skiman

Have 1990 RX7 convertable totally stock.
Was driving and check engine light came on and went into limp mode .
Shut it down and restarted check engine light went out and we attempted to make it home. Went in to limp mode again as we crept home. was only short distance.
Back at the garage I shut it down and when restarting the Check engine light do not come back on.
I attempted to check the error code by grounding the diagnostics connector :

when I turned the ignition switch on the Check engine light came on and then went off. No flashing

diabolical1

iTrader: (3)

welcome to the board.

my Gen II prowess is somewhat limited, but my first thought would have to be the MOP has failed or is seriously contemplating it.

skiman

thanks will be checkin the MOP today

but should not there have been error code of 26, or 27 indicating issue with metering oil pump?

Akagis_white_comet

iTrader: (4)

Erratic behavior usually indicates a bad ground, while Limp Mode in 89+ cars points to the OMP. Check the Brown/Black Wire on the 3-pin connector for continuity to the Chassis. If it's over 1 ohm, clean and re-ground it as shown here:
Proper RX-7 Grounding Procedures

The factory ground point is Ground #9, shared with the ECU, Air Flow Meter, TPS, IAT, Coolant Temp sensor & Boost sensor. It is under the UIM.

Follow Aaron Cake's grounding guide to rehab it and you should be good to go.

skiman

Checking the MOP using the FSM section D : I was doing inspection 1 step 1 : Stepping motor resistance > Question is do I preform this test at the cable just behind the Alt or is it done at the connection on the MOP ??

Will be double checking the Grounds as Akagis white comet recommended tonight

thanks

satch

iTrader: (1)

Directly from the sensor. Testing resistance from the harness would make the test circumspect because the wiring could add resistance to the numbers provided in the FSM.

skiman

Grounds test good :
When checking the steping motor resistance according to the FSM :section D page D-17
check resistance between the terminal (+B1) and terminal (SM1-SM-3) and terminal (+B2) and terminal (SM2-SM-4)
Looking at the picture I dont know which is +B1 and which is +B2

FLSaffire

Hi, I had this exact same problem with my 1990 rx7 convert S5 just a month ago or so. The code did indicate the MOP I believe (you can check my conversations here about this). I took it to a mechanic and had him put in the OMP which I got off Ebay. He replaced this as well as some ground issues I think. But it was the problem, as it hasn't gone into limp mode since replacing this part. Hope this helps you.

skiman

FLSaffire was yours giving you any error codes ? The CEL comes on when I attempt to drive but goes off when I shut it down and then check for codes?

skiman

Does anyone know if there is a way to check the system that produces the flashing/blinking CEL to see if I have some other problem and i should be seeing error code?

satch

iTrader: (1)

Ground the Orange wire in the check connector located near the lead coil and turn the key to on and if there are error codes they will then be displayed.

Seamoan

Had the same problem with my 89 vert. the error codes indicated a bad oil metering pump. I took it to the shop (Lucky 7) and we replaced the OMP and the ECU. Some say that a bad OMP will fry the ECU so you should get the ECU checked out or replace it entirely.

PROTIP: if youre driving and your car goes into limp mode, if you shut it off for a quick moment and then turn it back on, your car should be fine for a few minutes. thats how i had to get around for a while when this was going on with my FC. Rolling in neutral.

hit me up for any questions. im not a technician but i have had this happen to my S5 and now its fixed.

skiman

When I ground the Orange wire in the check connector located near the lead coil and then turn the key to on > I get no codes???the CEL does not flash or blink??

satch

iTrader: (1)

Did you check the bulb?

skiman

the CEL bulb should be good... as the light comes on before starting and when driving the vehicle gets to around 2500rpms when driving ....
thanks

skiman

Thanks to Bryan at Rotorsports Racing we are now back on the road....

Replaced MOP and ECU this corrected the problem

misterstyx69

iTrader: (142)

hmm...
I'd think that the members who mentioned the solution are to be thanked also,dont you think??

Bryan also knew and fixed what they confirmed already.

skiman

Thanks to all that helped .....

Bryan was able to provide ECU N353 that was in need of replacment.

Game of the Wangan

iTrader: (2)

Having the same issue as well on my S5 90 Turbo2 . I ordered a low mileage OMP but NOT the ECU along with new lines I'll be rebuilding in the process. Maybe my ECU survived lol