[Mk2] [Turbo] Overboosting and overfuelling related?

[G-force]

I've done a fair bit of reading about this and I've found I'm not the only one with these problems but I may be worse off

The following are my symptoms, which from my research, seem to indicate that im overboosting and overfuelling, but are they related to one another or separate problems?

Symptoms:

- Ridiculous mpg, I'm getting 17mpg with careful driving around town from a full tank, not going over 2.5k revs and putting my foot down once or twice.

- Strong fuel smell in the cabin

- Exhaust popping when floored, indicating unburnt fuel

- When floored, fuel cut after 5k revs. I have an ebc but the screen is mashed, will be buying a new one. but with a temp boost gauge, it showed 0.7 bar.

- Car simply not shifting aswell as it should. Feels lethargic although turbo is spooling well it just feels like its blocked somewhere. I raced my bro's s2000 (on a private road of course) and I got rinsed from a rolling 20mph start to 70mph. He was ahead by 10 car lengths at least. An N/A mr2 would be quicker I reckon.

- Silicone hoses are very soft, easily pokable although i've tightened the clamps and done visual inspections.

- Just done a diagnostic. Got error code 34 (overboost)

Do I have 2 separate problems here or are they linked?

Had the spark plugs, oil, and ht leads changed 2 days ago with no improvement to the performance.

All these problems result in a frustrated driver whos car isn't performing as he knows it should.

Any suggestions welcome

[The TVIS Kid]

What ebc do you have? Trying putting the car back to standard i.e remove the ebc, re-connect the boost tubes to the actuator and re plug the vsv back in (if it hasn't been cut). That should show if it's the ebc casuing the problem or something else. At least that way you have a clean starting point. My ebc seem knackered and makes the car overboost like made. I have fitted an mbc until i can get another ebc sorted but if you do make sure you have a boost gauge fitted so you can see what its boosting too.

[G-force]

I have a blitz dual sbc with the screen crystalline. cant see the numbers on it.

The vsv has been removed from the car so cannot reconnect it. so i think im gonna try for a new ebc as i need one anyway, but i would be very surprised and over the moon if it single handedly eliminates my problems.

I doubt it will fix the problem though because I've also read about the map sensor, lambda sensor, hoses, actuator and ecu reset to be looked at for my problems.

[G-force]

anyone else with advice?

[JJ]

Stock turbo is it ??!

Couple of things :

Check the ignition timing ( base timing ) - need advise.. jump back on....
At times, if the distributer has been disturb, the bolts can work their way loose and the distributer puts itself into a fully retarded state.

You mention exhaust ?? have you got a cat still fitted ? At times the cat can perish or even melt and obstruct the exhaust flow path which would make it feel lethargic.

If its overboosting.. unlikely to be the actuator .. they normally go weak and go there other way which is underboosting. Not illiminating the diaphragm splitting which would cause it to overboost.. but again... as others have suggested... run a direct line from the compressor to the actuator... and it should boost low.... then you know the actuators fine.

Your error code suggests its hit the boost limit... just reset it by pulling the ecu fuse for a minute.

Also check all the intake pipes to the intercooler and from the intercooler to the throttle.

Some of the earlier rev 1/2's intake pipes ( turbo compressor ) can perish which then draws in air from there = wrong fuel / ignition calculations = which will contribute to rubbish economy / flat performance.....

[G-force]

Its a rev3 and it's been decatted.

[justarn]

same prob fella, keep me updated!

[G-force]

Changed the ebc to a greddy profec b spec 2. still same problem but now i can see the numbers! hitting 1.4bar with low ebc settings at 5k rev, followed by a fuel cut. ARGHHHH!

[Olly P]

I would say overfuelling and overboosting are related.

As you know, my AFM was mullered and the car was popping flames and wasn't boosting properly. When I did push through the stuttery and sluggish boost, I could easily feather the throttle and hit 1.3bar of boost.

Even with my AVCR ebc disconnected and by-passed, I could still hit 1.3 bar in stock form.

A replacement AFM sorted, as once the air flow was regulated again, the boost was perfectly smooth, hard and now holds 1.0bar perfectly.

[Olly P]

Rogue did speculate it could be a sticky wastegate on mine before they diagnosed the AFM. They said it would have produced the same symptoms.

[RobCrezz]

It is likely to be either:

1) VSV or Boost controller faulty
2) leak in one of the vac pipes between turbo and actuator (including any boost controller or vsv)
3) Faulty actuator
4) Faulty wastegate.

Most likely to be 1 or 2, best to check them first.