no rpm while cranking

[Matt Cramer]

Check your VREF with the key on and engine off. An improperly wired up TPS can pull down this voltage when the throttle is closed and cause all sorts of trouble.

[akeboshi]

I cut the wires going to the tps off and capped them and now the tps signal starts at -18 and gradually goes up to like 43%. that's with the vref, signal and ground disconnected from the harness. Is it supposed to do that? Anyways I didn't like how the soldr joints looked on the db37 connector do I desoldered them and cleaned the flux off with alcohol and hot water. I'll desolate them back today and try again. I also separate the grounds alittle bit, all the sonsor grounds are crimped together and bolted to the firewall and the db37 grounds and sideband grounds Are on battery negative. I was just wondering if my msa files looked ok? I'll post again after the board dries out.

[trakkies]

IMHO, the sensor grounds should only go to the DB37. Grounding them elsewhere as well will likely cause stray currents to flow in them.

[Matt Cramer]

I cut the wires going to the tps off and capped them and now the tps signal starts at -18 and gradually goes up to like 43%. that's with the vref, signal and ground disconnected from the harness. Is it supposed to do that? Anyways I didn't like how the soldr joints looked on the db37 connector do I desoldered them and cleaned the flux off with alcohol and hot water. I'll desolate them back today and try again. I also separate the grounds alittle bit, all the sonsor grounds are crimped together and bolted to the firewall and the db37 grounds and sideband grounds Are on battery negative. I was just wondering if my msa files looked ok? I'll post again after the board dries out.

Yes, the TPS signal will float upward if you don't have anything connected. Does the RPM problem go away?

As Trakkies mentioned, the sensors need to be grounded to the MS, not the chassis; grounding the sensors to the firewall is a recipe for noise.

I did not check the MSQ file as there is no setting that will cause it to ignore RPM without a TPS reading. This sounds like a hardware issue.

[akeboshi]

It's been a while since I messed with the car but I was curious about how I ground sensor wires to the megasquirt? Do I run the wires to the db37 and solder them to the ground wires going out or do I solder them to unused solder cups? If so which cups can I use?

[trakkies]

It's been a while since I messed with the car but I was curious about how I ground sensor wires to the megasquirt? Do I run the wires to the db37 and solder them to the ground wires going out or do I solder them to unused solder cups? If so which cups can I use?

Since there's little current flowing in them, what I did was one very short tail to pin 19 as shown in the MS diagram, and all the sensor grounds to that. Fitted inside the DB37 shell.

[akeboshi]

thanks for the explanation trakkies, it helped me alot! i was wondering why the sensor grounds were white triangles in the wiring diagram vs the regular black ones. your comment made me look at it again and it actually says sensor grounds..... right over my head. now my tack is very smooth and the resetting has gone away. i will definitley document that on my lessons learned. anyways i was trying to start her again and im not getting spark on cylinder 1 and 5. 2,3,4 and 6 all have very strong spark (i checked this by unplugging injectors and one at a time pulling the plug from block and watching air gap) i cleaned up the rotor and checked cap for anything obvious and put everything back (they are pretty much brand new, just sit for a while) and i switched plug wires to make sure it wasnt just the wires. still nothing. i did however see a weak spark JUST ONCE on number one plug. would this be a bip 373 problem or under the hood problem. ill dig out the reciept from autozone tomorrow and take the wires/rotor/cap back and get new ones to try again. thanks for all the help.

[Matt Cramer]

What's the firing order? This is not likely to be a BIP373 problem. There is a chance it's a weird settings problem, but it's more likely to be an underhood issue.

[akeboshi]

firing order is 153624. i was hoping thats you wouldnt say that because everything is new. cap rotor dizzy coil, everything. what would prevent spark from going to 1 and 5 and give awesome spark to everything else. i cant check timing because of this problem. i looked but didnt see a setting for number of cylinders for spark, just number of injectors.

[Matt Cramer]

Having it skip two consecutive cylinders would take some very odd wrong settings or a spark cut rev limiter, but please post your MSQ anyway. I would suspect the spark plugs or wires.

