Idle surge (mostly in Park/Neutral)
I don't know about EFIlive, but in hptuners you have do do a write entire to clear you idle trims. Might want to try that too. They could be fairly far off with all the changes you've been making.
The NW has a pretty good sized IAC port. But I didn't want my TPS up around .65-.67. So the small hole allowed me to shut it down and up my IAC count. Helped stabilize idle too.
The FAST had a smaller IAC but was open around the blade much moreso than the NW. I had it set at .48V, but the IAC did less to help since the IAC port was more restricted.
Every time you flash the car, it resets them too.
The FAST had a smaller IAC but was open around the blade much moreso than the NW. I had it set at .48V, but the IAC did less to help since the IAC port was more restricted.
Every time you flash the car, it resets them too.
Didn't know a flash reset the TPS and IAC. So, if someone wanted, they could adjust the set screw, flash calibration only, and then restart the car and be just as good as if the sensors were unplugged for a minute?
Staging Lane
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Bleh....better. Car started and came up to temp then surged.
I tried barely adjusting the TB some to open it up and close it. Only effect was if I opened the screw enough IAC was 0 and it idled higher than it was set.
I tried as little throttle input as possible and found it to be LTFT at -12.5% so I tried reducing the VE by that and no go. So I tried 4% less than that and still no go.
Attached are the tune and 3 logs. Last log is a warm start with the adjusted VE.
I tried barely adjusting the TB some to open it up and close it. Only effect was if I opened the screw enough IAC was 0 and it idled higher than it was set.
I tried as little throttle input as possible and found it to be LTFT at -12.5% so I tried reducing the VE by that and no go. So I tried 4% less than that and still no go.
Attached are the tune and 3 logs. Last log is a warm start with the adjusted VE.
Your surge is happening even at high rpm idle... it starts by just sliding away from target idle speed and then progressively gets worse. Your fueling is not quite right and this is kicking it off... but it's the spark which I think is causing all the problems. Your spark correction table is what I would expect to see in a very well tuned stocker... it's really not enough for your engine.
This tune file has a more aggressive spark correction and should reduce the engine's tendency to drift from target idle. Log the same parameters as you did in the previous logs.
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From: Northwest AR
That would be my fault. I was under the impression from my reading on tuning that the spark correction should be reduced to prevent surge being caused by timing corrections as the cam loped.
For example I was able to get my truck with a tiny 205/210 cam to have a bit of lope sound by amplifying the spark over/under corrections.
Before I started having problems it was idling well with the timing locked at just about anything over 22* or so.
For example I was able to get my truck with a tiny 205/210 cam to have a bit of lope sound by amplifying the spark over/under corrections.
Before I started having problems it was idling well with the timing locked at just about anything over 22* or so.
Last edited by thunderstruck507; Jan 28, 2016 at 08:55 AM.
On The Tree
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From: fredericksburg va
Ok, working on mine, did drill a 1/8" hole, started around 50 deg, stalled right off, restarted ran great until 160 or so then surge was there, pretty bad, tried going up 1/8 turns on throttle blade and resetting TPS, used setting that showed here, seemed a bit better, by far not fixed, could find the proportional fueling in HP tuners, we are not great with by no means, so any help greatly appreciated, here's the tune as of today, Rob
Ok, working on mine, did drill a 1/8" hole, started around 50 deg, stalled right off, restarted ran great until 160 or so then surge was there, pretty bad, tried going up 1/8 turns on throttle blade and resetting TPS, used setting that showed here, seemed a bit better, by far not fixed, could find the proportional fueling in HP tuners, we are not great with by no means, so any help greatly appreciated, here's the tune as of today, Rob
On The Tree
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From: fredericksburg va
no this car I'm working is a NA 410 ci, GMPP cnc ported L92 heads, fast 102 intake, ebay 102 T/B(I used the same one on the turbo car) brian tooley cam
620/596 293/303 cam, turbo 400 w/north texas billet converter, 1 7/8 headers. We have been used mega squirt on the turbo car for a long time, just started used the HP tuners deal, he has had this car tuned by 2 different tuners that have a good rep so I am told and neither got it to idle worth a crap. Car belongs to my youngest son and we did the engine here along with the trans swap from M6. I am not up on this stuff as I am a old school racer, my older son who tunes the turbo car and has gotten this car the best from a tune he found on the HP tuners site, but this idle surge has been a big pain, so any help is greatly appreciated, Rob
620/596 293/303 cam, turbo 400 w/north texas billet converter, 1 7/8 headers. We have been used mega squirt on the turbo car for a long time, just started used the HP tuners deal, he has had this car tuned by 2 different tuners that have a good rep so I am told and neither got it to idle worth a crap. Car belongs to my youngest son and we did the engine here along with the trans swap from M6. I am not up on this stuff as I am a old school racer, my older son who tunes the turbo car and has gotten this car the best from a tune he found on the HP tuners site, but this idle surge has been a big pain, so any help is greatly appreciated, Rob
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From: Northwest AR
Ok that one was a LOT better.
