NEED HELP with high RPM ignition breakup - LS1TECH - Camaro and Firebird Forum Discussion

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NEED HELP with high RPM ignition breakup

Old 06-08-2018, 11:57 AM
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Default NEED HELP with high RPM ignition breakup

Need Some HELP...
05 CTS-V TSP torquer v2 cam
ZZP trunion upgrade
BTR 11/32 pushrods
TSP springs
Hand ported heads with valve job
Headers
Exhaust
K&N Intake
SLP 10% UDP
NGK TR6 gaped at .035
Accel plug wires

I am experiencing some high rpm ignition break up. It happens after 5k rpm. I get hesitation and sputtering. It usually happens 5200 -5600 rpm then runs good then starts breaking up again at 6000 rpm. I get a p0300 code. Tuning it myself. Runs perfect up to 5k then when it starts breaking up it goes rich. I think it runs rich because its not igniting the fuel due to the misfire. I pulled fuel from those ares and get the same results. I tried increasing the dwell time but had the same results.Hptuners shows that cylinder one get most of the misfires. I swapped coils but still get most of the misfires on cylinder one. I also ordered new ignition coils that should be here by this weekend. Any suggestions?

Last edited by Nazark_18; 06-08-2018 at 01:23 PM.
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Old 06-08-2018, 12:10 PM
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Is this a new build? I'd look at the springs-installed height etc.
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Old 06-08-2018, 12:12 PM
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Yeah put it together and tuning it. About 1000 miles on it.
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Old 06-08-2018, 12:32 PM
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I would suspect valve float
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Old 06-08-2018, 01:09 PM
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Really, withTSP .660" Dual Spring. Cam has .600 lift. I think they are like 415lb springs.
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Old 06-08-2018, 02:25 PM
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Really hard to say over the internet.

It sounds like a valve float issue and seen several threads with the same complaint that turned out to be spring issues.

Sure, it could be something else, but again it's over the internet so it's all our guessing based on your description.

A lot of times ignition failures (or weak coils) will show at lower rpm at high load, hard acceleration at 2k rpm in high gear for example. But with a cammed car you may get break up there due to the chugging from the cam.

Your gap is a little on the tight side for a heads cam motor. I'd run closer to .040-.045 on your build, but I can't really say I think that's the cause of your issue.

Try the crank sensor too, couple guys have had strange breaking up in certain rpm ranges and the crank sensor was funky.
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Old 06-08-2018, 03:35 PM
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If it was valve float would it cut in and out? It starts the visitation at over 5k rpmbut then goes away .Sometimes till redline sometimes for a few hundred rpms and comes back.
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Old 06-08-2018, 03:53 PM
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What valve springs should I use with that cam? 232/234 .595/.595
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Old 06-08-2018, 04:49 PM
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Are they installed properly? Also did you check the lifter preload? Are the valve stem heights set properly? Valve train geometry is extremely important in a HP engine. All the valve events need to be close to each other or you will experience problems. All of these need to be right if you expect top performance. If there are variations in the valve events at higher r's this shows up as random misfires. You also mention head porting, that needs to be right also. Good Luck, I'd start with the basics set up the valve train properly then see where it leads you. You honestly just can't toss a bunch of good parts into a engine without careful consideration to setup. You want every cylinder setup as close to each other as possible, even the valve depth etc. Very Important.
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Old 06-08-2018, 05:00 PM
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I didn't check the valve stem height. I did set the preload. I'm using ls7 lifters and 7.350 11/32 pushtods .That is what I got for a measurement.
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Old 06-08-2018, 05:15 PM
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What about the springs, are they set up?
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Old 06-08-2018, 06:05 PM
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I just put them in. It was a kit. I'm not a pro. I bought kit I thought it goes all together. For the heads ported with a valve job. Benn tunning it w HPtuners. All is good till 5k prm like I said.
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Old 06-08-2018, 06:06 PM
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I didn't measure spring height if that's what you are asking.
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Old 06-08-2018, 06:56 PM
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Hey bud. Read your OP & thought I'd just give my opinion. First thing was actually the TSP springs. I had those same springs & more than 2 failed. Was lucky. BTR springs are def the way to go. Just to mention TSP has lots of great stuff & I still buy from them. Just not the springs from my experience. The next thing is the TR6 plugs. Seems a bit cool. Are you going to be running some spray?
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Old 06-08-2018, 07:19 PM
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Again , got the new coils to try this weekend. I will also try to make the plus gap bigger as suggested, clean the MAF sensor .
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Old 06-08-2018, 07:23 PM
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Here is what plug one looks like.


​​​​​




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Old 06-08-2018, 07:27 PM
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Heat range looks good to me. Ignition looks off but I'm running 24 degrees at wot .the plugs have been there for about 1000 miles.

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Old 06-10-2018, 03:47 PM
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Thanks for the advice guys. I took the driver side cylinder head off and found a broken spring. should I be worried about piston and valve making contact? Idk if I should pull the head and check it out. It runs fine just had valve float 5.5 rpm .
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Old 06-10-2018, 03:51 PM
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Weak crankshaft position sensor? Poor engine ground. ? Something had to change,, unless it ran bad from square 1..
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Old 06-10-2018, 04:10 PM
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If it was an intake spring you're more than likely fine. Exhaust springs don't end good sometimes. Glad you found it.
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