[akeboshi]

you were right about the plugs. i put a timing light on #1 wire and it was making the light flash but no spark was coming out.i got spark to both plugs now but heres something i dont understand, i get 5 degrees of timing if i hook up the light to #6 cylinder wire but i cant even see the mark on #1 wire? i thought maybe the distibutor was 180 out so i checked just to make sure i put the engine to tdc on the compression stroke (removed plug) and i felt a bunch of air come out the hole. when i looked the mark was at 0 deg on the spot and i took off the dizzy cap and the rotor was pointing to #1 plug. i also checked the lobes on the cam. what gives? it wont even try to start. do i have something off under the hood or on my tune? also what do i need to set the input capture to? rising or falling edge?

[Matt Cramer]

you were right about the plugs. i put a timing light on #1 wire and it was making the light flash but no spark was coming out.i got spark to both plugs now but heres something i dont understand, i get 5 degrees of timing if i hook up the light to #6 cylinder wire but i cant even see the mark on #1 wire? i thought maybe the distibutor was 180 out so i checked just to make sure i put the engine to tdc on the compression stroke (removed plug) and i felt a bunch of air come out the hole. when i looked the mark was at 0 deg on the spot and i took off the dizzy cap and the rotor was pointing to #1 plug. i also checked the lobes on the cam. what gives? it wont even try to start. do i have something off under the hood or on my tune? also what do i need to set the input capture to? rising or falling edge?

Maybe your coil needs more dwell to get a hot enough spark. What condition are the plugs and wires in?

The ignition input capture needs to be set to whatever gives you a steady timing reading across the entire RPM range.

[akeboshi]

i just got BRAND NEW plugs for the engine but they were cheapies because i fouled up the good ones. wires are new about a year ago but they have only seen like 30 miles of use and car is always garaged. i can exchange them for free though. ill try more dwell when i get a chance. how much should i start with? 3.5? 4? im using a blaster 2 if that helps. btw i thought that the spark looked alittle weak on 1 and 5. also what would be the explanation for me seeing the timing marks on #6 vs #1. i dont get why i could see it on #6 and not #1 because if my thought pattern is correct im seeing the timing marks on the crank pulley when that cylinder is on the exhaust stroke no?

p.s. how did all my settings look?

[Matt Cramer]

It appears your spark on cylinder 1 is not strong enough to trigger the timing light.

[akeboshi]

its making the timing light flash but the mark on the pulley is not around on #1 but is on #6

[akeboshi]

ITS ALLLLIIIIIIIIIIVVVVVVVEEEEEEEEE!!!!!!! HAHAHAHAHHAHA!!!!!

[akeboshi]

hello and thanks again to everyone that has helped me thus far with getting my megasquirt installed and running. i have made alot of silly mistakes along the way but you all helped me though it to see another sucessful build. ill probably be here again but getting the car to start has been the biggest milestone for me. there were a few times when i was about to give up but i was able to sit down and think it out (slowly) and figure out the problems (even though they were noob mistakes) i think the real and only problem with this build was my inexperience (this was my first time soldering and wiring after all, and for the record im color blind lol) AND the fact that i did not ground the sensors right. i really did not notice this on the drawings for the v3 wiring and between that and creating other problems from not noticing that i thought i had messed up my controller and wiring numerous times. just so you guys know what to expect from not connecting the sensor grounds to pin 19 it is as follows,

i just took every single wire including the sensor wires and all of the megasquirt wires and soldered them together and bolted them all to the negative battery terminal. because i did this i had fuses blow out on the injectors twice, i had very unstable rpm readings. there were actually lots of symtoms from this including what i thought was the wierdest one was i only got an rpm signal when i pressed the throttle. wierd huh? also the controller would reset very rapidly while cranking causing the relays to click rapidly. i had a feeling after doing some research that it was ground related but i was looking in the wrong place for the gound. it wasnt until i asked trakkies how to ground to the contoller that i realised the mistake that i did. after i got everything straightened out the car unbelievably started on the stock megatune msq. unbelievable! i would say that this project has taught me so much about cars and also given me a new respect for anyone that does this successfully. it was worth the money just for the products but the support is just as great. thanks to matt and DIYAutoTune.com and everyone who has helped me!
marcus