Lack of power from 3500rpm
 

I'm hoping someone can advise me on an issue I've run into.

When I got the car a few months back, it drove absolutely perfectly, no issues at all. Now, since standing for a couple of months, it's developed a fault. Outside the problem area the car drives as it should , idles perfectly, throttle response is what you'd expect, boost is at a solid 10psi when at full throttle.

The problem comes in between 3500 and 4000 rpm at anything above 3/4 throttle or about 6 psi boost. Symptoms are a severe lack of power and a rumbling/bucking from the engine as if the ignition is being severely retarded to prevent knock. Obviously this has made me back off the trottle in case it could cause engine damage.

I've been working on the problem for a few weeks now and haven't been able to track down the problem. All electrical connectors look to be in good condition, there is no vaccum leak that I can detect (I'd imagine I wouldn't be seeing full boost if that were the case anyway). Fuel pump relay and speed relay work as they should.

In the time it was standing I've had the headlights out to repaint the brackets, but all connectors in that area look to be correctly installed. I've replaced the fuel filter (Put the original back after thinking it might be fuel restriction due to faulty filter, but no change) and fitted an aftermarket steering wheel which did trigger an airbag warning light (again, original relaced to check problem isn't there)

If anyone has any idea what it might be it would be greatly appreciated! My nearest RX7 specialist is a 250 mile round trip.

Details on the car:
1999 Mazda RX-7 Type RS
Apexi Power FC, no commander
Front Mounted Intercooler
Imported to the UK mid January 2015
Mileage 23,000

The car is unchanged from when I got it aside from what I've mentioned in the text. All mods were on the car when I received it from Japan.

you need a Commander to adjust the Tune.Sounds like a transition issue.

Also you may want to cruise the Power FC section of the forum to see if there is any info you can read up regarding this.

The fact it ran perfectly before, and that it was mapped by FEED in japan means I don't really want to touch the maps.

I've also only put Shell V-Power in it which in the UK has 99 RON, which is closest to what they have in Japan, so I doubt it's an octane rating issue.

well, speaking of fuels, here's a random thought. do you guys change fuels over there for winter?

Diesel does, I don't think most petrol/gas change much if at all, and the temperature here is only a few degrees warmer than January.

well, if all else is stock aside from the EMS and intercooler you mentioned, i guess your next order of business will involve your beverage of choice, a diagram and digging through vacuum lines and solenoids in the turbocharger system.

Can it still be a vacuum issue if the boost is showing a strong 10psi when the problem sets in? I thought that would rule that out?

well, as i understand it, there are several lines that control various things in the turbocharger system (which is why i make sure to refer to it as a system) on the FD, and while i'm sure they get their initial signal from somewhere in the intake, i'm not sure if a broken or missing line would necessarily show up as a leak that would, in turn, affect boost.

i'm just saying look into it, at least until you can get better advice from someone that knows more.

I've ended up taking the car to a specialist after giving up on tracking down the problem myself. They've thankfully found the issue.

Turns out one of the secondary injectors had failed.

Other than that the car has been given a clean bill of health. Any UK guys on here, I highly recommend WGT Engineering. They've been extremely helpful!

Glad they were able to find it. That's what it sounded like from reading through.