[KrimsonMike]

I have a 99 accord V6 109000 miles, no mods except an AEM dryflow intake. The engine light popped on awhile ago and gave me the p170 and p171 codes. I cant find a vacuum leak, or maybe I just **** at finding them, I replaced the MAP sensor, cleaned out the IAC valve, and the transmission was just rebuilt. (I had the engine problem before the transmission one). The car idles hard, and shakes, not smooth at all. the throttle response is slow, like pushing down, and down, and then the car lurches forward. On the freeway,, and even driving normally, it will just stop accelerating slowly, and I have to push down on the pedal to get any response. If anyone has had this problem and has some advice that would be awesome. I am about to take it to a shop but I am not strapped with cash and im tired of replacing parts with no change in the performance.

 

[nehonda]

How are you checking for vacuum leaks, just by sound or spraying carb cleaner on suspect areas? If you removed the throttle body did you replace the gasket?

It could also be a fuel problem making it run lean. You may want to check the pump and pressure regulator.

If your engine surges at idle like the one in this video its possible your IAC is bad. Since you said you cleaned your IAC and it still surges, it may need to be replaced. Both I4 and V6 IACs work the same way and the surging is caused by the IAC stuck open and the ECM cutting off the fuel to limit the idle speed, however it usually results in a P0505 code