What Is The Difference Between The 91 And The 96 1uzfe Engine

[Chris Baxter]

Greetings all, I'm replacing the engine in my 91 LS-400 with a 96, their both 1UZFE motors. Everything looks pretty much the same except the emissions and the vacuum lines. The 96 did not come with the engine wiring harness so I will have to use the one from the 91, I was told it was compatible, Is this true? should I swap the throttle bodies and emissions from the 91 to the 96. Is there anything else that needs to swaped. Has anybody done this swap before? I will be doing the timing belt and water pump etc. on the 96 as it is a used motor. Thanks in advance, CB

[chilkoot]

iirc the 96's are OBDII, while the 91 is OBDI. This will cause many electrical issues, and please somebody correct me if I'm wrong, but an OBD1->2 swap is more trouble than it's worth unless you swap the harness, ecu, and possibly the transmission (OBD1 and 2 transmissions might be different, I don't remember for sure though).

in other words, unless you've already bought the engine I'd seek out a low mileage '94 and rebuild the sucker to performance specs.

[TA in KC]

Remember that the 1990-1994 engines were non-interference, and starting in 1995 they were interference.

[lexlover1]

Remember that the 1990-1994 engines were non-interference, and starting in 1995 they were interference.

Has anyone on this site or know anybody that has a 95 that broke a timing belt? Did

it damage the engine? Always wondered and have never saw any posts about this I mean real experiences? Also what exactly was done in 95 to change the engine? Thanks very much for replies.

[TA in KC]

Remember that the 1990-1994 engines were non-interference, and starting in 1995 they were interference.

Has anyone on this site or know anybody that has a 95 that broke a timing belt? Did

it damage the engine? Always wondered and have never saw any posts about this I mean real experiences? Also what exactly was done in 95 to change the engine? Thanks very much for replies.

There was a huge debate about this earlier, do a search and you will probably find the original thread.

In the end, based on several people's experiences, it was determined that the 95-and-up LS has what we call a "quasi-interference" engine. The way the valvetrain and pistons are designed in the updated engine, there is about a 50/50 change of damage when the belt breaks. That is not a chance I would be willing to take. I would only wait for the belt to break on an engine that I knew for sure would not be damaged in any way if that happened.