Here's something different, LS1 running with all 8 injectors disabled

[evilstuie]

Hi All,

I'm hinting an ongoing problem with my motor that has got me to the point where I'm ready to pack it all in and sell the f+ckin thing.

The tune is set up from speed density (mafless) but won't run without the MAF plugged in and in the intake pipe, with that it will then fire up pretty much straight away.
With the maf not in the intake line it will fire up and immediately die, not sure if its the velocity from the pipe helping or what but that's not the problem.

The car will fire up with the MAF in place, and all looks normal with the o2 sensors while they heat up and run in open loop.
It will increase idle quite a bit, and if I blip the throttle at any point it will rise and hold at around 2700rpm and slowly slowly come down if I do nothing else.

Once the car gets to temp and closed loop kicks in, i look at the left bank headers and they're bright red glowing.
The o2's both start to drop off, and the wideband on the left bank is still sitting around 16-17 which is lean but red glowing header lean at idle?

The intake is a cheap chinse copy of the sniper EFI (fabricated sheet metal) and I was chasing the idea I had a vacuum leak that was leaning it out.
I did a smoke test with a macgyvered smoke machine and found it could keep a rubber glove 3/4 inflated and the only visible smoke was coming through the throttle body shaft. Not sure if these are meant to be fully sealed or if that was the only place the smoke could go and that's normal.

No other vacuum leaks, checked brake booster line, MAP, PCV and valve breathers, no leaks.

The biggest mysery though is once the car started leaning out, I used HP Tuners to disable the injectors one by one to see if there was any data to gain from it, and there was no change to the engine noise except for a split second on disabling injector 1.
I continued to do 3,5,7 and no change then 2,4,6 & 8 expecting it to stall out but nothing... it kept going.....

Is it possible for all 8 injectors to start leaking at the same time and cause this, or do I need to find John Constantine and get an exorcism performed on this monster?

[5FDP]

You could post the tune and logs as well so we could see how it's setup. Might be something wrong with the MAF settings and your timing to make the headers want to glow red.

[evilstuie]

yeah I tried to last night but my garage pc didn't want to play nice with the network. Illpost this afternoon with some other data to help

[evilstuie]

Ok, quick update and some files.
I checked the fuel pressure by turning the pump on and found it was a bit low, about 50 instead of 58 psi, and seem to bleed down faster than normal.
With my return line fuel setup it has always held pressure while running at 58psi, and then when i turn it off drops to 20psi and holds.
Now its dropping to about 10psi but quicker.

So decided to pull the intake and check if maybe a leaky injector was the cause, as well as check the intake gaskets weren't leaking.

Pulled it off and no leaking injector, all held while the pump was going, gaskets looked fine, one or 2 looked pretty close to the edge of the intake ports but nothing warped and still a clear line where they sat.

I haven't done a compression test yet as the f+(kin headers are in the way and can't put the tester on without removing the exhaust completely, but feel confident it's not a mechanical issue or I'd have a noise or the problem replicated on bank 2 as well.

On the left bank glow file, I get the car started at around 10mins30sec. Left bank starts out super rich then leans out once CL kicks in.

Any help is appreciated.

Motor is LS1 stock bottom end, 241 higgins ported heads, VCM710 cam, sheetmetal fabricated intake with 102mm throttle body, drive by cable, 3.5mm hole drilled in the TB plate, stock ls1 injectors (28lb i think)

[crew chief]

I was under the impression that to be mafless you need to fail the MAF. I feel you need P0101 P0102 and P0103 set to MIL on first error otherwise its still looking for the maf sensor

[evilstuie]

I was under the impression that to be mafless you need to fail the MAF. I feel you need P0101 P0102 and P0103 set to MIL on first error otherwise its still looking for the maf sensor

Yeah I saw that.
I had a guy on the forums helping me out with the base tune to get it going but he sent me a couple of different files and I think he was juggling a lot of over the internet tunes so he might have mixed them up.

It was running and idling well for a little while prior to getting the exhaust done on the car.
I thought maybe the o2 banks had been switched when they did the exhaust but i confirmed they're all correct.

We were chasing some ignition and wiring issues that have since been sorted out.

I'm thinking of loading the stock LS1 Auto tune back on and starting from scratch again to see if the problems go away, but the variations from bank to bank keep pointing me away from the tune as the root cause and something else. The tune may well be screwed but fixing that won't fix everything.

[evilstuie]

thumbnail_20220823_152225.jpg

Here's the spark plug from the worst one #7

Still waiting on the new throttle body to arrive so i can swap it and have a new iac and TPS at the same time with the non-drilled plate, put them on and probably block all the vacuum lines at the same time to isolate as much as possible on the stock tune again and see what happens.

[evilstuie]

hmmm... well with no response here I went a-searching again and found the chinesium intake I was using didn't line up with the ported heads very well and was leaking between the heads and intake. Looks like the intake needs to sit 2-3mm further forward.
Now I've got to figure out whether to elongate the bolts to give me the adjustment I need to align it, or try using a single piece intake gasket for each side instead of the individual port seals.

Anyone had a similar issue or luck with the Felpro printoseal gaskets?
head.jpg

[evilstuie]

possibly fixed so I'll test tomorrow, but no-one really answered the question as to how the engine can keep going with HPTuners "Supposedly" disabled the injectors. Or is the software just pretending it can disable them?

[evilstuie]

so another update:

The leak in the intake has been fixed and my idle map reading has gone from 90kpa to 50-60kpa.
The exhaust issue is still there though, and I've confirmed its happening on both sides.
My wideband still says about 15.5:1 and the o2 sensors drop down to about 340mv but i guess that doesn't mean much.
My best guess now is the timing that someone previously mentioned.

Is someone able to take a look at the tune file i posted and tell me if the idle timing is too high for a VCM710 cam:

Duration	232/234
Lobe Separation	@ 110
Valve Inlet	.590"
Exhaust	.596"

Coolant temp jumped to 101 within 3 minutes if running.

Here's the shiny glow:
https://youtu.be/KaDXZmYODn4

[evilstuie]

anyone?

[evilstuie]

Replaced throttle body without hole in the blade and all good now.