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Chazz

RX8 won't rev beyond 3,100rpm in 5th and 6th gear

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Carl you have great spirit keep at it man you will get there no better man than you mate.

Carl I have yet to see this deflood work. I got a 8 going last week that was flooded. Gave it a tow, 2nd gear 17 mph and on the 3rd drop of the clutch she started.
Running wild now thank god.B) give it a go best way to get her going no doubt.:)

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Took the pump fuse out, clutch and gas pedal to floor and cranked her for 10 seconds, wait 60 seconds. Repeated 10 times.
No joy.
Fuse back in and did same procedure as above. Got nothing.
I think it's time to have her take away on a trailer to Shadow Rotary.


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Is it actually injecting fuel? Did you open one of the plugs and check?

Or have someone crank it dry with the plugs out to get a dirty chuff-chuff-chiff test.

Might it be recirculating fuel back to the tank and not building enough pressure at the injectors or something weird like that?

 

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@Rex Ruthor, certainly did plug that Secondary Air Pump line to the AIR sensor.
@Dartz, Yeap it's injecting fuel alright. I'll do exactly that tomorrow, with the plugs.

@Aido, I'll do as you instruct once I've done what@Dartz and @Rex Ruthor suggested.

So I've a lot to do tomorrow, thanks for your help guys!


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Installed a new Thermostat today as the old one was shot.

Followed the Mazda TSB "rx8-engine-cranks-no-start" procedure A today. It's another way of de-flooding the engine.

Made no difference. Engine STILL refuses to fire-up.

Checked for the 5th time I think at this stage, that the plugs are sparking from the coils and they are doing so.

Was starting to think it was a compression issue but that can't be 'cause the engine crapped out and needed a rebuild at 108,614 Miles (174,797 KM).

The mileage on the engine today, as she sits idle, is 121,591 Miles (195,681 KM) so that's a mileage covered of 12,977 Miles (120,884 KM).

In that travelled mileage she's had 5 Oil Changes 2 Oil Filters and will get another oil change and oil filter change tomorrow as well.

Spark plugs change twice, 1st time at rebuild time, 2nd time 7 weeks ago.

So I'm confident that it's not a compression issue.

Will only get around to doing the tow-pull start tomorrow. Hooked up the tow eyes, all ready to go. Only realised today that the car has two tow eye positions in the front. Always used the one on the left, didn't know I had one on the right as well.

Learnt something new today.:P

Anyway is she doesn't start on a tow start tomorrow, I'm gonna pull everything back out of the engine bay, after I throw a complete wobbler, to make sure I've connected everything correctly and do a more detailed check on the primary and secondary fuel injector and rails.:angry:

Roll on tomorrow!:wacko:

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Chazz, i know you've been meticulously looking after the car after the rebuild. And I'm not wishing any bad JuJu here, but get it compression tested. If you have an hr, get it up to eoin and Anthony for a second opinion. For peace of mind if nothing else. 

Fyi, not to point fingers, but my previous engine crapped itself before 25,000 after a rebuild from someone well known who made a catastrophic error while rebuilding. The lads in Shadow spotted it straight away after opening the block.

Again, it's probably electronics, or vacuum issues, but I'd get the compression tested now that you've tried everything.

Fingers crossed for you anyway buddy

 

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Cheers Richie,

Have the brother dropping over tomorrow afternoon with his Power Probe 4 Injector tester.

At this stage I'm hoping it's an injector problem or a blockage in the rail.

If not and I can't get her to start on a tow start I'll have to have her put up on a trailer and  take to Shadow as she's be a non-runner. Fingers crossed.

 

 

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Okay so we got her going on a tow start this afternoon after a fashion
Had to keep at 2,000rpm idling for approx 10 minutes otherwise she'd conk out.
Anyway I drove her around the block a few times.
When I pulled up and let her idle she'd idle around 730rpm.

7b68e1ffd86700723494b2d905f5cd0b.jpg

While idling I'd increase the revs, she'd hesitate briefly dropping slightly lower, then picking up and increasing as I push further down on the gas pedal. She'd go all the way to the beep and when I let off on the pedal to idle she'd idle back at 730rpm approx.
Now I must mention that I took the air filter out otherwise she'd idle even worse.

We couldn't test the injectors with the Power Probe 4 as it's impossible to get anywhere near them with everything attached in the engine bay.
Tested the fuel pump and lines and all are working as they should.

