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Vibration Under Load

6K views 11 replies 7 participants last post by  Paolo 
#1 ·
Got a new one for the internets to work on! I was driving home today in lots of traffic. Traffic finally cleared up and started to get up to some decent speed. But when trying to get up to speed around 2500 - 3000RPM under a bit of load I get a crazy vibration. The car loses a bit of power and seems to struggle to regain it. I can replicate it every time I put a load and it's always within the same RPM range in every gear. Any ideas what it might be?
 
#5 · (Edited)
As lucky phil said, a bad or poorly gapped spark plug can cause misfires due to blow out under load. The plug gap can increase substantially over time. It tends to happen faster if you've increased the engine's power level. How many miles are on your car?

In my case a set of plugs are good for about 10k miles. If you decide to replace them, ensure the new plugs are gapped to 26 thousandths. That's a good number for a stock or FBO car. If you're interested in seeing how much a set of plugs can vary once they've been run for a while see below:

 
#6 ·
Thanks for this! Just passed 19k still all stock. I'm ganna take it in tomorrow to get looked at but it was strangely fine on my way to work this morning. I didn't push it too hard but everything seemed fine. Hasn't thrown me any lights or codes.

I'm ganna pray it's just a misfire and can be sorted quickly. I bought the car new with the FSA already done. I forced them to give me the paperwork saying it was done so if something with that arises it's on them.
 
#8 ·
Alright small update here. I wasn't able to get the car to the dealer over the weekend because the "RS Tech" only works during the week. Which happens to also be when I work, so I'm taking this Friday off to get it taken care of.

However.. In the days since this began, the car feels fine has all it's power and I can't notice anything different. That is until this morning immediately after getting a fresh tank of gas the check engine light comes on. I guess I can consider it a good thing because at least I can see what code it's throwing me.

The code is #P0300 which happens to be "Random Misfire", looks like @lucky phil was right. I'm glad it's that, could've been worse I suppose.

Well back to the 2000 Accord for a few days. I guess I'll just have the full 20k service done while it's under the knife.

I'll be back with an update when it's done. Thanks all!
 
#9 ·
Next update! I got my car back and everything seems to be fine! ... For now.

The dealer determined that my cylinder 2's spark plug was missing/broke the ground strap. I find this a bit peculiar though considering it wasn't consistently misfiring all the time. It was very sporadic and if the ground strap really was gone I wouldn't have cylinder 2 at all because there wouldn't be any spark at all.
Beyond that cylinder 2's intake shims were "undersized/out of spec".

Take a look at the whole service report below. There's also the apparent plug with the missing ground strap. Now tell me... Does this plug look like it's only 19,000 miles old? To me this looks like it's been through a lot more than that which leaves me skeptical.

Text Document Paper Font Paper product

Text Paper Document Font Paper product

Spark plug Auto part Automotive ignition part Automotive engine part
 
#11 ·
They never said, unfortunately; which is another reason why I'm skeptical that this plug was the actual issue. Assuming that it was the actual plug from the car, that would mean the strap is definitely somewhere in the cylinder.
 
#12 ·
Borescope.
 
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