My car has always done this from I think day 1, and I thought it was normal until I got in a buddies stock formula. It doesn't like to lug at 1500rpm at part throttle, like 50-75%. I am guessing its my old Bosch O2s, or my breather instead of a CCV vent, it did it when I had my torn CCV tube wrapped in duct tape. The car is back to part time DD duty and I want to sort these little details out now before putting in the new motor. No codes, it's not bucking or anything, it's just not smooth under 2000rpm at part throttle while lugging like in 6th gear at 50mph.

 

That's really low to be in sixth though. Not saying it's normal but you are lugging the engine. Why do you need to be in sixth at 50 anyway?

 

If it does it all the time in all gears under part throttle load I'd say a cracked plug.

 

So your gonna look into it after driving it for ten years? Well have the doc pull your head outa the crack between your cheeks first.

Okay I can explain it because your junker sat in garage for the last 9.9 years.

 

6th gear at 50mph is low, really low. With stock tires and gear, you're looking at 1125RPM. It's going to lug. I usually don't go below 60mph in 6th (it'll go lower, but it lugs/bogs).

lt1-xjs brings up a good point, arcing (even minor) or cracked plugs will cause some drivability issues. But it wouldn't lug/bog, it would shutter and buck a bit.

 

I don't purposely drive that low, and it isn't a problem, it just isn't as smooth as my friends stock one. It's got new plugs and wires, and its done this forever which is why I thought it was normal, but I can lug my friends stock one and you don't feel anything, dead smooth. I don't do it a lot, but driving stick with something in 1 hand sometimes you just have to power through a hill rather than drive with a knee and downshift.

 

It's your tune. You have the Ram air set up, that changed the MAF calibration and VE, the long tubes changes the O2 delay constants and and the VE. The RR changed the VE too.

In MAF mode you shouldn't have too worry about the VE changes the LT's and the RR made (but I'd tune for them anyway). The big one you'd want to address is the MAF calibration.

I'm assuming you have the ALDL cable and data logging and tuning programs?

 

I don't have an ALDL yet, it's on the list of **** I need. I think my stupid ported MAF is causing 3/4 of it, nobody even wants to trade me straight up for a stock one and I haven't had time to grab one from a junkyard. I need to replace the MAF and fix my CCV before I start dicking with the tune.

Come to think of it the first thing I did to this car was the ported MAF, a guy at work who had a viper and a vette (all it took to impress me when I was 18) gave it to me when I bought the car with the LT4 knock module. Could have been right around then this started, hard to remember a decade ago. ****.

 

You can tune for the MAF as is. Just have to remember the MAF calibration tables are for the ported MAF. So if you ever go back to stock, you'll have to revert them back to stock (if you have the stock intake tubing).

What's wrong with the CCV?

 

use eehack to test the effect of removing/adding timing in that range while driving. it's usually a botched timing table causing the problem.

still, shouldn't be driving it like that

 

My CCV tube was ripped, and in a pinch a few years ago before the Cecil shoot out I didn't want to duct tape it again so I threw a breather on the valve cover and capped off the TB. The ported MAF I left all this time because even though a lot of people say it hurts performance my times were good and I thought the low rpm thing was just another lt1 characteristic. I sent my stock one to Transamman on ls1lt1.com a few years ago who said he was going to do a dyno comparison of a stock ported descreened one vs a grannatelli vs a stock one, but he never posted the results. My tune was specced with the long tubes, ported MAF and a K&N intake. I don't think the MAF, Bosch o2s, or tune are hurting overall performance because of my track mph, but I do think they all contribute to the low rpm not-so-smooth thing. I do think either the CCV letting in unmetered air through the PCV or the rockers and intake affecting the tune have thrown the car off a bit because I have not hit 111 in the 1/4 since I did them, although I only went twice since, and if you remember my thread last year when I pulled it out of the garage after 2 years my plugs were arcing like crazy, and that could have been one of the reasons I only trapped 109 at the Cecil shoot out even though it went 12.39. I need to fix the CCV and take it to MIR and see if that gets me back to 110 at least.

I don't lug it often, or on purpose, I had just noticed when I did it in my friends car it was as smooth as all other rpms, and mine just isn't that smooth. The Bosch o2s and ported MAF were all newb mistakes I made the first year I had the car.

 

Im running Bosch O2s. From what I've read they work fine, but dont last long. Delphis are on the way.

Fixing the CCV should help with the unmetered air. Could be the fix you need.

Many times I've noticed that not much attention is given to the drivability part of the tune. It makes sense since that takes a while to get dialed in, especially in SD mode. Running a MAF tune certainly makes that easier, but everything needs to be addressed to get it driving right.

 

So who knew b body MAFs were smaller than f body MAFs? Not me, bought the wrong one, ends are not the right size. Got my CCV tube in tho, see if that helps.

 

Are the rear gears the same on your buddies car?

 

Yea, 3.42 m6, his was a 95.