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Major false KR on 2000 Malibu 3100

Zef_66

Zef_66

New member
So my wife has a 2000 Malibu 3100 engine with about 110k miles on it. For awhile she has complained that it lacked power and would "jerk" when going up hills. I initially thought the tranny was acting up. So I take it out and scan it. Holy schnikeys, the thing showed upwards of 15° KR!!! I was dumbfounded.

The entire car is stock. I haven't modded it at all. I did make some changes to shift points, fan settings, TCC lockup, etc. But I didn't touch the timing at all. None the less, I write the stock bin back to her car. So everything is 100% stock now. Still major KR.

So I wait till the tank of gas is getting low, and fill it with 93 octane. Scan it after a day or so, and still the same amount of KR. So I am assuming it is false.

Any ideas on where to start with this thing? I am lost.
 


Looks like you have some misfires occuring. Probably the main reason for the jerking and the kr.But then again that seems to go away. When my coil packs went out I had Kr in pretty big amounts too. I wouldnt say it's false KR but I Would say that it's not tune related obviously. I have never seen false KR in those amounts... 1 or 3 degrees maybe. I would check the normal stuff like plugs ect. Chack anything that may be hitting on something to cause that to happen when throttle is applied.




Other wise i dont know what to tell you. The way i tell if it's false kr or not is reduce the timing in the cells that the kr is occuring in. But im pretty sure your going to have the same results even if you did it that way. I mean fuel trims can cause kr but not that much...and plus it's a stock tune...so the ft's being off is kind of expected.
 
Misfires? Eh, 4 is not enough for me to worry about. I am going to check plugs and wires, but I did them less than a year ago, so I am pretty confident they are good.

As for coil packs, if they were going bad, wouldn't I get more misfires? I am just thinking, when I had a bad wire on my GTP, I was getting misfires in the hundreds. So I am not concerned about 4.

As for checking if it is false KR. I did take this scan, and lowered the timing in the cells where I am getting KR. Did another drive, and it didn't lower it at all. So I assumed it was knock. Also did the premium fuel test. Again, no change. Since it didn't change anything, I put the stock tune back in.

But on another note, I tried to get a scan last night, and it didn't do it. Maybe 3-4° KR, but not that much. But even still, there shouldn't be that much on a stock NA car. Anyway, I don't know if it was because it was cold or what. But I had my wife drive the way she usually goes to work, and it didn't get any extreme knock where she usually feels it being sluggish. But the scan that I posted was from the exact same route a couple weeks ago. But she said it did it this morn.

I don't know.
 
Oh well to be honest im not fimiliar at all with how the missfires are reported. I fugured if you had one that that was bad. Well I guess we can throw that idea out. And when i had my coil pack go out it jerked kind of like you were describing. I had to deleate code p0300 wich is the misfire code becuase of my cam. So it made diagnosing the problem a little tougher.
 
Did you chaeck the coil pack temperature? I heard you diagnose a bad cloi pack by measuriong the temperature. Looking for one being hotter than the rest. Did you try posting in the other website i recommended?
 


my mothers 03 malibu sounds about the same as your wifes...over the years, its just seemed to loose and loose power.... I know, It used to be my driver =P
 
alacran, elaborate on the measuring the coil pack temp. What you are saying makes sense but how would you go about measuring the temps? A IR non-contact thermometer? And what kind of temp difference would you be looking for to point the finger at a coil?
 
well supposedly the coils get hoter than normal as they fail. Basically you are looking for a diifference in temperature between each coil. I would use an IR gun since i have but many just go by feel.

IDK i just heard about this procedure but i have not done it. Although i should because of my mysterious knock. Hope this helps.
 


alacran said:
any updates on this?
Click to expand...

Sorry, but no real updates. I did check for something obvious going on when I changed her brakes. But I didn't find anything like loose/dirty wires or connections, or loose mounts.

But I haven't had time to do much troubleshooting with it. Maybe as the days get shorter I will have some time to spend in the garage.

She only puts like 100 miles a week on the car, so I don't worry about it too much. And she would LOVE to get a new car, so if it goes, oh well, she wins...haha.
 
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