LTFT Low / VE question

**TwIzTeD_3kGt** · 08-06-2013, 09:14 PM

A couple quick questions:

1.) I was able to get the front and rear to -7% and 7% between changing the injector size and the VE smoothing table. Is there any way to get those to under 5% each? Or is that an issue with the parts on my engine?

2.) Is there a point where I should stop adjusting the VE table? I think I've gone as far as 10-12% change on the below 100 numbers.

**NOMIEZVR4** · 08-06-2013, 10:08 PM

Here is a bit of advice that I found useful...Keep in mind though, not everyone suggests tweaking with the latency values. Some say to plug them in and leave them alone, others mess with them. Personally, I haven't touched them since I plugged them in, I've only altered the VE/Smoothing table and the injector scaling.

I'm running Delphi 1000cc with lows and mids +/-5...Stock lines, stock loop, hotwired 255. I had to only make alterations to the VE table to get idle/low trims in spec...Mids settled down on their own without me making any changes. I guess I should also add that before I made any changes to the VE table, like after I initially installed my injectors I had to scale them down all the way to 8XX (from 1000)before my o2's started cycling...My scaling now is set to 735. In your case, since you probably didn't mess around with the scaling values, thats probably the reason why you're having to make more changes to the VE table...its just a balancing act.

If low ~= mid & both > 0 then decrease injector scaling
If low ~= mid & both < 0 then increase injector scaling
If low > mid then increase latency values
If low < mid then decrease latency values

**kywhitelightning** · 08-13-2013, 01:50 AM

I have a 3-4% difference between the two banks and I believe I have a bent rod on the shelf from it. Obviously I was going for broke and actually broke when this happened but now that evoscan is logging both banks and not just the rear, I know this is a major factor in why that happened.

My injectors are not spraying evenly. I swapped the front and rear bank injectors and rails and the trim values moved with the injectors. The front was always lean before and after the swap the rear bank went lean the same amount. New injectors will be here on Thursday.

7% is a lot by itself but it looks like you have a 14% difference from what you describe. That's a lot.

Jeff

**TwIzTeD_3kGt** · 08-13-2013, 07:40 PM

Originally Posted by NOMIEZVR4

Here is a bit of advice that I found useful...Keep in mind though, not everyone suggests tweaking with the latency values. Some say to plug them in and leave them alone, others mess with them. Personally, I haven't touched them since I plugged them in, I've only altered the VE/Smoothing table and the injector scaling.

I'm running Delphi 1000cc with lows and mids +/-5...Stock lines, stock loop, hotwired 255. I had to only make alterations to the VE table to get idle/low trims in spec...Mids settled down on their own without me making any changes. I guess I should also add that before I made any changes to the VE table, like after I initially installed my injectors I had to scale them down all the way to 8XX (from 1000)before my o2's started cycling...My scaling now is set to 735. In your case, since you probably didn't mess around with the scaling values, thats probably the reason why you're having to make more changes to the VE table...its just a balancing act.

If low ~= mid & both > 0 then decrease injector scaling
If low ~= mid & both < 0 then increase injector scaling
If low > mid then increase latency values
If low < mid then decrease latency values

That makes sense, good chart there! I ended up scaling my injectors from 550 down to 500. After which I basically ended up undoing the changes I made to the VE tables.

Originally Posted by kywhitelightning

I have a 3-4% difference between the two banks and I believe I have a bent rod on the shelf from it. Obviously I was going for broke and actually broke when this happened but now that evoscan is logging both banks and not just the rear, I know this is a major factor in why that happened.

My injectors are not spraying evenly. I swapped the front and rear bank injectors and rails and the trim values moved with the injectors. The front was always lean before and after the swap the rear bank went lean the same amount. New injectors will be here on Thursday.

7% is a lot by itself but it looks like you have a 14% difference from what you describe. That's a lot.

Jeff

That was my concern, that it was an injector issue. These injectors sat on a shelf (in a case) for 3 years and I didn't send them out for cleaning/balancing before installing.

My mid trims are 3 and -3 front to rear. So a 6% difference in the same 'direction' as the low trim. Sounds like I should get my E85 injectors sooner than later, and get them new or at least balanced.

Now when you were going for broke did you see the knock before it blew? Or was knock not a possibility (meth/e85)? Also, was your lean bank the one that failed?

**kywhitelightning** · 08-14-2013, 01:10 AM

It was knocking badly.

At the time the lean bank (front) which I was unaware of was the one that was hurt. 3 & 5 both had peppered pistons and spark plugs and 3 bent a rod. No other damage was done. No other pistons or plugs were affected.

Problem was that my trims were only displayed from the rear bank or should we say the rich bank. I set the tune based on them and watched the WB for the AFR in boost. The WB sees all cylinders exhaust and I pushed the AFR near 12. I can only imagine that 3 & 5 were easily in the 12's if not touching the 13's. I also had a methanol line leaking from those junk push lock fittings that all the injection sites sell. From then on I have run compression style fittings everywhere and haven't had an issue with those yet.

Curious, do you know what it costs to have them checked, cleaned, and balanced? PTE 550's.

Jeff

**TwIzTeD_3kGt** · 08-14-2013, 02:19 AM

Originally Posted by kywhitelightning

It was knocking badly.

At the time the lean bank (front) which I was unaware of was the one that was hurt. 3 & 5 both had peppered pistons and spark plugs and 3 bent a rod. No other damage was done. No other pistons or plugs were affected.

Problem was that my trims were only displayed from the rear bank or should we say the rich bank. I set the tune based on them and watched the WB for the AFR in boost. The WB sees all cylinders exhaust and I pushed the AFR near 12. I can only imagine that 3 & 5 were easily in the 12's if not touching the 13's. I also had a methanol line leaking from those junk push lock fittings that all the injection sites sell. From then on I have run compression style fittings everywhere and haven't had an issue with those yet.

Curious, do you know what it costs to have them checked, cleaned, and balanced? PTE 550's.

Jeff

Sounds like it makes a lot of sense. I wonder how much of a difference in power potential it makes to have the fuel trims actually zero'd out...

Not sure on the cost, I looked into it a while back and deemed it not worth it. There was someone here or on 3si who had a thread dedicated to injector cleaning importance (Mas I think was his username). He was offering the service, but then he stopped dong it.

Just did a quick search and came up with someone else over there: 3000GT/Stealth International Message Center
$75 shipped.