A few issues after H/C/I
98 LS1 having some issues after H/C/I Having some issues on my 1998 Z28 after a heads/cam/intake swap.
Mods:
243 heads
BTR Stage 3 cam (all the accouterments to go with it, push rods, springs etc..)
FAST 92 intake
42lb injectors-Green FORD
Holley Sniper TB
EGR and AIR delete
LT's
I sent the computer to my tuner along with the cam card and the injectors I was using as well as the AIR and EGR delete. He mentioned something about not knowing the voltage offsets and short pulse modifiers are so he had to take a shot in the dark on that but he didn't really seem like it was going to be an issue and I'm still going to bring it to him to dyno tune now that it is up and running.
My issue is I'm having some surging and the idle doesn't really get below 1200 and it'll surge up to 2000 when I blip the throttle. I'm fairly certain it is IAC issue because I cannot detect a single vacuum leak and I redid the PCV routing when i swapped over the intake. I read the holley sniper doesn't fit the AC Delco (stock) IAC very well and looking back it went into place but had to be persuaded a little, I wonder if the IAC is too long and it's allowing air to get in??
Thoughts and comments are appreciated
Mods:
243 heads
BTR Stage 3 cam (all the accouterments to go with it, push rods, springs etc..)
FAST 92 intake
42lb injectors-Green FORD
Holley Sniper TB
EGR and AIR delete
LT's
I sent the computer to my tuner along with the cam card and the injectors I was using as well as the AIR and EGR delete. He mentioned something about not knowing the voltage offsets and short pulse modifiers are so he had to take a shot in the dark on that but he didn't really seem like it was going to be an issue and I'm still going to bring it to him to dyno tune now that it is up and running.
My issue is I'm having some surging and the idle doesn't really get below 1200 and it'll surge up to 2000 when I blip the throttle. I'm fairly certain it is IAC issue because I cannot detect a single vacuum leak and I redid the PCV routing when i swapped over the intake. I read the holley sniper doesn't fit the AC Delco (stock) IAC very well and looking back it went into place but had to be persuaded a little, I wonder if the IAC is too long and it's allowing air to get in??
Thoughts and comments are appreciated
A few issues after H/C/I Having some issues on my 1998 Z28 after a heads/cam/intake swap.
Mods:
243 heads
BTR Stage 3 cam (all the accouterments to go with it, push rods, springs etc..)
FAST 92 intake
42lb injectors-Green FORD
Holley Sniper TB
EGR and AIR delete
LT's
I sent the computer to my tuner along with the cam card and the injectors I was using as well as the AIR and EGR delete. He mentioned something about not knowing the voltage offsets and short pulse modifiers are so he had to take a shot in the dark on that but he didn't really seem like it was going to be an issue and I'm still going to bring it to him to dyno tune now that it is up and running.
My issue is I'm having some surging and the idle doesn't really get below 1200 and it'll surge up to 2000 when I blip the throttle. I'm fairly certain it is IAC issue because I cannot detect a single vacuum leak and I redid the PCV routing when i swapped over the intake. I read the holley sniper doesn't fit the AC Delco (stock) IAC very well and looking back it went into place but had to be persuaded a little, I wonder if the IAC is too long and it's allowing air to get in??
I also unplugged the battery for a few minutes, re-connected and unplugged IAC and TPS and cycled the key, plugged the 2 back in and it idled at a normal idle BUT surging returned about 500 feet down the road, turned into a gas station got some fresh gas in her and took her home where it continued to surge up to 2k on the drive back...
Can't remember if I ordered an AC Delco IAC or a cheap one off Amazon so I ordered one from Holley specific for the sniper TB...
Any help is appreciated.
Mods:
243 heads
BTR Stage 3 cam (all the accouterments to go with it, push rods, springs etc..)
FAST 92 intake
42lb injectors-Green FORD
Holley Sniper TB
EGR and AIR delete
LT's
I sent the computer to my tuner along with the cam card and the injectors I was using as well as the AIR and EGR delete. He mentioned something about not knowing the voltage offsets and short pulse modifiers are so he had to take a shot in the dark on that but he didn't really seem like it was going to be an issue and I'm still going to bring it to him to dyno tune now that it is up and running.
My issue is I'm having some surging and the idle doesn't really get below 1200 and it'll surge up to 2000 when I blip the throttle. I'm fairly certain it is IAC issue because I cannot detect a single vacuum leak and I redid the PCV routing when i swapped over the intake. I read the holley sniper doesn't fit the AC Delco (stock) IAC very well and looking back it went into place but had to be persuaded a little, I wonder if the IAC is too long and it's allowing air to get in??
I also unplugged the battery for a few minutes, re-connected and unplugged IAC and TPS and cycled the key, plugged the 2 back in and it idled at a normal idle BUT surging returned about 500 feet down the road, turned into a gas station got some fresh gas in her and took her home where it continued to surge up to 2k on the drive back...
Can't remember if I ordered an AC Delco IAC or a cheap one off Amazon so I ordered one from Holley specific for the sniper TB...
Any help is appreciated.
I don't have the tuning data, I mailed it off to him last spring and just between the new born and life, getting the car back together was put to the back seat. I emailed him on Sunday and I ordered an IAC specific for this sniper TB so maybe that'll clear it up. Thinking back my 2000 WS6 did the same thing after an intake and headers, had a Nick Williams TB on that thing and the new IAC cleared it up.... I'll keep you guys posted.
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I don't have the tuning data, I mailed it off to him last spring and just between the new born and life, getting the car back together was put to the back seat. I emailed him on Sunday and I ordered an IAC specific for this sniper TB so maybe that'll clear it up. Thinking back my 2000 WS6 did the same thing after an intake and headers, had a Nick Williams TB on that thing and the new IAC cleared it up.... I'll keep you guys posted.
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Verdad Gallardo Someone brought me a setup to toon with one of those Holley sniper TBs and I ended up sending him back home to rip it off and replace it with a stock one. Found that the IAC valve flow is very nonlinear at the last 10% it's range as it closes. Too much to bake into the IAC calibration...so away it went. Wouldn't be the case on every application but it should have had zero issues on a 6.0. Trash hardware is an epidemic these days... can't toon out just anything.
Got the new IAC in from Holley this morning. On my lunch break went and tinkered with the car, looked at vaccum lines again and the line going from the passenger head to the TB was off so I snugged that back up and installed the new IAC. fired it up and we held at 1300 RPMs for a few seconds and then she went to the normal range of 900's. I took the car for a 15 min test ride and all seemed well, no surging and she pulled hard like normal. I didn't push it too much but glad to have it rolling. Appointment for the 8th is set to get the car tuned on the dyno and until then I'll continue to drive it and break in the cam and transmission (trans was rebuilt right before the cam had maybe 200 miles on it before I put it in the garage)
Got the new IAC in from Holley this morning. On my lunch break went and tinkered with the car, looked at vaccum lines again and the line going from the passenger head to the TB was off so I snugged that back up and installed the new IAC. fired it up and we held at 1300 RPMs for a few seconds and then she went to the normal range of 900's. I took the car for a 15 min test ride and all seemed well, no surging and she pulled hard like normal. I didn't push it too much but glad to have it rolling. Appointment for the 8th is set to get the car tuned on the dyno and until then I'll continue to drive it and break in the cam and transmission (trans was rebuilt right before the cam had maybe 200 miles on it before I put it in the garage)
Yup as said above.. no need to break in the cam. You've already had several heat cycles on the valve springs too. I have read that when going to new dual springs to keep the RPMs below 4K, letting it cool overnight, then you're golden. Nothing else really needs a break in.