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thebesthonda, ASE MasterTechnician
Category: Acura
Satisfied Customers: 783
Experience:  26 years experience
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EL: ,The engine shakes 5 sec at start-up, then

Customer Question

The engine shakes for about 5 sec at start-up, then smooths out. This happens intermittently - in about 1 in 3 startups. OBD code p0304 (misfire cylinder 4). It looks like the problem worsens in wet and humid weather. No issues while driving. Power as usual. No issues while idling, changing gears, breaking. Checked oil and it looks clear and clean. Pulled coils and no visible oil on them or around the spark plug.
I had an engine overheating problem shortly after this issue appeared. The mechanic replaced the thermostat and changed the radiator cap. The engine Temperature is now ok, although it seems to be running a tiny bit cooler than before. Note this car is essentially a 2005 Civic, built for the Canadian market.
Submitted: 1 year ago.
Category: Acura
Customer: replied 1 year ago.
New: today I also got (in addition to p0304) p0303 and p0300 (random misfire). I took out the new coil. I put the supposedly bad coil on cylinder 2 and cylinder 2 coil is now on cylinder 4. So far the check engine light hasn't come back and out of 2 starts both were free of noticeable vibration. The mechanic is recommending purchasing another new coil.
Expert:  Billy replied 1 year ago.
Hello and Welcome! I'm Billy and i will assist you with this. Feel free to ask, if further info is needed.
My apologies for the delay, thank you for your patience.
Before buying a new coil, i would check the following:
- check for any vacuum leaks
- check the fuel trim data (on the scan tool), as they would point out a faulty MAF sensor, that would cause this
- check the injector (on cylinder 4), you can swap, as you did for the coil.
- and if the problem persists, i would check the cylinder compression pressure on all 4 cylinders, to see if number 4 has lower pressure causing the misfire.
Kindly get back to me with your findings, so we can proceed with the diagnostics, till the problem is fixed.
Customer: replied 1 year ago.
Thanks Billy. In the meantime I ended up taking the car a mechanic I trust. He is at a loss - told me he checked for vacuum leaks and everything is fine. He hasn't covered off the other points yet (fuel trim data, injector, compression). I'll leave work a bit early to chat with him. Thanks, ***** ***** stay in touch.
Customer: replied 1 year ago.
I mean to say "to a mechanic I trust"
Customer: replied 1 year ago.
By the way, since putting the "bad" coil on cylinder 2 and a few start ups later, I had BLINKING engine light. I shut the engine off immediately, read the code and the scanner showed - p0304. Only this code though, not the other ones. I turned the engine back on and it was a steady light. I figured I could drive. I cleared the light. Since then, the engine still shakes at start-up, but I haven't had any codes come back. The weather has also been very dry since then, adding more support to my hypothesis that it gets worse in wet or humid weather. I'll keep you posted. Let me know if the above info helps you any further (and thanks for your response!!!!)
Customer: replied 1 year ago.
Oh, and after having this last p0304, I decided to put the new coil on cylinder 4. I also cleaned the tops of the spark plugs as I noticed a bit of deposit (remember the spark plugs were put in 3 weeks ago). I used a microfiber cloth and each plug left a black mark on the cloth.
Expert:  Billy replied 1 year ago.
Hello again,
The blinking and then the steady engine light, is perfectly normal.
This is exactly what happens when you have a misfire detected.
Checking the vacuum leaks is a great way to start... next you need to get the other checks (to make sure you good compression, good injectors etc...) This would be the best way to diagnose, to prevent replacing parts at random (at your expense obviously).
Get back to me with the findings, so we proceed accordingly.
Customer: replied 1 year ago.
Hi Billy,
I have low compression on cylinder 4. Yesterday the car started overheating in stop and go traffic. And today I realized that my coolant level is extremely low and engine oil dipstick is showing about a quart or so too much oil. I still have the occasional misfire at start up. About 4 weeks ago a mechanic gave me a complete tune up, including thermostat change, oil and coolant change (thinking back, this was very incompetent and a complete waste of $$$). I am 99% sure it is a blown head gasket. It just took 4 weeks for enough coolant to seep into the oil. I have no other explanation. I found someone who can swap the engine for $1,400 Canadian. I'll go for that tomorrow... Let me know again how to rate you :). Thanks, Marin
Customer: replied 1 year ago.
Hi Billy, I hope I can ask one more question related to this issue. The first mechanic claims to have performed idle adjustment on my car. Can that be done on the 2005 Acura EL? Many thanks! Btw, is there a problem with the rating system? I can't select stars regardless of browser. I tried IE, Chrome and Safari.

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