Engine Workout

[Stang70Fastback]

So I've had (for years) a stumbling/stuttering problem that occurs with VERY light throttle from a stop to about 5-10 MPH. The car will falter a little bit, making it hard to smoothly accelerate without it feeling like I suck at using a clutch (and this is an automatic.) I've never been able to hunt down the problem and have lived with it.

 

After the autocross yesterday, the engine seems to be running noticeably smoother, and I haven't been able to recreate the stumbling issue. Ever since we had the head gaskets replaced at around 170k (by a mechanic who only mostly knew what he was doing) he told us that "they could blow again at any time, so we should be gentle with it." This was while the car was still my mom's and before I knew much about it, including how once you replace the gaskets, the engine should theoretically be fine indefinitely, at least with regards to that problem. Anyway, long story short, we took to driving this car gently, generally avoiding anything above 3,500 RPM. It's a habit I got into, to the point where I still do it today. It's probably part of the reason why the engine has been so damned reliable in the 90,000 miles since, however, after yesterday's autocross, and the resulting smoothness, I can't help but wonder if that is actually a bad way to drive a car, in the same sense that sitting on the couch all day might save wear and tear on your joints, but also makes you fat.

 

Is is "unhealthy" to never (or only occasionally for very short bursts) rev the engine higher? Perhaps it allows a significant amount of deposits to form inside? I'm wondering if an engine should be "exercised" regularly in order to help it burn stuff off? I'm starting to think maybe I should be a little more aggressive with this car, in order to clean out a lot of the crap. Perhaps the stuttering will return tomorrow, but perhaps it really is just a result of a whole bunch of crap that's been building up as a result of my leniency, and it all got burned off while we were beating the snot out of it for 8 runs. Does anyone have any input? I've found a lot of theoretical "opinions" about this online, but am having trouble finding anything that seems to be stated with the benefit of experience or hard data. Thoughts?

[JJay03]

I think its good from time to time helps clean it out. Part of the issue might be related to your iac valve.

[Stang70Fastback]

I agree. I actually replaced the IAC about two years ago to resolve a worse issue, but I replaced it with another used one, so I wouldn't be surprised if that one was acting up as well (last I checked, a new one was like $300, or something absurd.)