I just looked at the engine I bought for my 1990 Q45 which I had shipped to a local shop and it definitely looks like a 1994 or latter engine instead of a 1993 as advertised. I should have known better than get one off eBay especially since the picture wasn't very clear (see below) and the seller could not provide a VIN number. He could always claim it was manufactured in 1993 as most 1994's were. Is there anyway to get it to work in the 1990 without great expense. I would prefer the improved fuel injection system, and since the timing quides would not need changing I could save that expense. The injectors on my 1990 have plagued me since I've owned it and have been replaced several times. Also, is there some way to determine if it is a 1996? I question the sellers claim that it only had 56K miles since the valve covers were leaking badly and it didn't look that clean. I was suprised that it looked almost 3 times as big as the Mazda V-6 it was next to at the shop.

It was only $850 with the shipping and included all the components including the steering rack, subframe and driveshaft. Guess I could always keep it as a backup but since the 1995 I just bought from Doc (John) and only has 73K miles I might not need it in my lifetime and really don't have that much space in the garage.

Anyone need a 1994 engine?

http://cgi.ebay.com/ebaymotors...eName

Check out my Cardomain page and see page 3. There are pictures of my engine work that was done. The pictures are of my old 90 engine and newer 90-93 engine. There is a difference, but I can't remember exactly what it is. Maybe you can tell by pics.

The change occured in the 1994 model year. Visual clues are the throttle body and CAS look different. Not sure about the 1996 looks the same?

I'm pretty sure 94-95 are the same, but I believe 96 dropped variable valve timing.

Does anyone know if the 1993 Q engine looks the same visually as the 1994? A local shop that specializes in JDM takeout engine replacements said that there was a change to a camshaft sensor in 1993 that carried over to 1994 and latter engines and he thought that the 1993 model year Q45 engine looked the same as the 1994. If that it the case then the 1993 engine that I got for my 1990 could in fact be a 1993 and not a 1994 or latter engine as I had initially thought. Also he said that they swap the fuel injection system with what is currently on my car because the JDM FI is different and they can't legally use the one on the JDM engine. He is quoting me $1250 for the engine and $900 to install it with a 2 year warranty. He said that would include swapping the parts off my old engine. So price wise it sounds like the best way to go since no one else in town seems to warranty these used engines. I just need to check their references and hope that the car will make it to their shop which is on the other end of town. One thing that had me a little concerned is the low price and that the owner drives a 1991 Q45 but had never heard of the problem with the timing chain guides.

Most 94Q were made in 1993, thus the confusion.The model year 90-93 Q engines are externally identical, harness connector wise.

Obviously TCS, and active Q have differening minor harness additions or changes.......extra harness for extra temp sensor under plenum, stuff for TCS motor and auxillary extra TPS, California egr temp sensor addition, etc.

The 94 show up as different harness module [transistor driver] for ignition coils, CAS shape and connectors, drivers side front vacuum control solenoids for evap cannister, etc.

the difference is the distributer on front drivers side of eng. next to charcoal can. the distr. are have different plugs, u will need the plug from the 94 eng. cut/mend back wires for it 2 work on 90-93 engines been done many, many times before

According to Joe @ everythingnissan ... when I investigated this last year . . the block, crank, rods, pistons, bearings bottom end internals etc ... for the 94 were all the same parts numbers as the 91-93.

The heads plenum and multiple accessories were very different.

I had a bad rod knock in my 1991 Q45a. I bought a 1994 Japanese CRATED motor - never ran, still with all the factory paper protectors over the intakes etc ... - took my 1991 A heads off - had em up gussied up, and slapped em on that 1994 Bottom end. So far so good - motor and car are to be reanimated in the next 15 days or so. Now going thru and doing all the maint that was negleced by prev owners for 180k ....

Was it a close decision? I mean, why not get used parts from '94 heads and keep the entire new long block?

DAEDALUS,

Im not sure I comprehend your query ...

I have a 1991 Q45a ... 1991 Intake manifold and accessories etc ... I needed to have a 1991 not a 1994 motor :-)

I kept the complete 94 heads, as the ones from my 91 seemed fine - except for some routine cleanup one would do when doing a rebuild.

We werent aware the 94 head parts were direct bolt ons. I know that the Valves are different in the 1991's vs. 94's - sodium filled?

Thought it would be better to have a complete set of 1994 heads for resale or spare, than 2 sets of heads dismantled.

Hope I answered the right question you had.