1986 Toyota MR2 (AW11)

[AW111]

BenWRXSEi said:

Ditto. Hope it's not terminal.

Thanks.

Nothing is terminal, just expensive. I'm in way to deep to give up on this car now .

Whatever I broke, it will get fixed, but it may take a few months to get all the parts if I have killed a piston and need to strip it down.

To cheer myself up, I have been daydreaming -
1) Tomai do a set of cams that are supposed to be good for an extra 15 or so hp, and they are one of our customers, so I will get the boss to ask them for a trade price. He may even sell them an upgrade, and kill two birds at once.

2) A friend has recently totalled his rally car, and now has a spare aftermarket ECU to sell...

...If I have to rebuild the engine, it would be a shame not to upgrade it .

The ECU is the more likely upgrade - I still don't know why the car detonated so badly, but the factory ECU is now nearly 20 years old, and there are definitely gains to be made with a better ECU. Some of the factory ECUs have had issues with leaking caps and failing transistors, so I should at least open the case and have a look.

I will probably pull the head off this weekend, and will then know how bad it is.

[AW111]

I did a compression test on Friday night, and had no measurable compression on #4.
I stripped the top end over the weekend, and went to undo the head bolts, only to find my 12 point hex drive for the head bolts was missing - still in a mates shed.
I picked it up after work tonight, and lifted the head.

Step one - where's the damaged piston I was expecting?




Ok, find a container for 20 cam followers in order, pull the followers and shims, and flip the head over.

I think I can see where all the compression has gone :



See the exhaust valve at bottom right?



I don't think that piece should be missing .

I am taking the head to work for someone with more experience than me to look at, but I may get off comparitively lightly.

As an added bonus, all 10 headbolts (and the 10 I replaced when I last had the head off) measure up within factory spec, so I can re-use them. That saves several hundred dollars.

Now to find out what I'm up for the head - I would like to just get that valve replaced and reseated, but it depends what the head shop says.
Replacing 20 valves won't be cheap.

[Sillyhatday]

Cheapest option would be to just replace that valve

While it's all apart I'd be tempted to reseat the valves, stick in the better cam your thinking of and a new timing belt.

Sad times though. A cheap fix I'd say if you want it to be.

[AW111]

So I parked the car last year while I got some cash together.
Since then
Block bored and honed 0.5mm oversize.
Crank checked and linished.
Head porting cleaned up, and fitted with 1mm oversized stainless valves.
I ordered numbered bearings from Toyota after measuring everything - 4 x #3 and 1 x #4 mains, 4 x #2 big ends.
The mains all plastiguaged to 0.025mm (spec is 0.015-0.045), so the mains are assembly lubed and torqued home.
Pistons & head tomorrow.

I have replaced heads before, but this is my first full rebuild, so I am checking everything twice

[Jonmx]

Good work, glad you decided to persevere on rather than giving up on her!

[danllama]

Awesome news, glad to see an update!

[AW111]

It lives!

I fired her up this evening at last!
Just cranked until the oil pressure light went out, then connected the injectors and she starts and idles happily.
I have a borrowed tandem parked outside, so tomorrow I will trailer it to work, and run the engine in on the dyno next week.

[Veeayt]

Have you replaced the ECU?

[AW111]

Veeayt said:

Have you replaced the ECU?

I am currently running the Japanese blacktop ECU that came with the engine.
I had been thinking of fitting an aftermarket one this year, but that budget went on pistons, valves and machining .

I did open the ECU to check the capacitors, and fit a heatsink to the VVT switching transistor.

[Sillyhatday]

AW111 said:

I am currently running the Japanese blacktop ECU that came with the engine.
I had been thinking of fitting an aftermarket one this year, but that budget went on pistons, valves and machining .

I did open the ECU to check the capacitors, and fit a heatsink to the VVT switching transistor.

Good idea. Supposedly a failure mode of those ECUs. Strange that Toyota never fitted some heatsinking to them. They probably didn't, as they are so borderline to being too hot, or OK. That and the added expense.

Would it be right in saying that you now have similar HP to the SC models, yet with next to none of the weight penalty from carrying a supercharger?

