Intense gas pedal vibrations at high rpm under load in my 2003 Mitsubishi eclipse spyder gs 2.4L

I have been trying to fix my car with my father’s help for the past month or so. Usually I go to a mechanic but the problems were with the engine and all local mechanics were charging way too much.

A little history:

My car lost its timing belt. I got the cat used so I did not know the belt was due. Upon opening the rocker cover, it was clear that all the valves were up when it blew (or at least we think it was clear. No damage was visible but we’re by no means mechanics) so we decided to try replacing the belts and seeing what happened. Now my father did moat of the disassembling and I helped putting the belts on. The car fires up! So excited! I tried driving a little (just running some small errands) and realised all was not well. I noticed jerking from shifting gears and vibrating at high rpm. “crap maybe a valve is bent”. So I did some research and found it could be that I need an oil change, need to put a proper gasket on the rocker head, or need a new motor Mount. Okay fine did all those (one Mount was broke) and it fixed the jerk! Go for a test drive and it drives normal until you get ~1000rpm from redline. At this Point the gas pedal vibrates violently.

The symptoms:

Car drives fine until ~1000 rpm from redline. At this point the gas pedal vibrates violently, but the car will still increase rpm. There is no shaking at lower rpm. Speed does not effect the shaking, only rpm. Happens in first and second gear, I cannot test third and fourth as I don’t drive that fast on public roads. Idle seems fine. Doesn’t happen out of gear.

What I’ve come up with:

By researching and talking to friends I’ve found This couldn’t be a wheel alignment, or it would happen at all speeds and get worse as I go faster. There was a guy who had a Ford gt with similar symptoms and it was in need of a transmission alignment. I have no idea if this is a thing but I hope isn’t the problem. I don’t see how the transmission could have been misaligned Anyway. One of the timing gears is off by one tooth. This could be the problem but I don’t know if it would cause shaking at high rpm and we double and triple checked it. I wouldn’t love pulling it apart again to check again but I may have to. A valve could still be bent I suppose but again I don’t know if it would do this. The forum about the Ford gt also mentioned the engine could be getting starved of gas, but I don’t see why it would be now when it was fine before. Unless of course the timing is off by a tooth and it’s spitting gas at slightly the wrong time.

I’m pretty deep in this project now and really just want to drive my car. My father is fed up and wants me to just drive it but I don’t feel safe. I appreciate any help/input/ideas anyone could provide. Thank you.

I don’t know how fast you are driving in second gear if the rpm is within a 1000 of the red. And how many rpms does the red start at?

So just how fast are you going in 2nd gear at 5000 rpm?

Yes. Get the timing exactly right, then the valve adjustment, then test for compression. If it all checks OK, put in the spark plugs and drive it. Good luck and please let us know how things are working out.

second gear maxes out around 100 km/h. Red line is around 7000 i think if i remember correctly.

second gear takes me to roughly 100km/h

Cruising around 62mp/h/100km/h in second gear would not surprise me to cause some vibration. Have you ever tried to shift up to at least third gear?

Does Trever not know that he can cruise at 100 km in 5th gear ?

By the way, what kind of engine do you have in that car? The 12 valve 3.0 SOHC is a non-interference engine.

Recheck the timing of the balance shaft belt, there are two timing belts. When I replaced the timing belt on my son’s Eclipse I found that the balance shaft belt had broke long ago.

Title says he has a 2.4L

I’m sure he has, the way I read it is he doesn’t want to go to 5000 rpm in 3rd gear, would be speeding.

I am not cruising at this speed. I simply accelerate as quickly as possible which means shifting when I get to redline

The engine is the 2.4L one with the GS spec

The car only has 4 gears lol

Yes we replaced both of these. I would like to check them again but my father is adamant that they’re correct and since its a lot of work to get at them I am hesitant to rip the car apart again.

this is correct.

You wrote that you don’t feel safe driving this 17 year old vehicle but yet you feel the need to run it ti red line for no reason . No wonder you father is fed up.


Im sorry I think you misunderstand. I was just saying the timing being one tooth off could be the problem, but my father is adamant that the belts are on correctly.

Also I was saying I don’t want to go to redline in 3rd and 4th gear. I do not cruise at redline

I have done a compression test and all four cylinders were 180psi.

Since the engine is not the problem, is it possible that there is something that was removed to install the belts that needed to be torqued to spec and was not?

I’ve also noticed there is a metal grinding noise when I rev up past 2000rpm. It exists only at 2000 rpm and goes away above and below that number.

I did it as a stress test to find if the car has been properly repaired. I do not constantly go up to redline. However, it is a sports car and fun to drive so I will on occasion. Regardless of this it is also necessary to accelerate quickly while driving sometimes. The car is not properly repaired and thus any driving will not be appropriate. Please keep your comments specific to helping me repair the vehicle