Ats 2.0t ltg terrible idle after larger throttle body instal

[lt1z350]

Went from the stock 58mm to a 3.8 72mm and the idle has become horrible. Doing a quick log I saw it now instead of 5-10 degrees timing it has -17 and sounds like the cams are in terrible overlap as it is sucking at the tail pipes. So is it possibly trying to over come some max torque load at idle and doing anything it can to reduce load? I thought I saw a table for timing control used to limit idle or change idle speed at some point but now can't find it or maybe was some other computer as been working on a few vehicles. I did find a table for minimum allowed spark load so was thinking of putting 5-10 degrees in the tables around idle and see if helps but still have the cams jacked up and not sure what would cause them to respond as they did. Just looking for ideas or someone with a cobalt that might have had the issue as read at one point it was popular to go larger on them too.

[Jggregory99]

Post tune and log.... Have you tuned the MAF and VE? Also, the TB area Scalar..?

[lt1z350]

11-29 caddy safer tune.hpt
currently having an issue with my scanner so cant post a log on it. I am in the middle of contacting support on that one. After my update I lost access to most of my channels very common stuff for the car went dark like not supported. So if want to see or know a specific maybe I can get it. Just very little working wont even log kr or iat2 and tried a repoll and nothing.

[lt1z350]

yes I had setup maf no on the ve as cant get vve working yet. and nothing for tb scaller I just put it on today as most said it was a bolt and go but I have a larger turbo and sure that is also playing a role in it as car is pulling much harder so it is using the extra air where a stock turbo car they say no real feel to it just some throttle response. thanks

[Jggregory99]

If it was a small change of say 58mm to 60mm I would say yes... I could be Plug and play as there would not be that large of a difference in air... some minor tweeking could be in order, but nothing major... But, 14mm is a pretty large change. Throw in a larger turbo and you have some serious changes in airflow. I would tune that out and get the fueling dialed in before doing anything with timing.

[lt1z350]

got the trims closer with the maf but timing it still way retarded. Any thing your familiar with that will help with that off hand. My 07 tahoe has a idle torque you can disable that uses timing to reduce the max torque requested easy fix if had that table so thinking that minimum timing table. Once the timing is again right who knows what else is going to change again.lol these are so sensitve long gone are the days of throwing anything on a car without tuning for it. tried a cold air over the stock box and never could get that right. tip in miss and idle again were an issue so maybe get this worked out will be able to try getting rid of stock airbox again as it ran noticeably stronger with the cone filter down in the fender well.

[Jggregory99]

Well, over-fueling could very easily cause some serious knock and miss fire as the flame front travels further with more fuel. This could be the cause for the timing pull. Honestly, it really sounds like fueling is your biggest issue. But you said you have not been able to log KR or other PID's in the scanner, so until you get that issue dealt with, it is going to be kinda difficult from a diagnoses standpoint.

[lt1z350]

True might stick stock back on until I get my scanner issues fixed as still waiting on support to answer me on it and hate being blind. Thanks for help so far will get back on it soon as scanner is back to normal. Damn updates!

[ECaulk]

The LNF guys used to go to the LE5 throttle body which iirc the diameter is 64 or 65mm, but the ecu doesn't seem to like it. ZZP did some dyno testing with swapping the LE5 throttle body and it lost power, but this was back in 09 when a lot of options in HPTuners were not available. I've got a local that I tune and he went from a LNF throttle body to a LE5 and other mods and the car didn't make any more power (actually made about 10whp less same dyno same correction factor). I'm very tempted to tell him to reinstall the LNF throttle body.

I think with going as large of a diameter the ecu is having trouble closing the blade enough to limit the airflow and make the correct power to keep running, I haven't looked at your log as I'm at work. Not familiar with the LTG and what is available for adjustments, I'll try to find a stock file this weekend and look around.

[MarkTucker]

I will be installing the 67mm throttle body from ZZP's site onto a ATS here soon, and will be doing the tuning on it. Have yet to do a ATS with a larger throttle body yet, so can't give you to much information on helping with your issue other than getting your airflow and fueling dialed in.

But you might can try this out to see if it helps out any. I will be doing this when I get the throttle body installed.

Since there is no actual Idle Airflow Tab, you can try messing with the Airflow>Electronic Throttle>Throttle Area Limits>Max Area value.

