Loss of power? Overdrive? Misfire?
Thread Starter
Launching!
Joined: Mar 2013
Posts: 266
Likes: 0
From: Richmond, VA
Loss of power? Overdrive? Misfire? Ok I aint sure where to put this so if its in the wrong place sorry. Ever since I put my headers on and had it tuned I've been having this "loss of power" feeling when on the highway. Here is what its doing...When I am getting on the highway with about 25-35% throttle, its like as soon as I hit 55mph I lose 200hp. Now this is only my 2nd v8(if it helps 1st was a 305 sbc) and 1st ls1. So I know a little about the overdrive. But I can't tell if its the overdrive causing this feeling or something else. Before the tune my car would go in overdrive right around 65mph. Also, when the car is hot it sometimes starts up weird. Like it doesn't wanna turn over all the but then it just kicks right on. That's what is making me think something is going on. I've checked the spark plugs and wires. 02 sensors are basically brand new with like 5000 miles on them. Cant find any exhaust leaks either. Am I just being a hypochondriac about my car or does that sound normal.
My car-
2002 Z28 A4
stock internals, stock trans, stock rearend
LT headers, true duals
MSD spark plug wires
NGK Iridium spark plugs(haven't seen too many people running these and they are pregapped at .059 so I'm wondering if maybe I should try something different there?)
Frost tune
Thanks in advance for any help!
My car-
2002 Z28 A4
stock internals, stock trans, stock rearend
LT headers, true duals
MSD spark plug wires
NGK Iridium spark plugs(haven't seen too many people running these and they are pregapped at .059 so I'm wondering if maybe I should try something different there?)
Frost tune
Thanks in advance for any help!
It's probably the converter locking up, which is now coming in sooner than before. At 55mph it will be more noticeable than at 65mph.
You're not supposed to be getting on it while in OD locked up, so that's why it feels like it loses power. Once you get on it though, it should unlock and feel powerful once again. Just make sure the tuner didn't fudge up too much with those tables.
You're not supposed to be getting on it while in OD locked up, so that's why it feels like it loses power. Once you get on it though, it should unlock and feel powerful once again. Just make sure the tuner didn't fudge up too much with those tables.
Thread Starter
Launching!
Joined: Mar 2013
Posts: 266
Likes: 0
From: Richmond, VA
gotcha. I was pretty sure the feeling on the highway was just the tune. But that doesn't explain whats going on with the hot start ups. I thought of a better way to describe what its doing. When its cold and I start it up, it idles at 1000-1100 until it warms up and works its way down to about 600. When I start it up hot, its like it cuts on automatically at 600 which makes sense. But actually listening to the car start up hot, it just sounds weird to me. Idk maybe its just me but I've never experienced that in any other vehicle before.
It could be KR. KR gives the feeling of the car hitting a wall. The .060 gap is a bit large, you may want to just try cheap TR5s that come gapped at .040. You can get them at advance auto with a coupon code for like $12.
Thread Starter
Launching!
Joined: Mar 2013
Posts: 266
Likes: 0
From: Richmond, VA
That is exactly what I think it is. But I can't hear any knocking over the exhaust. But what I CAN hear is what sounds like some type of exhaust leak when under load. I've checked for them using water and a spray bottle with no leaks that I can find. I do know the gist of knock retard but I've never experienced it before so I'm not quite sure what to look out for. Maybe that exhaust leak sound I'm hearing is KR?
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No you can just drive in regular D wherever you want, just one below where most people drive. If you are ever racing with a 4l60e you should never be running it in OD shifter position. In regular d you shift just like normal but its like a newer car with a o/d off button.
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Brett Foote That is exactly what I think it is. But I can't hear any knocking over the exhaust. But what I CAN hear is what sounds like some type of exhaust leak when under load. I've checked for them using water and a spray bottle with no leaks that I can find. I do know the gist of knock retard but I've never experienced it before so I'm not quite sure what to look out for. Maybe that exhaust leak sound I'm hearing is KR?
You will not hear KR, but you will absolutely feel it. It feels like the car loses all of it's power if it's pulling significant timing. The stock PCM can pull up to 15 degrees at low to mid rpm. I don't see how entering overdrive can feel like it loses 200 hp, but everyone's butt dyno is different
. If that does not work find someone willing to let you use a tech 2 and use the data display function while it happens and check to see if any of the numbers are not where they are supposed to be.
Overdrive in the wrong spot is just like mashing the gas in a 6 speed car in 6th gear at 55 so it is remotely possible that is what he is feeling. My girl friend had a hyundai accent and she was convinced her car had something wrong with it and I drove it everywhere and never could get it to happen and all she was feeling was the car jerking from going into 3rd from od with the gas mashed.
I would say that KR is more unlikely than a simple misfire and a tech 2 with the misfire graphic would be the easiest way to tell you exactly which cylinder is acting up to trace a ignition or mechanical related misfire.
Thread Starter
Launching!
Joined: Mar 2013
Posts: 266
Likes: 0
From: Richmond, VA
Its just a mail order tune from Frost and he is almost impossible to get a hold of. I don't know anyone with a tech 2 so that's not really a option for me. What about spark knock? Could the bigger gap in my plugs be causing spark knock or the possible problem? When it was bone stock it would go in OD but I still had decent passing power when necessary. Now its like I have to mash the gas pedal just to pass somebody on the hw. But when its wide open it runs very strong from what I can tell.
Its just a mail order tune from Frost and he is almost impossible to get a hold of. I don't know anyone with a tech 2 so that's not really a option for me. What about spark knock? Could the bigger gap in my plugs be causing spark knock or the possible problem? When it was bone stock it would go in OD but I still had decent passing power when necessary. Now its like I have to mash the gas pedal just to pass somebody on the hw. But when its wide open it runs very strong from what I can tell.
Since it's a mail order tune, it very well could be real KR.
Yes your bigger end gap could be causing issues. I have tried .060" a few times and always went back to .045"-.050". .060" would break up. Bigger exhaust does not take away low end torque, that is a myth..well not enough to notice anyway. Maybe a few ft/lbs..negligible. Bigger is just about always better.
You don't need a tech 2. Hptuners logs everything you need to see, including misfires.
Since it's a mail order tune, it very well could be real KR.
Yes your bigger end gap could be causing issues. I have tried .060" a few times and always went back to .045"-.050". .060" would break up. Bigger exhaust does not take away low end torque, that is a myth..well not enough to notice anyway. Maybe a few ft/lbs..negligible. Bigger is just about always better.
Since it's a mail order tune, it very well could be real KR.
Yes your bigger end gap could be causing issues. I have tried .060" a few times and always went back to .045"-.050". .060" would break up. Bigger exhaust does not take away low end torque, that is a myth..well not enough to notice anyway. Maybe a few ft/lbs..negligible. Bigger is just about always better.
