lovemyRX7

so... wheres a good tutorial for re-grounding my ECU?

RotaryRocket88

iTrader: (7)

Aaroncake has a general grounding write-up here: http://www.aaroncake.net/rx-7/grounding.htm. The main ECU ground is included.

lovemyRX7

oh thats awesome... just what i needed. Thank you.

RotaryRocket88

iTrader: (7)

Slight correction that what I said before, slidefc3s.

The pressure sensor would have had power if you spliced into it, but it wouldn't have been powered if you just ran the wire to the shock tower & left the other side cut.

lovemyRX7

I hope you don't think I'm brain dead, but i don't quite follow...

HAILERS

If you grounded the BLACK/WHITE wire on the boost/pressure sensors plug, then you blew the EGI COMP fuse in the engine bay when you put the key to ON.

Just FYI: the ground wire on the boost sensor is spliced into the ECU ground wires that terminate on top of the engine. Same with the ground wire on the yellow two wire fuel pump check connector. They are all spliced together and terminate on top of the rear rotor housing.

Adding another gnd to the boost/pressure sensor never worked for me at all. The only thing that ever worked for my 3800 hesitation was adding/soldering a new wire to the ground wires AT the ECU and termination that new wire on the bkt that holds the ECU in place.

If you buy a copy of the MAZDA fix for hesitation (Factory Service Bulletin) you find that the additional gnd wire at the boost/pressure sensor was to compensate for a AFM problem (their words). Remember the gnd wires on the afm and ECU etc all tie together. See the wiring diagrams. Whether Mazda was right or wrong is another thing.

Cleanding gnd points on JC-01 or JC-02 or adding bonding strap from the chassis to the engine isn't going to do anything for the 3800 rpm hesitation.

The ground wires for the ECU are called out in the FUEL AND EMISSIONS section of the FSM in the CONTROL UNIT sub section. Like 3A, 2R, 3G and 2C. They are all tied together in multiple mechanical splices inside the harness and all terminate on top of the ECU's rear rotor housing.

Instead of gnding the gnd wire at the boost/pressure sensor, a person could just insert a new wire in the socket of the fuel pump check connector where one wire is a gnd common to the boost sensor and then terminate the other end of that wire to ?? whereever you want. Engine or chassis and you accomplish the same thing at doing it at the boost sensor. Probably won't cure the 3800 rpm hesitation. Might though if you feel lucky. See attached jpg of the wiring diagram for what I mean.

Series five are a bit different and really should not be having the 3800 rpm hesitiaton in the first place.

slidefc3s

hailers... your a mad man! thanks a bunch! im going to go check every fuse on the car again (i think i checked that fuse, and it was good... ill check it again.) looking at the wire diagrams is like looking at a language i dont understand...(me and wiring just dont go together) anyhow... i noticed that my secondary runners dont look like they have opened in quite a while, the car had been sitting for a bit (but started right up the first time i tried...untill i did the wiring screw up...) so thats probably the source of the hesitation. can i force them open and closed to "free" them up, and hopefully they will work again?? im still more worried about getting the car to start, and go from there... im new to the rotary scene, but not new to cars altogether, i got my fc a week ago, and cant wait to be driving this unique piece of automotive history. i cant thank you guys enough for all your help.

slidefc3s

ok...checked fuses by battery in engine comp, and driver side kick panel area inside the car, and all fuses look good. im stumped... are those the only fuse panels on the car? if i could kick myself for getting into this...

RotaryRocket88

iTrader: (7)

Are you checking them by just looking or with a multimeter? And you really only need to be checking the underhood fuses. Specifically, the EGI COMP fuse Hailers mentioned.

slidefc3s

I just looked at them. I dont have a multimeter handy... I could get one. What would I be looking for on the meter? How would I check with the meter? This is the first time any of my cars have given me an elec. problem!

RotaryRocket88

iTrader: (7)

You have to use a multimeter. If you've never used one, this may help: http://blip.tv/file/138422. Some auto parts stores also sell "fuse testers", which test for continuity. If the fuse popped, there won't be a connection from one side to the other.

As a quick test, you can pull the 30A retractor fuse (closest to the fender if you don't have the fuse box cover), and place it in the the EGI COMP fuse location. If the engine starts or at least tries to start, the EGI COMP fuse was blown. You can also test the other way around by sticking the 30A EGI COMP fuse in the retractor fuse slot, and turning your headlights on. If the lights pop up, the fuse is good.

slidefc3s

ok, I put the egi fuse in the retractor slot, and my lights still popped up. so the fuse is good... where do i go next??

HAILERS

The only fuse that you could possibly blow if you grounded the black/white wire at the boost/pressure sensor is the EGI COMP fuse. Are not any other fuse attached to the black/white wires.

You really need to buy a meter so you can tell what has power and what does not have power.

IF you grounded the brown/white wire at the pressure sensor, that could very well kill the device inside the ECU that creates what is called REF VOLTAGE. Nothing works without ref voltgae. No spark, no fuel injector action.

You need to figure out if you have spark or not. If you have spark, most likely you have fuel injector action and the engine should start .....if not flooded.

slidefc3s

i pulled the t1 plug, and cranked the car, and nothing. no spark. but Im sure it was the black wire with the white stripe that I spliced.

slidefc3s

I just changed my ecu with a known good ecu, and still no spark. Where should I start??

RotaryRocket88

iTrader: (7)

Pick up a multimeter. It's the only way you're going to be able to test components.

lovemyRX7

so....?

RotaryRocket88

iTrader: (7)

That post about the pressure sensor wire wasn't directed at you. Didn't you know the thread was highjacked?

lovemyRX7

lol i know... i got threadjacked.

slidefc3s

yea! I'm running off with your thread (I'd be driving off with it, but my poor car won't run...)! Did you get your hesitation issue resolved? I think my original problem was my secondarys not opening. Smear some grease all over your acuator rods and go for a drive, pull it till the hesitation, then see if the grease is smeared on the rods. You will be able to tell if the secondarys are opening.
I'm going pick up a multimeter today, and hopefully one of you guys can walk me through testing what needs to be tested ECT.

lovemyRX7

lol its ok, i know how to fix it, found a great tutorial from Aaroncake's webpage. just have to reground the ECU and that should do the trick. lol i dont own this thread or anything. thats what this part of the site is for, to help people fix their rx7's.

slidefc3s

Ok. Got my multimeter. Where do I start?? Please help!!

RotaryRocket88

iTrader: (7)

Start by testing the EGI fuses for continuity.

Then go to the FSM fuel and emissions section, and start doing the tests for the components listed there. You should start with the boost/pressure sensor, the CAS (Crank Angle Sensor) and the coils. The "control unit" portion will have a list of voltages you can measure at the ECU, as well, which can make the job a little easier. Touch one of the multimeter leads to ground and push the other into the back side of the ECU plugs, at the specified PIN. There is a PIN diagram in that same section.

slidefc3s

thanks rocket! I'll get to it!