91 n/a spitting after running a bit

mnrthrt · 06-11-2010, 09:04 AM

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 · 06-11-2010, 10:46 AM

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 · 06-11-2010, 11:01 AM

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 · 06-15-2010, 10:51 AM

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 · 06-15-2010, 01:39 PM

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 · 06-15-2010, 09:13 PM

omp yup it will do that too CEL.

FC Zach · 06-15-2010, 09:42 PM

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 · 06-15-2010, 10:34 PM

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

Rotary#10 · 06-15-2010, 10:34 PM

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 · 06-15-2010, 10:54 PM

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

FC Zach · 06-15-2010, 11:20 PM

Quote:

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 · 06-16-2010, 10:52 AM

rtek right?

project86 · 06-16-2010, 12:57 PM

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 · 06-16-2010, 03:37 PM

Quote:

Originally Posted by mnrthrt

rtek right?

Correct

Pete_89T2 · 06-16-2010, 05:33 PM

Quote:

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.

06-11-2010, 10:46 AM	#2
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN Posts: 4,043 Rep Power: 22	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. __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

06-11-2010, 11:01 AM	#3
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland Posts: 219 Rep Power: 17	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. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

06-15-2010, 01:39 PM	#5
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 19	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) __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group Last edited by vex; 06-15-2010 at 01:46 PM.

06-15-2010, 09:13 PM	#6
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland Posts: 219 Rep Power: 17	omp yup it will do that too CEL. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

06-15-2010, 09:42 PM	#7
FC Zach RCC Loves Me Not You Join Date: Mar 2008 Location: Eagleville, TN Posts: 2,267 Rep Power: 20	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? __________________ 1993 Yamaha GTS1000 1992 Celica Turbo AllTrac 1987 RX7 Sport 1979 Yamaha G1, KM24 powered 1975 Dolmar KMS4

06-11-2010, 09:04 AM	#1
mnrthrt cel=life story Join Date: Apr 2010 Location: blow Posts: 32 Rep Power: 0	91 n/a spitting after running a bit 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.

06-15-2010, 10:51 AM	#4
mnrthrt cel=life story Join Date: Apr 2010 Location: blow Posts: 32 Rep Power: 0	my girl did the cel check and got this. code 20-metering oil pump position sensor basic fuel injection and fixed timing. ...any thoughts?

06-15-2010, 10:34 PM	#8
mnrthrt cel=life story Join Date: Apr 2010 Location: blow Posts: 32 Rep Power: 0	hmm..looked up prices for an omp...would i be better off just bypassing it and running 2 cycle?

06-15-2010, 10:54 PM	#10
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 19	You have a few options when it comes to OMP. Convert, Pick and Pull, Buy New, Buy Used. __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

06-16-2010, 10:52 AM	#12
mnrthrt cel=life story Join Date: Apr 2010 Location: blow Posts: 32 Rep Power: 0	rtek right?

06-16-2010, 12:57 PM	#13
project86 Can't.Make.Up.My.Mind. Join Date: May 2009 Location: Murfreesboro, TN Posts: 1,377 Rep Power: 18	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.