I was racing against a friends focus in my gf's 7. I lost by a few car lengths. The engine runs really strong from about 2500 - just under 5000 then it just doesn't get the "kick" that I think it should have.

The BAC valve is not functioning, I'm replacing that this week, but was wondering what else might cause high end power loss. I assume that the cats aren't clogged because it still revs high, it just doesn't have the power that I think it should have.

If anyone has ideas of where to start looking they would be greatly appreciated.

Thanks.

 

Sounds like the "extra" 2 ports - those actuated at higher rpm by exhaust back-pressure - aren't opening. This is assuming that you have a non-turbo. If you're not sure where they are, they're on the passenger's side of the engine, and you'll see two small cans about half the diameter of a tuna can, one at the front and one at the rear of the engine, down low. See if you can move the actuating levers coming out of the cans - These levers move the extra port valves. If they move, then you probably don't have any pressure coming through the small rubber tube going to the cans. This tube connects to the cat and carries exhaust back-pressure to open the ports at higher rpm. If they don't move, the valves will probably have to be removed and cleaned.
I once had a spark plug wire fall off, and that also caused a loss of power, although the engine idled just fine. Check the wires first. You might get lucky.

 

I thought I should probably check the 6 ports. I was reading a little this morning.

Thanks.

 

um.. it might be the six ports but your gf has a 91 it's actuated by the vdi not back preasure s i would prob. start there i believe it is connected to the bac some how.... have you checkedall the basics like air filter spark plugs wires? these could crap out your top end too

 

Before you start ripping stuff apart to check the sixth port actuators do yourself a favor and give the car a tune up.

New plugs and a fuel filter at the minimum, an air filter won't hurt either. Then on a low tank of gas run fuel system treatment in it and drive it hard to clean out the secondary injectors, which may be clogged and be the cause of your poopey top end.

My car was doing this as well, in fact, it would stop accelerating entirely when I hit 7500 RPM's. At 6000 RPM's it felt like hitting a brick wall.

The problem was that the car had been sitting around for a couple months before I acquired it. I put the cleaner in after changing the plugs and the filter, ran the **** out of it, and it cleared right up. Now it accelerates hard and smooth all the way past redline.

If that doesn't fix it, then start ripping stuff apart to clean up your sixth port actuators.

 

I am sure it needs a tune up. I just haven't had time yet for htat either.

I guess that I'll start there. I do need to replace the BAC though. The idle is erratic sometmies and when I disconnect the BAC the idle doens't change at all.

 

The BAC won't affect your car besides its idle, so thats not the reason for the not up to par high-end. If the car pulls nicely from 2500-5000 then its probably not the 6-ports either as they open around 3800rpms. The car is a 91, so it has a VDI manifold that opens around 55000rpms. Its similar to your 6-ports, its an actuator that changes the length f your intake runners giving you a little kick of power when it opens up. This is probably whats not operating on your gf's car.

rx74ever - The VDI has nothing to do with the 6-ports. on 89-91's its the airpump that supplies the air, that opens the 6-ports. And the BAC isn't related to the VDI or 6-ports either.