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PostPosted: Sat Apr 26, 2014 7:34 pm 
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Hi,
I was wondering if anyone had had the problem with an ST185, that it has no power when the engine is cold. The car starts very well, normal idle revs, about 1200 on choke (900 off choke), doesn’t stall or die, but when I try and pull away at junctions there is no power, were talking less power than a 2CV, making it almost impossible to pull out into traffic. In order to accelerate I have to use more throttle which engages the turbo, but this still only increases the power a little.
It gradually gets better as the engine warms up and after 5 minutes driving it feels completely normal again. If I start it when warm it drives normally.

I don’t know if it’s related, but most of the ignition system has been replaced in an attempt to sort an error code 12 problem and Nibbles kindly helped out with the ECU. I still get the engine management light come on briefly when I accelerate, the warmer the engine the higher the revs at which this occurs. Initially it’s around 3800rpm then rises to about 4700rpm after which it tends to go completely. There are no symptoms when the error code comes on, the car feels normal. Before it’s fully warm the light can also occasionally come on when I’m slowing down gradually for a junction.

I also run a Greedy B-Spec solenoid boost controller at 1.25bar, so have fitted slightly colder plugs. They are NGK BKR7EIX 2667 Iridium IX Spark Plugs. I don’t think it’s the plugs, as the car starts very well, but would welcome advice, if others have had this experience on slightly colder plugs.

The problem doesn’t correspond with any single change I made to the car, so I’m really struggling to pin it down.
I’ve also noticed poor fuel economy, 21-22mpg on what is mostly a steady 70mph motorway commute to work and I would expect it to be around 27-28mpg on that sort of run.
I’d very much welcome some ideas on what could be causing the lack of power with the cold engine and if anyone has an idea on the code 12’s I’d also be grateful to hear from them.

Louise


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PostPosted: Sat Apr 26, 2014 8:45 pm 
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Just to fill in s bit more information, I changed the capacitors that normally fail in these ecu's. I can't remember whether one or both had started leaking, but the damage to pcb was minimal and I doubted they would have caused a problem.

Is this the fault you were having before I did the ECU ?

Have you checked for fault codes after the flickering engine light ? did you then reset the ECU ?

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PostPosted: Sun Apr 27, 2014 4:06 pm 
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Hi Chris,
thanks again for your help. Before you worked on the ECU the car would often not start or would suddenly cut out making it unusable. Since you changed the capacitors it always starts and the error code 14s that accompanied the 12s have gone away. :D

I've got into the habit of checking the error code and clearing the ECU after every trip, so each time it's a new 12 coming up.

This cold running problem is new, I don't think it's related to the ECU, but I mentioned it in case it is. I would like to get to the bottom of why I get these code 12s every time I use the car. It's a bit like 'the boy who cried wolf', I already pretty much ignore the engine light, which is not a good habit to get into. :(


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PostPosted: Sun Apr 27, 2014 6:25 pm 
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I also think they are unrelated.

Code 12 means the ECU is seeing a starter signal (STA) for at least 2 seconds before it sees any movement in the distributer. I can think of a few possible scenarios -
1 - Something is delaying the starter turning after you have turned the key, this delay being introduced between the STA signal and the starter itself. Could be immobiliser related.
2 - Something is inhibiting the distributer signals to the ECU for a few seconds. Do you have any device to delay starting until oil pressure is up ?
3 - The ECU is seeing a permanent STA signal.

Does the code 12 appear every time you start, or only if the light flickers while at higher RPM as described ? Do you get any other codes coming up after that has happened ?
I'm not aware of any scenarios which flash the engine light on the standard ECU without storing a code. On the Apexi PFC this is done to indicate high levels of knock.

I presume some form of fuel cut defender is fitted if you're running 1.25bar. What is actually being used and does the standard boost gauge appear to work normally from vac up to full scale ?

The lack of power could be weak mixture if the cold start injector circuit isn't functioning, but I would expect this to affect cold idle more than higher throttles. It sounds more like the ECU is going into some form of 'safe mode' and retarding timing.
Alternatively, is the engine misfiring with a regular 3 or 2 cylindering (sounds like a subaru) in which case it could be plug related.

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PostPosted: Mon Apr 28, 2014 10:22 am 
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I don't know enough about the car but for 1.25 bar on a st185 engine I assume it has been rebuilt at some point or will soon need one?

As a simple check I would pop the dizzy cover off to check the rotor arm hasn't worked loose.

Chris' analysis is much better than mine but a couple of simple checks

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PostPosted: Tue Apr 29, 2014 3:13 pm 
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Hi guys thanks for getting back in touch.

Regarding the boost:
The car used to have a fuel cut defender fitted, but once I realised this was the case I removed it to reduce the risk of me damaging the engine, it’s a stock engine, including the original head gasket.
I’m getting to 1.26bar as read by the Greedy, I did wonder if it may not be accurate as I have never had a fuel cut (since the device was disabled) and the car doesn’t feel supper fast. If you asked me to guess, it only feels about 20bhp up on stock, certainly not 60 or 70bhp which I would expect from 1.26bar.

Relating to the poor cold running:
I replaced the dizzy cap and rotor arm at the weekend, with no change to the cold running problem. I’m going to change the high tension leads, when the new ones arrive, but I don’t think it’s them as I’m not getting any quenching at high boost.

