well i posted the same question a few weeks ago in the msp forum and got no help so here's another shot, i thought i might find some wiser folk in here???? as soon as the car switches into open loop under wot the af goes straight lean, and if i stay there for a second longer you can hear it detonating, or ping...which ever the two is caused by lean combustion? but no one could come up with any ideas and the only things i could could think of would be fuel related i.e. failing fuel pump or injectors, since it only happens under wot when the engine wants more fuel? just put new plugs in so thats not it. i dont think it is spark related but anything is possible. i havent seen redline for 6+ months now and im startin to go thru a little withdrawl. if anyone could point me in the right direction i would appreciate it. only mods are cold air, gutted cats, type s, mazdaspeed axelback. is there anyway i can hook up a a guage to read read fuel pressure at its peak flow, and what should that be at wot if anyone might know?
running lean in open loop
- Thread starter mzdfc3s
- Start date
- :
- Protege5 2003
mzdfc3s said:
Please clarify, is this problem in open loop (car recently started) or in closed loop (car warmed up)?
I don't think the car ever normally "switches into open loop" from closed loop.
ke20sprinter
Member
- :
- Daily Driver Protege5
First off, welcome 
I'm assuming, based on your name your have the 2nd Gen. RX7?
So, I googled "RX& forums" and came up with this:
http://www.google.com/search?hl=en&lr=&q=RX7+forum
Most MSP guys are used to pistons, not rotaries...Only thing I can think of...Are you boosting beyond stock psi? Maybe bigger injectors, better fuel pump...List can go on. I'd suggest checking those other sites, they'd have a better answer for you.
Hope that helps.
WiL
I'm assuming, based on your name your have the 2nd Gen. RX7?
So, I googled "RX& forums" and came up with this:
http://www.google.com/search?hl=en&lr=&q=RX7+forum
Most MSP guys are used to pistons, not rotaries...Only thing I can think of...Are you boosting beyond stock psi? Maybe bigger injectors, better fuel pump...List can go on. I'd suggest checking those other sites, they'd have a better answer for you.
Hope that helps.
WiL
mzdfc3s said:
There should be a way to hook up a fuel pressure guage somewhere around the fuel rail. Possibilities include fuel pump, injectors, fuel regulator, and possibly throttle position sensor. I suppose there could be an ECU issue since it is only in open loop, but I'd guess a fuel issue first. I don't know the proper fuel pressure, perhaps someone in the FI forum would.
yeah i've got an 87 fc here, ive been around the community for a while...bought the msp new in 03 but havent been here in so long i had to get another screen name. i figured i could post this question here since the p5 and msp are pretty much identical excluding the forced induction part of it, but that is nothing new to you guys either. so theres really not much else to say. the car is all essentially all stock. in the summer time ive been runnin 8-10 psi and nothing in the winter. this could happen no matter if the car is cold or warm. another thing that has me puzzled is tere is no associated cel with this so i dont think its in the ecu?
socommatthews
Member
- :
- MP5 & 1st gen RX-7
iknow my MP5 was running lean and it ended up being bad O2 sensors.i know yours is turbo but its the same motor so you might look in to it.i didnt think O2 sensors would ever do that but apparently they do w/this car.
Yeah, especially since you're asking questions about a MSP, right? I'm out of my element turbo wise, but I'd start looking for a vacuum or boost leak somewhere. Open loop on a boosted motor also depends on going into boost I believe. That's why you can use a boost trigger/ voltage clamp to enable a piggyback to work on a boosted car. So I'd start looking at other issues, too.
socommatthews
Member
- :
- MP5 & 1st gen RX-7
yea you would have a cel.mine would loose power noticeably once or twice and then the cel would come on.
