Hi people,

Need some advise on why the 8 is running lean at WOT between 2k and 6k rpm. After that until redline we have an AFR of about 12.5:1.

On the dyno at WOT the car produces only 130 WHP.

I have ruled out Plugs, leads, coils and maf (another MAF from a known good 8 was replaced and problem not solved), CAT inspected and is fine, compression in the mid 7's with one rotor face at around 6,9. All injectors have been physically removed cleaned and flow tested. Looked for vacuum leaks but none visible.

Car starts up within 1 second cold, 1 second at full op temp (turn off and then turn back on) and about 2-3 second when between cold and hot. Idle is steady.

My thoughts are the fuel pump, but then why does it work fine at higher RPM?

Any thoughts are very much appreciated.

 

what was reporting the afr?

 

A wideband O2 sensor when dynoed..

 

Another thought that just came to mind is the possibility of the TPS not giving the signal to go to WOT. So what we think is WOT really isn't? Maybe I'm just talking crap...

 

130 Hp is really low...so you definitely have a problem

Are the injectors hooked up properly? It is common to mix them up when re-installing the harness

Any other symptoms? CEL...missfires?

 

The injectors were removed and cleaned following the thought that they may be clogged in order therefore to solve the problem. So cleaning them didn't help.
No Cels, only slight nudges if you lightly press down on the throttle when in gear between 2k-3k.
Could a stuck open SSV be causing a lean condition between 2-6k? thus the loss of power in that range? As I said before, after 6k the car takes off.

 

Did you check the injector plugs to make sure they were hooked up correctly?

 

Yes

 

I'm stumped...
The car is going to an RX8 specialist tommorow.. I am so so stressed.. I hope its something simply.
I will update on the findings...

 

Ok... just go news....

They tell me that the secondary fuel injectors for some reason are not adding any fuel, possibly due to an electrical or ECU fault. This is not really my worry though. They did a compression test and here are the results:

Rotor 1: 6.5, 6.5, 6.5
Rotor 2: 4.5, 4.5, 4.0

All this at 300 RPM as I have the upgraded starter.

How the hell does my car start in 1 second hot or cold? I have no idle problems or cut outs what so ever. 1 Month ago a compression test at Mazda showed the following:

Rotor 1: 7.73, 7.82, 7.78
Rotor 2: 7.08, 6.82, 7.34

At 257 RPM.

Is it possible that the fuel starvation from the seconday injectors caused this much damage in 1000k total?

 

The problem in the end was a cracked intake manifold when the reman was put in in 2007. The car also had bad coils, leads, very dirty air filter and very old plugs. She is running great now almost 3 years and 30k later.

 

So did compression really drop in 1000 miles because the car was running lean? Or did they do it wrong?

How did you find the crack in the intake manifold?

 

I really don't know if compression is low as the car starts up cold at 180rpm and hot at 250rpm with no problem whatsoever. It pulls hard etc. It started hot with a dying battery also, like crank wait crank wait bam.

The leak was diagnosed at a rx8 specialist Easytunning here in Greece who allegedly made the compression test before the fix. I wasn't there so I don't know if they did it or not and how they did it. I personally have a hard time believing the second comp test.

 

Alright thanks man glad you got it fixed