hello rx7 crew, i am a high school senior and i resonantly made the transition from the 13b to the ls1. I decided to use the micro-squirt ecu. i wired the engine completely and had a friend who wires cars for a living look over my wiring. here is the problem. a few weeks ago we did the first start up. the engine started up immediately on the first try, and ran good. a few weeks later i installed the radiator, filled with coolant and started it up again (no wiring was touched during install). the engine and it ran good, let it warm up/burp. My o2 sensor had not been working correctly at the time (bc i wired it wrong, sent the wide-band ground to the "sensor ground" instead of the "chassis ground") i was the o2 sensor was not reading so i killed the motor and was going to adjust some o2 sensor settings, ended up not changing any thing. went to start the motor again and it would not run. when ever i went to turn the starter over the computer lost connection to the ecu. now the computer can not connect at all. sometimes the computer will randomly connect to the ecu, but again whenever i turn over the motor it looses connection.
a friend of mine says it is most likely the computer because in the lower right hand corner of the turner-studio it says, "the info is invalid". i disagree, because when i do a port search on turner-studio it comes up empty handed most of the time. some times, again randomly, it will pick up a connection and say, "Found: 91 On RXTX: Port:COM4, Baud:115200". will click accept, then pop up will show saying i need to change ecu definition. i have changed the "ecu definition" multiple times to the different preset files, but sill no luck. it is the most random and difficult problem i have come across on a car. it confuses the hell out of me. and pisses me off because im so close to being back on the track.

FYI:
has fuel
getting spark
getting air
crappy computer (needs to be puged in at all times, slow af)(just orderd my comuper for college "lenovo ideapad700" we will see if that has any effect)
using USB to serial adapter
no blown fuses
ecu has ground and pwr
random connection at times
when connected looses connection when cranking

any help would most apreciated!

thanks,

alex

 

First, make sure that your wiring is solid with respect to power and ground to the ECU. Not to assume your friend doesn't know what he/she is doing, but most installations I see from "automotive wiring experts" I wouldn't touch with a 10 foot pole because replacing all the wire nuts, lamp cord, Vice-grip crimped joints, re-used connectors, cold solders, non-adhesive heat shrink and such basically mean a full rewire.

Is your ECU receiving power from the starter lug? Very common to do and absolutely wrong.

Where is the ECU grounded? It needs a SOLID battery ground or SOLID engine ground.

Is the engine block grounded properly? At least two large ground straps (4 gauge or larger) to the chassis.

Battery grounded properly? At least a large strap to the chassis. Personally I like to ground the battery to the chassis and the starter.

Where is the ECU getting switched 12V from?

If all of that checks out, then re-flash the firmware on the ECU and re-load your map from a backup.

 

agree with all that. connect a voltmeter to the + and gnd at the ecu, see what voltage you have, then watch if it goes down when you crank the engine. if it does, something is wrong*, probably something quoted above. post what happens w/above test and can suggest more then if desired.

*edit: if it goes down a lot, i meant...