True or False: Missfires cause the converter to stay unlocked.
11-24-2008, 09:35 PM
#3
True, but, most of the time what is actually causing that problem in a modded engine isn't actually real misfires, it's just variation in crankshaft rotational speed. It's interpreted by the computer as misfires. As stated, tweaking the misfire tables cures it.
11-24-2008, 11:26 PM
#4
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Misfires will inhibit lockup but that would tend to come and go
with load, speed etc. Unlocked always, is either a really
persistent misfire or a slip code. You can see whether misfires
are responsible, with the scan tool. TCC_Mode will show a
-3- (HPTuners) if it "woulda, but".
with load, speed etc. Unlocked always, is either a really
persistent misfire or a slip code. You can see whether misfires
are responsible, with the scan tool. TCC_Mode will show a
-3- (HPTuners) if it "woulda, but".
11-25-2008, 08:31 AM
#7
Most of the time just multiplying them by 5 does the trick. It still has the ability to detect misfires, but is desensitized enough to not recognize the increased variances.
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11-25-2008, 10:05 AM
#8
My tuner used HPTuners to tune my car. Ran perfectly for a couple weeks. (Probably 2-3 startups total during this time.) Then during a short 85 mile trip it just stopped locking half way through the trip. I got the slipping code P1870. Never locked since. On the day i was putting it away for winter storage it died a few times at the lights. Which i have never had happen before.
What do you guys think? Get my tune looked at in the spring?
What do you guys think? Get my tune looked at in the spring?
11-25-2008, 10:40 PM
#10
True.
It is a "limp mode" function.
It is used to reduce the load on the engine in the event that misfire is too excessive. It is not a very effective way of diagnosing a problem, but it does help reduce misfire.
It is a "limp mode" function.
It is used to reduce the load on the engine in the event that misfire is too excessive. It is not a very effective way of diagnosing a problem, but it does help reduce misfire.
12-05-2008, 07:16 AM
#13
I got a question for thought for yall.....
Does a balanced engine give yall the fits with misfire codes, or just stock engines?
The reason I ask, I have 2 cars here that I've tuned, with no problems. 1 engine I put together, which I had the machine shop balance the rotating assembly. 1 engine, another machinist put together, and it was balanced also. Neither of these cars gave me any trouble with misfires, both have cam, heads, stall converters, the works.
Now I have a car with heads, cam, and stall, but stock bottom end, and it has issues with misfires. I'm showing ever cylinder is misfiring consistanly at idle, and misfires intermintently at mid rpms loaded. I'm about to decrease the diagnostic sensitivity of the misfire to cure the problem on this car, but this was just a thought. There's some people out there that have a lot more experience with this than I, just wondering if yall have seen the same thing or paid it any attention.
dm
Does a balanced engine give yall the fits with misfire codes, or just stock engines?
The reason I ask, I have 2 cars here that I've tuned, with no problems. 1 engine I put together, which I had the machine shop balance the rotating assembly. 1 engine, another machinist put together, and it was balanced also. Neither of these cars gave me any trouble with misfires, both have cam, heads, stall converters, the works.
Now I have a car with heads, cam, and stall, but stock bottom end, and it has issues with misfires. I'm showing ever cylinder is misfiring consistanly at idle, and misfires intermintently at mid rpms loaded. I'm about to decrease the diagnostic sensitivity of the misfire to cure the problem on this car, but this was just a thought. There's some people out there that have a lot more experience with this than I, just wondering if yall have seen the same thing or paid it any attention.
dm
12-05-2008, 12:18 PM
#16
My tuner used HPTuners to tune my car. Ran perfectly for a couple weeks. (Probably 2-3 startups total during this time.) Then during a short 85 mile trip it just stopped locking half way through the trip. I got the slipping code P1870. Never locked since. On the day i was putting it away for winter storage it died a few times at the lights. Which i have never had happen before.
What do you guys think? Get my tune looked at in the spring?
What do you guys think? Get my tune looked at in the spring?
A few guys have said missfires create intermittent lock up, but mine isn't locking at all. I only drove it like 3x on short trips but it never locked.
12-05-2008, 12:38 PM
#17
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I swapped cams and consistently showed P0300, so my converter never locked up. I raised misfire detection to over 1500rpm and my problem went away.
You need to scan the car and first determine if you are actually registering misfires. If you aren't detecting enough misfires to trigger the protection routine, your problem is elsewhere.
