91 NA Vert. stock. no mods at all...

It's been running fairly well until last night. It started okish, didn't really rev up for the Accel warm-up (only got to about 1450rpm and rough) then idled down to 400-600rpm running roughly. If i press the accelerator GRADUALLY it will speed up semi-smoothly until it hits 2000rpm then it acts like somebody's turning the key on and off REAL fast. IF I push it harder it will rev higher, but doesn't sound good at all, rough and rich, and the tach will sometimes drop to '0' and not move unless I rev it up and down repeatedly, sometimes it will 'bump' briefly. If I hold high rpm (5-6k ish) it will randomly seem to smooth out briefly then return to rough running. Timing is dead on with the initial setting jumper in but ocassionally jumps WAAYYY off (around 20* retarded) and runs horribly till it jumps back. Cant really tell whats going on, first guess is a dieing ECU but I just don't know. any ideas??

Thanks in advance!

 

If the tach is dropping the 0 and the engine is still spinning sounds like the trailing plugs arnt continuously firing right.

 

well, no, probably not, but neither are the leading for the brief moments the engine acts like it's 'off'... not sure whats doin here.

 

Anybody? Ideas, thoughts, plans, suggestions?

 

Have you pulled the codes?

http://www.1300cc.com/howto/how2/codes.html

 

Pulled the codes... here's what I got:

1- Ign. coil (trailing)- Trailing ign. pulse cut
20- Metering Oil Pump position sensor { mine has a mech. MOP???}
26- MOP (Step Motor)
30- Solenoid, Split Air Valve

Ideas?? I'm looking in the FSM for the split air valve... didn't see it in the Hanes manual I have. Open for suggestions on the Code #1!!

((NOTE)) the coil checks out ok, and I've swapped it with a known good one.

 

It could be ECU. Try a different one. Also make sure that the grounds are all ok. But if your RX-7 is a 91 than you have a electric OMP. If there is a problem there it can cause the car to go into limp mode.

 

Grounds are all good... I checked and cleaned all of them while trying to get
it running to begin with.

I ABSOLUTELY have a mechanical MOP, thinking it may have been swapped
at some point, but there are NO connectors at all on the pump, and it's got
the linkage going from the T/B down to it.

I was affraid it might b the ECM. Guess I'll track one down and try that. Anybody
know where I can get an electronic MOP for cheap?

 

you have to put up a picture of that engine.
Seeing that 1989-1991 engines(s5) have an Electric Oil metering pump.Do you know if the engine was swapped for an S4?./if it was run On the s5 Computer?
where IS the OMP?./.If it is Running on the S5 harness and the S5 Computer and there is Absolutely NO Omp,then That is the Problem
The OMP Must be hooked up to the Harness,Even IF you go to an S4,OR decide to run Premix,.Or the ECU will Go into Limp mode..NO OMP=Limp Mode on an S5.

 

There are a few pretty good pix of the engine on my profile page. I'm 99% certain this is the original engine, it's an S5 for sure, it is an S5 ECM and harness, I just cant find a single plug, wire, connector or anything at or near the OMP that anything would connect too. anybody got a pic of the pump that shows the wires or connectors? The only thing I can come up with is that someone took the electronic pump off and replaced it with a mechanical. The OMP is on the lower pass side front of the engine, pretty sure thats where they all are. I've pulled the lines and seen oil dripping out of them, and the 'injectors' are clear. It's oiling, the linkage is adjusted per the FSM, it just doesn't look like there's any place to hook up a sensor or anything. Side note, it ran GREAT for about a week. it wasn't perfect, but I'm thinking replacing all the vac lines, clean the injectors and put a new set of plugs in it will cure that little bit of inperfection I was noticing. I did NOTHING to the car before the change... ran fine tuesday, wouldn't run for crap wednesday night when I went to take it out. funky!!! Keep the suggestions comming, I'm lookin for an ECM for it, and troubleshooting the trouble codes as they come up!!

 

code 1 sounds bad. your car is also in limp mode because of the OMP. pocketlogger.com will sell you a ECU chip that will eliminate this problem.

if you look around your engine bay there is probably a eOMP that has two big white plugs coming from it. could be ziptied somewhere on the passenger side.

 

Thanks Walken, I'll look. It seems I have an S4 engine in my S5 car!!! It's got the metal filler neck/ thermostat housing, 2 bolt mech. OMP, and a couple other things I found in the s4/s5 ID threads. NOW... what can I do to most simply make this thing happy again?? chip the ECM? put an S4 ECM in, I'm really lost now!!! I thought I had most of this thing figured out and now this!! If I don't get any answers here, I'll start a new thread (after searching as much as I can handle, I'm almost crosseyed now!!)

THANKS ALL WHO HAVE HELPED SO FAR!!!!

 

Using a S4 ECU will be a nightmare to wire up. Locate the E-MOP that they have tied up somewhere and check the wiring to it, chances are it either can disconnected/pinched a wire/etc. It's rare that they mess up if they're just tied up. Also check your trailing wiring/wires. Try cleaning up the connections/etc and reseat it. Then pull the negative battery terminal off, tap the brake to make sure there's nothing residual left, plug it back in and see if it goes away.

 

Thanks ifryrice, I kinda had that assumption, but wanted to hear it from someone else too. The eMOP is NOT there... dunno how it ran so well without it, but it did. I'm going to buy the Rtek7 v1.0 chip and put it in later this week... that SHOULD cure the problem. I'm fairly certain that the ign/fuel cut is a result of the missing eMOP and the engine trying to preserve itself. I have fixed all the other 'trouble codes' and only have the eMOP crap left...


THANKS AGAIN TO ALL THAT HELPED ME!!

 

Well, it would've never ran properly without their being one 'somewhere' or at least some attempt to mimic it. Locate the connectors for it and see if there's anything plugged into it that's hidden somewhere or if someone tried to jam resistors/etc in there. You might be able to re-do whatever they did temporarily till the RTEK arrives.

 

Here is a crazy problem I have been having lately....

Apparently, My ignition switch is not working correctly, and I lose some interior functions and my car will miss sometimes. Whats the fix? jiggle the key in the ignition socket.

Sad, but true. It pisses me off. You should try this, and see if it helps.

Sorry for the uneducated sounding answer, but I haven't pulled my ignition switch apart yet to find out WHY it is doing this. It is an easy check, so I'd recommend doing it, just to see.

 

ifryrice: It does not have anything in the eMOP connetctors. and odd tho it may sound, it ran prety good for about a week (I JUST got it running, think it's been sitting for around 3 years) then just went straight to pot the other night... I cannot explain it! oh well tho, I'm workin on fixin it and it's gonna be kewl!

jjwalker: Nope, not the ignition switch... I wouldn't get the 'ignition and fuel cut' trouble code, it wouldn't keep running on one coil pack, and prolly wouldn't do the 2k to 15k drop and pick right back up every time like clock work. It's gotta be 'self preservation' mode due to the missing eMOP... we will all know in about a week when I get the Rtek.

Thanks again for all the suggestions and ideas!!!