In reply to Vigo :
We just talked about that.. Lots going on, both of us are working to keep it running and nobody is looking at the gauge. We're doing that next
In reply to Vigo :
We just talked about that.. Lots going on, both of us are working to keep it running and nobody is looking at the gauge. We're doing that next
We are gonna check fuel pressure while running AND run directly out of a fuel jug and return to the fuel jug and bypass most of the fuel system.
It still FEELS like fuel or lack thereof.
We have been running the fuel system out of a VP can with clear hose and a filter, for sure fuel is flowing and we are still having issues. As a last ditch effort we picked up a spare ECU Monday night and the results were exactly the same.
I'm about 95% done building a Megasquirt that was supposed to go in this winter so while I wrap that up @wvumtnbkr is yet again going through the factory harness. I have tuned a piggyback ECU before but I never had to play with anything in open loop and at idle so I'm not entirely sure how prepared we will be to have the car on track for endurance racing on October 5th. Friday practice may be logging and tuning with a laptop zip tied to the cage somehow...
Yep. Checked fuel pressure. VERY steady.
rewired all ECU and sensor grounds. Same issue.
Rewired all VRef wires between sensors and ECU. Same issue.
Changed ECU. Same issue.
tested AFM, MAP, and CTS per FSM procedures.... Same issue and all test good.
Im gonna do a coolant system pressure test and a compression test to make sure engine is healthy.
I don't see clean injectors on that list...
Sorry!
Put in freshly rebuilt RX8 injectors which are supposed to be better in every way. Same issue.
Thanks for the reminder.
ya got me on this one I'm stumped.
I can mail you an N326 or N327 ECU if you want to see if it fixes it due some bad ECU issue and even a fuel pump if you really need it.
So you've got pressurized fuel in the rail and the ability to deliver it. This means that either the AFM is reading incorrectly (either a sensor problem or not all the air is physically going through it) or the ECU is simply not delivering the fuel due to some bad signals somewhere. I'm not sure what bad signals would cause an RX7 ECU to go really lean.
What really matters is how much fuel is coming out of those injectors, and you're not going to see that with a chunk of clear hose. Hmm, what about voltage at the injector? Any chance it's low so the injector is sluggish to respond?
I didn't see any pictures if your intake setup, but there's no chance that you've got a massive leak crack/leak in the gasket somewhere and it's only injecting enough fuel when you crank the AFM door open, is there?
Which side of the flapper is your FPR referencing? If your fuel pressure gauge is just referencing atmospheric, does that 37psi change when you move the AFM?
Fpr was tried connected or disconnected.
The fuel injectors were left hooked to the fuel rail and we turned on ignition. Then, we hooked up a spare cas and spun it by hand. The fuel pattern looked great!
We are in a time crunch, so I think we are going full speed ahead with going megasquirt at this point.
wvumtnbkr said:Fpr was tried connected or disconnected.
With the same result? That doesn't sound right...
Can't argue with full-Megasquirt-ahead, though.
Megasquirt may not solve the problem if it's something like low voltage in the harness. Might let you work around it, but if it's a developing problem it may keep getting worse. I'd try to get it solved before throwing another really big variable in the mix.
You can't eyeball fuel quantity delivery by looking at the injectors. What's the voltage on the 12+ side of the injector?
+1 for starting some simple voltage checks. +12v on the right side of the injectors, +5 on the right side of all pertinent sensors, etc.
HOWEVER: as someone who didn't race in the challenge last year while sitting on the sidelines on my car because I was fooled by a voltage check - make sure to check voltage both running and not running. If there is high resistance somewhere (like the bad ground in my case) the voltage can show good until current starts flowing. The more current the worse the voltage gets.
Speaking of which, you have triple checked all the grounds right? Specifically the fuel pump ground and the injectors ground(s).
Keith Tanner said:Megasquirt may not solve the problem if it's something like low voltage in the harness. Might let you work around it, but if it's a developing problem it may keep getting worse. I'd try to get it solved before throwing another really big variable in the mix.
You can't eyeball fuel quantity delivery by looking at the injectors. What's the voltage on the 12+ side of the injector?
