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96 accord 2.2 A/T 134k
I drive on the interstate every day for work. And every day I go up the on ramp I feel like an a**hole holding up everyone behind me because my car takes forever to get up to speed. I had the trans rebuilt 20k ago and it shifts fine, it’s just the engine that feels like it’s lacking power. Worse and worse lately. To the point where I actually don’t mind being behind a semi at a red light. My car gets up to speed just as fast, no time lost. (Maybe theres a little exaggeration there) no stumbling or clunking happens, the car is just slow and I wish there was a solution other than “get a new car.” Or “that’s just how 4cy engines are.” logical suggestions are greatly appreciated… 🙂
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Your question is going to get you more questions before we can help you. Does the PCM have any codes stored? Look for them even if you don’t have a check engine light on. Does the engine sound any different with this lack of power? When was the last time basic maintenance items like fuel filter, air filter, timing belt, & spark plugs were replaced? Any braking problems that you can think of?
No check engine light and no codes stored or pending (I carry an obd2 scanner in my purse) timing belt / water pump replaced and valves adjusted by Honda. I don’t think the fuel filter has ever been replaced. Oil changes done every 3k. The egr is new I pulled up the fuel rail and unclogged the ports and cleaned the injectors. New alternator starter battery radiator and hoses plugs and wires (ngk) and distributor assembly and air filter. All motor mounts have been replaced. replaced the iac a few months ago. (Had vibration and idle issues) both front and rear brakes were replaced last year and fluid has been changed, no issues there. Vss replaced (had issues w speedo bouncing) I looked in the throttle body and it appears to be clean. All enine gaskets replaced not a single oil leak. The vehicle runs great (idles a little high when first started but calms down once it warms up) puuurrrrs when I get up to speed on the highway.
One immediate thing I’d try is changing that fuel filter. Yours should be under the hood close to the firewall and the brake booster IIRC. Also pull your air filter to make sure it’s not obscenely plugged up. Furry woodland creatures can do terrible things in air boxes.
The next would be to pull the upstream O2 out entirely and then go for that next test drive. If you’ve got a vacuum gauge, you could tap into a manifold vacuum source and do a snap throttle test before and after pulling the O2 sensor and get the same info as the test drive would provide as to whether or not your catalytic converter is plugged.
I’ve replaced the O2 sensor last year, threw a code. If anything was happening w the cat wouldn’t it set a cel? The air filter is clean. I’ll do the fuel filter tomorrow. Someone also suggested a fuel induction service would that help or hurt? My scanner has live data are there any numbers i should be paying attention to?
It’s really really unlikely that the EVAP code has anything to do with your power loss. You can ignore that code for now unless you’ve got a smog check to pass in the recent future. The PIDs I’m interested in all look fine at speed too. It’s time to get dirty and start eliminating the variables. I’m still content on diagnosing that catalytic converter to start with. If you’ve got a Harbor Freight store nearby, you can pick up a cheap vacuum gauge for about $15. Here’s one of Eric’s typical awesome videos to show you exactly what I’d like you to do with your car.
Keep in mind that I told you to do a snap throttle test while Eric showed you a steady throttle action/reaction kind of test in his video. The snap throttle test is different in that you’d quickly pull the throttle wide open for a second and then let it snap shut while watching the vacuum gauge. When you open the throttle, the gauge should drop to zero and then instantly spike up closer to 25″ of vacuum on the gauge once the throttle snaps shut. That’s for an engine that’s breathing normally. If the exhaust is restricted, the vacuum might already start out a little low (less than 19″ on the gauge). Then when you snap the throttle open, it will drop to zero as it should, but then be slow to get back to the vacuum reading you started out with.
This is where you’d then pull an O2 sensor to further confirm a restriction. You’d start with the upstream O2 and go for a short test drive. If you get your power back, you’ve confirmed the restriction, but you go another step further by reinstalling the upstream O2 and then pull the downstream O2. If you still have your power gain back, you’ll know the restriction is farther down in the exhaust. If you lose your power again, the restriction is in the cat.
I just happened to diagnose a bad cat today myself. The interesting thing about my diag was that the engine behaved like it had a misfire. My misfire counter showed absolutely no misfires though. My vacuum gauge was fluctuating the needle violently between 15-20″ with the throttle applied steady at 2000 RPM and my snap throttle test was a little questionable with more needle fluctuations. My point with this is that not all exhaust restrictions will behave the exact same way. There’s always a difference in severity. Keep it in mind while you’re doing your own diag. Try my way and Eric’s way of testing for that restriction.
**Edit** I was taught that a typical good range of vacuum for a healthy breathing engine is in the 17-21″ range. What I typically see in fuel injected cars is 19-22″ I would almost expect your engine to run at least 20″ if it’s breathing right.
Well I ordered a fuel filter from honda, I’ll get it Tuesday. I know from past experience that a bad O2 sensor or no O2 sensor causes a horrible stumble while accelerating. I’ll have access to a vacuum gauge Sunday to do that diag. Fortunately in Florida we don’t have emissions testing so a cel for an evap is not a big deal, however getting it fixed is going to be… I don’t know anywhere that has a smoke machine except maybe the dealership. Hopefully there is a way around using one.
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