So I have a 1989 NA 5 speed coupe with only 79k miles. I've only had it for the past 1k miles but the past two days it has been suddenly bogging down and the check engine light comes on. So on the freeway, the car will keep running but if I try to add throttle it does nothing. After I pull off, the car does not die but I need to shut it off and back on again, and then it's like nothing happened. Check engine light disappears.

and this repeats every 15-20 minutes.

Anyone have any ideas? I leave the car parked outside for several days at a time, if that makes any difference.

The only change to the car I have made recently is pulling the stereo out and cutting a few wires...which seems to have made my dash clock reset every time and keep my ebrake light on. Could this possibly have an effect?

 

Search for "limp mode"

Your oil metering pump has gone out or become disconnected and the ECU retards timing and fuel so that you can "limp home" without damaging the engine. On your series 5 you MUST have the Oil Metering Pump there otherwise your ECU will constantly be doing this.

 

most likely as stated above you have a bad OMP...either broken or disconnected. I had the same problem on my 90 TII. You could replace the OMP, or you can use an after market ECU or ECU chip like the RTek to fix this issue...however if you do so, you will not have a working OMP and you WILL NEED TO premix fuel every fillup... which is easy

 

but at any rate

pull the freaking codes!

jesus...

 

sorry to have to ask this but I cannot find it after searching (keywords bring up too many threads)

what is the procedure to checking the codes on the s5 rx-7?

I only know how to do it for the FD =)

 

near the leading coil(forward coil pack) there is 2 green connectors, locate the single wire connector.

turn the key off, find a scrap wire and run that single wire connector and attach it to ground with the spare wire.

turn the key on.

watch the check engine light flash, retrieve codes. actually VERY similar to FD in that respect.

either of these will put you into limp mode and run the car under limited power:

27 - MOP (General) - Basic Fuel Injection and fixed timing
37 - MOP (General) - Basic Fuel Injection and fixed timing

 

Karack:

the car still does the same thing but I can't pull any codes from it. after it does it's limp mode thing I turn the car off and then turn it back on and the code is gone. is there a way to get it to store longer?

 

nope, these ECU's don't retain codes for more than 1 drive cycle. you'll have to get it to recur and then pull the codes.

 

thanks for that last bit of info karack. pulled a code for 13 and 27. replace OMP pump then?

 

I think I will stop driving this car in the meantime.

 

13 is for the pressure sensor on the RF strut tower and yep, code 27 means something is dying in the OMP system. there is a few threads on the forum that explain how to check the whole system to hopefully prevent it from happening again rapidly. sometimes it is not the pump that is at fault but the wiring and the ECU gets cooked in the process. since yours is intermittent i would say it could be either the pump or wiring but the ECU is still ok.

 

WTF? S5s STORE codes Ben! S4s do not..

 

I couldn't get em after going through a few cycles, but was able to right after it happened.

 

suppose i just haven't noticed it, would make sense but the stock ECUs are about as smart as a rock.

 

out of curiosity, how much driving on an intermittent limp mode would it take to fry the ecu? I've driven maybe 50 miles since I first started getting the codes but I've parked it for now until I can find an OMP to replace it.

 

hard to say, i haven't driven a vehicle extensively with the issue but if it was still semi functioning when you parked it i would say you should be ok.

 

I just had d same problem on my 91 gtu, it was d OMP so I replaced it wit a junkyard special n replaced d ECU n d problem is gone. She runs like a charm now, try doing d OMP resistance check first n dat will tell u if its bad.....u can find d specs in d FSM

 

Here's a link to where u can find d specs for everything, hope it helps. http://www.rotaryheads.com/PDF/2nd_gen/