Need advice on tune and MAF tables

[dermotw]

Hi,

Well here's my current tune, please remember my engine is quite a lot different, even if I do have same MAF...

The outside temp does have an effect, and if it's cold it's more critical that the numbers are somewhere near right, but what you are describing is more than some minor inaccuracy!

http://www.vf750.co.uk/imagedump/all_on_128.hpt

Are you sure that there isn't something else? I also don't see how your injectors can be saying they are open a lot (big MS numbers) and duty cycle low at the same time. Even if you are swapping injectors as well as manifold, STILL the numbers are what is commanded, and that is decided by the tune...

If your injectors are swapped with manifold and they are wayyyyy too big, then the fueling will go to hell, but the MS numbers would be same I think, just the big injectors dump much too much fuel for same period opening.

I had assumed you knew, but swapping injectors is a fairly precise business, you need EXACT figures for some tables before you even begin. No trial and error.... However your existing inj. would be fine I would have thought.

kr D.

[Nickatina7]

Only thing I'm noticing is when I have my regular intake on the injector m/s is as high as 14ms when cranking the engine. And when I throw the c6 intake on it is as high as 33ms when cranking. Duty cycle in both is about the same. This is in SD mode and in a regular tune. And I can smell gas when it dies with the c6 intake on. So it's dumping lots of fuel in with that intake on for some reason. And this is with the card IAT and the LS1 IAT. It's like the tune does not like the air flow at all from this corvette intake I guess. Kinda lost on what to do.

[Nickatina7]

Same injectors?

Yes. Same stock injectors from the GTO

[dermotw]

I'm hoping that "stock injectors from the GTO" means "the same injectors as I had on the original manifold". As I said, injector change <<IS>> a big deal...

Here's a pic of my startup from cold. Within 1 second of startup, I am at about 4.5Ms inj. pulse. It's 4.5 because its unusually cold here at 17C when I started it, lol, and the commanded afr is 10:1 then, as you see in the graph. During actual cranking it says all sorts of numbers for injector timing, some of which are probably balls... It will rapidly goto 14.7:1 or so air/fuel (way before its fully warm).

Capture.JPG

Now here is it idling after a run: about 2.5Ms, which is "reasonable" for idle.

warm.JPG

-and finally, at around 5200 rpm in 2nd, about 12.2 Ms / 45%. I run socalled "36lb" injectors, i.e. bigger. Standard LS1 ones from my year were 28 lb (If I remember right!). The originals would have worked in general but they'd have gotten a bit desperate at 6500rpm in 5th etc! The 36's get to around 85% duty cycle at full throttle/high gears.

5200.JPG

I can't escape from the idea that there is something fundamentally wrong/not setup properly for you to have numbers like you have reported...

kr D.

[Nickatina7]

Oh I'm sorry I don't mean I'm putting a c6 manifold on there. Just the intake from the corvette. Not the intake manifold. The engine is all stock. Stock injectors and stock intake manifold. And those GTOs come with an LS6 intake manifold.

[Nickatina7]

I'm hoping that "stock injectors from the GTO" means "the same injectors as I had on the original manifold". As I said, injector change <<IS>> a big deal...

Here's a pic of my startup from cold. Within 1 second of startup, I am at about 4.5Ms inj. pulse. It's 4.5 because its unusually cold here at 17C when I started it, lol, and the commanded afr is 10:1 then, as you see in the graph. During actual cranking it says all sorts of numbers for injector timing, some of which are probably balls... It will rapidly goto 14.7:1 or so air/fuel (way before its fully warm).

Capture.JPG

Now here is it idling after a run: about 2.5Ms, which is "reasonable" for idle.

warm.JPG

-and finally, at around 5200 rpm in 2nd, about 12.2 Ms / 45%. I run socalled "36lb" injectors, i.e. bigger. Standard LS1 ones from my year were 28 lb (If I remember right!). The originals would have worked in general but they'd have gotten a bit desperate at 6500rpm in 5th etc! The 36's get to around 85% duty cycle at full throttle/high gears.

5200.JPG

I can't escape from the idea that there is something fundamentally wrong/not setup properly for you to have numbers like you have reported...

kr D.

So my car will look just like yours when started and when it warms up. With my 90* intake tube and filter with LS1 MAF. But when I stop that and bolt on my C6 corvette over the radiator intake with the card type MAF it will not stay running what so ever. It will start then sputter and die. And this is every time, with my stock tune, with my stock tune with the card MAF and IAT values entered in, with my stock tune with the old MAF values and card type IAT values entered, and even in SD mode with the MAF disconnected and the MAF failure (p0103) set on first error. With my other intake tube and filter etc it will run with my regular tune and will run in speed density mode with MAF disabled. It will just run a little rich but STFT will start to even out the AFR, and I'll have LTFT disabled.

[Nickatina7]

I can post a log of my car running normal and in SD tuning mode with the regular intake tube attached. Then I can post a log of it starting and dying with the c6 over the radiator intake in SD mode and with the regular tune.

When I get to wifi I can. Otherwise there might be data I've posted back in the thread a little bit.

[dermotw]

Hmm. Well thats just more confusing then. Since you apparently get MAF frequency data and reasonable temp data you can't have a wiring error, and from what you say, only the maf/iat are changed at all.

