Hello all!

Well, I have been detuning my car because of some problems that I can't seem to get sorted out. I keep losing coolant from my coolant overflow tank due to what I believe is a cracked radiator top outlet. I am seeping fluid from under the hose clamp, and from what I can tell it's cracked under it. Anyhow, it seems as thought he car is developing a mind of its own recently. Here is more info:

1st, the gas mileage increase "mod" of upping the cruise area to low 15's. My car is getting constant lower gas mileage with this mod. I have a bunch of data logs where the car at 65 seems to be working fine, but at 70mph, the car wants to run at low 14's afr. I was playing with my idle values, and got the car to successfully idle in the low 15's, but my crusing just doesn't seem to want to work. I have been forcing the car into open loop mode by setting all the values in my open loop tables to 10 up till 4500rpm's. I have had very little success with this, the cruise values. I was thinking this was simple, but I am thinking that the TPS values are comming into play somehow/somewhere. It seems from my data log's that when the car is reading lower than roughly 27 TPS, the AFR's are in the low 15's, but when the car is over 27's, it goes to low 14's, sometimes dipping into the 13's. I am simply not seeing the results that some other are having. Any ideas?

2nd. The car is hitting some very serious knock numbers. Reference the log attached. What the heck was the car doing? What happened? I still cannot figure out what is going on. I have detuned the car by almost 3/4 degrees of timing and the car is still doing this. The bad thing is that when this log happened, a buddy behind me said that it looked like a lit cigarette came out of my tailpipe. (The ambers from one being thrown out the window) I am wondering if I should take off my intake and see what kind of shaft play my turbo might have. What happened in this log? I still can't figure this one out, and the car is doing it every single time I get on it. I have been through two full gas tanks now, and am on the third tank now, all from different stations, so I know it wasn't a tank of bad gas. I have also verified there is no boost leaks either, so I am good there.

Any ideas?

Also, would anyone with an 05 0011 ROM be willing to check out my ROM to see if there is anything wierd in there? Razorlab, or anyone else with an 0011 05 ROM?

 

Also, can anyone give me some input on the fuel trim values?

Do I finally need to get off my bum and scale my MAF?


One more thing, do any of you think that massive knock spike would be caused by the top clutch
switch getting triggered when NLTS is turned on?

 

Have you tried messing with the Open Loop Throttle high/low load tables?

I had the same problem you where having, as have others. I have been meaning to mess with the open loop throttle tables to see if that would help. I just haven't had time.

 

The cruise AFR issue sounds like you simply need to adjust some of the higher load areas in the fuel map. If your crossover is 45% or so, you'll be in open loop everywhere above that value. So, if you are cruising at around 75% you need to adjust those fuel cells as well.

I watch my vacuum when cruising. I know that if I go above -8 or so I'm not getting the benefit of the lean cruise anymore.

Also, higher gears will put you in higher load cells during cruise. Sometimes 4th will leave you around -15 in/hg (~65% load or so) and 5th at the same speed will land you at -5 in/hg or less (~85% load) but at a lower RPM.

So, try to lean out some more cells in the lower RPM regions of the map to compensate for load in higher gears.

 

Tom, humbly speaking, avoid driving it until you know the source of the knock sum activity.

Does the knock happen at low loads (less than 5psi boost)? I solved that ugly one just from scaling the MAF back to stock - took me almost a year to figure that one but the load units were scewing the knk fltr reading.

If for some reason you think your MAF is bad I have a spare one you can slave in there.

 

I had to edit it so I can understand (attached) the log.

Maybe the aggressive timing retard is enough to make the tailpipe glow? O2 feedback also shows resp. open loop at cruise, but why does it dip below 100 right after pull was aborted, is that normal?

 

My experience with open loop values... lets say I went back to stock, MPG was worse.

My thoughts: the narrow band 02 sensor is made to look for stoich and unless we can tap into the voltage table I suspect that this, the EGR and some other emision "factors" create havoc with the closed loop "adaptation".


PS. Check your sparkplugs!

 

For checking the spark plug, I have been really really good about that, checkign them to see if the tips were showing signs of running too lean. I have a brand new set in there now just in case, but the old ones weren't showing any degrading sign's.

One thing that *could* have made the ambers is just before I went out, I was replacing my nuts on the manifold with all Stainless Nuts, so I was shifting the maifold around a lot. I am wondering if I knocked a bunch of carbon deposits loose, and shot them out the tailpipe. Oh well, at least I have good looking nuts now. He he...

The attached log is mostly what I am concerned with now, as I cannot have any fun with my car until I can get that figured out. I am thinking of putting in the stock timing map, and going out for a run to see if the reduced numbers make the problem go away.

I know my car had a pretty agressive map in it before, and I always felt OK with it because I monitored it alot. With the cold weather setting in, I figured the tune would be a little safer because my average intake temps have dropped about 20 degrees, bringing me farther away from the knock threshold.

That log posted above is really scaring me because I have it those kind of knock values 6 times now, trying to do pulls to find out what is wrong here.

 

The reason I believe it dipped back below 100 is because of the way I had my open loop maps set-up at the time.

I am thinking I am going to put the open loop values back to stock, turn off the NLTS (To rule out the clutch switch getting triggered), and try a few pulls again next time I have time.

 

O2 feedback is directly related to the MAF scaling, so if that is off the O2 feedback can go 100+ or 100- to compensate in closed loop. Not sure why you found that odd ...

 

afr's look lean when you are spooling possibly contributing to your knock events.

richen it up to 11:1 and see if your knock goes away, then you can work on leaning it back out

 

The coolant out your overflow. Is it exiting the dump tube?

 

from his post it looks like it's getting sucked in by the radiator and leaking out the cracked radiator top outlet

 

There is an important distinction that I'd like to draw so I'd like to make sure not assume, yall mean?

 

Yeah, to answer a few of your questions..

The coolant is leaking out of the underside of the neck on top of the radiator. One thing that I have noticed though, and don't know what conclusions to draw from it is the coolant overflow tank, the bottom is really muddy. The coolant in the tanks is a real murky brown (I run the GM orange stuff), and I am not sure if this is normal or not. I usually have to fill it about once every two months, but it is a small leak on the top of the radiator.

Plus, I stuffed my nose into the cap of the overflow, and could swear I smelled what seemed to be a faint smell of gasoline. I would think that with my nose stuffed into the coolant tank the coolant smell would be overwhelming from other smells from the engine bay. If I really did smell a faint smell of gas in the coolant, and it's continually muddy/murky brown, could this be evidence of a blown or starting to blow headgasket?