Overboost Problem?

[cdm]

It's an overboost problem :(

Do tell...Can anything be done about this problem? Is it at all bad for the vehicle? I wonder if it is only happening on cars that have had some kind of mod. ie, center muffler or chip etc.

[Ninka]

The car shouldn't do this in standard configuration, as the wastegate should be quick enough to prevent the pressure from getting too high.

You will always see a spike in the pressure for a turbo'ed car, as the pneumatic action of the wastegate actuator takes a split second to open.

As I reported in my previous post, this should be no more than 7-8 psi, which I am sure Ford has allowed for in the ECU settings.

The problem is that when you start modifying you change the expected parameters, and a modified intake and exhaust will certainly cause the turbo to spool up quicker (that's why we modify in the first place!), and this may just cause this "overboost" cutout :(

The first thing to do is to check that all electrical connections are securely plugged in. It has been suggested elsewhere that the front connector under the ECU might actually be unplugged, causing overboost. Also I would check the wastegate control solenoid under the battery, and make sure it is also connected securely.

The engine management software is extremely engine protective, and I would not be worried about the cutout and rough running causing any permanent damage. Actually it is so protective that the engine will maintain a low level of boost (about 5 psi) even without any wastegate connected.

I guess the valve timing or ignition is retarded (or both) to a point where the car just can't boost enough to cause damage.

When I fitted my CAPA stage 1 1/2 kit (I also have a 3" stainless exhaust, and cold air intake) I did it to get around the cutout at fairly low boost, AND IT WORKS :idea:.

Now I do not work for CAPA, but it seems a good investment if you want to increase boost moderately, and your warranty is probably out the window anyway, with exhaust and intake modifications.

Hope to have been of help

[TURBO4LT]

Ninka does the capa boost box cut into any wirring or does it just plug in? And how far can you adjust the boost? cheers

[Ninka]

Yes one wire is cut on the pressure tranducer in the intake manifold, and this wire is then looped through the "Boost Box"

This should be possible to do in a fully reversible fashion, so that the car can be put back in standard config. with no trace of the "Boost Box"

The box is capable of boosting to 13+ psi, but obviously this is not recommended without other modifications to the fuel system, oil cooling and exhaust etc.

[TURBO4LT]

Thanks for the info once again ninka,I like the idea of being able to remove it whithout to much evidence that it was there. Cheers

[cdm]

Hey, thanks for all the info re:overboost Ninka! Very helpful.

Chris.

[Guest 56Mainline]

Ninka is right on the money re his entire description & details on overboost.

At 8.5 psi no worries. Even with peaks at 9.5psi it's OK. But see 10psi for more than 1.5seconds and overboost is detected & the ECU administers engine protective measures.

The level of those measures is based on the frequency and duration of overboost events.

Fuel cut can occur and be removed by the ECU once you back off the accelerator & reduce revs, then engine control is retruned to normal. At other times the ECU requires you to stop & shutdown the motor before a reset occurs.

On my vehicle, fuel cut definitely occurs after 10.5psi.

[Guest 56Mainline]

Oh yeah, with modified vehicles running increased boost, the fuel cut is more evident on cold dark mornings when the air is both cold and heavy with mositure. More dense air + over boost condition + insufficient fuel supplied by standard injectors = overly lean air/fuel mix = detonation = deployment of engine protective measures by ECU.