Engine wouldn't rev over 7k on track
 

Did a track day at Buttonwillow a couple of days ago. It's a 2005 with a stock engine, other than an HKS cat back.

Car ran great most of the time, but there were a couple of instances when the car wouldn't rev to redline after a few laps. Both times I ended my session when that happened, and both times the car ran fine the next time out.

It was as if I was hitting the rev limiter, but the computer had moved the limiter much farther down the scale. Someone told me that some car computers will do that to keep damage from occurring under certain circumstances. Is this true? I've also tracked two NA Miatas and a WRX, and none of them did that.

I've tracked this car three or four other times, and never had this problem before. It wasn't especially hot out, mid-seventies I think, and the car's coolant temp was never higher than 212, usually 208f.

https://cimg4.ibsrv.net/gimg/www.rx8...f5dca7e309.jpg

How many miles on the engine? On the car?
Stock Catalytic still in-place? Original?
Any CEL codes?
Have the coils and plugs been replaced recently?
How did you measure engine temp?

We just went through this in the "won't spin past 5800 rpm" thread in the S1 troubleshooting area. Check your fuel pressure under WOT. Most likely the fuel pump is going bad and not keeping up to the engine demand.

https://www.rx8club.com/series-i-tro...4/#post4837306

Engine Power Loss
• chokes as revs increase
o O2 sensor failure (too rich)
o MAF failure
o MAF disconnected
o e-shaft sensor fouled
o accessory belt fraying
• high end power loss (hard fuel cut)
o Rev limit reached
• high end power loss (jerky and stumbling)
o Ignition failure
o fuel pressure loss
o e-shaft sensor fouled
• high end power loss (smooth)
o Catalytic converter clog
o air filter clog
• low end power loss (smooth)
o Engine compression loss
• low end power loss (stumbles)
o Ignition failure
o front O2 sensor failure
• revs slowly but smoothly
o O2 sensor failure (too lean)
o catalytic converter clog
o air filter clog
• sudden power drop at a specific rpm
o Intake valving actuation problem
• trouble getting to redline
o Ignition failure
o front O2 sensor failure
o catalytic converter clog
o air filter clog
o e-shaft sensor fouled
o fuel pressure loss
o MAF failure

Thanks for the advice and suggestions. Regarding what I was told about the ecu, has anyone heard of that, the ecu limiting revs due to a pattern of driving? I had been revving beyond redline, and the engine was probably fairly hot but not over heating. Are ecus programed to protect the engine under the right set of circumstances?

As I said, once the car sat for a while, it was fine. Once I let it sit for only about 10 minute, then drove it down some local roads. It was fine. It was also fine on the 250 mile drive home, including some runs to redline.

As team said ... fuel pump.

If the ECU has to intervene, there will usually be a check engine light and associated code. They don't proactively reduce the redline, certainly not on these cars (except the whole 2009+ warm up thing... but that's not your issue). If the engine is knocking or something isn't working correctly, the computer may react at the instant it happens, but not for the duration of a session.

The fuel pump, on the other hand, has no such intelligence behind it. The symptoms fit a dying fuel pump. Once it cools down, it works fine again. Having more fuel in the tank can help, but nothing except a new fuel pump will fix it.

Whoever told you that is misinformed.

• high end power loss (jerky and stumbling)
o Ignition failure
o fuel pressure loss
o e-shaft sensor fouled

• trouble getting to redline
o Ignition failure
o front O2 sensor failure
o catalytic converter clog
o air filter clog
o e-shaft sensor fouled
o fuel pressure loss
o MAF failure


As was stated in two sections of the above Engine Power loss list, your issue could be fuel pressure loss, which could be the fuel pump. Series 1 fuel pumps are very prone to failure over time, especially under heavy load like tracking and redlining your car, and worse under low fuel tank levels. . Remember that pump, if original, is over twelve years old.

BTW there is a recall for replacement of the fuel pump filter assembly, fuel tank resin rings and fuel tank insulation pads. Any Mazda dealer will do that free of charge. I would have this done free and see if it helps. Just contact your local Mazda dealership with your car's vin number to get the recall. It makes no difference if you are the original owner or a subsequent owner, your car is entitled to the recall replacements.

As has been reported here, in some cases after inspection, the entire pump assembly is being replaced by some dealers, not just the pump filter assembly. Other dealers, are replacing just the pump filter assembly.

Here's a follow up. I tracked my car a couple of more times since the original post. Had the problem again yesterday at Thunderhill. Car ran fine first few sessions, but then started acting like it was running out of gas. My fuel gauge showed a quarter tank of gas, so I filled the tank and the car ran fine for the rest of the day.

I suppose that's the problem, but I don't know why the car would run poorly with about four gallons of gas in it, that seems like plenty, even with it moving around under centrifugal force. Anyway, I'm happy I could solve the problem just by putting more gas in the car, and so far I haven't needed a new fuel pump.

The fuel pump draws gas from the passenger side of the tank by means of a venturi that uses the excess flow from the fuel pressure regulator.

A weak fuel pump (or failing resistor) will spend less time providing flow in excess of demand. If that happens (especially in a long left hand turn where the fuel sloshes to the passenger side), you may fuel starve.

This is normal for an s1 rx8 , and the reason why many opt change to the series 11 pump !

That is a problem with Series 1 pumps, especially with low fuel levels and hard turns on a track. I changed to Series 2 pump a couple of years ago and solved that issue.