Hey guys, I have a 1991 s5 vert. She will start fine. Idles where it should and the throttle responds quite well while in neutral. However, once I get moving, and I put the throttle down, the check engine light comes on and the engine will then practically do nothing. Any ideas on what the issue could be?

thanks in advance
-RX7FREEK-

 

Check for what code(s) it's throwing. My guess would be 20, 26, 27 or 30, which are related to the MOP/OMP. Your symptoms sound like limp mode, which is the fail-safe mode when the pump fails. The solution requires a new pump, and in many cases a new ECU. The ECU can be damaged by pump failure.

http://www.johnr.com/cpucodes.html

 

sounds almost like mine right now...strange though mine doesnt give the check light

 

keep us update.. im actually considering adapting a omp bypass to inject clean oil instead

 

Okay, so after taking her to the local overpriced Mazda dealership (lol) I was told that the OMP and TPS were bad. so I bought used ones off of ebay and installed both. The problem still persists. any ideas?

 

I just Pulled off my UIM and found all the hoses on my 88 vert were cracked and leaking. The omp was just dumping oil on top of the engine and causing a leak.

 

Pulling codes:

http://www.banzai-racing.com/FD&S5_error_codes.htm

If the car runs smoothly above 4000 rpm then you need to check the TPS plus the primary injectors as the primaries are the only injectors which work below 3800 rpm.

 

A fouled S5 OMP can damage the ECU.

 

So, a bit of an update. I failed to mention previously that when idling, the engine will rev to around 1000 and drop to around 800. This happens in around the course of 1 or 2so seconds. This will happen repeatedly until I apply some throttle. Around 3000+ it will run smoothly.

 

The TPS needs to be set properly to spec or you have a minor vacuum leak.

 

^ Ditto. The TPS can also have a dead spot in the resistance sweep that'll cause the idle to hunt.

 

Forgive me for my ignorance, But how would I set my TPS to spec? (assuming the TPS is any good) Also, how would I check for a dead spot in the resistance sweep? And if one is found, how would I go about resolving this problem?

Thanks

-RX7FREEK-

 

Green/Red wire is set to one volt w/key to on after the car is fully warmed up which usually takes twenty minutes of driving to accomplish.