You seem to having as much luck as I have in general with those ringlands Chris. You're a lot clever man than me so I am sure you will sort it (hopefully this time) sorry I don't have any useful ideas, but wish you all the best with it. Has made interesting reading (and looking up what half of it means lol) I dunno how my block is but you are welcome to it if its any use to you

So what at the symptoms of ringland failure?

Without stripping everything down, how can you tell by the way the car runs?

Lump idle? Loud clanging?

I assume this is down to the design and build of the OEM Toyota pistons and you will never have ringland failure again after replacing your pistons with forged ones?

One of the first symptoms is uneven cranking - a bit of a wheeze every 4th one. (assuming it doesn't fire up before that)
After that it's 3 cylindering especially at low RPM, lots of smoke from breather or from dipstick tube.
A compression test will often show it up but not always.

Forged pistons are much tougher than standard but they can still be melted or broken if conditions are extreme.

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If at first you don't suck seed, try drier grain.

Others have described it as a Subaru ish sound. I believe that the design of the forged piston is the key factor here if they are to be but as Chris says a forged piston will not help is things go badly wrong.

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GT4DC Events Co-ordinator
1996 ST205 UK

higher octane fuel, burns slower than lower octane, thus in effect retarding ignition.

so if mapped for 95, and a safety given, dont go thinking 99 is even safer... you have in effect saved pre-ignition from the slower falme burn, and so moved the high power stoke later into the engine cycle. at high rpm, prehaps burning whilst the exhaust is still open ?

map for 99, throw in a couple of degrees safety, but mapping on 95, then safety and always using 99 is not good really.

ideally map for both, and have a toggle between two.

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Darryl

Quick question, what fuel have you been using? Dorris

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Black CS 2771

Mostly Vpower, sometimes Tosco 99, sometimes 95 for long road journeys.

The failures still seem to be mostly linked to competition on loose surface with donuts round cones. This last time I stayed off the rev limiter by lifting my right boot to keep RPM under control so I don't think it's limiter related. Even so, it's still prolonged high RPM at highish load which you don't tend to get otherwise.

Planning to have a forged engine in within a couple of weeks and I now have readouts for the EGT's so hopefully a bit more diagnostic data. I've also now got a bore gauge so will get an idea how worn the bores are - I suspect hot blowby gasses may be the reason.

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If at first you don't suck seed, try drier grain.

Keep us informed mate would be very interested to know the out come of this. D

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Black CS 2771

Quick question - does anyone know a good source of rings for JE forged pistons 86.5mm ?

My hunt on the net isn't showing up much.

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If at first you don't suck seed, try drier grain.

I'm sure Fensport could get them / have them?

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GT4DC Events Co-ordinator
1996 ST205 UK

A quick update to this, following a discussion in the pub the other evening about my new ECU design and IGT /IGF signals and why the standard ECU monitors IGF.

The 185 has been plagued by an intermittant high boost misfire for quite a while. Not a constant one, but sometimes it will miss the odd beat every second or so, getting worse when driven hard for a time. I had put it down to me running the standard 185 ignition setup which some people have said is inadequate for the higher boost of 205 engines.

When I put the ECU into the 205, the problem wasn't there, so I assumed it wasn't ecu related. After a few weeks, I started to notice it in that too. It was only after prolonged spells of high boost, but seemed to be getting worse. Following the discussion on here about coil on plugs and charge times, I looked at the setting on the ECU and it was running a 3mS charge time. I wondered if this was too long and overheating the coil so dropped to 2mS, which ran fine. I tried 1.5 but that started misfiring. Having settled on 2, the misfire has never come back on the 205 so it does indeed seem like an overdriving / overheating issue.

Anyway, on to the discussion in the pub and how can overheating cause an intermittant misfire.
A coil is literally a coil of insulated copper wire wound on a former. It expands with temperature, but if that expansion caused the insulation to break through and short between turns, it would remain broken through. Symptoms are wrong.
So, on to the igniter. Basically a power transistor or MOSFET. It will quite possibly have built in protection so it switches off with overtemperature. So, drive the transistor too early to charge the coil. It then overheats and switches itself off early - spark occurs early, maybe 1mS early - that's 36 degrees too early at 6K RPM.

I'm now looking at monitoring IGF on the new ECU !!!

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If at first you don't suck seed, try drier grain.

Just realised, a long time since the last update. To fill in the gap, got the forged engine running and within about 200 miles started getting overheating issues which have some of the hallmarks of cracked block. There is a slight possibility it could be a blockage in the water system as I didn't use my original water pipes. I have already tried changing the thermostat with no difference, and have removed and checked the pump with no apparent fault. Next step is checking bypass pipes, and if that shows nothing then it's head off for a look.
TBH I haven't had the motivation to get on with it. I was hoping to over xmas but had a bad back for most of it, only starting to settle down now.

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If at first you don't suck seed, try drier grain.

For people not familiar with the shorthand (including me!). The IGT is the ignition trigger signal, it tells the coil when to fire. the IGF signal is a feedback signal that says that ignition took place.

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp

Coming soon

Chris De Bear is Nibbles in this years epic blockbuster ...

Ringlands 457
"This time it might be different from the last time"

The only franchise with more sequels than Rambo

I wrote a guide for the 165 on all the ECU pins... it's also generally applicable to the 185 and 205

http://www.gtfours.co.uk/what/ecu_pinout/165/ecu_pinout.doc

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Kris
95 ST205 - slept for 10 years, now waking up...
Avensis
http://www.gtfours.co.uk
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Turbocharging - the replacement for displacement