Didn't really start surging until near 160* and it wasn't so violent. Got a little worse up to 192* and I tried giving it some throttle and that started a violent surge but I was able to ease off and get it to recover.
Below is a log from a dead cold start with a freshly calibrated wideband (took it out of the pipe for free air calibration then put back in).
Didn't really start surging until near 160* and it wasn't so violent. Got a little worse up to 192* and I tried giving it some throttle and that started a violent surge but I was able to ease off and get it to recover.
Below is a log from a dead cold start with a freshly calibrated wideband (took it out of the pipe for free air calibration then put back in).
Staging Lane
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Your IAC counts are now over 100 on a hot engine... you need to crack your TB open a bit and get those counts down to 40-50. You then need to reset your TPS... you'll also then need to redo your rafig/rafpn. Your log doesn't look too bad overall. Your fueling is causing the remaining surging so you'll need to do some work there. I don't know how you've set up your wideband, but you seem to be getting best fueling at 15.5, so that's what you should be tuning towards.
I've made a few adjustments to your tune file... this should help with the surge you get coming off throttle.
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From: Northwest AR
Thanks again.
Yeah the wideband thing is weird. It is mounted about a foot behind where the exhaust meets the header in a regular bung. It's on the passenger side which I suspect is my "lean" side due to the fuel rail being flipped so that it feeds from the passenger side. Anytime the car was running good it's always been in that 15.5-16:1 AFR range at idle but goes to normal as soon as throttle is applied and the exhaust velocity speeds up. My duals have no crossover so maybe it's a lack of scavenging?
My roommate has the same wideband and at one time the same cam and his is at stoich at idle, but he also still has a y pipe setup (although I can't remember if the wideband bung is in the I or one of the pipes pre-merge.
Should I still be able to do a RAFIG/RAFPN if the car is in open loop idle? I tried to do a log for it a while back and it either just didn't want to make any corrections to what was there at the time or it wasn't getting the data it wanted to see to start calculating the correction.
Thanks a million for your help and I'll work on the remainder this weekend. Hopefully be paypaling you some beer money for your efforts here because I was clearly in over my head (not that it seems to take much to get me there with this tuning stuff)
Yeah the wideband thing is weird. It is mounted about a foot behind where the exhaust meets the header in a regular bung. It's on the passenger side which I suspect is my "lean" side due to the fuel rail being flipped so that it feeds from the passenger side. Anytime the car was running good it's always been in that 15.5-16:1 AFR range at idle but goes to normal as soon as throttle is applied and the exhaust velocity speeds up. My duals have no crossover so maybe it's a lack of scavenging?
My roommate has the same wideband and at one time the same cam and his is at stoich at idle, but he also still has a y pipe setup (although I can't remember if the wideband bung is in the I or one of the pipes pre-merge.
Should I still be able to do a RAFIG/RAFPN if the car is in open loop idle? I tried to do a log for it a while back and it either just didn't want to make any corrections to what was there at the time or it wasn't getting the data it wanted to see to start calculating the correction.
Thanks a million for your help and I'll work on the remainder this weekend. Hopefully be paypaling you some beer money for your efforts here because I was clearly in over my head (not that it seems to take much to get me there with this tuning stuff)
Thanks again.
Yeah the wideband thing is weird. It is mounted about a foot behind where the exhaust meets the header in a regular bung. It's on the passenger side which I suspect is my "lean" side due to the fuel rail being flipped so that it feeds from the passenger side. Anytime the car was running good it's always been in that 15.5-16:1 AFR range at idle but goes to normal as soon as throttle is applied and the exhaust velocity speeds up. My duals have no crossover so maybe it's a lack of scavenging?
My roommate has the same wideband and at one time the same cam and his is at stoich at idle, but he also still has a y pipe setup (although I can't remember if the wideband bung is in the I or one of the pipes pre-merge.
Should I still be able to do a RAFIG/RAFPN if the car is in open loop idle? I tried to do a log for it a while back and it either just didn't want to make any corrections to what was there at the time or it wasn't getting the data it wanted to see to start calculating the correction.
Thanks a million for your help and I'll work on the remainder this weekend. Hopefully be paypaling you some beer money for your efforts here because I was clearly in over my head (not that it seems to take much to get me there with this tuning stuff)
Yeah the wideband thing is weird. It is mounted about a foot behind where the exhaust meets the header in a regular bung. It's on the passenger side which I suspect is my "lean" side due to the fuel rail being flipped so that it feeds from the passenger side. Anytime the car was running good it's always been in that 15.5-16:1 AFR range at idle but goes to normal as soon as throttle is applied and the exhaust velocity speeds up. My duals have no crossover so maybe it's a lack of scavenging?
My roommate has the same wideband and at one time the same cam and his is at stoich at idle, but he also still has a y pipe setup (although I can't remember if the wideband bung is in the I or one of the pipes pre-merge.
Should I still be able to do a RAFIG/RAFPN if the car is in open loop idle? I tried to do a log for it a while back and it either just didn't want to make any corrections to what was there at the time or it wasn't getting the data it wanted to see to start calculating the correction.
