Bad rev hangs

[BruceH]

Wow, did not think I'd get this many replies. Appreciate all the knowledge and info you guys, very helpful! I don't plan on touching that screw either! Though I have a BBK twin 62, I'll just be taking it off and cleaning it. Dashpot settings WILL be played with next tune! Also does anyone know any more specifics on dashpot?

Dashpot is one of the parameters involved with the throttle body. A google search will tell you more than I can type.

In short the tune electronically makes adjustments for idle, part throttle, and coming off of the throttle. The adjustments predict airflow requirements for the motor during these conditions.

If the predictions aren't just about perfect the result will be hanging revs, surging, and even motor shutdown during normal driving.

Changing cams, tb, or anything that affects airflow will require adjustments to the predictions for a smooth, stock like driving experience.

IMO being able to tune for aftermarket cams, throttle body, increased displacement, anything that affects airflow during normal driving is what makes or breaks a tuner.

Tuning for safe wot is pretty easy and straight forward. Being able to tune it to drive the beast in normal traffic conditions without issues is what requires skill.

 

[redfirepearlgt]

Dashpot is one of the parameters involved with the throttle body. A google search will tell you more than I can type.

In short the tune electronically makes adjustments for idle, part throttle, and coming off of the throttle. The adjustments predict airflow requirements for the motor during these conditions.

If the predictions aren't just about perfect the result will be hanging revs, surging, and even motor shutdown during normal driving.

Changing cams, tb, or anything that affects airflow will require adjustments to the predictions for a smooth, stock like driving experience.

IMO being able to tune for aftermarket cams, throttle body, increased displacement, anything that affects airflow during normal driving is what makes or breaks a tuner.

Tuning for safe wot is pretty easy and straight forward. Being able to tune it to drive the beast in normal traffic conditions without issues is what requires skill.

AMEN Brother...now pass the mustard. Heard this from more than one tuner.

 

[Boone]

If the predictions aren't just about perfect the result will be hanging revs, surging, and even motor shutdown during normal driving.

My tuner is located 1.5 hours from me, and I don't feel like calling him every time I want to make a little tweak for drivability. I have, or have had, all the issues above. I would like to adjust the dashpot settings on my tune to see what I can do to improve the daily driving performance. Where should I go to learn more?

I feel like I'm opening Pandora's Box here.

 

[redfirepearlgt]

If I am not mistaken the tune must be open before you can make adjustments at the level these guys are speaking of. Second you will need the software package. If you have both of those, then you will be able to begin opening that "Pandora's box". I plan on picking up a book recommended by several guys on here about advanced tuning before I chance down that road. I am just waiting for cooler weather so I remain motivated to completing the read. Engine Management Advanced Tuning by Greg Banish is the book. Like you I would like to be able to make mild tweaks as well, but I'd rather know what I am doing before clicking that compile button or whatever the final process is that generates the tune file.

 

[skwerl]

IMO it is not a 'do it yourself' type adjustment. You cannot even access the adjustment without buying the pro tuning software from SCT. This is, in fact, exactly the type of item you call your tuner for every single time and have him adjust the tune.

 

[Boone]

Thanks, Skwerl. Exactly the kind of information I was looking for. Btw, I spent half of the Cubs game last night surfing your house thread. Tapatalk crashed on page 47 of 87. Feel like I know you now.

 

[sgfreak96]

Back up the ponys. Did the BBK TB get added and now you are trying to tune for it? The BBK was known for issues just as you are describing back in the early days when it first hit the market. I was looking into one but the forums were lit up about this TB and that exact same issue. Because of the need to transfer the motor controller over I don't know if it was buyer induced error in assembly due to inexperience, failure to read the instructions, poor/missing direction on the motor swap by BBK, or inferior quality workmanship. But regardless the TB became the nemesis for BBK which had been the standard in mechanical TB's for years prior to that. They many have resolved the issues as the unit is still on the market, but it is alwasy nice to provide ALL of the facts on a trouble shooting problem and not just some. Anything less is the same as spitting into the wind.

Many who went through this put their factory TB back on and the problem went away.

BBK may have resolved this issue. But I have not found a reputable tuner peddling them. Most push the FRPP unit because it is very tune friendly but does come at a cost.

