Heat Soaked Restart Issues

[edcmat-l1]

Don't be a dick.

The cunt needs to warm up and be sending data before cranking ya fuck stain.

Love you Ed

LOL where's the smooch emoji? LOL

[Cringer]

have u tried raising the maf s/s startup g/s for the hotter temps u only have 7.3 g/s there but ur min air and startup are almost double it so it may be using that table till the maf is good ?

I have tried that. In fact the tune I uploaded called "hjtrbo 20 pct more FA1.hpt" has the MAF SS values set to 20 g/s and I increased the stepdown value as well.

With all the airflow changes I am looking for changes to the calculated cylinder airmass and a corresponding change to the IPW. The strange thing to me is that the cylinder airmass remains flat while cranking, while VVE, MAF, and Dynamic Air all increase....and IPW decreases.

Here is what I mean...
air vs fuel2.jpg

[hjtrbo]

Don't hit me. Back to basics, in the old days they used to say 3 things...

Looking forward to seeing what the wideband reads as it's cranking and running up.

[ns158sl]

I dont think cranking fuel has much input from MAF/Dyn, being that MAF reading is extremely inaccurate at cranking speeds.. InjPW is going down based off MAP from the OL IVT table. FA fuel and OL tables are pretty much the only ones that affect cranking related to heatsoak issues. Try leaning it out in your problem areas with a preheated WB that doesnt cutout when cranking, like a separate battery if needed, and see what happens.

[07GTS]

I have tried that. In fact the tune I uploaded called "hjtrbo 20 pct more FA1.hpt" has the MAF SS values set to 20 g/s and I increased the stepdown value as well.

With all the airflow changes I am looking for changes to the calculated cylinder airmass and a corresponding change to the IPW. The strange thing to me is that the cylinder airmass remains flat while cranking, while VVE, MAF, and Dynamic Air all increase....and IPW decreases.

Here is what I mean...
air vs fuel2.jpg

yea that does look odd, ok just went over a few things purely for a test see if its any better or could be worse

[Cringer]

yea that does look odd, ok just went over a few things purely for a test see if its any better or could be worse

Wideband output added.

Results: not much changed. However, it is interesting to note that the 30 minute heat soak test did reveal a nice initial RPM spike up to 333 rpm right at the start of cranking. Then...as always IPW drops. But seems like a step in the right direction. Would the next step be adding fuel to the IVT gas gain since it takes MAP into account (need to add more to the 95 kPa region)?

I appreciate this 07GTS!

Cold Start.hpl
Warm Start after a couple minutes of idling.hpl
Hot restart after 16 second shutdown.hpl
Heat Soak 30 minutes.hpl

[hjtrbo]

Wideband is definitely leaner on the 30min restart vs the 16sec.

[ns158sl]

I guess being that was a drastic change, you could split the difference to see where the engine is happy. Id definitely leave the added crank spark. What size cam? A lot of stock cal's will lean out the FA around 300-600 seconds, probably for the idea of fuel evaporating as it is sitting. How far off from stock are you with the EQ and Injtemp tables?

[07GTS]

Wideband output added.

Results: not much changed. However, it is interesting to note that the 30 minute heat soak test did reveal a nice initial RPM spike up to 333 rpm right at the start of cranking. Then...as always IPW drops. But seems like a step in the right direction. Would the next step be adding fuel to the IVT gas gain since it takes MAP into account (need to add more to the 95 kPa region)?

I appreciate this 07GTS!

ok yea that spike in rpm is usually where it should fire up into run, try this one its just a little more changes crank fuel and spark hope the spark might help catch the peak rpm to keep it going and little more fuel as it seems lean, see which direction it goes if its better might just need more crank fuel, also your injectors are within that manifold i seen in your videos ? they may be getting hotter within same with the fuel in the lines could all be evaporating faster on the hotter start, also noticed u have flex is this on petrol or ethanol ?

[Cringer]

ok yea that spike in rpm is usually where it should fire up into run, try this one its just a little more changes crank fuel and spark hope the spark might help catch the peak rpm to keep it going and little more fuel as it seems lean, see which direction it goes if its better might just need more crank fuel, also your injectors are within that manifold i seen in your videos ? they may be getting hotter within same with the fuel in the lines could all be evaporating faster on the hotter start, also noticed u have flex is this on petrol or ethanol ?

No change, unfortunately. This is what I always run into. Cold and hot starts are seemingly unimpacted. Also, heat soaked starts are unimpacted. It is like nothing ever changes.

Current Tune1 07gts test2 - cold start.hpl
Current Tune1 07gts test2 - hot start 103 sec.hpl
Current Tune1 07gts test2 - heat soak 31 min.hpl

[Cringer]

So this is interesting. I did my normal 30 minute shut down heat soak interval, but this time I opened the hood and put a small fan directly on the ECT sensor....

