My late 91 SE 5-speed died in my driveway, and would not start. Had to use the starter motor to pull her up to the house and to unblock the driveway.

Towed her to the mechanic - who thinks the computer died. He's out searching for another computer, but says you have to match the "numbers" to swap - you can't just swap an ecu from one year to another year.

I've looked through the threads, and it seems that there are some differences between the manual and automatic ecus, and some swaps have been made that work. However, no one mentions the "numbers" that the mechanic says must match.

What's the common knowledge out there?


And, while I've got your attention, how likely is it that the ecu dies while the car is running, in the midst of a downshift from 2-to-1 to pull into the driveway? Is the mechanic looking for zebras?

 

As far as I know only the engine and transmission type have to match.

 

oh wait, just noticed the 5spd part. Pretty sure you just have to match the engine then. 5spd can use either a manual or automatic VG ECU.

 

I don't have a lot of experience with swapping 3rd gen ECUs, but I wouldn't make such a confident statement at all - especially given that eg our local 3rd gens run with no O2 sensor at all by design ................ and some emission standards may dictate a different ECU map

 

An auto ECU will run the 5 speed just fine. Most VG guys who swap transmissions to a 5 speed leave the auto ECU in it with no issues. I'm almost 100% certain that you (Ryder) just need "a" VG ECU. You should be able to get any fed-spec ECU from any 3rd gen with a VG engine. Auto or 5 speed it should not matter. GXE or SE it should not matter. IIRC the only thing that would make a difference is the fed-spec vs. Cali-spec ECU. But that shouldn't be an issue with you being in Canada (LvR has a unique case being overseas, but I'm pretty sure Canadian 3rd gens are the same as fed-spec U.S. 3rd gens).

Now, if he (your mechanic) wants to be 100% technical/OEM, then, yes, I guess he'd want to find matching "numbers" (i.e., same year, trim, "batch" of ECU's), but that's just kind of overkill IMO (plus it will probably justify him charging a WHOLE BUNCH more).

Other than that, I've never heard of an ECU just suddenly dying like that, but I suppose it's possible, but very, very, very unlikely. If I were you, I'd just find a nearby 3rd genner with a VG and swap in his ECU to test it. Otherwise you might be in for a costly part-swapper-mechanic ordeal

 

Mechanics probably aren't going to find as good a deal as you will find if you just run to the junkyard or find someone on this board with one for sale. You can actually swap ECUs yourself in a matter of minutes.

I got a VE 5-speed ECU from someone here for $25.

I know with the VEs, you can run the AT ecu in a 5-speed, it just loses the variable intake, but the car runs fine. I have done this personally. I would assume the VG is the same. Since you don't have a VI, it should work without any missing functions.

I also agree with James that there could be something other than the ECU being bad, but that's something you could probably swap and try quickly just to see if it's the problem.

 

I got a VG 5pd ECU laying around somewhere.

 

I know the mechanic picked up an ecu from the local pick-a-part place. They only want $18 for ecus this week - I'll see what he charges me.

He's a pretty good guy too - he has a policy that if he can't fix it, he won't charge for it.

Thanks for the comments, folks. I'll let you know what happpens.

 

I'm a long time Nissan user and Nissan ECU's rarely fail....I have the original Ecu still installed in my 86.5 Nissan Hardbody 2.4L 4cyl w/338,000 mi. I've own Mitsubishi and Toyota as well and I'll say Mitsubishi's Ecu's really suck and are always suspect to fail...I guess I've been blessed and never had any drama with Nissan Ecu's. Just GM, Mits, Dodge, etc...have given my problems!

 

[sigh]

OK - it's not the ECU. Replaced with another - still no go.

He found another test that indicated that the ignitor is fubar. Today, ignitor was replaced, and still no go.

I think I'm going to drag her back home and work on her myself...

m

 

That's what the forums for, describe what's wrong with a little more detail and I'm sure someone can help out.

And what's the ignitor? The distributor? Spark plugs?

 

Well, the mechanic can't figure it out, and I can't afford to pay him $80/hour to guess, so she's coming home.

He's checked the ecu, swapped distributors - all to no avail. I haven't spoken to him directly yet today, but I need to ask him if he's checked the usual mechanical stuff. I'm just wondering if maybe the fuel pump packed it in. Or, if the timing belt snapped. Dunno if he's looked at either one of those things - all he says is the ecu is not getting a "start signal", and I'd be da**ed if I know how he knows that.

So, I'll be asking more in the forums... here's hoping thousands of enthusiasts are better than a mechanic.

The nice thing about this guy - I only had to pay for the tow to his place. He stands behind "If I can't fix it, I don't charge you." This afternoon, he and the boys are getting beer for their efforts...

 

if the distributor is spinning, your timing belt is intact. if you flick the key on and hear a humming sound, the fuel pump works (at least to some extent).

take a spare spark plug and put a wire to it, then hold the ground against the intake manifold and have someone crank the engine over. getting spark? if not, focus on ignition stuff. if yes, focus on fuel-related stuff.

 

If I'm not mistaking a cam or crank position sensor, can also make a car not start. Wouldn't hurt to check them. I've seen it on a chevy, just not sure if that would matter on a nissan.

 

So - I've made arrangements to drag the beast back home. All the mechanic charged me was the initial tow to his shop - if he can't fix it he won't charge for it. I know that he's spent probably 10 hours on the car, so I figure a case of beer is worth it for his efforts.

I get to the shop with the beer, and the car's still there. As I hand the beer over, the mechanic says "I've got something to show you". He grabs the keys, goes to the car, and fires it right up (!).

He said he was putting it all back together again, replacing access covers and the like, and noticed a loose wire behind the fuse/power block. He cleaned it up, put it back where it belonged, and problem solved.

He thanked me for the 'safety meeting supplies', chalked his time to education, and I took the car home with no additional charges.

Best $30 I ever spent on beer. [grin]

Thanks everyone for your suggestions and support. Hopefully one day I can return the favour...

Michael