EDIT: I just reread the thread as I forgot everything previous. You were already making 128WHP. So probably making more power than a SC

Edited by Sillyhatday on Saturday 27th May 14:26

[AW111]

Power is similar to the late JDM supercharged 4AGE from the mid 90's.
My engine is supposed to be 160 hp at the flywheel according to Toyota.

I test drove a supercharged AW11 as part of my research before starting the transplant, but it didn't feel quite as nimble as mine.

[AW111]

So It's summer down here and the MR2 is back in service!
Th aircon failed last summer due to an electrical fault of some kind : the a/c relay would just chatter continually.
A small coupe with a steeply sloped windscreen and charcoal interior is no fun in 40+ weather, at least in traffic, so it got parked up, and stayed parked up over winter.
I got a 1998 Subaru Outback (that's practically new for me!) and it's a great winter hack.

Anyway I fired it up a few weeks ago, and it was running ok, but had a nasty hesitation at light throttle openings. The general consensus on t'internet is that these engines are very finicky about oxygen sensors - mine tested ok, but a bit slow, and it was carboned up from all the oil the old engine burnt.
Time for a new sensor, but an OE Denso replacement is over $150 - for a narrowband sensor
After a lot of digging, I found the Bosch equivalent sensor element, then scoured the catalog until I found one with the correct plug and lead length - ironically a Subaru one. However, it is a screw-in type, and the exhaust fitting is bolt-on. No problem - I dismantled an old bolt on sensor to get the stainless flange, and Lindsay at work tig welded a boss on it and tapped to size:


Then it was milled down to about a 5mm boss.
Works a charm. The sensor fits perfectly and the hesitation is gone.
Now if only I knew why it's idling pig-rich . I've tested the air and water temp sensors, and they're both ok.

[AW111]

Small update.

I had to replace a noisy front wheel bearing, and noticed the front brake disks are at their wear limit, so I've a new set of disks & pads on order. Since the mk1a is slightly different to the more common 87-89 model, it took a bit of research to ensure they're the correct ones.

I've also ordered some completely unnecessary bling, but have no idea when they'll arrive :



They are JDM wheel caps to suit the mk3 wheels I'm using.

Next spendy bit - new tyres all round. Probably going to be Pilot Sports. The current Pirellis are now rock-hard with age, although legal tread depth.

Then - rear suspension refresh. I've got new Tokico inserts, but need bushes / balljoints / rod ends.


I doubt this car will ever be 'finished', but as long as it's drivable, who cares?



I have another project underway - setting up an Arduino to drive an electronic speedo movement from a Celica so I can ditch the tired cable driven one.
That can wait for winter hibernation, as I'll have to remove the instrument cluster and hack the circuit board around a bit.

[danllama]

Good update, loving the new wheel caps. A photo of the car would have been appreciated, can never have too much A dub.

[AW111]

danllama said:

Good update, loving the new wheel caps. A photo of the car would have been appreciated, can never have too much A dub.

I looked for photos on my phone, but all I found were mudflaps.



I'll take more photos soon.

[danllama]

Haha tease! Probably for the best, don't have money to add an AW to the stable just now!

[AW111]

Waiting, waiting...

Front disks and pads have arrived.

I've now got rear suspension parts on order from 4 different suppliers:

Generic ball joints
Toyota pillow bushes
SuperPro poly bushes
HardRace toe arms (stock/replacement parts are NLA)

I may do the front brakes first, since the ETA on some of the suspension parts is May

To be fair, the supplier admits they can't give a reliable estimate at present, so who knows when they'll arrive.

[tomsugden]

Just reading this thread for the first time and was surprised to see it only has one exhaust pipe. I'm sure they had two in the UK?

[AW111]

tomsugden said:

Just reading this thread for the first time and was surprised to see it only has one exhaust pipe. I'm sure they had two in the UK?

They had a single pipe / cat / muffler, with twin exits from the muffler & twin tips


Mine has a larger bore exhaust to suit the engine, and the biggest muffler I could fit. It's still not quiet.

[AW111]

A package arrived!



Blue flake metallic!