427 SBC** Update..now starts..but ..)**

[91blkvette]

Not been able to get this engine to run. It's trying to, but something is holding it back. ***CORRECTED**

Motor is in a C4 Corvette. MS3/3X was wired in with the factory ECU, now the fECU only controls the gauges. Stated out using the HEI7 distrib & ignition, but noticed only 7 cylinders were firing ( fixed inj wiring). Also realized the ECU was shutting off the fuel pump, added fuel pump control to MS3, good fuel press now. Changed the HEI7 out for an MSD HEI8 ( planning on installing a customized Holly Stealth Ram). Currently using a Superram intake with a 58mm BBK Throttle Body.

[billr]

Hmm, nobody else has jumped in, so I'll try to get this moving...

Why is your req_fuel set to about double the calculated value? Have you tried speed-density? Have you positively-for-certain verified ignition timing at the crank is the same as what MS thinks it is? What is the cranking compression?

A question for all folks out there: I thought the req_fuel calculation included a data box for stoic of the fuel to be used, I'm not seeing that now. Was that removed (and why), or am I just confused? Isn't the stoichiometric AFR a required factor for determining req_fuel correctly?

[91blkvette]

First..the good new.. I now have an engine that starts .. Went back to an older tune that got a short run before sucking the rails dry (due to the Corvette ECU controlling fuel and shutting off the relay, now MS controls the pump). I also noticed that required fuel change from other tunes I had.

Now I have a different problem with a high idle (~1500 rpms). and I have to put some throttle in to get it started.

Have not verified idle timing yet due to 1) that high RPM, 2) the remote oil filter mount I had to use due to running ARH headers, is dripping oil on the headers (no bueno), 3) I noticed that my TPS reading drops to 0 after a few seconds.. But..to answer your questions this is a big cam, 10.65 comp, with 230 Dart Pro 1 heads .

So..I have some issues to sort out..but progress. New files attached.

[billr]

I'm not accepting any excuses for checking ignition timing. Set it for "fixed" and check at cranking, that 1500 rpm "idle", and all the way up to your max speed. It should stay the same at all speeds. I see the fueling load is now speed-density, but ignition load is still alpha-N. I expect it can work that way, but would sure be more confusing for me. More to the point, using MAP vs. rpm for the spark table is much more common, it is the way dizzy curves were done for years when there were only centrifugal and vacuum advance available; you will probably have a better chance of finding help (here and other places) relating to an S-D based spark table.

Edit: Are you at high altitude, is that why the MAP never gets above about 80 kPa? I am puzzling about how your battery voltage is getting recorded down to .2V, I would think the MS would go off-line well before that and stop sending data for TS to record.

[91blkvette]

I'm not accepting any excuses for checking ignition timing. Set it for "fixed" and check at cranking, that 1500 rpm "idle", and all the way up to your max speed. It should stay the same at all speeds. I see the fueling load is now speed-density, but ignition load is still alpha-N. I expect it can work that way, but would sure be more confusing for me. More to the point, using MAP vs. rpm for the spark table is much more common, it is the way dizzy curves were done for years when there were only centrifugal and vacuum advance available; you will probably have a better chance of finding help (here and other places) relating to an S-D based spark table.

Edit: Are you at high altitude, is that why the MAP never gets above about 80 kPa? I am puzzling about how your battery voltage is getting recorded down to .2V, I would think the MS would go off-line well before that and stop sending data for TS to record.

As I said before..I have oil dripping on my headers..and I don't want my Vette...in addition to the $14K or so new stuff I've invested in, to catch on fire. So I run it briefly and resolve one problem at a time.

I changed fuel to SD.. and over-looked the ign load. Will change that before next attempt at start. Also noted the MAP reading ( only about 100' above MSL here). Should be 100..

Battery voltage @ .2v? Something isn't right, I'll investigate that too.


Thanks for looking at this..

[billr]

Yeah, get the oil leak fixed, that is the "first" thing to do. Still, you could (and should, at initial install) check timing while cranking, no ignition or fuel, with no danger of fire...

[91blkvette]

Yeah, get the oil leak fixed, that is the "first" thing to do. Still, you could (and should, at initial install) check timing while cranking, no ignition or fuel, with no danger of fire...

Did that a long time ago ..must had about a hour's worth of 10 sec video clips of checking cranking timing. Videocam on a tripod works well when you don't have helping hands..

[kaeman]

I guess that your are running small or stock throttle body, which is why the kpa never gets higher than 80... because the tps says you are only opening the throttle 16% positive and -4% negative. you need to recalibrate your tps sensor. so it doesn't go into the negative numbers. Did you open your throttle more than 20 %? If so you have some serious restriction in your intake air ducting or a plugged filter. Did you calibrate your map sensor?

[billr]

That 80+ kPa max MAP was with the engine not running, TB size should have no effect. I think the OP knows max MAP should be about 100 kPa at only 100' altitude.

[91blkvette]

I guess that your are running small or stock throttle body, which is why the kpa never gets higher than 80... because the tps says you are only opening the throttle 16% positive and -4% negative. you need to recalibrate your tps sensor. so it doesn't go into the negative numbers. Did you open your throttle more than 20 %? If so you have some serious restriction in your intake air ducting or a plugged filter. Did you calibrate your map sensor?

Found out why the MAP reading was incorrect. If you select the wrong one..well.