91 n/a spitting after running a bit

[mnrthrt]

while i was on r&r i drove my 7 every day. for some reason my girl is driving it at home and after about ten minutes the cel comes on and she can't give it gas without it stuttering and not going anywhere. if you accelerate extremely slow its fine. if you turn the car off, wait about 3 or 4 minutes it comes on and runs perfect even dogging it but then the check engine light comes on again and it wont run for shit. no mods on motor other than an air filter replacing the box. it was on there when i bought it. anyone got any ideas? has new spark plugs, fuel filter.

[djmtsu]

Go to the FAQ stickied at the top of the 2nd Gen section. There should be instructions in there on how to test the CEL, and what the codes mean.

Come back when you have that info. It sounds like a fuel pump, but that will not throw a CEL.

[Rotary#10]

It seems like the car is going into ' limp home mode' I had a trailing coil go out and car barely ran but still got me home.

[mnrthrt]

my girl did the cel check and got this.

code 20-metering oil pump position sensor basic fuel injection and fixed timing.

...any thoughts?

[vex]

Almost sounds like the OMP is on the way out. Check it to spec, make sure it's functioning, then work backwards from there. (You may also want to check your timing, ensuring that the coil hasn't gone out)

[Rotary#10]

omp yup it will do that too CEL.

[FC Zach]

My thoughts exactly, same happened to me with a friends S5. The "basic fuel injection and fixed timing" problems could be directly related to a malfunctioning OMP. I thought those rarely went out, could there be a possibility that it just came unplugged?

[mnrthrt]

hmm..looked up prices for an omp...would i be better off just bypassing it and running 2 cycle?

[Rotary#10]

Out 1 of the 3 rx7s I've owned, I only failed on one of them. And that was due to high mileage. 171k

[vex]

You have a few options when it comes to OMP. Convert, Pick and Pull, Buy New, Buy Used.

[FC Zach]

Originally Posted by mnrthrt

hmm..looked up prices for an omp...would i be better off just bypassing it and running 2 cycle?

You would still need an OMP connected to prevent the ECU from going into Limp Mode, or you could have your ECU chipped so it doesn't look for the OMP.

[mnrthrt]

rtek right?

[project86]

i think what you can do with the omp on the s5s is actually take all the guts out so it doesnt work anymore and leave it plugged in. and then just premix. youre right about it not running if its not plugged in.

[FC Zach]

Originally Posted by mnrthrt

rtek right?

Correct

[Pete_89T2]

Originally Posted by project86

i think what you can do with the omp on the s5s is actually take all the guts out so it doesnt work anymore and leave it plugged in. and then just premix. youre right about it not running if its not plugged in.

Nope, that won't work.... The stock ECU is looking for (a) electrical continuity with the OMP stepper motors, and (b) a correct feedback signal (variable resistance) returning from the position sensors that are part of the OMP - these position sensor(s) monitor the OMP position, so the ECU can have closed-loop control over it. Anything that mucks up these conditions forces the ECU into a limp-home mode. So your problem lies in three possible areas, not necessarily in order of likelyhood: (1) Bad OMP, (2) Bad wiring, (3) Bad ECU.

I would recommend getting the FSM, and following the troubleshooting procedures to the letter. There's a nice flow chart that starts with the CEL error code, and walks you thru all the steps to troubleshoot the OMP. It's not too hard to do, but you'll need to know how to use a volt/ohm meter. Given the age of our FC's, it's not uncommon to have wiring harness problems that cause these sorts of issues, sometimes at random and intermittently, so following the FSM troubleshooting procedures before just blindly swapping OMPs & ECUs will save you some grief.