If your tach stops working on a B13 ecu, odds are Q457 burned out. Its sort of a bit to the left of the center, right above two transistor arrays (kind of long black looking things). Its got three pins, and is dead easy to replace (compared to the B14, which is a pain in the butt). I haven't looked up an off the shelf replacement because I've got stacks of parts ecus I pull from. If anyone needs this part, shoot me an e-mail and I'll pull one.

That is all. :)

I dont have a b13 but calum you are the man, period.

Calum, Thanx for repairing the Tach you ECU MACHOMAN!!!

Once again, Calum fishing for complements ;)

Here's what I've been working on. This is designed to be a kit you can order and assemble yourself. Basically its a generic benchtop engine simulator. Obviously its aimed at 4 cylinder Nissans, but its flexible enough that with a little hacking it can simulate a variety of engines (really just the crank and cam angle sensors are the trickiest to do). As it sits, it will perfectly simulate an engine for a B13, and almost for a B14. I've still haven't quite got the ecu throwing no codes, but its getting there. I've also finally got the code for reproducing the CAS signals perfect, so the rpm is rock steady. Very cool. Makes testing ecu functionality easy. I've tried to keep everything low cost, even the power supply is a cheap surplus laptop supply, and the little chinise multimeter shown is for watching the total current used by the ecu (very good for quick and dirty trouble shooting).

This has made for some interesting discoveries. With a stock B13 ecu (rev limit at 7.5k), any guess what rpm exactly the stock rev limiter starts? And how exactly it works?

Top view:

http://www.calumsult.com/calumsu/random/ECU%20sim%201.JPG

Setup:

http://www.calumsult.com/calumsu/random/ECU%20sim%202.JPG

and what the tach signal looks like at 7.2k rpm. This is with only a 5V pull-up, and driving an LED, which is why the voltage is lower than what you would see looking at a real tach signal in a car. Same basic waveform though.

http://www.calumsult.com/calumsu/random/scope%20shot%20-%20tach%207krpm.bmp

The 'scope btw is new, I really needed to replace my old large Tek 'scope since we've downsized from a house to an apartment. I just couldn't swing the going rate ($3k+) for the Tek scope I really want (TDS3014B, I'll pick one up eventually), so I bought this Chinese dude in the meantime. I'm really impressed with it for the money. If your on a budget and in the market for a scope this is the one to get. Its a bit on the slow side (analog input speed, not in response to control changes), just 25MHz, but thats still plenty usable for looking at ecu stuff. This is where I bought it, and its only $329 shipped:

http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=PSSA002&Category_Code=PSSA

!! how much for that bad boy then?

I'm still working out the total cost. I'm going to sell it as a kit for no profit. Probably between $100-150US with all the parts. The board itself is $54, the power supply is $14, and all the trim pots add up.

sounds like a bargain to me

Should've assumed you were using a Tektronix oscilloscope, but didn't think about it. I'll check out some of their used ones on campus when i get a chance and see if I can come up with something for you=)

With a stock B13 ecu (rev limit at 7.5k), any guess what rpm exactly the stock rev limiter starts?

Isn't it 7750?

C

The OWON is the first non-Tek scope I've liked, and most of that is probably due to its price, and the fact that they've knocked off the look and feel of the Tek TDS2000 series almost exactly. This is sort of the SSAutochrome of scopes I guess. I wish they had just knocked off the TDS3000 series, its sooooo much nicer. The TDS1000/2000 suck butt once you've used a TDS3000 and gotten used to it. The TDS1000/2000 (and the OWON) have a super crappy LCD display that doesn't look good unless you look right at it, the TDS3000 looks superb at any angle. I'll take either though over a CRT scope right now, just for the bench space.

I probably will buy a TDS3014B (or equivalent in a faster speed- 3034 3054) on down the road and move the OWON to the garage. You can get a battery pack for the OWON, so it would make a decent car trouble shooting scope, although its not quite as handy for that as a hand held scope. The TDS3014B really is the best general purpose workhorse scope out there. Small, good screen, easy to use, 4 channels, fast input and fast sample rate, ethernet connectivity, and it can take a battery. The only downside is it doesn't have a usb port, but thats ok. I hear its going out of production in 2008, so I bet Tek has a new version with USB in the pipeline. I hope they don't screw up the simplicity of it, but its probably going to be priced at $7-10k new so I'm probably not the target customer anyways. :)

Isn't it 7750?

C

Nope, 7500. Buuuut it actually starts kicking in earlier than that. It starts cutting fuel to individual injectors at like 7300 (I'll document the actual rpm points sometime). Its neat, it does one cylinder at a time too. So if your at 7300 its cut cylinder 4, but the other 3 get fuel, then you bump up to 7350 it cuts 4 and 3, etc (I just made up those numbers btw, but thats how it works). Kinda cool.

Nope, 7500. Buuuut it actually starts kicking in earlier than that. It starts cutting fuel to individual injectors at like 7300 (I'll document the actual rpm points sometime). Its neat, it does one cylinder at a time too. So if your at 7300 its cut cylinder 4, but the other 3 get fuel, then you bump up to 7350 it cuts 4 and 3, etc (I just made up those numbers btw, but thats how it works). Kinda cool.

I thought it was well known about the soft cut?