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Reply To: Rough Idle/Engine Hesitation when engine hot

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here Rough Idle/Engine Hesitation when engine hot Reply To: Rough Idle/Engine Hesitation when engine hot

#959434
Sean Fleming
Sean Fleming
Participant

Old thread, but I recently had this issue and wanted to share, since it’s also a cause of bog. My 2011 CRV was bogging when hot and pulling away from a standstill. It was hesitating on first acceleration. I ended up replacing exhaust components / cats, but that didn’t fix it. Cleaned throttle body, that didn’t work. The issue was actually the cold air intake I had installed a few years prior. The issue didn’t arise, though, until after I did a valve adjustment and opened up the intake valves slightly, which increased intake air flow into the engine even more. Further, I did the valve adjustment in the winter and the issue didn’t come up until it was hot in the summer, so that further perplexed me, but it all made sense in the end. With a cold air intake (CAI), your engine is running too lean. Despite the marketing BS, your car isn’t going to run better with a CAI, UNLESS you get it tuned in / you get a professional (assuming you don’t have the skill) to re-flash your PCM to handle the new air flow. They have to re-program the MAP sensor inputs. I have another car, honda accord, that I put a CAI in and it never really ran better, until I took it to Xenocron tuning solutions, outside NYC, and they flashed the PCM with Ktuner software. After that, it ran so much better / faster. In the case of my CRV though, Ktuner didn’t offer re-flash compatibility, so the solution was to remove the CAI.

Anyway back to the problem with the CRV. What happens is, when your engine is running lean (too much air) it’s also running hotter than normal. Too lean = too hot. That issue gets exacerbated by it being hot outside. Throw in factors like sitting idle with the A/C cranked, waiting to pull out into traffic, and you’re really heating up the cylinders. When your engine is running that hot, you start to get engine knock. Your knock sensor will sense this and the ECU will retard the timing to prevent pre-ignition and knock. Essentially, the ECU causes the engine to slow / hesitate for self protection (prevent knock). In my CRV, the ECU was so good at this it never threw a code / CEL for knock or anything, so I couldn’t tell what was happening at the time. I eventually took it to the honda stealership and they recommended putting the stock intake in. I doubtful, since the CAI wasn’t an issue for the first few years after install, but they were right. So what I learned was, don’t put a CAI on your car, unless you plan on getting it dyno tuned in. Further, I wouldn’t even put a high-flow air filter in. I recommend keeping it all stock, if you aren’t getting it tuned.

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