Has developed miss only at full throttle 3500 to 4000 rpm range. Shudders, cuts on & off rapidly. Otherwise runs great. Replaced MAS, plugs, wires, fuel filter. Tested TPS; seems ok. Does it after slight warmup; not when cold. 93k mi on it. Have had a vibration at about 72-76 mph for a couple of years. Tried 2 sets of tires (Michelin Primacy on it at the moment). Thought vibration due to tires, it seems to be worse when pulling a slight incline light throttle;engine related? Had Cooper tires (when the vibration first started) changed to Michelins thinking that would fix it.
Hello and welcome to JustAnswer!
Your description of it cutting on and off rapidly sounds like you might be feeling a lowered rev limiter. If a cam or crank sensor signal is lost it may be imposing a low rev limiter, but you could be feeling an actual engine miss also. You may have a coil pack failing or bad ignition module, or fuel pressure may be dropping under a load. The first thing I would recommend is seeing if any fault codes are setting that may be related to the problem. If you don't have a code reader or scan tool available you can have codes read for free at most parts stores like Autozone.
If the vibration was exactly the same through two sets of tires then you should be able to rule out tires. You may have an out of round wheel though which could be checked with a road force balance machine.
The fact that it seems to get worse when accelerating points toward either an engine miss or worn inner CV joint. A worn inner CV joint will cause a vibration or shake that is throttle dependent.
I had codes checked & only had a MAS code (after which I cleaned, and then replaced the MAS. I think cylinders 2 & 3 had an infrequent intermittent miss at idle. Is there a way to test the rev limiter? The vibration stays when I put it in neutral and let the engine idle at around 75 mph. But it does seem worse under light load, but it doesn't seem to do it in lower gears at lower speeds.
I forgot; the miss only occurs at or right at full throttle; it winds up no problem like at 90% or less throttle.
I have not had it tested since my parts replacements.
Ok. I will have to get back with you, as it will be a few days before I will be able to get it back in to the mechanic for another test. Thank you.
You mentioned the inner CV joint. How do we check it? We also have another symptom which I forgot to mention. When driving in the mountains, descending a steeper incline at speed (50-65 mph) and applying the brakes, we have a severe shudder which feels like it is in the front end. A light application of brakes isn't so bad, but applying more pressure initiates the severe shuddering. Hard braking will diminish the shudder.
I subscribed but when I started to give you an "excellent" it says it will charge me $18. I thought the subscription covered that.