I'm running a boosted d15z1, just got it on the road a month ago. Runs ok, power decent, boosts to 5-6psi. It's in an obd0 chassis and I'm running it on the correct civic vx 49 state obd1 P07 ecu with the 5 wire O2. I've got code 48. Guessing I've got a mistake in the O2 wiring. I don't have any shielding and maybe other problems. Also code 3, MAP sensor.
One problem is that while running around 3K, if I let off the gas just a little, or step on it just a little, the tach drops to 500 rpm or so. Step on it and it goes right back. Doesn't affect the performance at all. Car runs the same whether the tach is jumping or not. Doesn't die. My cruise shuts off at the same time so I assume the ecu is not sending the tach signal out when this occurs. No codes other than 48. Any ideas? I was thinking bad tps?
If anybody is still reading this I have some new info. I didn't tighten the coil wires and one of came loose, thus the tow truck. The tach jumping problem persists. However, after about 30 minutes of driving the problem goes away and is replaced by rough running at part throttle. Just a little above part throttle it runs good. Tach doesn't jump. But cruising on the freeway it sputters and bucks. Any ideas? Codes 48 and 3. Running pig rich because of code 48. 20mpg.
I was running with no valve cover ground which I fixed and haven't really tested yet. With a bad O2, though should I really get only 20mpg? This is a 2500 lb AWD car. I was getting 31 mpg with a d15b vtec.