Hi,
I have modified a Tahoe/Blazer MY 1994 that had a stock 5.3 TBI and 4L60e with a 6.2 engine from an Escelade MY 2007 and replaced the transmission with an 6L90e. Project described at http://www.hptuners.com/forum/showth...-the-old-4L60e
All done and car starts , idles and runs reasonably OK save for occasionally the engine dying when slowing down for traffic light stops. My main issue is the sudden downshift at normal driving acceleration. at around 30-40 mph it downshifts suddenly breaking rearwheels and RPM shooting to redline , pretty scary.
This event occurs at 1:24 min . The tune is stock (copied from my DD Denali XL MY 2007).
Apart from one of the O2 sensors not responding , the rest seems to be OK. The MAF sensor is brand new.
any clues or leads
just attached the tune file as well, its all stock as i said.
I will be mildly accelerating from a traffic stop and then and by the time i get to 5th or 6th gear it will suddenly downshift all the way to 2nd or 1st (not sure). So I don't go WOT at all, in fact it sometimes happens when I ease off the acceleration. Its driving me crazy.
By the way, I just took out the ECM and plugged into my family DD Yukon Denali AWD (XL) and everything was OK. The difference is that my DD Denali is stock Engine and 6L80 Transmission while in this 1994 Blazer project I have Denali 2007 engine with a 2009 6L90. The other issue is one of the O2 sensors is not functioning (loose connection somewhere in the harness) which doesn't make for an optimum smooth engine running but I cant imagine that is causing this huge downshift !?> or could it ?
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