205 Ecu Conversion

**BETSY**

New member
Hi Guys, i have started again with getting the st205 system running on my st165/st185.

basically the car will start run for a couple of seconds and then dies.
if i touch the throttle it does even quicker!?

when it runs it sounds smooth and no miss fire.
There are no error codes at all.
I have disconnected the ISC and this makes no difference, on a 165 it should idle at 1k rpm.
FC wire has been cut from the COR and the wire has been connected directly to the Ecu COR ---> Ecu
tried running the car with the st165 Ignitor, no difference.

any suggestions, at a dead end :-(
 

**BETSY**

New member
Hi, had another crack at it today with a few results.

I found i had a few wires the wrong way around on the Igniter, no tacho, but have set them correctly and now tacho works fine.
It seems the car doesn't like to run or rev with the ISC connected!
if i disconnect it i can make the car rev which sounds smooth but it still won't idle?
on the 165 system if you disconect the ISC the car runs at 1k RPM as it should.
I get the same results running a st205 ecu as a rev3 ecu.

When the car does stall i can hear the fuel pump continue to run for 3 seconds after.
I bridged the AFM connector pins to enable the fuel pump to run full time, same has been tried in the diagnostic socket, and the car still doen't run any better.

I have a Fuel pump relay which was modified years back to run the pump @ 13V constant, again same results.

Adjusted the st165 Throttle position sensor to both extremes.. again same results

Unplugged O2 sensor... guess what ;) same results :-(

Again NO error codes, car fires on the button no problem.


Any one throw any ideas my way?

TIA
 

Gary ST165

New member
hi Steve,

have you tried leak testing or replacing the isc valve?

datajon recently found a leaky isc valve caused similar symptoms as you describe...


hth.


Gary
 

**BETSY**

New member
Hi Gary, I haven't swapped it out but the Idle was silky smooth running the st165 system?

wondering if i may have to run a st185 ISC, Throttle position sensor etc?
 

coyoteboy

New member
I think part of your problems could come from the fact that the 185/165 ignitor is different from the 205 one. Now seeing as theres physically not much difference in the requirements of the engine I'm wondering if the 205 ignitor has some sort of jiggery pokery more than the 185 and the feedback signal to the ECU is not happening as teh 205 ecu expects it?

From my experience with the 'squirt this engine will idle under the most appalling conditions (7:1 fuelling, 19:1 fuelling, timing between 0 and 40 degrees at idle) so its unlikely to be anything other than incompatibility of components. Is the ISC valve wired the same way (RSC/RSO polarity)? It wont start if the ISC is shut, and it'll rev its balls off if its jammed open. (i managed to get mine to hit 5Krpm with just the idle valve open!)
 

**BETSY**

New member
Hello Matey, Im using a st205 Ignitor, same symptons when trying to use a st165 Ignitor.

I also am using a st165 ISC which is a bit bigger than the 185 unit and the pins are labeled ISC1 and ISC2
the diagram shows the unit to be the same internaly as the 185/205 units but of course they are labeled RSC and RSO as you mention.

next parts to try are a st185 T/B with TPS and ISC

Big thanks for the replies :)
much appreciated
 

coyoteboy

New member
OK, thought you'd have covered that angle TBH but sometimes we all miss the obvious! ;)

I cant see too many other reasons for it not running right. If it idles ok for a few seconds then i cant see it being a TB thing, but that will iron out the possiblility of the ISC control setup i suppose. Keep us posted, im fascinated now lol
 

**BETSY**

New member
Im curious as to how this system rellay works, purely by looking at the temperature of air by the air filter, intake manifold and vacuum/boost?

Yeah its almost like something is switching off after a couple of seconds?
 

coyoteboy

New member
The 205 speed-density system?

It monitors manifold pressure and temperature (the airbox sensor is only to judge ambient temps for reference) and looks at RPM. From the temp and pressure it knows the air density. From the RPM it knows the approximate flowrate. The maps are then tuned to correct for the inaccuracies in the relationship between theoretical airflow and RPM (Actually VE tables are Volumetric Efficiency maps, showing how well the cylinder fills with air at that RPM and pressure, and hence how much air you have at any one time).

This is why a speed-density system needs a remap with modifications whereas a flapper style AFM doesnt - if you improve your volumetric efficiency (what most mods aim to do) you screw up your mapping. The 185 AFM just measures the extra air and fuels to suit at those RPMs.

J
 

**BETSY**

New member
Hi J, makes sense , Thanks.

Sorted the problem...

I had a FCD fitted!
obviously a a car that isn't heavily dependent on a map sensor to work is fine, not so on a st205 system though!

The car starts, revs, idles and EVERYTHING! :)

how do people run more boost on a st205 system? 17psi fuel cut?
 

coyoteboy

New member
17psi yes, but with the 20b turbo, id stick to 1 bar on a 26 unless your IC is good. AFAIK theres no way of getting higher than 17psi on the 205 due to the sensor being the fuelling sensor, no.
 

**BETSY**

New member
Hi, I'm running a TT s148 turbo on a st205 charge cooler set-up coupled with twin Pace charge heat exchanger rads and W/Inj.
Intake temps are VERY low.

shall report back with how the test drive goes tonight ;)
 

coyoteboy

New member
:) You running the 205 pump or the 165 pump in that? Which one is it you're offering to sell me on the OC :D My CS CC setup is "sans pump" and im dying to see what effect a decent setup has over the stock air to air topmount!
 

**BETSY**

New member
I run the st165 Cc pump.

make a note to ones self, the st205 system is running 16' BTDC, dizzy has been left alone and the st165 system was running 10' :shock:

done a fair few miles in the car now and all seems good, shall try some more boost and report back ;)
 
I work for a High guality electronics manufacturer.
I design, make and repair aerospace products everyday.

If you have a bad / damaged 205 ecu send it to me and I can try to repair it for you...

I can have the profiles for the IC chips and I can test / inspect your ECU

I am working on making new profiles to enhance the ecu's
These enhancements would include such features as

Remove / Update :
REV limit
Boost limit
Fuel cut level
Speed limit

I am working to incorporate the following adustible options.
shift / launch control
fuel gain control
over-rev control

Keep in mind - not all ECU's are repairible, My team would have to inspect it and decide on the nature of the damage.
 

**BETSY**

New member
The main Issue with the st205 ECU is it throws code 54 due to there being no Charge cooler present, if converting to IC or ecu swap.
Certainly would be a worth while looking into it :)
 
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