What would you guys change to add some air during a gear shift. Car just seems to stumble for a second once you put it n gear. Drives fine, fuel trims are good, idle is great.
Is this more of a cracker or follower issue?
What would you guys change to add some air during a gear shift. Car just seems to stumble for a second once you put it n gear. Drives fine, fuel trims are good, idle is great.
Is this more of a cracker or follower issue?
Post a log of the issue and add cracker and follwer as well as idle air trims to your pid list
Throttle cracker gives you extra airflow based off RPM VS MPH.
Throttle Follower gives you extra airflow based off TPS vs MPH
If you need airflow changed for a different gear at idle it will be your based airflow table. But Timing also has a table for P/N and Gear so if there is a pretty decent difference between those tables it can cause a issue.
What size cam and what torque converter?
I'm following this post to learn. Thank you for your explanation! I'm new and to clarify the terminology "throttle cracker" = "idle cracker airflow" and "throttle follower" = "idle follower airflow"???Originally Posted by RDF1
then from post #2 the term "idle air trims" is "idle adapt (STIT)"??
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That's not an exact description. just a quick explanation to get you thinking in the right direction.
But yea your heading in the right direction. Look at the channels and do some data logging. you will see where its using which airflow adder and how fast they decay out.
If you post your current tune and a data log of the stumble. we might can help you figure it out.
I use EFILive majority of the time so that is the table names im used to using, i forgot to use the correct ones for HPT.
BTR stage 2 cam on a stock converter. So it's not ideal. Customer plans on coming back for the converter in the summer. It just bogs when going into gear, especially when it's not at operating temp.
Is it the 227/238 cam?
I have to turn down several tunes a month cause the kids kept getting big cams put in their trucks and they dont want to spend the money for a converter plus they have 35"+ tires with stock 3.42 gears and they just cant comprehend how this whole deal works. They go from tuner to tuner to tuner and never satisfied.
Have you tried to give it some more airflow in gear?
Yes, 227/238 but it's in a Corvette and not a truck.
Yes, I added air in gear and it holds the idle just fine the rest of the time. Just when it gets first put into gear. Once it's warmed up you don't notice it.
I'm a pretty old kid, 30.5" tires (not huge mud boggers,) 4.10 gears, 3.35 1st gear (T56,) in a ~4700 LB GMT800 pickup. 220/220 .600 .600 cam (Texas speed 220r.) When I bought this cam more than 2 years ago it was to go into a 4.8, 4L60E! I got busy, and now I have an LQ4 6.0 with 243's. If you see this, I feel as though this cam will do well in this app, but do you know of any that would be better?
I know this is derailing OP's thread so if you want, you can send me a PM, or just ignore..
To OP: what is your timing advance doing during the gear shift?? Also, since it's only when cold, what are the differences in logs between cold/warm operation?
Last edited by eighty6gt; 02-02-2023 at 06:44 AM.
Get a log of the issue and post it up. Perhaps we can see the cause in action.
Amen. We can get it running right but your mid 230's duration cam in a otherwise stock tahoe with stock manifolds / converter/ and awful gearing is going to make shit "useable" power and get terrible mileage. I thought about offering a consulting service seeing how I've been doing this for so long and I drive all kinds of setups.. It would be a better deal for the customer and me if we pick out a good package.. but realistically no one wants to listen anyway. I'm sure tiktok youtube and facebook know better.
I digress anyway..
Do you have a wideband on it? How is the base timing tables in park and neutral.
If the VE table is just a touch rich in the higher kPa areas around idle it will make this dip worse.
Timing in the base park an neutral tables can help offset this.
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