Hey, Ive been reading the ECU/megasquirt threads and the useful posts since yesterday and working on my car to get the MS connected but i have had no luck. This MS was made by Brain according to the last guy i bought it off of. It was setup for a greddy 1.6 kit for a 90-93 car. I followed all of the steps that Brains thread on how to build and install your MS and the software but i get stuck at the point when i need to connect my MS. The MS is all wired up and connected to the car and i did remove the ST SIG fuse. When i turn the key to have power flowing to the MS two red lights turn on on the MS. I then connect my USB to serial cord to my laptop and the MS. The MS however doesn't respond to the megatune, my laptop however does make a notification sound to let me know that something was plugged in.

I played around with the communication settings in MEGATUNE but noting worked. After sitting around in the car for hours trying to connect to the MS but getting no response from it what so ever i decided to see if the car will even start with the MS plugged in, with AFM, and stock TPS. The engine cranked a few times and then turned over. It almost died but i gave it a bit of gas and it stabilized at 1,500rpms and slowly came down to 1000rpms.

I decided to drive the car around the block to see how good/bad it would run. Every time i let go of the gas the car would bog and try to turn off unless i got back on the throttle. When i pressed the clutch pedal down the rpm gauge would jump or go straight to 0 rpms and the car would sometimes die in the process.

So at least i know that my MS is working but i don't get what i need to do to connect it to my computer...any help?

 

Hey, just a quick update. I did some more searching on Google and found that it could be that the cable im using is at fault. Can anyone verify this? problem is that my laptop doesnt have a serial port.

 

There is a serial to usb adaptor cable for ms on the diyautoune site. 25-30 shipped i believe. Of you get that one make sure you install drivers for the cable before using it

 

this is what i have. Not by the same company but its the same thing.

http://www.google.com/products/catal...ed=0CDsQ8gIwAA

What do you mean drivers for the cable? Im not very literate in this stuff, im sorry.

 

So i got the cable working but only on a different computer (a slow computer). I started Megatune and opened the file "9093 Base Map with AFM" and the car ran like crap. Now i dont have a timing light yet but should it turn off, misfire and freak out when i cruise to 3000rpms in 1 frist and then shift into second. (rpms drop to 0 and car shuts off unless compensated with a bit of throttle) I dont think this has to do with my stock tps because the rpms dont slowly drop but it slams down to 0rpms like i shut the car off.

 

ya they all do that, its how they run....lol.... im kidding, check the timing, make sure the wideband, clt and iat are all calibrated, calibrate the tps if its the 4 wire too. what are the afr's like when you drive it right now? go do that stuff and see what it does, make sure the other settings are in good order too... then youll probably have to go use veal for a while if you get tunerstudio, otherwise your stuck making logs and running them through megatune to try and tune it, if your not just doing it all manually....

 

I dont have the iat or tps installed. i didn't know i had to have these installed in order to run the MS with the AFM installed. I have the parts but i didnt want to do anything permanent until i know i can get the car running decently for its my DD. I can check the wideband readings from the stock o2 sensor right?

Im a big visual learner and have serious trouble understanding anything from text as i have trouble visualizing how to apply what im reading to what im actually doing when im hooked up to the MS1. Is it possible to find someone on this website that is experienced with MS and lives near by? Anyways, ill try my best to get these readings and post them for more input.

thanks alot!

 

If the ECU was made for a variable TPS, and you have the stock TPS in there, then each time you don't press the throttle, the ECU shuts down.

 

The car stays on at idle but once i start driving it it shuts off every time i let off the gas.

Is there a way of taking the stock TPS off without damaging it? I tried earlier and it seems pretty snug even without the two screws...

 

Is the connector for the TPS disconnected? It should be.

 

It was connected, i thought i read the install thoroughly... so with the TPS disconnected the car should shut off at idle?

 

No, with a MS set up for vtps running on a car without vtps, you need to leave your on/off tps disconnected to work properly, and use mapdot. Just leave it unplugged.

Also, if you haven't set your timing, do that asap.

 

Yea, my friend has a timing light that he will lend to me but for the next few days ill be at school or work all day. Maybe i can get in there in the morning on Thursday or Friday. If not then ill be working on it on Sunday for sure. Whats a mapdot by the way?

 

It's MegaSquirt guestimating where the throttle is by using manifold air pressure (map). The dot refers to the dot graph it's reading off of. I *think*.

 

The stock TPS needs to be disconnected with a MS that is modded for a vTPS. If you do not disconnect the stock TPS, then the MS shuts down whenever you are not pressing the throttle, because the stock TPS acts as a shortcircuit on the MS' 5V power supply.