Rep Power: 0

Need help with car.. 95 civic with a D16y7 in it.. running stock ecu.. It starts fine, when you first crank car it may idle low at first but idles great when warm.. my problem is that it runs great for about 15mins of driving.. then you feel it loose power and runs rough when you try to accelerate. Have a Genesis 4.0 that says code is "fuel system lean". You can cycle the key going down the road and pop clutch and runs great again for 15 more min.. o2s shows no higher than 0.82v low as 0.02v. Is this right?? Am I looking in the right direction?. Any help is appreciated. Thanks

 
Rep Power: 518

If it is consistently doing this......Disconnect the front O2 sensor and drive it. This would force the computer to use it's base fuel map without O2 sensor corrections.
If the problem goes away then I'd think it's a flaky O2 sensor.
If the problem persists, then I'd look elsewhere.

Fuel pressure testing while driving, tape the gauge to the windshield?

 
Rep Power: 0

I have checked the fuel pressure before but will again. There is only one o2s on the 95 civic I have. I have checked the data stream on the scan tool and I see nothing unusual. When it acts up if I get it to reach 3500rpm's or higher it runs great.. get below that and it runs like its off time.. Another thought I had was the D16y7 may run but not be fully be what ecu P06 can run

 
Rep Power: 518

Yeah, ok. Duh on my part.

Most swing close to a full volt between high and low. Yours may be heading south, that's why I thought to disconnect it and let the computer use base fuel map (open loop).



Right now with the sensor still connected, does the sensor read near 0v when it acts up, and acts lean?
What are the fuel trims doing at that moment? Climbing, dropping, or staying steady?

Has it ever run correctly on this current combination?
(I don't normally deal with swaps or cars from that era these days.... I deal with much newer stuff that is stock.)


Was it checked during the time it acts up?
What does the fuel pressure do while the engine is acting lean?
(That's why I said tape the gauge to the windshield LOL)

 
Rep Power: 0

Ok. I checked fuel when it was acting up.. fuel pressure is 42psi and responsive when accelerating but acts like fuel cutting out.. different codes today.. o2s voltage to low and coolant temp sensor malfunction.. yesterday it was fuel system lean. Data stream showed nothing unusual when acting up. Could I unplug the only o2s on the car and run right?.. no change in o2s reading when it acts up..just to add.. tried new o2s and same result.. also ohm the wires to o2%u00DF
S and command temp from ecu to sensor

 
Rep Power: 518

Well, a false reading coolant temp sensor could drive fuel extremely rich or extremely lean, and do it without setting a code for the sensor itself as long as the values are still plausible. Once the values stray outside the range of acceptable readings, it sets a fault code.

So if you never had it disconnected while keyed up, I'd say to double check its wiring and probably replace that temp sensor. (On the end of the head near the distributor. It's the 2 wire sensor not the single wire sensor.)

Then erase codes and test drive, see if that takes care of the other codes.