# Help me diagnose what's wrong with my car **URL:** \ **Category:** Factual Questions\ **Created:** [September 20, 2005, 5:50pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568 "2005-09-20T17:50:56Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Hey\_It\_s\_That\_Guy](https://avatars.discourse-cdn.com/v4/letter/h/6f9a4e/32.png) [@Hey\_It\_s\_That\_Guy](https://boards.straightdope.com/u/Hey_It_s_That_Guy)\ **Post date:** [September 20, 2005, 5:50pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/1 "2005-09-20T17:50:56Z")
Hello all, I drive a 1996 Honda Civic hatchback that has been very reliable, except for when I had to replace the transmission last summer. Still, I commute 40 miles each way to work, and I just passed 100,000 miles. I’m due for an oil change and I figure this is a good time to have a general checkup, since I have to drive it so much. But lately, my car has been driving extremely loud and taking a long time to accelerate. When I enter onto an expressway, it seems like it takes forever to get up to a safe highway speed, and even coming out of a stop at a normal red light, I have to press down on the gas to accelerate, accompanied by a loud engine sound and a slow acceleration. It also seems like I’m using up more gas than usual. I have a feeling this is all connected to whatever the larger problem is, but I’m afraid I don’t know much about cars, especially diagnosing problems. I’m sure this is something a mechanic can pinpoint, but I’d rather go to one armed with some general information. ---
**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\ **Post date:** [September 20, 2005, 6:28pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/2 "2005-09-20T18:28:36Z")
Ok, I’m not a mechanic. I’m a software engineer, and without knowing what “loud” sounds like, I probably can’t tell you more. However, there’s a chance you’ve got a misfiring/non-firing cylinder. This can be because the spark plug is not firing (bad spark plug, bad wire, distributor rotor/cap). This can also be because you’ve blown a head gasket. Check for unusual whitish smoke coming out of the exhaust, that would be coolant burning in the engine and is a sign you need major service. Hope this helps. Hopefully somebody more knowledgeable about cars will come along and explain it better. ---
**Author:** ![Hey\_It\_s\_That\_Guy](https://avatars.discourse-cdn.com/v4/letter/h/6f9a4e/32.png) [@Hey\_It\_s\_That\_Guy](https://boards.straightdope.com/u/Hey_It_s_That_Guy)\ **Post date:** [September 20, 2005, 6:41pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/3 "2005-09-20T18:41:22Z")
> [@groman](#): > > Ok, I’m not a mechanic. I’m a software engineer, and without knowing what “loud” sounds like, I probably can’t tell you more. > > However, there’s a chance you’ve got a misfiring/non-firing cylinder. This can be because the spark plug is not firing (bad spark plug, bad wire, distributor rotor/cap). This can also be because you’ve blown a head gasket. Check for unusual whitish smoke coming out of the exhaust, that would be coolant burning in the engine and is a sign you need major service. > > Hope this helps. > > Hopefully somebody more knowledgeable about cars will come along and explain it better. By “loud,” I should clarify that it sounds like the engine is roaring, especially as I’m attempting to get it up to speed. ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [September 20, 2005, 7:00pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/4 "2005-09-20T19:00:58Z")
You might have a piston with a hole in it. Or a busted exhaust manifold. Something that is playing havoc with the normal compression and/or permitting unburned gases to enter the exhaust system. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [September 20, 2005, 7:03pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/5 "2005-09-20T19:03:39Z")
How’s the clutch? From 3000 miles away, I’m guessing you might have a slipping clutch, or a blown transmission. (Is the car stick or auto?) If it’s an auto, check the transmission fluid level - your problem might be nothing worse than low fluid. ---
**Author:** ![Hey\_It\_s\_That\_Guy](https://avatars.discourse-cdn.com/v4/letter/h/6f9a4e/32.png) [@Hey\_It\_s\_That\_Guy](https://boards.straightdope.com/u/Hey_It_s_That_Guy)\ **Post date:** [September 20, 2005, 7:20pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/6 "2005-09-20T19:20:40Z")
It’s automatic, and I replaced the transmission last summer (extremely expensively). ☹ ---
