Engine shudders when cruising/accelerating

Hello all, I have a problem that has me and my mechanic stumped. I have a ’98 cavalier, 2.2 l with 160,000 miles on it. I first noticed the problem when cruising at any speed, mostly at 55, 56 and 75 miles an hour. The car would seem to shutter like the engine had cut out. For a while it only did this when trying to maintain a speed. Then it began doing this when trying to accelerate. Then it started doing it while idling.
I’ve replaced the fuel filter, air filter, did an oil change and engine flush. Checked the spark plugs and wires, all seem good. Got some advice from here, a mechanic and the Haynes repair manual that it could be the fuel pump. Needless to say, it’s not the fuel pump because I’m writing this.
My mechanic hooked it up to his computer and its not reading any codes, in the current or in the history. However a couple months ago I sprayed off my engine after some work and it threw a code for a cam position sensor. However, I disconnected the battery to see if it was actually a bad sensor or if it was just a little waterlogged from the hosing. I ignored it since it hasn’t thrown the code again. However, now I’m grasping at straws for an explanation and a fix. Would the CPS cause this? Or has anyone seen this problem and has a fix for it? I would like to get this resolved and my mechanic says untill it throws a code we're kind of stuck.
Thanks,

i used to have a mazda mx3... same type of problem occured (at least i think same problem by your description)... anyways it turned out to be the spark plug wires... just one of them werent working correctly which caused that piston to not work and the overall car to shake/shutter like that due to imbalance of firing pistons. i know you said you checked this and it doesnt seem to be the problem but i just thought i would share with you that i had a similar problem and that was how it was fixed... all new spark plugs and wires to be safe was my remedy.

Thanks for the reply. I thought along that route too and went along the wires (waiting for a shock) and didn’t get one. My mechanic also said that if there was a misfire the computer would record it and all the info associated with it.
Thanks again.

does it do it only when engine is hot ? Ask your mechanic about the coil packs. when the engine gets warmed up and if they are weak they could be starting to fail.

my dads taurus had the same kind of problem and with those miles you need to change your timing belt, it might be slipping throwing off timing which causes a shudder in the engine. just a possibility

my dads taurus had the same kind of problem and with those miles you need to change your timing belt, it might be slipping throwing off timing which causes a shudder in the engine. just a possibility

His engine does not have a timing belt, but has a timing chain instead. It is extremely rare for a timing chain to skip.

The hesitation occurs whether the engine is hot or cold. I asked about the coil, he said if it was going bad and causing a problem it would throw a code. But I don’t know how long a coil pack generally lasts, and at 160,000 miles I could have exceeded that life.
As far as the belts go, the serpentine belt is in good condition. I had it off a couple months ago for the water pump and it didn’t have excess cracking or wearing. I don’t know an easy way to check the timing chain, but I’m pretty sure if my timing was off it would hesitate constantly and be hard to keep running. But correct me if I’m wrong on that.
Thanks for your help.

160,000 miles is likely the problem...........lol

bad coil packs wouldnt necessarily throw a code, and they are a very common problem on these cars, and i suppose they could cause a problem like what your having now, does your engine run fine the first few minutes you have it started? if so its definetely the coil packs, but even if not, it could still be the coil packs

Try pulling all four spark plugs, and compare them together. Note any differences between the four, as well as the general condition of all of them, and report back. Pictures would be even better!:iceslolan

Yea Muff, my problem could be its an old car. But what kind of fun do you have with a new car? No guessing what that noise was, no wondering if your car will choose to break down now. And that would be just boring. Besides, you never see people breaking into 10 year old, crud covered cars. They always choose the shiny, new ones to take the stereo speakers out of.
The temperature of the engine doesn’t seem to affect whether the hesitation occurs or not. It did it this morning within 45 seconds of my car being started (cold engine) and when I had been on the highway for 25 minutes already.
However this evening I sprayed off my engine to prepare for my impending plug removal and it happened a whole lot afterward. But it didn’t throw a code, so I’m still at my guessing game.
Is there a way to test to see if my coil is going bad or is bad? Also when I have my plugs out in hand, should I try to clean them, or just replace them since they are already out of the block?
Thanks for all your ideas.

Yea Muff, my problem could be its an old car. But what kind of fun do you have with a new car? No guessing what that noise was, no wondering if your car will choose to break down now. And that would be just boring. Besides, you never see people breaking into 10 year old, crud covered cars. They always choose the shiny, new ones to take the stereo speakers out of.
The temperature of the engine doesn’t seem to affect whether the hesitation occurs or not. It did it this morning within 45 seconds of my car being started (cold engine) and when I had been on the highway for 25 minutes already.
However this evening I sprayed off my engine to prepare for my impending plug removal and it happened a whole lot afterward. But it didn’t throw a code, so I’m still at my guessing game.
Is there a way to test to see if my coil is going bad or is bad? Also when I have my plugs out in hand, should I try to clean them, or just replace them since they are already out of the block?
Thanks for all your ideas.opps ..sorry wasn`t trying to offend you . what I was refering to is at a 160,000 miles motor could harm internal problems that sensors ,coil packs etc just are not going to correct. I would Change you plugs and do the wires also if that hasn`t been done in the past few years

Sorry if I came off like you offended me. I have a sick sense of humor so I don't think that it's possible. I realise the car is getting old, but unlike a tick or a rough idle this thing isn't constant, so that tells me it can be fixed and I'm hoping that i can get it to last a couple more years. after all, its not just a car, its a conversation piece of what I did with my weekend.:grinyes:

Well i feel pretty stupid. New plugs and wires fixed it. I'm pretty sure the wire going to the #3 cylinder had a break in it b/c when i pulled the boot off the plug the clamp that grips the plug stayed on the plug. the wire end of it was a bit charred and black so i think that was it. All the plugs were worn about the same, nothing spectacular to report there. Now to just try and get a few more horses out of the engine and it'll be good for a few more years.

Well i feel pretty stupid. New plugs and wires fixed it. I'm pretty sure the wire going to the #3 cylinder had a break in it b/c when i pulled the boot off the plug the clamp that grips the plug stayed on the plug. the wire end of it was a bit charred and black so i think that was it. All the plugs were worn about the same, nothing spectacular to report there. Now to just try and get a few more horses out of the engine and it'll be good for a few more years.LOL ...........Good deal . try to change`m before the next 160,000 rolls around. Thanks for posting your end result :lol: