Big flatspot on Bluetop 4AGE- but I think I might have an idea

[JMR_AW11]

Have you checked inside the ECU to see if it is stock?
eg look for an aftermarket piggy board with an EPROM?

[Lauren]

I haven't seen inside the ECU, not at this point. Looks pretty stock from the outside, but yes guess there is a possibility that it's not.

I think the first port of call is to check what cams I have. I know kept going on about cam cover gaskets, but they are re-usable, it's the crush washers for the cam cover bolts I need, so have ordered them from MrT.

If it's not got a mental cam in there, then I reckon it's highly unlikely someone has fiddled with the ECU.

I've just been enjoying driving it a bit, was a tad naughty, but can't help myself!

[tottacrolla]

a couple of things Lauren.
TVIS is it working correctly ?
If it does have uprated cams and the TVIS is still working it might be worth trying it with the TVIS permanently open.
I tried this on a slightly modded 4AGE and it made a big difference to bottom end power. In the end I just did away with all the TVIS stuff.

[MartG]

Could be worth a try ( and easily done ) - if it has got warm cams fitted then the single inlet tract that is used before T-VIS opens could be choking as it approaches 3.5K rpm

[aw11rally]

I agree, when I fitted HKS 264s to the standard 4age in Cogboy's MR2 it was crap until I dissabled the TVIS, top end was fine I.e. TVIS open but mid range was rubbish. Keeping tvis open greatly improved things. Easy to do so definitely worth a try.

[Lauren]

Thanks all, some good points there. Will give it a try.

[Lauren]

Any idea on what vac hose I need to disconnect? I've never really messed around with TVIS much before.

[aw11rally]

The vac hose hidden under the inlet from the vac can to the actuator. I just pulled it off the actuator and screwed in a stainless screw. Seems to work and should be much easier with all the space you have up front, a bit tight in the back of the two.

[Lauren]

Ta for that. What we did was just zip tie the vacuum hose closed where it joins to the actuator under the inlet mani'. It still has a flat spot but it does (I think) help the low down torque and it seems that it helps at 3K, so effectively (I need to do a better test drive) it's made the flat spot a lot smaller and it's only a small fluff now. I only went out earlier to take a friend for a spin and so he could take some pro photos.

But, I think it's helped, so thanks guys, much appreciated.

Have to admit, had nearly forgotten how addictive the sound of a 4AGE at full chat was. Happy days.

[MartG]

It may be worth trying it with the T-VIS plate gutted to remove the obstruction of the butterflies. A lot of faffage as an experiment but could help

[tottacrolla]

My '86 also has a bit of a flat spot at the same revs and the engine will almost stall when pulling away gently.
I have cured this problem before but it means adjusting the TPS..........
good luck with that

[Lauren]

I'm not sure I'm prepared to go to those lengths at the moment Mart.

Mark has driven it and reckon it's made no difference. Will just have to drive it as is I think until I've got the dosh to get it on the rollers.

We haven't checked the TPS, though I admit to not having any trouble with stalling.

[PW@Woodsport]

Lauren what about a basic fault code pull and an ignition timing check?

[Lauren]

Lauren what about a basic fault code pull and an ignition timing check?

Yes, we should do the fault code check really. It's not difficult. Not sure how good it's going to be to check the ignition timing as it's not standard. But we can't find our timing light, so going to roll with it for the mo as it's not that bad really, until I get the crush washers so I can whip the cam covers off and see what we've got.

We've just been so busy with all the visitors we've had to come and have a go in the car and all the other things we've been doing to it, it's almost felt like we haven't had time! We'll get there, just pretty tired now, but all good fun.

[Lauren]

ECU has a load of aftermarket stuff inside it. Mark is investigating. Pics to follow. Wonder what else has been fiddled with?

[toxo]

ECU has a load of aftermarket stuff inside it. Mark is investigating. Pics to follow. Wonder what else has been fiddled with?

Oooh, this just got very interesting Pics!

[tonigmr2]

Very interesting indeed! Possibly also a bit worrying, fuelling might need checking?

[Lauren]

I will post pics shortly, but honestly we are none the wiser for staring at an extra circuit board that replaces the main processor.

Does make it hard to know what we are working with. I'm not overly worried as I think I would have blown it up by now, if it was seriously amiss, but would have been nice if it was easily identifiable.

[Lauren]

How weird is this, after putting the ECU back in, the flatspot seems to have dissapeared and it pulls like a train. Just took Tom out for a ride, it pulled all the way to the redline lovely. Weird.

[aw11rally]

Did blitz do an Access ECU for the AE86. The Blitz ECU I've just fitted to my Mk1.5's 3S-GTE looks identical to the original ECU, including code numbers Etc etc etc. The only differences being internal circuitry and some security style blitz stickers over the joints in the cover.