Gents,

Not sure if this is a trans issue, but I did install a new trans and converter so I'm hoping to eliminate them as the issue.

Before going down for the winter I made 450whp SAE at my dyno tune in November with a Circle D 3200 stall and a stock 4L60 with a Transgo HD2. Tune was good, 2-3 shift was barely holding.

This winter I did the following upgrades:
RPM Level 7 4l60E, 0 miles after refresh (yes, I know its overkill, but I got a good deal)
Not that it matters, trans also has huge B&M aluminum pan
Cut/Clean/ Restall the TC to 36-3800, replace external cooler
(External cooler is plumbed in after the cooler in a Becool Al rad.)
Reactor Aluminum Flexplate, CDS/ARP Hardware
Replace OE liquid/liquid PS cooler with air/liquid
Reduce runout on ABS/TCS reluctor wheels, reinstalled ABS fuses
(currently no brake or TCS lights on, would only work to 50mph after 9" install and would throw those lights, but I havent been to 50mph yet)

Car starts and idles like a champ, I can blip the throttle to 4k in park and it doesnt stumble or do anything unusual. However, if I have the car in gear I cannot get the throttle above 2k without the motor falling flat on its face to the point it almost dies. Sometimes it does die. The trans will shift from 1-2-3 automatically (I live on a long steep hill), but the stumble of doom still appears at 1800-2k RPM. Speedo works, engine coolant temp works, I can hear teh IAC working at cold start. I've done several TPS resets. I do not get an SES light, I have checked the sensor fuses. I've double checked the 02s and even swapped them moving the unused back to the front. If I unplug the MAF it will not idle, but it will run if I keep it alive. It does not backfire or even run rough, it just falls flat if I open the throttle at all and recovers when I close it. I dont have a code reader, but I have one on order. . .and I cannot drive this thing to the parts store in its present condition.

Is it possible that my tune is doing something that the new combination of higher stall and built tranny dont like? I have a call in to the tuner to see what he thinks.

TIA for any input.

 

This is certainly one of the stranger problems I have read here.
I assume then that the tune did not change over the winter?
The tune for a high stall converter are rather minor; that is not the issue here.
Have you tried driving it with the MAF disconnected?
(Avoid WOT with MAF disconnected just to be safe.)

When you get the scanner, scan the MAF, MAP, TPS % and voltage, and O2 sensors.

There is a similar thread where the OP cannot go above 3000 rpm:
https://ls1tech.com/forums/automatic...r-rebuild.html

 

Tuner got back with me. His first suggestion was that it was likely the MAF and to have my wife unplug it with RPMs up at ~1500. It worked, ran like a champ on SD, even idled ok. . .The crazy transmission and stall do what they should. Definitely doesnt feel like the stock trans.

Is just me or should a $260 MAF last longer than 12 months and 2k miles?

If mods would like to move to external engine now that its definitely not a trans issue I'd appreciate it. Thanks everyone for looking.

PS. Thanks Mrvedit. Your recommendation was clearly a good one, posts crossed in the air.

 

Glad you figured it out.
Is it a stock or aftermarket MAF?
I would first check the connections for corrosion which may have set in over the winters.

 

Its the TSP 100MM MAF...so I think the cartridge is replaceable. But good call on the connectors, I hope thats it. That stuff was all disconnected for the last 4 months.

As always, thanks for the spot on help. Vedit should get credit as sponsors for your work, lol.