88 notch

I have a running problem while cruising. 331, gt40 heads, anderson n41 cam, 30#injectors, 255lph pump,95mm mass air, 70mm throttle body, edelbrock performer rpm. while cruising at constant speed sometimes it jerks like an engine miss, air fuel goes rich then lean and then comes back to normal, it's just like letting off the throttle while cruising and then just tapping it. sometimes it does it and other times it does it alot. also what should air fuel ratio be under wot!

thedude

My car did that for a little while after I put my edelbrock performer on, especially in fifth gear, least thats when I noticed it. After a while it just stopped. Mine was pretty suttle though. Not quite a miss fire. Could it be a compression problem?

88 notch

the engine is a DSS 311 with less than 1000 miles on it! if I downshift out of fifth it goes away.

thedude

Man, that sounds just like mine. I brought it into a mechanic to have them see if I was crazy, and they told me there wasn't anything wrong. When I got it back, it had stopped. Unfortuneatly I really never learned what was wrong. The mechanic told me that often times when installing a new intake it takes some time to break it in.

88 notch

that sounds weird, but I bought the car used with the intake already on it, and it is a couple of years old? the engine was blown up when I got it

88 notch

has anyone had this problem

larsif

Have you checked your fuel filter lately? Sounds like it could be a fuel problem. Is the misfire violent?

88 notch

I haven't checked it, I will check it and see, I might not get posted back on the forum for a while because it is snowing and icing it's ***** off here. when it "misses" it's like letting off the gas and just tapping the accelerator a little bit, you know that clunk and lunge when you have the play in the drivetrain, thats what it's like. It's as much as if two cylinders were misfiring at the same time.

88BlueGT

Never heard of breaking in a manifold [&:]

88 notch

well drove my car today, it was an awesome day but the mustang ran worse today then it did when it was colder. this morning it was in the thirties and it ran as it has in the past. this afternoon on the way home from work it ran totally worse when it was in the fifties. I think the bucking problem is temperature related. I was wondering if it is the air charge temperature on the lower intake- seem possible? or if anybody has any other suggestions would be great