I’m hoping to bounce some ideas off some experts regarding my first start-up on my first build. Engine is on a test stand with accessories on. Oil pressure is good on a mechanical gauge.

The engine has started, but only with throttle and will only idle with throttle. Throttle response felt sluggish, and i couldn’t get it to blip to 3,000rpm. It usually backfired out exhaust as it dies. I was able to get a scan using hp tuners. I’m still pretty new to tuning but i saw my O2’s were at 0-20mV the whole time, which I believe is maxed out lean. I checked a spark plug and it was black, so I assumed I had a false lean reading due to one of two things: A) O2 too close to exhaust exit (they were in long tube header collector, nothing after that) or B) header not fit tightly against header due to the header hitting the stand. I remedied both of those issues by notching my stand until the headers fit right and clamping a tail pipe extension on my collectors. Reset LT fuel trims, and O2 readings were better (~300-450mV), but then I couldn’t get it to start last time I tried.

I am fairly certain I am fighting a bad battery, which is not helping the starting problem, but I had been able to jump it with my truck up til my last attempt, when even that wouldn’t do it. Is it possible a dead or dying battery could be giving my pcm/sensors trouble due to low voltage?

along with the battery, maybe I have a loose or not connect ground.

Could my lifters not be filling with oil? Will they fill with oil at cranking speed?

My plan is to try a different battery, check for sparks and fuel in each hole, crank motor without sparks or fuel until I see oil in the valve train.

My tune should be close enough to start idle I think. (First try at it though so who knows lol)

Is there anything else I need to check? Any help would be appreciated.

engine:
6.0 .005 over w/ 4” stroke for a 403
236/244 112+3 @.050 Camshaft
Trickflow 225 cathedral heads
johnson hydraulic roller lifters
11.38 static compression
8.3-8.5ish dynamic CR can’t remember atm
93 oct fuel
340lph pump
60lb injectors
60 psi fuel on the regulator (after the rails)
fast lsxrt102 intake w/ 102 throttle body
stock 78mm maf
when it started i had 50-70kpa on the map with throttle cracked just enough to stay lit

 

Your tune probably needs work. Why don't you post it up so people can give you pointers.

 

By all means. This is my very first try so be gentle lol. Also be sure to explain why to make recommended changes, for my education.

 

Here are 3 scans of the engine - one with the above tune, two scans with some fuel added during cranking. I am starting to wonder if I am having an electrical issue. It wont start most of the time, and when it does, something seems to either cut fuel or retard the spark - you can see the rpm drop despite me holding the throttle +20% open. I didn't see any knock codes, just the EGR low voltage. I did verify that lifters are full of oil, and that each plug was sparking. I did notice after a while that 5/8 header tubes were hot to touch, while the other three were merely warm. 1, 2, and either 3 or 4 were warm while the others were almost too hot to touch.

 

As an update: I had plugs that were fouled - it looked like potentially oil fouled so I ran a compression test to rule out rings or head gasket. Every cylinder compressed to between 187 and 205 psi. I also get black smoke, not blue smoke so probably not oil fouled plugs. I used a noid light to check for pulses at the injectors, all of them pulsed. I cleaned the spark plugs to try again today. Removed the air filter because it looked dirty. When I did the scan during crank and very brief fire, I got knock retard. I don't know why it wasn't showing before, but you can see the KR go up and spark drop in the scan log. I tried taking timing out (not 100% sure if I was in the right table or not) but it didn't seem to make any difference. I took as much as 7 degrees of timing out before I decided to punt for the night and see if I could find any information online. Plugs look rich, but they should be rich during cold start so I don't know if that's a problem or not. Plugs in order of which cylinder they came out of. At this point my only idea is to try a gallon of octane booster or race fuel just to see if they eliminates the knock retard.