**Author:** ![Fridgemagnet](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@Fridgemagnet](https://boards.straightdope.com/u/Fridgemagnet)\ **Post date:** [September 20, 2005, 7:29pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/7 "2005-09-20T19:29:09Z")
Sounds like a leak in the exhaust system. The closer to the manifold the leak is, the louder the noise and the bigger the drop in power. Exhaust leaks put big lumps into the torque vs. engine speed graph, and you might feel a big drop in power as you go through a certain engine rpm. Makes your engine very thirsty too. Might also be part of your head gasket blown away, but that’s an outside chance. It’ll be the exhaust I reckon. Get a quote from an exhaust dealer. They’ll quickly find the fault once they’ve stuck it up on a ramp. ---
**Author:** ![Hey\_It\_s\_That\_Guy](https://avatars.discourse-cdn.com/v4/letter/h/6f9a4e/32.png) [@Hey\_It\_s\_That\_Guy](https://boards.straightdope.com/u/Hey_It_s_That_Guy)\ **Post date:** [September 20, 2005, 7:53pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/8 "2005-09-20T19:53:52Z")
I live near a Tires Plus that is open until 7 PM during the week, and I have a coupon for $20 off an engine diagnostic there. I’m planning to go tomorrow evening after work, and I’ll mention all these points. I’ve been in town less than a year and haven’t needed a mechanic yet, but I’ve heard this Tires Plus is very well-managed and honest. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [September 20, 2005, 7:59pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/9 "2005-09-20T19:59:29Z")
Sorry to say, it sounds like a transmission problem. Most people recognize an exhaust leak as sounding like a bad muffler, and while performance could be affected, I’ve never seen an exhaust leak cause anywhere near the degree of sluggishness described. As mentioned, check the tranny fluid level and top up as necessary. Do it correctly – the procedure for Hondas is different from most cars, and your neighborhood “car guy” may not know that. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [September 20, 2005, 8:51pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/10 "2005-09-20T20:51:45Z")
Intake fitting off (Intake noise is loud enough they go th great lengths to muffle it these days. and it tends to sound like a “roar”. If it were bad enough to be loud, and downstream of the MAF, it could put the engine into a limp-home mode, accounting for the loss of power. ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [September 20, 2005, 10:14pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/11 "2005-09-20T22:14:28Z")
> [@Fridgemagnet](#): > > Sounds like a leak in the exhaust system. The closer to the manifold the leak is, the louder the noise and the bigger the drop in power. I once had an MG Midget with a crack in the exhaust manifold. So much loss of power that I could just barely make it up hills. Going downhill I’d get going as fast as possible, then on the uphill I’d drop from 70 MPH down to 5 or 10 MPH by the top of the grade. Patched it with muffler tape and sold it. The buyer took it to his buddy to look it over and he gave the car a clean bill of health. Glad he wasn’t _my_ mechanic. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [September 20, 2005, 11:16pm UTC](https://boards.straightdope.com/t/help-me-diagnose-whats-wrong-with-my-car/322568/12 "2005-09-20T23:16:16Z")
I’ve heard one plugged catlytic converter that made a loud noise under heavy power. More of howl rather than roar though…took me a long time to track it down, as it really sounded like gear noise to me. Anyway, that killed the power as well. Supposin’ that new transmission isn’t shifting down to first gear? A stalled torque converter might make a lot of racket, and acceleration would suck. Based on the OP, it sounds like it is probably an automatic. (“I have to press on the gas to accelerate…”) Yes I know it’s a nearly new transmission…which means it would be a manufacturing defect manifesting itself rather than wear-out. Something as simple as a bad seal could cause fluid loss, and that could cause issues. Pretty sure Civics have electric fans, or I’d suggest maybe a locked up fan clutch.