I'll throw up two videos of her, one as she idles the other as I increase the revs so you can see and hear what I'm on about later on. Going to start stripping everything out at the moment.




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Here are two videos of her idling around 730rpm this evening.

The 1st one from outside, notice the vibration.

Idling at 730rpm.MOV

The 2nd video is from inside, notice when I increase the revs she drops back to 730rpm.

730rpm idle.MOV

Now what we also did today was to test the new fuel pump that it was actually pumping fuel. I disconnected the pipe from its connection located beside the washer bottle and turned it on and it pumped the fuel as it should. So no problem there. She struggles to start but when she does I have to pump the gas pedal to get her going.

Mine and the brothers thinking is, that it's fuel related.

The reason for this train of thought is, the fuel pump is working, the coils, leads and plugs are all good as we could see each plug spark on testing. When the gas pedal is pushed the revs slightly dip then increase. She idles very low, as she should be idling around 920rpm to 1,000rpm. This leads us to the conclusion that when the throttle body is opened up under acceleration, more air is brought into the system but it appears that the air to fuel ratio is way off. To much air and not enough fuel at idle. The same applies when driving, it struggles.

Getting NO CEL codes at all except the P0410 but that's to do with the removed Secondary Air Pump as it's not needed on my CATless setup.

I didn't get to remove the injectors this evening as the rain started and darkness fell. I did however get the two bolts on the injector rail off and slightly pulled it up and with a torch could see that there is a lot of dirt around the rubber seals and they also look somewhat perished. Touching the base of each injector I could feel three of them slightly wet and the forth one, one nearest the firewall, bone dry.

Tomorrow I'll pull them out and test them to see if they spray or drip.

Praying to the Rotary Gods it's the injectors and not a compression issue.

 

 

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Removed all the injectors today and cleaned them thoroughly as the photos show

7ebb77d5f9b8a4f79cb84d09825fe9a4.jpg
40468a990f5dd35dbfcb839325bab13f.jpg

Put everything back, primed the fuel system 4 times, meaning turning on and off the electrics not starting the engine. Did the ECU reset pedal dance.
Then turned on ignition and BOOM!
She came to life!
The after about 2 minutes idling she started acting up. Revs started hunting then she died. F&@K!
Restarted her again this time I had to tap on the gas pedal to get her to fire up. Once I take my foot of the pedal she dies.
Now she will start cold and hot if I tap the gas pedal, but once I remove my foot off the pedal she dies.
Getting no fuel leaks from anywhere.

Anyone got any ideas at this stage?

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Check all the nipples and vac lines around the LIM and UIM Chazz - idle hunting and cut out only started after SSV cleaning. One of the intake nipples may have fallen off- a vac leak would sit with your issues.

gas it all over with brake cleaner and listen out - especially around the LIM.

 

 

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Thanks Dusty I'll do that tomorrow. I've had my father over helping out and it's like to cats and dogs fighting between us over what it could be. He's a piston head with 20 years rotary experience from when he worked on my mothers RX7 series 1.
Keep telling him the RX8 engine is a different beast altogether.

Anyway gotta get this sorted as I can't miss another annual meet.



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No cracks or leaks whatsoever found today.

So here's what I diagnosed today. She won't start cold or hot unless I put the gas pedal to the floor and ease back about an inch, then she fires up. Have to keep the gas pedal more than half way down otherwise she dies.
So I started to thing if that's the case the throttle is not opening as it should.
Removed the air box and throttle body accordion so I could see clearly the butterfly plate within the throttle body. Got my assistant to turn electrics to the ON position, NOT the ignition position, and to press the gas pedal slowly so I could see the movement of the butterfly plate.
Guess what? No movement until the gas pedal was almost on the floor. Did it a good few times and noted that the gas pedal is depressed 80% of travel to the floor before any movement of the butterfly plate. That to me is NOT normal.
I may have found the problem at last. Further checks on the electrics on the throttle body and the pedal position sensor to do this afternoon.
Fingers crossed I've nailed it! 🤞



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Installed new Throttle Body and Accelerator Pedal today. She starts but won't hold idle unless I put light pressure on the gas pedal.
Rechecked the e-shaft sensor and it operating as normal.
Got under the car and started tracing all the electric connections and found only one problem, the post CAT sensor wires are damaged and one of them is completely disconnected.
Seeing as I've a gutted CAT and the P0420 code is deleted from the system when it had its mini-map would this be my problem with starting and idling?
Time to go surfing on the inter web to find out.


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