Low RPM smooth throttle
#1
Low RPM smooth throttle
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.
#4
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.
Okay I can explain it because your junker sat in garage for the last 9.9 years.
#5
TECH Addict
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.
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.
#6
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.
#7
TECH Addict
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?
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?
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#8
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. ****.
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. ****.
Last edited by bufmatmuslepants; 03-14-2016 at 07:34 PM.
#9
TECH Addict
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. ****.
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. ****.
What's wrong with the CCV?
#11
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.
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.
Last edited by bufmatmuslepants; 03-15-2016 at 04:59 AM.
#12
TECH Addict
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.
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.
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.