.24v
5. When parked with engine off and ignition on it reports around 13volts for 30-45 seconds
6. Once ignition off/key removed and then after 30-45 seconds it reports 0.23volts.

Does this sound typically for Limp mode, thinking it is because it is reducing vacuum to wastegate/reducing boost to protect engine given its state.

I'll let engine cool down and redo the above tests before it jumps into limp mode, see if the results are different.

Cheers,
 

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Discussion Starter · #8 ·
Just completed similar above tests while not in limp mode.

Not in Limp Mode - Testing with PIN1 and ground to engine chassis
1. At idle it reports 4.23volts approx
2. While parked and reving to 3,000rpm it goes up to 7-9volts
3. When driving in gear, 1st, 2nd, 3rd and forth the voltage goes up to 9-10 volts.
4. Reported boost from stand still going from 1st to 4th and hitting 3,500RPM in each gear is as follows
1st = 9.5psi (7-8v)​
2nd = 13psi (8-9v)​
3rd = 13.5psi (9-10v)​
4th = 14.2psi (9-10v)​
5. Limp mode then appeared after about 5 minutes of driving and the previous post results appear again. Boost through all gears is then limited to 7.5PSI approx and max 3,000RPM

I feel like this seems normal ECU control over the solenoid voltage (at a guess),

Should this engine be producing more boost, ive read it should be around 1.5bar equalling 20psi or so, this might be due to the faulty solenoid behaps?

Cheers,
 

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The f9q usually runs around the 15 psi (1.1 bar) but can hit 20 when being worked under load at high revs. Depending on conditions you will probably find it hovering around 15 to 18 psi under acceleration

If its detected an issue the ecm limps about 6 psi and 2800 rpm by dialling back the injection and timing, and opening the waste gate solenoid if required (if boost vanes get stuck open) and closing the boost control solenoid (dropping volts) so your 7 and 3000 sounds about right for a limp.
The boost control solenoid works reverse to how people think, more voltage = more vacuum = bigger turbo vane opening = more boost.

You have done well getting results from a multimeter, looks like your one isn't too fussy about its dc input being chopped
 

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Discussion Starter · #10 ·
great, thanks for the info. I've actually got a spare 'ECU and Keybarrel' I can test to see if there is a different result in voltage. I'll remove the solenoid again and test flow rates at 4 to 10 volts and then also 12 volts. Will be interesting to see if there is amassive difference between 10 and 12 volts.
 

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I think you will find its a dicky solenoid giving inconsistent flow thats triggering the code. Ecm is commanding a certain vane opening and expecting to see corresponding boost and air flow and ain't getting it.

Multimeter is not going yo be accurate but at Keats using the sane instrument will give you a base line, but I'm not sure its going to show much difference
 

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Going from my bad memory, I think there's a maf, map and a boost pressure sensor.

Suzuki took a working system developed by Renault and wrote their own ecm firmware, which in my opinion was wrong. They turned a reasonable system into a real pain as the diagnostic codes don't always line up. The Renault forums have a lot more knowledge on these things as they are common and dont seem to give the same troubles.
Suzuki took a transverse engine, mounted it longitudinal and never thought about servicing. Try taking the turbo off, or getting to the thermostat with the engine in place. Oil changes are hard enough.

Not sure what's on the vacuum line, sorry.
 

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Discussion Starter · #15 ·
ok cool, thanks heaps!

Quick question about the MAF, if the car is idle fine and you unplug the MAF should the idle of the car alter/being rough? When i do this engine continues to idle fine and the limp mode light appears.
 

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In a diesel it doesn't do the same things you expect from a petrol. It will be changing back to its default settings and triggering the limp light, but you probably won't notice an idle change, but will notice lack of power when driving.
A petrol being a bit more sensitive to mixture changes will usually drop or become rough in idle.
 
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