BTW, I don't know how you did the MAF wiring, but I used a Y adaptor I bought off ebay, which means all the original plugs in the harness are still used.
In pic below you can just about see the adaptor;

engine bay1.jpg


It also means that you can test whats going on by just e.g. unplugging the MAF part of the adaptor, without playing with the config even. The ECU will just fail it and it (should) keep right on running fine.

You can even do same with the IAT. The ECU will fail it and adopt a midrange temp as a 'guess', and if you are in a reasonably temperate place (say 50-70F) then you'll hardly notice that either!

[Nickatina7]

Hmm. Well thats just more confusing then. Since you apparently get MAF frequency data and reasonable temp data you can't have a wiring error, and from what you say, only the maf/iat are changed at all.

BTW, I don't know how you did the MAF wiring, but I used a Y adaptor I bought off ebay, which means all the original plugs in the harness are still used.
In pic below you can just about see the adaptor;

engine bay1.jpg


It also means that you can test whats going on by just e.g. unplugging the MAF part of the adaptor, without playing with the config even. The ECU will just fail it and it (should) keep right on running fine.

You can even do same with the IAT. The ECU will fail it and adopt a midrange temp as a 'guess', and if you are in a reasonably temperate place (say 50-70F) then you'll hardly notice that either!

Yeah I had the adapter so it has the two plugs that plug straight into the old IAT and MAF plugs. I have the MAF unplugged when trying the speed density tune and leave the IAT plugged in. That works with the LS1 intake but when I do the same with the c6 intake it doesn't run. And the IAT temp is the exact same on each one. 54* F which is super close to ambient air temp. I have to change the resistance values when I swap over to the card IAT when I do. If I don't change the values then it reads 18* F when I turn on the key. I haven't tried with the MAF and IAT completely disconnected yet but I was told to leave in the IAT because that has a direct effect on fueling in speed density tuning.

[Nickatina7]

It's really confusing as to why it won't run at all when all I'm doing is changing the physical intake tuning and filter. When in SD tuning mode with LS1 intake it hesitates a little bit on start up but does run. With the vette intake it starts and almost immediately falls on its face. I can't even keep it running with a little throttle. And you can smell fuel.

[Nickatina7]

I can post a pic of my intake on there later. I had to get a silicone adapter to fit from the LS1 throttle body to the c6 intake pipe. 4"-4.25". And the only length they had was about 3.5" long. So the plastic intake is sitting pretty close to the throttle body. Could this be causing some kind of turbulent air? Even if it was it should still run with the MAF totally out of the equation though right?

[dermotw]

Yes, if the MAF is disconnected or those 3 DTCs set, then it only uses the VE table(s). If you have a a fairly old ECU (like mine) then there are TWO VE tables, and when the MAF is 'broken' then it will use the smaller, secondary one.

EDIT: I went back and checked - you don't have such an early ECU with the 2 tables, you have only 1 table (meaning yours is later/better ECU...).

Turbulent airflow is indeed a problem on these cars (I mean, F-bodies) due to the short air path before the MAF, even when standard. You will be getting into the use of airflow straighteners ("honeycombs") and in fact I run one on mine. But thats not going to be the cause of such a dramatic issue...

This thread might help too;

http://ls1tech.com/forums/conversion...erences-2.html

I recall I needed it but I can't remember if I had to do any pin swaps for my cable. And anyway, a disconnected MAF won't influence anything!


-D

[Nickatina7]

Yeah I'm not understanding why it won't run at all with no MAF. I even tried extending the distance between the intake and throttle body. I might need someone's tune to copy in there and make small changes to for my car. Just to get it started and running so I can go from there.

If anyone is in the Sacramento area that can help I will pay.

[5FDP]

With no MAF at all as is disconnected and totally gone, the IAT's drop to -38 and can prevent the vehicle from running correctly.

[Nickatina7]

So i entered the stock LS3 MAF values again and tried starting it. It ended up starting and with a little bit of throttle input actually stayed running. But would not idle. Once it was above 1k rpms it ran smooth. However i quickly shut it off cause the fuel seemed to lean out according to the wideband. But if you look at the m/s of the injectors they get way too high with the injector duty cycle. and the MAF frequency and flow rate never seem to change at all.

[Nickatina7]

And it threw a p0102-Mass or Volume Air Flow A Circuit Low

[Nickatina7]

and the maf is plugged in and facing the right way (with the arrow pointing towards the TB). I can maybe back probe the MAF and see if its working correctly? Seems like I should get some kind of hertz reading at idle right?

[Nickatina7]

Ok. Holy shit. finally figured it out.

Found out that the adapter i bought online for the LS1 maf and iat plug and play harness had the ground and signal wires swapped! I pulled the wires out of the connector and swapped them and now it runs smooth. Just have to fine tune the MAF a bit. I was wondering why i wasnt getting a MAF reading. I cant believe that company screwed that up. Ill attach a pic of the harness. And my log of it actually running with the c6 intake and card maf.

[dermotw]

The aftermarket... sigh... why is it always so hard...

-D

[zapp109]

I just had the same issue with Warr Performance adapter.