I’m going to check the static timing at the weekend and look at the AFM (air flow meter) as that could be changing the dynamic timing.
I’m also going to replace the hoses on the car air, vac and water as most are now over 22 years old, and are starting to fail. Any recommendations on which ones to go for?
To Chris’s point, I regularly reset the ECU in case the code 12s are putting it in safe mode, however I still get the cold running problem before I get another ECU warning light. I guess there could be something more fundamentally wrong with the ECU that pulling the fuse won’t fix.
With respect to misfiring I’ll have to look up what you mean about ‘3 or 2 cylindering sound’, I don’t have any experience of Scooby’s, however the idle isn’t rough on start up, it seems completely normal.

Code 12’s:
Thanks again for your help with this Chris. I never get an ECU light & code 12 on start-up, only when the car is actually running. I believe that would rule out your suggestions 1 & 2. I’m not aware of any device fitted to delay starting.

Just to confirm my understanding is correct, the STA signal should only be sent to the ECU when the car is being started. Once it’s started the STA signal stops and it should be impossible to generate a code 12. If that is the case, a code 12 when running must result from your point 3.

Your point 3 is interesting, I’d never thought of that. I’ll have to give some thought as to how to test for a permanent STA signal and what would generate it, I don’t have an oscilloscope. The entire ignition system has been changed since the start of my problems, the starter was the very first thing I changed, so I’m surprised that the new kit didn’t cure it.

Thanks again,
Louise


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PostPosted: Tue Apr 29, 2014 7:48 pm 
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You will hopefully find the following useful if following signals about.

https://dl.dropboxusercontent.com/u/831 ... T185RC.pdf

The last circuit diagram right at the bottom shows the ECU circuit for the CS/RC variant. Page 62 of the pdf shows the starter circuit. It would appear that the STA signal comes straight from the starter switch, as does the motor itself.

So, to generate a code 12 would require a false STA signal to ECU AND a loss of distributor signals. Seems unlikely while going along with no apparent symptoms.

It may be worth starting it, then switching off and checking for a code 12 before it's had a chance for one of it's spurious engine lights. It may just be possible the 12 isn't generated by the spurious engine light while driving.

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PostPosted: Tue Apr 29, 2014 8:20 pm 
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IMHO turn boost down to 0.7 bar ish, reset ecu and see if it is better in the cold. Don't turn the boost up until the problem is resolved and even then with a std engine 1 bar is probably too much so stick to 0.9 bar max.

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PostPosted: Wed Apr 30, 2014 10:31 am 
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Hi Diceman,

could I ask a small favour, do you know how to reduce the power on a solenoid boost controller (Greddy Profec B Spec 2)
The reason I ask is I obtained the 'High' settings below from another forum which should give ~1.1bar, as you know I'm reading 1.26 bar. I tried setting the 'Low' up to give less power, but as you can see below, the settings I've tried made no difference to the peak power. I have to admit to not knowing how to reduce the power using the options available.

High
Set 45%
Gain 35%
Set Gain (Start Boost) 0.7bar
Warning 1.1bar
Limiter 4%
Max Boost Recorded 1.26 Bar

Low
Set 30%
Gain 15%
Set Gain (Start Boost) 0.5bar
Warning 0.7bar
Limiter 6%
Max Boost Recorded 1.26 Bar


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PostPosted: Wed Apr 30, 2014 6:30 pm 
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usually switching off the power to the boost controller will disable it and leave you on minimum boost.

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PostPosted: Wed Apr 30, 2014 9:26 pm 
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Yes, unless you have boost creep or it's plumbed in wrong.

Turn it off and see what boost you get.

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PostPosted: Thu May 01, 2014 10:05 am 
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Hi Diceman,
I hope I don't seem really 'blond', but if I turn it off how will I know what boost I'm getting as it's the boost controller that shows the boost value?
The gauge on the car doesn't have a scale.

I assume the answer is to purchase a separate gauge and use it whilst setting the car up. (I don’t want another device mounted to the dash board or next to the windscreen so I would take it off after setting up the car.
It would also answer the question of whether the Greddy’s read out is accurate.
I could ‘T’ it off the vacuum pipe to the Greddy as it already runs through the bulkhead.

I'm confident the device has been put in correctly as it was fitted by Ian at TRD and he certainly knows his GT4's.

Any recommendations on an accurate gauge, it doesn't need to look pretty as it will only be in the car when I'm running diagnositcs?


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PostPosted: Thu May 01, 2014 11:04 am 
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This would be a fine choice:

http://www.demon-tweeks.co.uk/motorsport/gauges-auxiliary/stack-turbo-boost-pressure-gauge-mechanical

:)

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PostPosted: Thu May 01, 2014 1:06 pm 
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"hold down the "select" switch for atleast 2 seconds, the display will still show the base boost (in real time) the display will also show the PEAK and LAST BOOST"

http://www.greddy.com/upload/file/PRofec_Bspec2.pdf

Page 14 second bullit point.

You can turn off the boost control but the display still functions.

Ensure you have reset the Peak boost or that it auto resets after engien switch off. If you see 1.26 bar when the car is first started you need read the manual and figure out how to reset it.

Take the car for a short run and report on max boost achieved.

If still high then reduce the SET figures after that to lower boost if needed. If reducing it right down doesn't work you have glorious boost creep.

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PostPosted: Thu May 01, 2014 1:46 pm 
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Hi Sirius, thanks for the suggestion on the gauge.

Diceman has definitely made me feel blond, as I should have realised the Boost controller had a means of turning it off (Hold select switch down for 2 seconds) ;-)
I’ll have an experiment and see what happens.

Can boost creep occur with the stock turbo? I had assumed it could only happen if I slapped a larger aftermarket one on.


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