Hello! Longtime lurker but finally signed up to post myself. I have an '08 with 158K miles. I've had a few problems recently that I'm not sure are related, but I'll include them in case we have some Sherlocks out there who can spot a pattern.

The issue happening for the past week or so is that I start my car up, and it pretty violently shudders, and hesitates as I start to pull out of my parking spot, especially when I throw it into reverse. Even when I'm giving it gas, it is just really slow to respond. This lasts really just as long as I'm backing out and getting onto the road, and then it responds fairly normally.

Spark plugs were replaced just two weeks ago, because I've been feeling as though my car is shaking more, especially at speeds of 60+. Not convinced it totally solved the problem, but it seems a bit better. (I had taken it in after getting back from a road trip — during the road trip I stopped at a friend's shop and a guy there told me it was just shaking because my tires are wearing unevenly. In any case, that's clearly not the reason why my car is shuddering after starting up.) It has also been louder lately when running than it used to be.

Haven't had coils replaced recently, and I don't think I've ever had a valve adjustment done. I was trying to diagnose online and some sites suggested a fuel filter or pump issue. I really don't have much of an idea. Reading through the forums made me think maybe valve adjustment, but would that really be the reason for such a weird response when starting up? Thanks in advance for any ideas! I'm getting a little disheartened about pouring more money into my baby and wondering if this is just the beginning of a slow demise...

 

First, we need more details. What brand of spark plugs did you put in? If not Denso, then you put the wrong thing in. What brand of tires are on the car? Are they new/old? While I doubt that is the problem, cheap tires can be prone to flat spots especially if they have not been maintained with balancing, rotation and alignment.
Second, I think you actually answered your own question. These Fits need three things: Denso spark plugs, Hitachi ignition coils and periodic valve adjustments. No Fit owner should attempt any other repairs until all three of those routine maintenance items are taken care of.
Third, the Fit is one of only a few cars in history that can claim that repairs in the car's old age was money well spent. Very few things go wrong with these small gems. Do those aforementioned three maintenance items and they run seemingly forever.
My guess, since this is occurring at start up is that it is the intake/exhaust valve clearances are out of specification. Get a valve adjustment done right away.

 

As stated above, need to verify that the correct plugs were installed. Besides Denso, NGK's are completely fine as well, but they need to be Iridium like the OEM plugs. No copper or platinum plugs. Fit's are spec'd with iridiums.

I'd also recommend checking ASAP that the plugs are tight. These motors have a frequent problem with ejecting loose spark plugs.

Also, as you stated, valve adjustment is very likely needed. They are due every 60k miles on GD Fit's, so you are way, way passed the maintenance period if they haven't been done.

Don't let any of this scare you into getting rid of the car. As long as the GD Fit's have the correct plugs, working coils, and the valves adjusted properly, there are very few other things that go wrong. These ARE maintenance items, not repairs.

 

Also worth asking about the transmission. Sounds like you have an auto? If so, when was the last time the fluid was changed?

 

Sounds exactly like the problem my wife's was having around the same miles. Definitely look into the valve adjustment. If I remember correctly, her exhausts were all too tight out of spec. Solved this and the car ran like new. Her dad wouldn't believe it was the problem either but he finally caved and helped us do the valve adjustment and it fixed it.

Her cars problem symptoms were exactly like this, made worse on cold days, but still present on hot days. Got to the point where she had to go outside and crank the car 10 minutes before leaving for work or it would die when she put it in gear.

 

In my opinion, the author of the video has the same problem (as I read in his comments), but the dealership mechanic told him to change fuel injectors (!) which did not help .


The video, however, is very valuable for those who are removing a lower part of the intake for whatever reason