6l80 down shift
Thread Starter
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Joined: Jun 2016
Posts: 76
Likes: 16
From: Chicago IL
6l80 down shift
Hi everyone,
I’m having an issue with my trans on partial throttle down shifts and hoping some one can help me figure out what’s going on. Here’s a very quick run down about the car/issue.
The car is an 07 base auto 6l80, I bought it with an A&A si trim sc kit full exhaust on a dyno jet it put down 580.
I have some other posts floating around explaining more in detail but, I blew the engine. FINALLY got a new engine in, it’s a decent little build with out building a full out race engine. I installed a CCP Jam cam recommended by BTR. And added a meth kit. (Again just a quick run down, I’m skipping a novel of details) I Brought the car to be tuned at a well know highly recommended shop in the area. The final results were not to bad, on a mustang dyno peak numbers are 680hp right around 6000 rpm and 673 ft-lbs at 4300.
I’m still on the stock trans and converter so the tuner said he had to keep the torque converter from locking up at times it normally would to avoid surging caused by the cam.
The Over all street manners are really good, the car Drives smooth, Upshifts are nice and crisp.
I know when I’m going to put my foot down, I need to manually drop gears and that’s working fine.
The issue I’m having is say... When getting on the highway, the car is in 5 gear I apply some light throttle the trans drops down to 4th, I decide I want to accelerate a bit harder and it goes to drop to 3rd, when this happens, there is a very obvious slip. The car 100% did not do this before and it is not a shift flare. it’s a slip. It did throw a code 1 time P0797. When this happens I am by no means flooring it I’ll say somewhere around 1/2 throttle. I feel that the issue is somewhere in the tune. Either something the tuner adjusted or maybe something not being set right where the trans isn’tready for the additional power at a given throttle percentage. But I’m just speculating. Has anyone dealt with an issue like this? Have any ideas.
Any feedback is appreciated
I’m having an issue with my trans on partial throttle down shifts and hoping some one can help me figure out what’s going on. Here’s a very quick run down about the car/issue.
The car is an 07 base auto 6l80, I bought it with an A&A si trim sc kit full exhaust on a dyno jet it put down 580.
I have some other posts floating around explaining more in detail but, I blew the engine. FINALLY got a new engine in, it’s a decent little build with out building a full out race engine. I installed a CCP Jam cam recommended by BTR. And added a meth kit. (Again just a quick run down, I’m skipping a novel of details) I Brought the car to be tuned at a well know highly recommended shop in the area. The final results were not to bad, on a mustang dyno peak numbers are 680hp right around 6000 rpm and 673 ft-lbs at 4300.
I’m still on the stock trans and converter so the tuner said he had to keep the torque converter from locking up at times it normally would to avoid surging caused by the cam.
The Over all street manners are really good, the car Drives smooth, Upshifts are nice and crisp.
I know when I’m going to put my foot down, I need to manually drop gears and that’s working fine.
The issue I’m having is say... When getting on the highway, the car is in 5 gear I apply some light throttle the trans drops down to 4th, I decide I want to accelerate a bit harder and it goes to drop to 3rd, when this happens, there is a very obvious slip. The car 100% did not do this before and it is not a shift flare. it’s a slip. It did throw a code 1 time P0797. When this happens I am by no means flooring it I’ll say somewhere around 1/2 throttle. I feel that the issue is somewhere in the tune. Either something the tuner adjusted or maybe something not being set right where the trans isn’tready for the additional power at a given throttle percentage. But I’m just speculating. Has anyone dealt with an issue like this? Have any ideas.
Any feedback is appreciated
Last edited by Judge387; Nov 20, 2018 at 12:39 AM.
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 408
From: Montreal
St. Jude Donor '13
Does it slip for a second and then work normally or does it slip until you let off the gas or upshift ? If it slips until you let off then it sounds mechanical, rather than tune related.
See if it still slips if you manually shift down in the same situation.
See if it still slips if you manually shift down in the same situation.
Thread Starter
Advanced
Joined: Jun 2016
Posts: 76
Likes: 16
From: Chicago IL
Manual down shifts are fine, I honestly done know how long it will slip. I feel it, I panic and let off the gas, Ive felt the issue on the 4/3 down shift and the 3/2 as well. It does not slip on normal cruising, it just does it when I’m feeling a little froggy. I pulled the snap shot data when it logged the code that one time it set, and calculated torque was at 384 ft lbs and tps was reading 34%. I can post up the pictures of the snap shot if that will help anyone. And again up shifts are fine, 1-2 up shift and 2-3 up shifts are fine cruising, miled to moderate acceleration all the way to WOT the trans does not seem to have any issue grabbing the next gear. If I use the paddles and hold it in a selected gear it is also fine. The trans seems to have no problem holding 1st, 2nd, or 3rd all the way to red line 4th 5th and 6th I don’t seen to experience any issues as well but I only hit these gears while cruising.
Instructor
Joined: Sep 2010
Posts: 152
Likes: 8
From: San Diego California
Trans fluid is likely low causing your issue. These transmissions actually need to be over filled. Since the engine was just replaced, it probably lost some and was not addressed. You can search my post history and get instructions regarding filling the trans.
Thread Starter
Advanced
Joined: Jun 2016
Posts: 76
Likes: 16
From: Chicago IL
Unfortunately.... this could be a possibility. I didn’t loose a ton of fluid but I did loose some, just figured it wasn’t enough to cause any issues. If the trans is really that sensitive about the fluid level I’ll get the car up in the air and top it off.
