i know its probably already been discussed here but i was wondering how this works. you can use the stock 3.1 OBDI computer?? do you use the 3.1 intake? how does the 3.1 wiring harness and computer work with an engine that was running on OBD II when a 3.1 is an OBD I engine? do you just eliminate all of the OBD II hardware? is the exhaust identical, the 3400 would have used multiple O2 sensors and would have had an EVAP monitoring system. are all of the connectors for the EGR, TPS, IAC, fuel injectors, ect the same? does the 3400 run on MASS airflow because the 3.1 runs on MAP. if you swapping in the entire engine is the throttle assembly in the same location?
i once did a swap in a 89 camaro, i went from a 305 tbi to a 350 tbi. is the process similar?
what about the reliability of the 3400? i dont think the 3400 is as reliable as the old 3.1/2.8 engine were. allot of 3400's had problems with rockers being pulled out of the heads (well i heard about one of those occurrences in a grand am GT), they also had numerous cooling problems... much like the 3800 the intakes on the 3400's are made of plastic junk. the old 3.1 intake was made out of better material.
my 3.1 runs too sweet for me to want to pull it. what about installing a turbo on a stock 3.1, they did in fact make 3.1's in turbo form.
The computer has no idea what it's running. All you need to swap is the EPROM. Forget about the differences between OBDI and II. You have a few options for exhaust, none of which require a second O2 sensor. The sensor plugs are the same. The throttle is in the same place. The intake is not plastic (not sure where you got that from). The 3400 is reliable.
All these questions have been asked and answered hundreds of times. There are other sites out there with more info than here too. Check out V6Z24.com.
i was under the impression that GM moved to plastic intakes on the 3400 much like they did on the 3800. i guess im wrong on that. i think i have read that the 3400 is more prone to cooling system problems then the 3.1 was. i also know someone at work that has a grand am GT and apparently the rocked somehow pulled out of the head. im not talking from personal experience because i have never owned a 3400 powered vehicle. the most modern engines i have owned are 3800 series II engines, and those are getting old themselves. i wish it was easy to swap one of those into a jbody, i know its been done but it cant be easy. its a 90 degree v6 and its quite a bit wider then the 60 degree v6 engines.