I can check voltage at injectors.
The megasquirt will be all new wiring and new sensors. That's one of the reasons to move forward with jt.
That's the reason I put a MS in my Rx-7 many, many moons ago.. I was getting sick of chasing 215k old rotary wiring issues :)
Ransom said:wvumtnbkr said:Fpr was tried connected or disconnected.
With the same result? That doesn't sound right...
Can't argue with full-Megasquirt-ahead, though.
Meaning that the issue didnt change.
The FPR lowers fuel pressure at idle and then when revving would allow it to go to 42 psi (from 37). Disconnecting it from the vacuum source keep sit at a steady 42 psi.
wvumtnbkr said:Sorry!
Put in freshly rebuilt RX8 injectors which are supposed to be better in every way. Same issue.
Thanks for the reminder.
woah woah woah. RX8 injectors are 330cc, are they not?
Keith Tanner said:Megasquirt may not solve the problem if it's something like low voltage in the harness. Might let you work around it, but if it's a developing problem it may keep getting worse. I'd try to get it solved before throwing another really big variable in the mix.
You can't eyeball fuel quantity delivery by looking at the injectors. What's the voltage on the 12+ side of the injector?
With the engjne running, meaning the injectors are seeing a load.
This is where having a scope would be handy, since a voltmeter won't respond fast enough.
But the symptoms scream vacuum leak. Did you do simple things like verifying that the intake manifold didn't rattle itself loose, clamp off the PCV system hose and the brake booster hose, double check the gasket on the EGR blockoff plate you no doubt have installed? (And if you have an EGR valve in there to plug the hole, replace it with a plate, EGR valve diaphragms can fail)
How about BOTH air temp sensors?
Knurled. said:wvumtnbkr said:Sorry!
Put in freshly rebuilt RX8 injectors which are supposed to be better in every way. Same issue.
Thanks for the reminder.
woah woah woah. RX8 injectors are 330cc, are they not?
yellows are 400CC at 40psi, they flow 800CC at 80psi...
the red ones are somewhere in the low 500s I have not flow tested mine but I have on the yellows.
fidelity101 said:yellows are 400CC at 40psi, they flow 800CC at 80psi...
the red ones are somewhere in the low 500s I have not flow tested mine but I have on the yellows.
I'm pretty dubious of a 1:1 correlation between raising pressure and raising rate... I'm under the impression that you get some serious diminishing returns as you raise pressure. E.g. if you check Deatschwerks' generic pressure/flow estimator, 400cc@40psi estimates at 566cc@80psi... I wouldn't have guessed that in particular, but it jibes with my understanding that due to the restriction as you try to move fuel through a given orifice faster and faster, you get more and more restriction.
Which is pretty far off topic, excepting that it makes me wonder about the rest of the data.
In reply to AnthonyGS :
I'll have them send you another memo.
Get another TPS and see if that works.
Your statement of going MS to save time made me chuckle as one of the very first things recommended in any MS conversion is to start with a good running engine. You don’t have that at the moment.
dean1484 said:Get another TPS and see if that works.
Your statement of going MS to save time made me chuckle as one of the very first things recommended in any MS conversion is to start with a good running engine. You don’t have that at the moment.
Yep. We have tried for 2 months to get it running with stock stuff. Isnt working. Time to go nuclear. It's not to save time. It's to get it running before the race.
The tps doesnt do much with these engines. We have tried 2 different ones that both test good.
Tried to check voltage at injectors. We get batt voltage running or not.
The yellow rx8 injectors are 420cc or 440cc depending where you look. That should be plenty to get it to idle and rev in neutral even if under sized a bit. We also tried the stock injectors with no difference...
AnthonyGS said:I have a question about a previous post. You said unplugging the TPS made no difference? If that’s the case isn’t a bad TPS at this point? The TPS tells the engine to start adding fuel since air is coming soon. Taking the TPS out of the system should make a change.
I heard you are having a problem with your TPS reports..... either way I didn’t understand your TPS explanation.
I'm not convinced much of the sensors really do anything on these engines for this era to be honest.
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