Ok,

So I got a stock ecu yesterday, and the car won't go into boost.

So here are the symptoms,
(it's like in limp mode)

The Boost gauge once it comes close to 0, it starts sputtering and the car pops like it's flooding and the BOV opens up and vents.

Neutral Revving, the car goes up to 4 psi so the first turbo is functioning properly.

I did a search and tried to go through each step and figure out what's wrong.

The mods to the car are:
Deleted airpump
Apexi Noir Catback
Stock BOV's Vent into the atm
deleted airbox, just pipes and air filters on it
Walboro 255 High Flow Fuel Pump

The Boost gauge reads about -10 to -13 psi.
at Idle.

Any one know what might be wrong?!

 

Any one have any ideas?

 

vac sounds a tad low for a stock (I assume) motor, but nothing unusual. What ECU was in the car previously? You mentioned you got a stock ECU yesterday... any smoking, etc?

 

Have you checked all IC pipes/couplers for leaks? I had similar problems building boost one evening after I had removed some piping to fix a different problem (leaking coolant line under y-pipe -> IC pipe). Turns out I had forgot to tighten down one of the couplers fully.

It could be something as simple as that..

 

Yeah I checked all the couplers. cause I had an eclipse that had the same problem, and it was a boost leak... very big boost leak from a coupler.

My rx7 had an Apexi Power FC in it before the board smoked, and I had to send it back to apexi to get it fixed.

The pin on the board that showed a burnt area was a ground wire for the apexi board

 

If the motor isn't ported, that's a fairly low vacuum reading depending on your idle rpm. So, what's your idle rpm? Have you check for ECU codes since installing the stock ECU?

 

This problably is way off base, but I recently had huge problems with my car not running well (if at all) simply because I hadn't fully inserted on of the ECU plugs.

I'm sure I'm the only one stupid enough to do it, but you may just want to check the plugs and possibly even hit the connections with some electrical cleaner. Just a thought....

 

Yeah, my Idle sometimes drops down to 600 rpm. I'm wondering if it's a bad map sensor. I'll check the ECU plugs again...


driving me batty this car... I have reached the love hate relationship of rx7's finally

 

Just FYI, the stock ECU usually idles like crap without the airpump connected. You typically need to adjust the idle a little higher (around 1000 rpms) to get it to smooth out.

 

Actually, -10 psi is 20 inches of mercury vacuum. So, if it's really in psi, he has abnormally good vac. He needs to figure out what units of measure it really is.

Has the car flooded recently? Could your plugs be fouled up? Try a timing light or spark tester on each plug wire.

 

yeah.. it's -10 psi... i'll adjust the idle up.. hmm the car did flood.. the power fc could have fouled the plugs up...

keep the recommendations coming because I'm going to check all of them..

 

Well, if it's -13 psi, then your vac is too good... so something is off there.

If there was a resulting flooding problem, the PFC could have caused fouling indirectly.

The reason I mention plugs is because you mentioned exhaust popping/misfiring. I'd imagine that's coming from unburnt fuel from poor spark.

 

What are you reading your vacuum from?

 

I'm reading the vacuum right in front of the MAP sensor.

Jack

 

Are you using a gauge, if so what gauge?

 

i think he means what gauge are you reading your vacuum from? most everything measures vacuum in inches mercury, and positive pressure in psi.
the exception my profec e-01 read vacuum in psi. My guess is you are mistaking inch/merc for psi.

 

So, ok went back out to the car this morning.

Ok, I lied, Vacuum is measured in Mercury.

I have only -10 mercury. I located the vac leak. There is this hose coming off the throttle body with a inline pill that is black. it comes from the underside. and it's just dangling, the guy let it loose where is this supposed to go? I'm trying to search for that vacuum diagram for the rotary 13b to try to find it.

 

You can find vacuum diagrams here:
http://www.fd3s.net/vacuum_hose_replacement.html

 

It isn't the line to the map sensor is it? Check that

 

yeah that should be the vacuum line for the MAP sensor. There are two vacuum tubes from the UIM one goes to the map sensor. I don't know why. my vacuum lines are all messed up the previous owner has it running every where.

 

I'm having the exact same symptoms, wont make ANY boost, gets to 0 PSI, then just pops repeatedly. My car is throwing a code related to the KS, so im replacing that in a few days.
I just got done doing the vacuum simplification, and had a few boost leaks. Make sure you track ALL those down first. I built a little boost tester out of a 4" rubber pipe-end from a local hardware store, and a tire shrader valve. Just tighten a hose clamp down on it post turbo (intake) and hook up an air compressor.
I hope the KS takes care of my issue, but ill be watching your outcome as well. Good luck.

 

KS? Knock sensor?

Jack

 

aye, knock sensor

 

So I find that the car runs fine when it's cold and the car does go into boost when the motor is cold.

The Motor once it reaches operating temperature, won't go into boost

This is what I deduct:

The vacuum lines expand with the heat and the inner diameter of the hoses open up enough to leak enough.



When I'm under load the vacuum reads between -17 to -20
At idle it sits from -10 to -13
All at bars of mercury.
(could it be a thermostat? what heats up and makes the car go into limp mode?)

Jack

 

no to your thermostat, you would have over heating problems if this was an issue
2 i hope you arent driving the car hard when it is cold, thats a no no
3 have you done a compression check?

sounds like you probably have a vacuum leak use carb cleaner while the car is running and just spray it around if your engine bogs down you have a leak in that area.

Is that hose you found still dangling?
It might be something with the sequential system for the twins if the car is still running them sequential. I'm guessing u have a boost gauge?