5-0 Ignite hot start issue

S15 SR20, running a Link G4. Wring harness is stock and .5mm air gap from wheel to sensor. Car had no issues on the dyno, no misfires or crank signals missed. Starts fine when cold or after an hour or so of sitting.

If car hot soaks for a few minutes it's hard to start and you can watch missed crank signals start counting up, engine does attempt to start but just stumbles. If I clear flood and crank for a few seconds I'm able to get the engine to fire up.

I have tried a few changes on the hot start fuel but it doesn't seem to change it.

If anyone has some tip and tricks before I drop down the rabbit hole for hours.

If you hook it up to a battery tender while it’s heat soaking, does hot start improve? Cranking rpm and voltage can make it or break it especially with big injectors and non-factory coil dwell settings. At least see if giving it a little more juice while cranking improves the missed triggers.

Do you have a log of the warm crank?

it sounds like it might be getting too much fuel from what you're describing by it starting after a flood clear

Ok tried the battery charger and booster pack, no change. Tried changing the grounding point on the battery to the engine and no change.

I do need to crank it for a bit and possibly a few times in flood clear to get it to start.

Starts awesome cold, fires right up and if you let it sit about an hour it will fire back up aswell after drive.

I got to do some logs tomorrow.

Ok, that eliminates a big chunk of variables.

The missed trigger thing might not be problem.

As the other post said, pull some fuel out.

I believe the link has a few different schemes for starting fuel so it’s hard to make a specific recommendation on what to adjust. It will depend on how you have it setup. Don’t be afraid to cut it all out and slowly start reintroducing it.

Here's the Link strategy for starting fuel.

If you can log these parameters, voltage, RPM, ign angle, etc you'll get a good picture as to what you need to adjust

If the trigger error counter is increasing when cranking then there is a trigger issue. Adjusting fuel settings isnt going to fix a trigger issue. If it is a old "non-plus" G4 then unfortunately there is no built-in trigger scope so you will need to either invest in a standalone scope or take the car to someone who has a scope, you are unlikely to be able to solve a trigger issue without seeing what is actually wrong with the signal first.

What specific trigger kit do you have?

So where I'm at, I did a trigger scope and there is some noise when the engine is running. 5-0 Ignite would like new shielded wiring from the Link to the sensor and powered off the 5V ref and not the 12V.

Battery Voltage keeps dropping below 10V cranking, did a voltage drop test on ground circuit and I got over 500mV drop. I need to redo the battery feed and ground. Tested battery with my tester and its saids its good. I would like to install a larger battery aswell.

Engine continues to start good cold so the customer is enjoying going to meets and shows so they can't have the car down for more than a day.

None of that sounds all that relevant. "Noise" is unlikely to cause a trigger error at cranking speed. I cant see how changing the sensor power supply to 5V is going to be any better than 12V? The signal only needs to cross the same 2V threshold regardless of supply voltage.

You mentioned "trigger scope", that suggests you dont have a G4 ecu, so what ECU do you have? Can you attach a scope capture taken when the engine wont start.

Attached is current tune file, a trigger scope while running and a lengthy datalog of car starting from "cold" and then being restarted multiple times until it eventually displays the no start issue.

(Accidentally saved the no start trigger scope improperly so it has no data, will have to redo)

**I do understand that the battery voltage is dropping well beyond ideal and this often causes various driver issues - however a booster pack only allows the engine to crank faster/longer and eventually "catch" - also while on the dyno we used a Snap-on professional charger equipped with a high amperage programming/start feature and the problem persisted even when cranking voltage was held at 14.7v

Hi Dave,

What injector size are you running in this car?

During cranking, it only delivers 0.7% injector duty in initial cranking and doesn't get the engine going until it is over 2%.

The engine has ID-1050 in it.

Really need a triggerscope capture when it is playing up to confirm, but there are a couple of clues in the log that suggest that it is something around the missing tooth gap that the ecu is not happy with. Whenever the trigger error occurs and the sync resets the last trigger 1 state before it happened was "tooth after gap". This suggests the ecu didnt receive the first edge after the gap at the crank angle it expected.

Have you confirmed the sensor air-gap is still within the specified 0.4-0.8mm when hot?

If the air gap is correct, one thing that would be worth trying is changing the trigger 1 edge to rising as some hall or prox sensors at low speed will have one edge that is accurate while the other edge may drift around. You will need to re set the base timing after changing the edge.

I got the car for a few days this week, I'm going to remove the valve cover when hot and check sensor clearance. I've also talked to 5-0 Ignite and they think the off-set is to high at -117 and it should be closer to -97.

I need to recheck everything but I think it runs to good for the timing chain to be off.

OK warmed up the car and checked the sensor air gap and its .4mm, removed a shim and checked it cold and its .7mm. Talked to 5-0 Ignite and they say .7mm to 1.1mm for air gap but there instructions say .4mm to .8MM air gap.

So I'm going to try it and see what happens.

So in the end what fixed the hot start issue was to remove another tooth and make the gap -2.

At this point is starts and runs now when hot.