I have an 03 mustang gt 100000 miles. the tourqe converter locks up under load and at high rpms in second gear, lugging down the motor. in 3rd it often studders before lock, but not after overdrive. the local tranny repair guys say to just drive it. reading no codes.

5.000rpm's high revs and you run into problems with valve bounce ( hitting pistons) ,ring slap, gudgeon pin knock, big end noise and possible main bearing noise . You may also be getting a hydraulic lock in the hydraulic followers that is holding the valves open too long. Unless the engine has been specifically built for these rpm's any loose ,worn on unsuitable part will cause problems I am thinking that you have around 100.000 miles on the clock after 7 years and the motor is not young Ford V8 engines specifically built for a 500 klm race are limited to 5.500 rpms because they destroy the timing chain if driven over that speed .

Hi, It may be in LIMP mode.

What is "limp-home mode" ? This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.

Common failures on 4L60E, symptom any possible repair:

Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmission is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the under-hood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.

No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter :ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it's moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later.

3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.

If you can get the Jimmy for no more then $500.00 and the engine sounds good and body is good, you may want to invest in the repair of the jimmy. Also note that to have a close look at the fuel line along the frame on the drivers side just by the back doors, the line is know to corroded there on all the SUV's

u only did part of the job most people change the air intake first put in a cool box or k&n type which causes some of same problems as opening the exhaust-- ur letting to much air out no back pressure and not enough air going in causing an imbalance also ur going to have problems with o2 sensors/cat sensors also mass air flow down the line

Sounds like it could be the ECU (electronic control unit); easy to change. I have bought used ones a lot cheaper than new ones and work fine. Your year may be located under the glove box to the right behind panel (my older car was passenger side under the mat). They are easy to change out regardless of location.

Check the shift silonoid first

If this happens right after you shift it is likely the check valve in the fuel line at the pump. If not occuring after the shift you may be experiencing spark blow out. Try reducing your plug gap to .035 and see if that helps. This is especially important if you have made any modifications that will increase your boost over stock levels.

power brake truck rpms should be around 1800 if not bad tourqe converter in transmission

have you been tuning it? look for the vacuum hose you knocked off.

TOURQE CONVERTER LOCK-UP

It should be attached to transmission block, I will see if I find a diagram.