Sapphire 4x4 overboost problems, standard bhp
 

I'm going crazy here. I have a standard setup, had my head rebuilt and the engine sounds silent like it did over 15 years ago :)

When I floor it, my boost gauge shows the turbo wanting to boost to 1.1 and sometimes 1.5 bar and obviously cuts out. I expect it to go 0.9 then to 0.8 as it always has for over 18 years. Is this the behaviour of a faulty Amal valve? What's an alternative to an Amal valve, struggling to find a new one. Boost control kit?

I also might have a secondary issue of slight hesitation after 4k rpm, not sure if they're related but need to address boost issue I think first.
George

Have you replaced the dump valve recently?

Check the wastegate isn't stuck shut by disconnecting the actuator
from the wastegate arm and make sure it moves freely.

It is possible that the amal valve is faulty. To check it simply conect the
pipe from the compressor housing direct to the wastegate actuator.
If it still overboosts then you may have an actuator/wastegate fault

Thanks for the advice Guinnless, I will attempt to bypass the Amal for testing. I bought a new actuator recently thinking it was that, and it made no difference. I will let you know results. Again really appreciate you responding to my thread :)

[QUOTE=Guinnless;6618735]Have you replaced the dump valve recently?

Forgot to answer on this, I haven't changed the dump valve recently, this issue is ever since I had another head put on. The dump valve and all other bits were stripped and returned during that process. Can the dump valve have a bearing on it also ?

So I joined the pipe from the compressor housing directly to the actuator, the turbo was boosting to 1.5 bar and then would cut out (safety I suppose) so I think the Amal valve might be ok, and as you suspected Guinnless, could be wastage actuator related.

That made me start trawling back through my receipts. I bought an actuator about a year ago from Motorsport Developments during the time I was getting the head done as I was advised my old one was not moving freely. I foolishly bought a -34 Garrett, where I think I should have ordered a -31. I've only realised this as I have just started driving it again. Now do I put a -31 on, or can I keep the -34 and make an adjustment to suit the turbo? The car is totally standard, 4x4 91 Red engine. What are my options?

Did you get an upgraded head gasket?
If so, get some greens, a 3 bar map and a chip to match ;)

I'm not 100% sure but I have the assumption that -34 actuator cannot keep the boost pressure low enough to be able to run standard boost. Standard or -31 actuator should be able?

Can someone confirm? :?

No chance, you will struggle to get a -31 down to std boost pressure.

Unplugged Amal and a -31 actuator gives 0.7 bar boost, but don't think that would work with a standard chip otherwise. If moar powaar is out of the question, you need the std actuator.

[QUOTE=gchristophi;6619630]If the dump valve was leaking before it was stripped the boost may have been turned up to compensate. If the valve has since been fixed then you will have too much boost.

If you are making 1.5 bar on a -34 then either the wastegate is faulty and isn't opening properly or there is too much preload on the actuator. You should only have around 3mm of preload on the actuator. Adjust the actuator until it just slips onto the wastegate arm pin and then add two full turns and then refit to the wastegate arm pin. It should take a little bit of effort to stretch it on but not too much.

If still overboosts then the wastegate is likely to be at fault.

A -34 has a 12psi spring though, so with even very minimal preload to prevent the gate rattling it will be to strong to make std boost pressure only.

Yes I have a group a gasket fitted Rdvil. I've had the car for 22 years running standard so I don't really want to start modifying it now. Thanks for the advice, it's tempting :)

Thanks loomer, I'm going to try reducing the rod but I have a feeling that it will never be right on a standard cossie as you suggested. I have however found my original actuator and so I'm going to install that to see if anything changes.

[QUOTE=Guinnless;6619988]Thanks for the info again Guinnless, I'm going to give those a go as they're great points and easy to do. I might nitro a dump valve but I have my old actuator so might fit that and record the turbo boost levels then.

Thanks rdvil, I think a std actuator is on the horizon, I'm hesitant about taking it to greens, stage1, 3bar map.

Value these days id probably highest for an unmodified cossie...but since I'm not a fan of rationalizing affairs of the heart, I'd say DO IT!

As long as the car is in good nick, extra power would make it feel like it did all those years ago before you got used to 220 horses ;-)

Only problem is finding a genuine 3 bar map...which is one reason why I got stuck in stg 2 by GGR. It's a blast anyway, and don't have to be worried about being shamed by any diesel volkswagens...

It's an amazing feeling as I've been in modified cossies and you just can't stop smiling. On the flip slide, those modified cossies I've been in are not around now :( . Mines in good nick, but it's still 24 years old and I'm conscious of pushing it at an age like this. Need to have it running sweet, keep it good nick and now that saffs are climbing in price, who knows? In my 22years of driving it, I know that you can hemirage £££'s at it very easily.

Based on my much much shorter experience, I'm still confident it's not the power that kills these things but the abuse. You're clearly not abusing yours, as boosting cold or shutting down hot kills standard cars as easily as modified ones. Driving fast, going around a track? Old Ford seems to love that stuff, extra power or not :DD:
And after all, boost is still relative to the right foot. On normal driving there's no extra stress on the car and even the fuel economy is same. Install a lambda and a closed loop chip, economy could be even better than a red top usually gets.

I admire original spec cars and respect people who keep them that way, it just feels like the poor cossie is...chained up somehow, and needs that 300 horses to feel free. It is still pretty close to standard, and behaves that way, turbo kick just goes on for a bit longer.

I get ya man, I'm gonna do some other bits first and get the car as I want it, so it's gonna be a slow project as it's not my
Primary car. I had a spring break, I changed the whole suspension, now the track control arms are making a noise, so gonna change those and get the car tracked, then the shrinking door cards, then I might get my gearbox looked at (mt75 3rd gear selector) etc etc. Thanks for the advice on the chip etc, noted for future and again massively tempted.

Hey if you figure out a way to fix those door cards, don't forget to share!
Hope you didn't fit Bilsteins as I did this spring, as those things are SOFT...