You will obviously need to increase the stock value, being that you say you are running a 72mm throttle body. I would recommend trying something around 3,000 as the value. Reason behind me getting that number bases back to scaling the ETC Area Scalar in the PCM's with a Idle Airflow tab.

Furthur explaining of the number: you need to find the area of the throttle body. Being a 72mm throttle body, but you have to put into account for the throttle blade and shaft taking up a bit of room of the throttle body. So just estimating, I subtracted 10mm from the throttle body diameter. Then just found the area of that.

So (pi x radius x radius)= area. 72mm - 10mm(throttle shaft)= 62mm diameter. (pi x 31 x 31)= 3,019.07

[lt1z350]

Sounds good will try that today. I will say as far as power goes it is big on this car seat of the pants is a lot. 40mph toll will turn tires now where didn't before and no tune change. I know I was a bit rich so sure it got me more in line on afr but with running a larger turbo I can tell the setup likes it a lot. I have a large front mount all 2.5 inch pipe so that throttle body is now the restriction where as I can see on a stock setup it is more then likely a waste of time as so far guys that did it say no retune is needed and my car is way out of wack. I can hear the overlap from the cams in the pipe at idle like it totally changed the cells it is in now for idle besides the -17 on timing. I was thinking seeing the max value for torque too high at idle so doing all it can pulling a ton of timing to get it back under that number. I found a table for that last night so going to try it along with your recommendation. Will let u know how it goes so when you get to it might be an easier fix if that car also is similar in mods to mine.

[lt1z350]

Ok got my logs back this morning if wanting to see a specific item let me know other wise doing a idle log now to post with just a bunch of normal stuff I am logging

[lt1z350]

12-10 caddy idle.hpl

I will be installing the 67mm throttle body from ZZP's site onto a ATS here soon, and will be doing the tuning on it. Have yet to do a ATS with a larger throttle body yet, so can't give you to much information on helping with your issue other than getting your airflow and fueling dialed in.

But you might can try this out to see if it helps out any. I will be doing this when I get the throttle body installed.

Since there is no actual Idle Airflow Tab, you can try messing with the Airflow>Electronic Throttle>Throttle Area Limits>Max Area value.

You will obviously need to increase the stock value, being that you say you are running a 72mm throttle body. I would recommend trying something around 3,000 as the value. Reason behind me getting that number bases back to scaling the ETC Area Scalar in the PCM's with a Idle Airflow tab.

Furthur explaining of the number: you need to find the area of the throttle body. Being a 72mm throttle body, but you have to put into account for the throttle blade and shaft taking up a bit of room of the throttle body. So just estimating, I subtracted 10mm from the throttle body diameter. Then just found the area of that.

So (pi x radius x radius)= area. 72mm - 10mm(throttle shaft)= 62mm diameter. (pi x 31 x 31)= 3,019.07

thats good thinking but I am terrible with remembering math (build transmissions for a livng) lol so did you try your formula to see if that is close to the stock value with stock throttle body? I didnt know how you got 31 to try with the 58mm tb. That way if the value is off from what the stock value is then can apply that error to the new value you found if needs it. Hope I am making sense. Here is a log and it is a little long I let it warm up then at the end idle in gear for a while at least a min on end of log. Even has a slight miss to it at random. Going to try your value here and see just wanted to post up a log for others maybe following that didnt comment cause no log.

[lt1z350]

So far so good much better idle did more work on maf in idle area where was way lean and did a ve correction to that area too. Isles good in gear and out. Throttle response is better too. It is having an issue going from in gear to out. When put back into park it is hunting and searching for a stable idle. Up to 800 down to almost stall about 400 then pop throttle and ok or let it sit and will eventually get a good idle back. Other then that I would say pretty good. So now got to get that figured out. Only idles at 0-1 degree of advance where think stock was 8-10 so maybe something to do with timing. Now can drive it and not feel like will die at a light. Will post my updated tune with an old one so can compare my exact changes in a little bit. Back to putting my lsa blower on my 07 Tahoe as have to get done and driving today. Wife out of town gives me time for my projects. Lol

[Jggregory99]

I will be installing the 67mm throttle body from ZZP's site onto a ATS here soon, and will be doing the tuning on it. Have yet to do a ATS with a larger throttle body yet, so can't give you to much information on helping with your issue other than getting your airflow and fueling dialed in.

