Did some datalogging and have some questions

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Kraze

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Well, to start off the car is a '97 base Mark VIII with 113k miles on it. All the regular maintenance has been done (fluids, filters, plugs, Mercon V, seafoam) but I think it might be time for new O2's and fuel pump. The car doesn't seem to be running up to par, it gets around 12 mpg in town, 20 mpg highway, and the 0-60 on it is around 8 seconds or higher.

So anyways, I did some datalogging with my Xcal 2, just for the hell of it really, and had a couple questions.

First is the knock sensor. I logged this and the values go all the way from -5.750 to 4.5. I take it that the car is pulling timing?

I also logged the fuel trims, but I have no idea how to interpret those either. I was thinking maybe they would help me see if I really do need a new fuel pump or not, but then again I don't know how all that works.

So if anyone has any experience datalogging with an Xcal 2/Livelink and wants to take a look at my logs to see what you can see, it would be greatly appreciated.

Here's the log of two WOT runs to 100+ mph.
Here's the log of just some highway cruising then a little in town driving.
Right-click save as to get them.
 
I took a quick look at your cruising log your STFT look fine for a stock tune little rich but typical.

I would clean the MAF, get a good filter, replace the front and rear o2's as general maintenance, and replace your fuel filter (passenger side front wheel well) to replace everything except the o2's should take you less than an afternoon.

Did a tuner put a tune on the Xcal2? or are you just logging with it?
 
It has a tune from Torrie at Fast Parts Network, other than that it's stock.

I cleaned the MAF not too long ago, would I need to do it again?

And I read that you usually don't need to replace the rear O2's since they only monitor the cat?
 
I can't look at your logs because I have Sniper Special Forces, can you tell me what your load % (Volumetric Efficiency) is at WOT?
 
Hmm.. Well I logged the load but I don't know if it's what you're talking about. It's around .68-.71 with a spike or two up to .73 at WOT. Maybe that would be 68-71%?

Does that sound right or am I looking at the wrong thing?
 
That seems really low and could be why your car is sluggish and getting poor gas mileage. What is your MAF voltage at WOT? It should be in the 4.3-4.8 range otherwise your MAF is out of spec and causing your car to run lean.
 
The highest my MAF voltage got was 4 and that was right before the 1-2 shift at WOT.

What makes the MAF run out of spec?
 
Kraze said:
The highest my MAF voltage got was 4 and that was right before the 1-2 shift at WOT.

What makes the MAF run out of spec?
Click to expand...

Usually age and possibly containments like dirt or oil. I would say try to get a used maf and swap it out and datalog again. My 98 LSC maf was around 3.9-4.0 at wot and causing my car to be lean, I swapped the MAF from my 96 and its now in the 4.3-4.5 range and the car runs a whole lot better.
 
Hmm.. well I live in a pretty small town and I've never seen a Mark in any of the junkyards around here. Do any other cars use the same MAF as the Mark that might be more common?

Or should I just try cleaning the MAF again to see if that helps?
 
The MAF thing is good info. I think I may pick up a new one now that I know this!
 
Kraze said:
Do any other cars use the same MAF as the Mark that might be more common?
Click to expand...

The only application that I know that uses the same MAF as the Mark 8 is far more rare than finding a mark 8 in a junk yard.

it's the first generation Lightning Pickup with the 5.8 EFI motor.

Check Ebay, there are usually 3-4 Mark 8 MAFs auctions running most of the time
 
Actually, all year 93-98 have the same 80mm mass air but the connection pigtail is different on the 96-98 OBD2 Marks.
 
Well I picked up some CRC MAF cleaner yesterday, so I'm going to just try cleaning the hell out of mine first.

In the meantime, anybody have any idea how to interpret the knock sensor data?

And I logged the O2's voltage too if anyone wants to take a look at that and see if they can find anything wrong with it.
 
98LSC32V said:
I can't look at your logs because I have Sniper Special Forces, can you tell me what your load % (Volumetric Efficiency) is at WOT?
Click to expand...

Sniper Special Forces doesnt matter here..no bearing.

Save the file, it should open it microsoft excel.

all the tables are labled and the values are visible.

you "would" need to have Office Excel installed though
 
Or you can download Livelink for free from SCT. Here's the link (get version 4.17)
It's alot easier to read the graphs in Livelink than it is in Excel lol.
 
phreakness said:
I took a quick look at your cruising log your STFT look fine for a stock tune little rich but typical.

I would clean the MAF, get a good filter, replace the front and rear o2's as general maintenance, and replace your fuel filter (passenger side front wheel well) to replace everything except the o2's should take you less than an afternoon.

Did a tuner put a tune on the Xcal2? or are you just logging with it?
Click to expand...

rear o2 sensors have nothing to do with tune or fuel economy. all they do is monitor weather the cats are working properly or not.
 
I didn't realize you have the datalog saved as an excel file. I looked at your first file where you went WOT a few times, your load is definitely very low, it's about what a stock Town Car would get at WOT... not good. I don't understand the incoming airflow measurements SCT uses so I can't comment on that but your timing advance looks pretty ideal. You can probably add 1-2 degrees at WOT and gain some more power but you need to fix your low load issue first. Find another MAF and datalog again.
 
Did you take a look at the knock sensor though? I'm not sure, but I think it's pulling timing on WOT. The knock sensor doesn't register anything at any other time.

And I'm going to clean the hell out of this MAF that I have now and datalog again and see if that helps. If it doesn't I'll probably just buy the LMS kit.
 
Kraze said:
And I'm going to clean the hell out of this MAF that I have now and datalog again and see if that helps. If it doesn't I'll probably just buy the LMS kit.
Click to expand...

Something you may or may not realize....

If you get the LMS maf kit, you will need to use "your maf sensor" from your housing...

If your MAF sensor is dirty, then swapping to an LMS maf wont resolve the issue as you will still need to buy a brand new MAF sensor to install IN the LMS maf.

just a heads up.
 
98LSC32V said:
If it's pulling timing it's not pulling that much...
Click to expand...

I agree, and the timing it's pulling obviously the car "cant use it" at that throttle setting and RPM.

It does look like that 1-2 degree's is coming back in later in the RPM range though...

looks like the KS's are doing their job and when knock goes away the 1-2 degree's returns.
 
XLRVIII said:
Something you may or may not realize....

If you get the LMS maf kit, you will need to use "your maf sensor" from your housing...

If your MAF sensor is dirty, then swapping to an LMS maf wont resolve the issue as you will still need to buy a brand new MAF sensor to install IN the LMS maf.

just a heads up.
Click to expand...

Oh.. no, I didn't know that. Hmm.. looks like I'll just buy a new sensor then. I wouldn't want to get a used one only to find out it has the same problem as mine.

Could the low load and MAF voltage be caused by anything else other than the actual sensor? Or is that definitely the cause of my problems?
 
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