Mildly tuned 7 falling flat on face at upper revs
 

Guys,

I had my car mapped a couple of weeks ago and it had a couple of problems at the time. First off was some ignition breakup, as you got higher up the revs the car would start to stumble a little and chuck black smoke out the back as it did. I could put new plugs in and it would fix it for about 30 miles and then it would start happening again. The second problem was that the car would also sometimes fall flat on its face, a much more pronounced death of all power as opposed to slightly erratic acceleration caused by the first problem described.

I as advised to put B9EGV's in the car gapped to 0.3 by someone who had very similar problems to the first one. I did this and the erratic acceleration/ignition breakup/black smoke stopped and the car ran good.

However, it is still doing the more pronounced absoloute death of all power problem. it literally feels lik im going along and i stamp on the brakes for 0.1 of a second and then get back on the gas. There is no black smoke out the back when this happens.

The mods on the car are as follows:

PFC thats been re-mapped
Stillway intercooler
feed downpipe
decat section
3.5 inch catback
greddy intake elbow
B9EGV plugs
magnecore 10mm igniiton wires

Thats all i can think of as far as power mods go. The cars boost pattern is about 13-10-13 (mapped to suit) but ive tried lowering the boost to 10-8-10 and even raising it to 15-12-15 (when i was running a bar of boost, it was actually set like this first and ive since lowered it)

Boost is stable when the problem occurs, and its invariably 6,000 rpm up that i get the problem. Sometimes it happens once and the car then continues to accelerate to redline, other times 2 or 3 times in quick sucession.

Has anyone experienced this and know what causes it? Engine temps are good, injector duty cycle at the time is good (high 70s i believe, its hard to look) knock levels are low (my PFC displays a bar graph for the knock, and it rarely goes above %25 full, generally stays around 10% when on it hard)

One thing i have noticed is that when i parked up this evening after it was doing it, my air intake temps were reading 7 degrees. They couldnt have been, more like 57 degrees, but PFC only showed 7. Also, the other day i was driving along and my intake temps in about a 30 second period went from 42 degrees down to 16 degrees and back up again to 43 degrees while i was cruising at 30mph.

could a faulty air temp sensor be causing this? as my understanding is that the car doesnt really care what the AITs are, its just informational?

any help greatly appreciated, i just want it work like when it did when it was stock! :Kill1:

Thanks

How do your plugs look when you take them out?

you are probably having blow bye and oil is getting on your plugs and it is not getting enough spark. If that is not it you might just be having some very bad breakup, try adding a few grounds (if you haven't already) and also get a ignition amplifier (I highly recommend the HKS Twin Power)

it could also possibly be the fuel system...did you modify that at all? maybe even a dirty fuel filter...

I was about to ask what your O2 sensor reading was during the break up.

Tim

Do you have a datalogit? If so, might want to run a log and post it in the PFC section.

Why did you have it retuned? Sounds like the tune might not be all that great....

I suspect you need a better ignition system. amps, coils, wires, and grounds would cover it.

The car is only about 330bhp - surely the stock FD ignition system is good enough with uprated wires?! I See plenty of cars running around with this sort of power on standard amps and coils.

I could add more grounds, but why would it only do it sometimes if it was a grounding probem?

MY fuel filter is 8,000 miles old if that. Injectors cleaned 6,000 ago. ENgine rebuilt 6k ago, everything is fresh.

I have the PFC tuned because i de-catted the car. You cant run an RX7 with a massive intercooler, decat and no emissions equipment without a PFC.

Plugs look fine when i take them out, nice browny colour. No melting.

Where do iget a datalogit?

Get datalogit from rx7.com or direct from the kiwis at http://www.fc-datalogit.co.nz/support.html

stock ports or street ports?

If you want to compare maps, I posted the original Apexi map in the PFC forum a few months ago.

Im having a very similar problem with my car. If I run full 9s on my car I get HORRIBLE breakup, but if I run 7s and 9s it doesnt happen, whats the deal?! My car is moderately modified, btw

Stock ports.

And FYI - i wouldnt know where to begin comparing maps, and i was running 9s all round.