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Discussion Starter · #1 ·
The question is 'haver I broken it'.

I tried my spare ECU (2.3CSE T tcs ~200bhp) today (to check it before sending to Sweden).

Car started, ran, drove and seemed to boost to the correct level on a very short straight (orange/red border).

Swapped it back my Aero box and checked the car started again.

This evening when getting to drive home, I have no APC, hits overboost all the time (at 1st I thought it was adaption). Checked APC fuse 5 and it was blown.

Fitted a new 10A fuse which hasn't blown, bust still nor APC.

Checked APC valve and it's gor 3.2 ohm across 2 pairs of pins 1-2 and 1-3 (3 ohm from 2-3).

Is there something else to check?

Would the temp ecu have blown the fuse? it's not blown since.

Andrew
PS, Ruby was good.
 

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Andrew, it sounds to me like it may be a coincidental APC solenoid failure... the two I have read:

1-2 2.5ohms
2-3 2.5ohms
1-3 5ohms

and

1-2 3 ohms
2-3 3 ohms
1-3 6 ohms

ie 1-3 appears to be the sum of the resistance of the other two.

I can't see how the temp ECU could have caused the problem, and the APC fuse appears to be in the line to the solenoid- if I pull mine I only get base boost.


Good luck!
 

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Discussion Starter · #3 ·
I've just unplugged the APC valve and I'm still getting overboost, so I looks like it's stuck closed. (may need to swap C & R to get some control (base boost).

It's not making any clicking when unplugging/plugging when idling.

I thought I'd read somewhere that Trionic 5 APC control failure can cause dead APC valves.

I have one on the carly I can swap out, but don't want to fry that too so want to rule out most bits before changing.

If the new 'temp' ecu is a killer, I may have to use that with apc fuse pulled for a few weeks while my real box is breathed on. I don't want to tweak a box that doesn't have full APC control.

I may refit the temp ecu and see if the fuse goes again (which it might not if the valve is now dead).

I was confused why I didn't get a double value from pin 1-3.

Andrew
 

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Andrew,

With the APC disabled, either by unplugging or pulling the fuse, you should only get base boost .

Pin two is a common point between the two solenoid coils so reading from pin 1 -3 you should have double the resistance of either 1-2 or 2-3.

Trionic ECU's do appear (from my readings) to kill the APC solenoid when they fail. Certainly my ECU has fried three solenoids in quick sucession and I now use a bleed valve. Your ECU may have been for sale because of its fault. The ECU seems to fail in a manner which leaves one of the switched ground points (for the APC solenoid) permenently grounded (perhaps a transistor goes on short?). This causes an permanent current to flow through the coil of the solenoid (rather than a pulsed current) which can cause damage to the coil before the fuse blows.

HTH.

Nick.
(edited for cwap spelling)
 

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Discussion Starter · #6 ·
Nick,

ECU was for sale as the whole car had been broken, but was advertised as 'working - no errors'.

Looks like it might not ben the one to be chipped, but will be the one used short term while the others chipped, so no Aero and Aero stg3, but limpable and Aero stg3.

I tried to take it to bits tonight but broken my Torx on a rusted screw.

Tomorrows task is to do some Carly to Aero voltage comparisons with new and old Aero ecu and unplugged APC valve, followed by original Aero ECU and the carly's APC valve to check that I've not killed that too.

I will also try to see if the APC valve can be resurected.

Andrew
 

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Discussion Starter · #7 ·
I've had the APC valve off now and it is closed solid from both C and R ports

I have ordered another one (£35) and while I wait for it to arrive (Wednesday probably) I've measured the voltage from the centre pin (green/red) to pin 1 (green) and pin 3 (red) at idle.

2 -> 1 13.28 v
2 -> 3 4.07 v

The carly on the other hand reada 4.72 and 4.00 respectivly.

Could someone else out there with a trionic and DVOM take a couple of reading for me, as I want to make sure that the near shorted pins 1-2 (0.3 ohms after rechecking today) have not fried the ecu doe to too much current being drawn by the faulty APC valve (which in turn was probably killed by the temp faulty ecu fitted yesterday....).

Andrew.
 

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Done, but not a lot of help I'm afraid...

2 > 1 -11.6V
2 > 3 -11.7V

Relative to ground, pin 2 sits at +13.5V

However my pin3 is blue, not red.

What would seem to be common between my known working one and the carly is that pins 1 and 3 are at nominally the same voltage at idle, unlike your aero.
 

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Discussion Starter · #10 ·
Thanks Mark, that makes me feel a little more comfortable.

My pin 3 is blue too, I just typed the wrong colour...

The fack thet mine a differing voltages might be an issue, but your 11.7 isn't too different to my 13.28, and the lower of mine are not to different to the carly's...

I was worried that they should all be arounf 4-5 v, obviously not.

I didn't check pin2 to ground, but will now.

Andrew

Edit:

I wonder if that's how it works, pin 2 is battery voltage and fused (10A), and the ecu balances pin 1 and 3 down to almost ground and just raises 1 or 3 to throw the APC one way or another. If the voltages are different for too long it all warms up and dies? confused by that last sentence myself...

ie. raise 1 to 13v and pins 2-3 becomes effective. A bit like the bulb warning mechanism.
 

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Discussion Starter · #11 ·
Finally took the plunge/risk and put the Carly APC valve on the Aero to see if it worked or blew...

It worked thank 'insert deity of your choice here'!

I've now got the battery off as the T5 has adapted down to only 12-13psi.

So no long term damage done, just a scare.

Just got to get that new valve for the Carly, in the mean time I'll fit that MBC

Andrew.
 

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Andrew,

The APC works by the ECU pulsing the solenoid first one way then the other at 90Hz, but the time it is allowing the boost pressure to show to the wastegate is varied in duration within that 90th of a second (it's pulse width modualted in other terms). This allows more (or less) pressure to be shown to the wastegate controlling it precisely.
When one of the transistors(I presume) in the ECU goes on short it A) doesn't work any more and B) tends to take the APC solenoid with itself rather than just blow a fuse.


Nick.

PS. Anyone got a spare '93 ECU about?
 

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Intersting info... I see know why the Townsend site says "never try to test the solenoid by connecting directly to battery voltage" or similar!

One thing that confuses me... some people describe a "click" when the ignition is switched on, others describe a buzz. Is this a pre vs. post Trionic difference?
 

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Discussion Starter · #17 ·
Faero - My working BPC/APC valve's have never made any noise at idle on either the Carly - DI/APC and the Aero - Trionic T5

MartinC - I just rang my local non franchised Saab specialist, Hannants and Sons in Swaffham. I assume it will be a good used one.

Andrew
 

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thanks scaero - although now I'm worried/interested.

My Solenoid buzzes at what I would have though is the oft quoted 90hz - it has the correct resistance and gets a nice 12v on its power inputs. I hoped all was well. (pulling the power to it results in base boost only - as expected)
Turn the ignition on and you can hear it with the bonnet open. I'm not sure if I would be able to hear it with the engine running though..

Ah well - might go back and double check this area too. Anyone else hear buzzing noises? all the time? Maybe its just hours of aural pummelling from massive PA systems..

Good you got your BPC sorted though!!
 
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