Contour Enthusiasts Group Archives Forums Modifications Zetec Maintenance Harshness/Vibrations above 3,000 RPM

My car has begun to develop a mid to upper RPM harshness that it has never had before. In any gear, if you run it up past 3,000 RPM, you can feel and hear the engine making some booming kinds of noises (hard to explain), then when I shift to the next gear and the RPM's drop, it is smooth again until it gets up into the same 3K + range.

The worst of this is when I am on the interstate and I'm going about 80 mph. At this speed, if I mash the gas, the car will shudder violently. It still accelerates what feels like normally, but there is all kinds of shuddering going on while I have my foot in it. As soon as you back out of the gas and just keep the pedal there to maintain a constant speed, it feels nice and smooth again (well, for a Zetec).

I'm thinking I'll clean the MAF again and see if that helps. It hasn't been very long since I did this, though. Maybe this time I will get some pipe cleaners or something and try to scrub the little wires. When I spray the electrical cleaner in there, it never really comes out shiny like new, so maybe a gentle scrubbing would help.

Do these MAF's ever get to a point where they can't be cleaned and have to be replaced? Any other ideas as to what it might be?

Thanks.

whens the last time you changed out your sparkplugs and wires

Definately clean your MAF. Also change your air filter, and clean the throttle body. Be sure to check for any obvious blocks in the air intake. Change the fuel filter as well. The description of your problem is either a fuel or air problem that is developing when there is more demand for both. Finally, add a bottle of gas line antifeeze. With cold temps, fuel can get a lot of water in it, which may cause some fo the problems you are describing. If none of this works, consider having your fuel line pressure checked.

Thanks guys.

Plugs and wires are new. I will change out the filters, clean the MAF and throttle body, and look into the fuel delivery.

I see that you are from Arizona, so chances are cold isn't a problem... most likely. Wouldn't hurt to add a bottle of the fuel cleaner/water remover stuff though. Go with the easy and cheap things, like filters and cleanings, then move up to the more complicated and pricey stuff, like injectors and a new MAF. Info on all of these has been covered tons of time, so a simple search should give you all you need to know.

I also wonder if this could be a fuel pressure problem, i.e. a fuel pump going bad...

OK, I bought a new tall can of electric parts cleaner and pulled the MAF. Decided this time that spraying the wires alone wasn't going to cut it to get 140K miles worth of baked on goodness off of the wires.

Since I didn't really care if I ended up breaking the MAF or not (I was just looking for a reason to buy a new one and guarantee new MAF performance), I went ahead and used Q-Tips soaked in the electrical cleaner on the wires. Turns out they are not as delicate as some people think. I was able to really scrub both of them good with the Q-Tip. Probably would have been a better idea to remove the sensor wires entirely (to get to the back of the sensor wires) by loosening the tamper resistant torx, but I didn't have the right bits on hand. Maybe next time.

Anyway, stuff was coming off of the wires that would not come off by just flushing it out with the spray alone, and the wires looked nice and clean after I was done.

I went ahead and threw in a new air filter, even though the old one wasn't too bad.

Today I went for a drive on city streets and on the highway and could not get it to vibrate at all at speed when the pedal was mashed!!! Also, the engine seems more responsive, clutch engagement is smoother, and it even sounds better to boot.

I am extremely happy with the results and am hoping that this solved the problem.

Blows me away how well this engine pulls and runs for having 140K on the clock. I can't imagine it feeling much better when new.

Thanks for your help

OK, while cleaning the MAF sensor has made the engine run fantastic again, the vibration/shuddering at high rpm's/high speeds reared it's ugly head again this weekend when I took a 250 mile trip. Strangely enough, it needs about 10 miles of driving at around 70 mph or so to exhibit the problem.

The car shook so badly on the interstate drive over the weekend, I decided I'd take it to my favorite mechanic and have him take a drive right away. There is no way I have time to diagnose/work on this thing right now with school in full swing.

We took it out on the freeway and it started vibrating and immediately he said that the problem was a loose drive axle. After driving it this weekend it made me more confident it was something drivetrain related vs. engine or suspension related. The engine pulls hard and smoothly, but I could tell something in the drivetrain was shaking the car around like a rag doll.

Anyway thought maybe someone would like to know what the problem ended up being. 1 or 2 new axle shafts later and I will be enjoying the hell out of driving this car once again! Thanks again for your suggestions!