But you might can try this out to see if it helps out any. I will be doing this when I get the throttle body installed.

Since there is no actual Idle Airflow Tab, you can try messing with the Airflow>Electronic Throttle>Throttle Area Limits>Max Area value.

You will obviously need to increase the stock value, being that you say you are running a 72mm throttle body. I would recommend trying something around 3,000 as the value. Reason behind me getting that number bases back to scaling the ETC Area Scalar in the PCM's with a Idle Airflow tab.

Furthur explaining of the number: you need to find the area of the throttle body. Being a 72mm throttle body, but you have to put into account for the throttle blade and shaft taking up a bit of room of the throttle body. So just estimating, I subtracted 10mm from the throttle body diameter. Then just found the area of that.

So (pi x radius x radius)= area. 72mm - 10mm(throttle shaft)= 62mm diameter. (pi x 31 x 31)= 3,019.07

There is an an easier way... (New/old=Difference) x Starting tune Scalar= New Area Scalar

So... 72/58 =1.241 x 1930.5= 2396.4

[ATrim]

When i went to the 2.5l NA throttle body i used the max area value off the malibu and the car did not seem to make power when i changed this value, i did not mess with it much just went back to the old value. But you could just look up a factory tune with that TB to see what value they use and try it?

[MarkTucker]

12-10 caddy idle.hpl

thats good thinking but I am terrible with remembering math (build transmissions for a livng) lol so did you try your formula to see if that is close to the stock value with stock throttle body? I didnt know how you got 31 to try with the 58mm tb. That way if the value is off from what the stock value is then can apply that error to the new value you found if needs it. Hope I am making sense. Here is a log and it is a little long I let it warm up then at the end idle in gear for a while at least a min on end of log. Even has a slight miss to it at random. Going to try your value here and see just wanted to post up a log for others maybe following that didnt comment cause no log.

You can also give Jggregory99's method a shot, I have honestly never done the Area Scalar that way. But try it and see if it helps or makes it worse. I am only going off of what I will be trying once I get the throttle body installed.

But as for your question about using that formula to see if it matches the stock value.
The stock value from my 2015 ATS is 1,930.5. Doing the formula that I posted put the value at 1,809.6.
And that might be off cause of only guessing on the throttle shaft thickness.
Just for the heck of it, I used that same formula but said the throttle shaft thickness is 8mm instead of 10mm, then that would put the stock value at 1963.5.
So very close.

[MarkTucker]

And also just for the heck of it, I pulled a stock 2012 Camaro RS with the 3.6L V6 LFX engine. Which uses the 72mm throttle body, it's stock value is 3351.5. So you can also give that value a try.

[lt1z350]

I pulled it for the moment as fighting two vehicles is too much as just put an lsa blower on my 07 tahoe. Mark if u can help there just let me know and will pm you. As far as the caddy the 3000 value did help a ton the power didn't really change but idle did and if wasn't surging when I went from drive back to park and almost stall it would be pretty damn good. Wife is back in car so don't need her freaking think it will stall. It seems to take a second to try to learn the change from in to out of gear so the load must need to be changed? I was going to up the max load table when I put it back on. Going to take my catch can back off at same time as I just can't take that damn whistle any more. It makes it go way lean at idle so will have to readjust my trims for that anyway so all at one time will keep me sane. Atrim I guess your still stock turbo as throttle body made a big difference on mine. Have to go back and dig your email back up or just get my tune off this post and look at it as so much more timing from where we were when trading tunes back and forth. Car is really fast yet to dyno but walks off most of the new 5.0/srt8/ss cars easy. Up top power is sick with just that little bigger turbo. A well spent 1000 bucks now that I have the tune better and still think it has more in it I haven't found for power from playing with injection and cam timing as I just run stock cam timing in it as seems to work better then other tunes settings. I think it is around 400whp which is what I had hoped for. As exceeded my 110 quarter mile mph by quite a bit by how it runs against some known fast cars on the street. My knowledge on tuning the cams and soi are what little I have read so that's next for getting power as I have maxed the timing and have the afr really good on it.

[lt1z350]

Also sorry for long response time tahoe and Holliday have me tied up. I hate when following a thread and goes dead due to they fixed it or gave up then never re post findings. Pointless to start a thread when people do that. I will follow up when get it back on it.