89 ECU

[rancid240]

are there any differences, i know both are SOHC but are there any differences that would not allow the ECUs to be interchangeable.

[9591]

The ECUs in early '89 are different than the ones in late '89. The late ones are *probably* (IMO) the same as the '90. You can tell the difference between early and late by checking the airbox on the car it came out of: if it has the air temp sensor on the side, then it's late. Nissan added the sensor, lowered the compression, and made changes in the ECU all at the same time.

[dsjunkie]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (9591 @ April 06 2002,02:23)</td></tr><tr><td id="QUOTE">The ECUs in early '89 are different than the ones in late '89. The late ones are *probably* (IMO) the same as the '90. You can tell the difference between early and late by checking the airbox on the car it came out of: if it has the air temp sensor on the side, then it's late. Nissan added the sensor, lowered the compression, and made changes in the ECU all at the same time.</td></tr></table><span id='postcolor'>
yeah....there's about a 5 hp and 10 lb torque difference between '89 and '90.....yeah and the compression ratios are different too ('89-9.0:1 and the '90-8.6:1 makes it the most turbo friendly 240 stock consitering the dohc all have ratios of 9.5:1 <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>)....so there has to be some ecu changes to crank out that much power b/c you dont switch to a lower compression ratio and get more power out of it....however that would be really cool if you could <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/cool.gif" border="0" valign="absmiddle" alt=':cool:'>....so to answer the original question, IMHO i believe that it is safe to say that the ECUs are NOT interchangable since there has been some changes on the internals; HOWEVER, if you are a bit adventurous and have a bit of time (and maybe some $$$$, depends on how it goes <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/nervous.gif" border="0" valign="absmiddle" alt=':nervous:'> ) try and see if your '90 ecu could work on your '89 engine....i'd like to hear what it does &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/sly.gif" border="0" valign="absmiddle" alt=':sly:'>

[9591]

Notice that I differentiated between "early" '89 and "late" '89. Earlys had 9.1:1 CR, lates had 8.6:1, same as the '90.

BTW, where'd you get those HP and torque figures from?

[rancid240]

crazy, i thought all 89-90s were the same. &nbsp;never knew the differences. &nbsp;well the person who has the 89 that i want to buy the computer off of, &nbsp;i have a 1990, has a DOHC swap that was done before he bought the car, so he doesnt know. &nbsp;can i tell by the date the car was made (you know the sticker with the VIN on it). &nbsp;Well anyways i am doing this so i can give this ECU to a friend who is going to give me his JWT and UR pulley for $300. &nbsp;i think its a pretty good deal, but his car is an 89!!!

[gschroeder78]

The guy I bought my '89 from said he put a new engine in. How do I know if he put in a '90, a late '89 or an early '89? Is there anything on the engine that would tell me?

BTW, I did have the air sensor on the box but he could have kept the old airbox. Anything else that would clue me in?

Thanks

[dsjunkie]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (9591 @ April 06 2002,08:15)</td></tr><tr><td id="QUOTE">Notice that I differentiated between "early" '89 and "late" '89. Earlys had 9.1:1 CR, lates had 8.6:1, same as the '90.

BTW, where'd you get those HP and torque figures from?</td></tr></table><span id='postcolor'>
my chiltons manual...i know it sounds really weird and i shouldnt take it as the word of god (and i dont) but that's what it says....

[9591]

The Nissan TSB that explains the changes made to the '89 only states the "engine number" that they start at: KA24-D12039. I have no idea where the number can be found. The TSB is dated 5/18/89, so any vehicle manufactured after that date likely has the late engine. If built earlier, who knows? Maybe Nissan was slow getting the bulletin out.

[geeaj]

The gist of it is that if you have an 89' sohc and you see a air temp sensor mounted feeding to your stock air box, then you have the "regular" compression motor.

If your 89' was built before March or thereabouts, you will have the early high compression motor with the air temp sensor.