Normal/No Fan 30 min:

• ECT 190*F (87*C)
• IVT 190*F (87*C)
• Tip 170*F (76*C)
• Lambda was .74

Hood Open with small Fan 30 minutes:

• ECT 158*F (70*C)
• IVT 158*F (70*C)
• Tip 142*F (61*C)
• Lambda was .72

On start up the RPM's jumped to ~450 and waffled before finally starting. Overall much better with the artificial cooling. To me this sounds like the injector offset temp numbers are too high (spraying too much fuel).

Which brings me too...

ok yea that spike in rpm is usually where it should fire up into run, try this one its just a little more changes crank fuel and spark hope the spark might help catch the peak rpm to keep it going and little more fuel as it seems lean, see which direction it goes if its better might just need more crank fuel, also your injectors are within that manifold i seen in your videos ? they may be getting hotter within same with the fuel in the lines could all be evaporating faster on the hotter start, also noticed u have flex is this on petrol or ethanol ?

These are FID injectors (not a typo, not ID, not FIC). I could only get sketchy data so I sent them to Greg Banish for the official testing and am using his data. Unfortunately, he did not provide the offset temp data in his results. I asked him specifically if I should zero it out and he said no, but didn't offer any help beyond that.

Also I am back to the OEM LS3 (rod mod) manifold and throttle body for now. I will probably revisit the XS LS3 manifold at a later time.

But to be fair, this hot start issue was always a problem even on the factory LS3 injectors and factory L96 injectors. Though it is worse with these FID injectors.

Current Tune1 07gts test2 - heat soak 30 min with fan on ECT sensor.hpl

[Cringer]

I guess being that was a drastic change, you could split the difference to see where the engine is happy. Id definitely leave the added crank spark. What size cam? A lot of stock cal's will lean out the FA around 300-600 seconds, probably for the idea of fuel evaporating as it is sitting. How far off from stock are you with the EQ and Injtemp tables?

GPI SS3 cam 233* / 253* duration at 050 and .646" / .637" valve lift.

I have been using PPV flex fuel startup stuff including the FA1 table. Not sure how I got the offset numbers...they don't match the LS3 or L96 injectors...maybe it came from the initial sketchy data I got with them prior to sending off to Greg Banish. Based on my fan testing it sounds like the temp offset is too high.

[07GTS]

ok few more changes clutching at straws, just had to move some changes around to get the heat soak temp range better

[ns158sl]

I think I would use a injector tip temp table from a L96 and leave it. By rights that is a characterization of the injector. Thats why I thought it was weird people were playing with it to cover up thee ol rich after flash lol. I think then leaving that as a constant, then start adjusting OL EQ and FA fueling. My guess FA fueling will probably be your best bet.

[GHuggins]

Tip temp should be dialed in. I dial them in on all of them I do. Airflow changes through the motor changes the fuels effects, thus changing the tip temp characterization. I've not had a hot start issue because of it. In fact I've greatly helped hot start issues dialing it in

For most - .0078 is good for about 1% trim change.

That cam shouldn't have hot start issues, at least I haven't seen any from it. That's a pretty nice cam for an ls3 too.

[Cringer]

For the record I'm NOT advocating zeroing out the tip temp offset table! I would do anything to get the correct values! Until then messing with it is going to be a diagnostic tool until I can get decent heat soaked starts. Once it is reliable I can slowly add it back in and adjust the OL tables I guess.

[ns158sl]

Airflow changes through the motor changes the fuels effects

My understanding is it is how the actual injector is delayed from actual tip temperature? So if the engine is delivering the same ECT/IAT/MAT/Runtime, it would be calculated the same even if the airflow changed? Especially if the MAF/VE table is calibrated, then the TIP temp would be adjusted for airflow in the PCM?

[GHuggins]

As best I've concluded, which can be 100% incorrect, tip temp especially on the newer ones seems to be characterized for a running engine and is why you can take the same injector and have completely different cals for it in different motors. Granted gen 4's seem to have been done separately, but I still adjust it with the same thought process. Doing this keeps fueling exactly the same for all operating ranges. Doesn't have anything necessarily to do with hot after flash, but instead hot after flash can be used to dial it in if you drive it and correct from the same style driving log after hot flashing. This will keep hot restart fueling the same as cold start as long as you don't have something unusual going on elsewhere.

Is this hot soak restart issue only with alcohol? OR is it all the time? Is it really only "3" seconds to fire? Just making sure I understand it correctly.

[ns158sl]

So that would fix the issues related to closed loop fuel trims?

[GHuggins]

So that would fix the issues related to closed loop fuel trims?

Yes and open loop fueling for the whole temp range. However, this doesn't mean that it may not need to be 0ed out. I actually just checked the last stage 3 and 1 gpi cams both that I did I had found it needed to be completely 0ed, but I was running injection just above 520 boundary on the stage 3 and 540 on the stage 1 for the best fueling.

EDIT - This is a completely different "decent" cam in an ls3 just for reference. I've dialed it in to be good to 110 C.... The method may not be correct, but it works even with hard driving coming up from a cold start to keep fueling in line. Then for what it's worth, this one actually had a hot start stall issue in the area that was overly rich and I had to remove fuel from. After fixing this, that problem went away.

tip temp.jpg