88TTop

After checking the search and comimg up empty I put this out there... when driving my 88 5.0 5 speed through a parking lot with my foot off the gas, how come the car...for lack of a better description...goes lug lug lug lug? As if it is belt driven and there is alot of slack in the belt.

mjr46

if you let the rpms drop on a stick shift car to the point where it starts to surge= normal, expecially if you have a lumpy cam in it

88TTop

So if I am already in 1st gear what do I do to avoid this?

mjr46

you can't let the car push it's self along without giving it some gas.....now if the car does it / surges when you give it light throttle pressure then make sure your maf is clean and no vaccum leaks exist

88TTop

No maf on my 88 but vaccum leaks are always a possibility. So what you are saying is this is common on 5spd cars.

mjr46

not to sure exactly what you are feeling, it's one of those things that sitting in the seat and going for a ride and have you explain the prob would make diagnosis alot easier

Project 5.GO!

You got it the first time. He's talking about letting the car push itself in first gear. Like you said, this is normal. Low speeds and letting the car push itself is always going to make jerk forwards and backwards.

Check for vacuum leaks, because that will make it worse. I had that one happen to me. When I need to drive slowly in a parking lot or something, I always let the car glide in neutral, then give it a little gas in first to help it along.

PRO50SC

Mine does that. Never really bothered me too much cuz I knew it was a characteristic of the car.

88TTop

Thanks guys...just wanted to know there was nothing seriously wrong. Too many things to love about the car to sweat the little things.

Liquid_02

Haha, Anyways, your description was actually quite good as what you are describing is called lugging an engine, which honestly, should never be done as it is EXTREMELY hard on the engine, it's hard on near every component in the engine, from bearings (thrust bearings especially), to cylinders. When I pull an engine apart I can tell you exactly how the engine was driven, how often it idled, if the customer rode the clutch, or if it was lugged, just by looking at simple components, thrust bearings tell a good story generally.

Lugging an engine is essentially working an engine harder than you are allowing it. If you shift early into 5th, and it's revving a grand and your foot is to the floor trying to get the rpms up, that's lugging an engine as well. This is not a characteristic of a Mustang, every vehicle with a standard will do this, except diesels, to a point, diesels make enough torque they are near impossible to lug unless they are towing.