Good luck. Sorry to sound like such a downer.

Car's original tune I bought it with had no issues in rev hang or any throttle response issues at all. Car is currently being retuned from scratch from a stock tune. So far have adjusted for maf size & cmcv deletes. Car running quite well other than hangs. Next tune to further tweak maf size and add timing. Still have yet to adjust the dashpot or play with it.

 

[46addict]

IMO being able to tune for aftermarket cams, throttle body, increased displacement, anything that affects airflow during normal driving is what makes or breaks a tuner.

Tuning for safe wot is pretty easy and straight forward. Being able to tune it to drive the beast in normal traffic conditions without issues is what requires skill.

This makes me wonder now if dyno tuning is inferior to datalogging on the street & remote tuning. Is there a way to load a dyno to accurately tune for street driving?

 

[sgfreak96]

This makes me wonder now if dyno tuning is inferior to datalogging on the street & remote tuning. Is there a way to load a dyno to accurately tune for street driving?

Dyno tuning always win. Street tuning takes far longer, and load dynos are controlled environments. If a car acts up in a scenario, it's easy to replicate with the dyno to see the issue. I just don't have cash loads to throw at dyno tuning. So I'm spending a couple hundred bucks and spending months learning how to tune with my buddy!

 

[RocketcarX]

I'm curious, what is your oil pressure at hot idle? Is the car an auto or manual?

 

[stkjock]

A combination of Dyno and street is optimal. However doing pulls on the street is not typically the best idea.

 

[Boone]

This is, in fact, exactly the type of item you call your tuner for every single time and have him adjust the tune.

I emailed my tuner about the issue I'm having with over revving. He responded, and told me I'd have a tune emailed to me today. I haven't installed an email tune yet, so it looks like I'll be learning a new trick. Who says you can't teach an old dog?

 

[sgfreak96]

I'm curious, what is your oil pressure at hot idle? Is the car an auto or manual?

No clue, car is a manual though. I can try an get a reading when I'm back at school, which is where the car is.

 

[BruceH]

My tuner is located 1.5 hours from me, and I don't feel like calling him every time I want to make a little tweak for drivability. I have, or have had, all the issues above. I would like to adjust the dashpot settings on my tune to see what I can do to improve the daily driving performance. Where should I go to learn more?

I feel like I'm opening Pandora's Box here.

It's more than just dashpot. It can take awhile to get it close to perfect. Every mod that affects aiflow affects driveability. IME it takes awhile to get it close, it may never be perfect.

SCT Advantage 3 is the software that will enable you to do your own tweaks. IMO the best option is to contact lito for a tune.

This makes me wonder now if dyno tuning is inferior to datalogging on the street & remote tuning. Is there a way to load a dyno to accurately tune for street driving?

Real driving with real, loaded data logging is always superior. The problem lies in finding a place to do wot pulls without breaking the law.

Dyno tuning always win. Street tuning takes far longer, and load dynos are controlled environments. If a car acts up in a scenario, it's easy to replicate with the dyno to see the issue. I just don't have cash loads to throw at dyno tuning. So I'm spending a couple hundred bucks and spending months learning how to tune with my buddy!

There is no way you will ever get driveability correct with dyno tuning. You can come close with a loaded dyno but it's still not going to replicate driving in traffic.

The best thing about a dyno is that it allows for safe wot tuning. If you are on say a basic dynojet without load control your tuning won't be accurate. In fact, unloaded dynojets usually require pulling some spark advance after getting tuned.

 

[RocketcarX]

No clue, car is a manual though. I can try an get a reading when I'm back at school, which is where the car is.

Manual trans? Now I'm def curios about the hot idle oil pressure.

 

[sgfreak96]

Manual trans? Now I'm def curios about the hot idle oil pressure.

I doubt the oil pressure has anything to do with it, as the car ran fine with no rev hangs on the tune I bought with it, in terms of revs at least. Problem with that tune was terrible running when cold and poor poor mpgs.

 

[deebo05]

if you are running the bbk 62mm tb you WILL need to adjust the set screw that is why your rpms are hanging, dealt with it on a bunch of them.

you need to back the screw down a little to stop the rev hangs. its a trial and error deal.

if you messed with dashpot in the tune return them to stock.