Converter lockup

[RR5.0]

I recently got my car dyno tuned and am very happy with the results. The car drives 100x better and is noticeably faster. Well worth the money. However we had an issue on the dyno with locking the converter in 4th gear. It would lockup and stay locked fine in 3rd but wouldnt hold in 4th past about 5500rpm.

Car is a paxton wastegated at 10psi on the 3.33 pulley, converter is a Circle D 4C. Dynojet dyno, car made 590/495 with the converter unlocked in 4th. Made 585/483 locked in 3rd gear. I dont really care about the numbers but I know it should make more.

What could be keeping the converter from locking? Does the car think it is seeing wheelspin? Or not enough load?

Need some insight before I pull this converter out.

Thanks!

 

[onefastmf]

I had a issue like yours, the converter was slipping when locked on the dyno, the computer see's the slip and unlocks it.

 

[RR5.0]

So the converter needs to be pulled and repaired? Or is this a tune issue?

 

[dennisn]

op are you on 93 or e85? For pump gas I'm not sure i'd consider those numbers low.

I doubt it's the convertor. Talk to your tuner.

 

[RR5.0]

Im on 93. My tuner is the one who dyno tuned it. He could not even force the converter to stay locked. He also had a vortech car in the week before me that made 624/505 on pump gas and stock pulley.

 

[RR5.0]

As an update I contacted my tuner again and Circle D. The converter seems to be slipping in 4th before it comes out of lockup. Most likely a clutch issue so I am going to pull it out and send it back to Circle D to be repaired.

 

[onefastmf]

Same problem I had, but mine wasn't a circle D, what fluid are you running? Stock?

 

[RR5.0]

Yes stock fluid, mercon lv. Ill probably refill with that when i swap to stock and then going to change to amsoil when the circle d goes back in

 

[onefastmf]

I would leave stock fluid in, that's what was causing the slipping issue with me, I used, don't laugh! John Deere hydraulic fluid and it was slipping, switched back and it want slipping anymore. I'm not familiar with the amsoil Trans stuff, but I think you want your Trans fluid to have some bite to it.

 

[Offaxis]

do you have the converter set to lock up when your racing? Some people do I was just wondering.

 

[onefastmf]

Yes I lock it.

 

[Offaxis]

What kind of diff did you notice compared to not locking it up. I've never locked mine up

 

[onefastmf]

Not sure, my tuner has always had it set to lock, I remember back in my grand national days it was worth 2-3 tenths

 

[Scott8583]

I have a stock converter with (fresh) stock fluid and mine wouldn't stay locked in 4th on the dyno... Runs fine at the track. 800whp

 

[cjd223]

We burned our own eproms back then. We would lock the converter up when it shifted to 2nd gear. My T-Type would pull 28 lbs of boost in 1st gear. We would pull back timing and boost as it went down the 1/4. Had to run 110 octane gas.

Not sure, my tuner has always had it set to lock, I remember back in my grand national days it was worth 2-3 tenths