Thanks a million for your help and I'll work on the remainder this weekend. Hopefully be paypaling you some beer money for your efforts here because I was clearly in over my head (not that it seems to take much to get me there with this tuning stuff)
Staging Lane
Joined: Nov 2015
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Should I still be able to do a RAFIG/RAFPN if the car is in open loop idle? I tried to do a log for it a while back and it either just didn't want to make any corrections to what was there at the time or it wasn't getting the data it wanted to see to start calculating the correction.
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From: Northwest AR
So I'm still not entirely convinced there isnt an electrical or mechanical gremlin.
Car starts and gets to temp fine, idles pretty good even warm now. It does hold RPMs coasting so I'm guessing you added a lot to the throttle cracker or follower to prevent surge coming off throttle. Or the tps might not have fully reset after I cracked the blade last.
I did a quick drive to try to log some date for VE and MAF correction and not only does the data look very wrong to me, but several times during the drive at low rpm medium load the car nosed over severely (like what happens when it runs out of fuel) but it was fine at high load higher rpm and even pulled steady at heavy throttle.
Sometimes it would surge and I could watch it go into a fueling loop and other times it would idle steady.
The CALC.VET maps created appear to be commanding severe fueling increases in the idle cells.
I'm going to get under the car when it's cool and check for any wires touching the headers and also look for signs of exhaust leaks. I still might try swapping on the coils from my truck.
Your tune seems very good and it almost has this feeling like the car is fighting it. At idle it has some pretty extreme timing swings and the idle feels pretty rough in the car (solid motor mounts) but not like a full blown consistent misfire.
Could it perhaps be a crank sensor issue? I've never seen one have issues, they've always just full blown failed on me and the car wouldn't run at all.
I'm attaching both the CALC.VET log and a log with the usual parameters which is shorter.
Car starts and gets to temp fine, idles pretty good even warm now. It does hold RPMs coasting so I'm guessing you added a lot to the throttle cracker or follower to prevent surge coming off throttle. Or the tps might not have fully reset after I cracked the blade last.
I did a quick drive to try to log some date for VE and MAF correction and not only does the data look very wrong to me, but several times during the drive at low rpm medium load the car nosed over severely (like what happens when it runs out of fuel) but it was fine at high load higher rpm and even pulled steady at heavy throttle.
Sometimes it would surge and I could watch it go into a fueling loop and other times it would idle steady.
The CALC.VET maps created appear to be commanding severe fueling increases in the idle cells.
I'm going to get under the car when it's cool and check for any wires touching the headers and also look for signs of exhaust leaks. I still might try swapping on the coils from my truck.
Your tune seems very good and it almost has this feeling like the car is fighting it. At idle it has some pretty extreme timing swings and the idle feels pretty rough in the car (solid motor mounts) but not like a full blown consistent misfire.
Could it perhaps be a crank sensor issue? I've never seen one have issues, they've always just full blown failed on me and the car wouldn't run at all.
I'm attaching both the CALC.VET log and a log with the usual parameters which is shorter.
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Staging Lane
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I think that there's something wrong with your PCM. Your fuel trims spend most of their time at -12.5%... not more and not less but exactly that amount, and it's the same for both banks. Try doing a FULL flash of the oldest tune file you have and then do a CAL flash of your current calibration. If your OS is corrupted, then this should fix it. If it doesn't fix it, then you might need a new PCM.
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From: Northwest AR
Checked for burned wires, reset TPS again, and performed a full flash off my LS2 swap base tune (car ran perfect for about 1600 mile trip to Biloxi on this tune).
I then did a flash of the basetune3 file above.
Fuel trims still want to hang out at -12.5 and the surge is still present.
Guess the only way I can check to see if the PCM is the issue is to write the tune for my truck to it then install it in the truck and see if there is an issue? I could probably find a PCM to buy but then I would have to pay to unlock it.
The only other thing now that it has a stumble is could the fuel pump or Corvette regulator be giving out? Seems that would show up as a pressure fluctuation when the idle is surging if so.
Here is a log from today where I start it cold (fires right up and idles like a champ) then start driving and once temps get above 130-140* or so it begins acting up again.
I then did a flash of the basetune3 file above.
Fuel trims still want to hang out at -12.5 and the surge is still present.
Guess the only way I can check to see if the PCM is the issue is to write the tune for my truck to it then install it in the truck and see if there is an issue? I could probably find a PCM to buy but then I would have to pay to unlock it.
The only other thing now that it has a stumble is could the fuel pump or Corvette regulator be giving out? Seems that would show up as a pressure fluctuation when the idle is surging if so.
Here is a log from today where I start it cold (fires right up and idles like a champ) then start driving and once temps get above 130-140* or so it begins acting up again.
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From: Northwest AR
Truck runs perfectly and trims like normal. Another check off the list.
Guess it could still be the car's harness? It would have got moved around a good bit during the engine swap then again during the valvetrain setup and again while checking hot lash right when the idle issue really started.
Guess it could still be the car's harness? It would have got moved around a good bit during the engine swap then again during the valvetrain setup and again while checking hot lash right when the idle issue really started.