Hi guys, I could really use your input on something.
If I put both hands on the intake manifold I can feel irregular skips/misses. The engine runs fine for a while and then a skip/miss. After this it continues to run fine before another skip/miss and so it continues. The skip/miss is just very slight, like when a heart skips/jumps over a beat. I can also barely hear it in the tailpipe.
A bone stock LS1 should idle smoother than that I think. How old are the plugs? You have a log file?
Jason
1996 Camaro SS M6 - 24X conversion - stock bottom end - heads - shorty headers - 58mm TB
Ultradyne 230/238 .565/.565 112+4 - 30 LB red top SVO injectors - LOTS of suspension...
2002 GMC 2500 HD Duramax M6 - Just starting the tune on a stock motor now that I have a good clutch on order...
I just swapped my used LS1 long block with a new crate engine. The PCM will be re-used from the old engine. Both long blocks are stock engines. I am using the same PCM with the same tune.Originally Posted by JasonS5555
I re-used all the electrics and sensors from the old engine. The only new sensors are the Cam- and Crankshaftsensors as they were already installed on the new engine.
Spark plugs are brand new, the rest is from the previous engine.
I will try to make a log today.
Make sure to do a crankshaft variation relearn as your crank and corresponding sensors are completely different now.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
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As I said on tech, you need to do the CASE learn procedure for the new crankshaft sensor. It doesn't matter that it's all stock or the tunes are the same. The sensor's ability to communicate with the PCM is predicated upon this "relearn." It is running rougher than anticipated because of a random misfire that CASE learn will fix.
Things to check if the CASE relearn does not fix the issue:
-Plugs & Wires (for smooth idle put stock heatrange Iridium Plugs in gapped at .040)
-Harmonic Balancer (as these age the rubber begins to break down and they do not dampen as well as they used to. I recommend using one from ATI stock size, no underdrive, steel snout, aluminum pulleys, they are better in every way than a stock balancer)
-Exhaust leaks (look at the fuel trims each side should be within 5% of the other side, if they aren't something is wrong)
-Motor mounts and transmission mount (as these age the engine will shake more and more, a friend of mine just has this issue on a 2006 GTO)
-Clean your maf and throttle body, the carbon build up really effects idle quality
-Check for vacuum leaks, even a small one can effect the idle quality
Should be smooth as glass if all is well.
Thanks for all the feedback!
I have included two logs - do they look ok?
2200rpm.hplidle misfire.hpl
Injector spray pattern if it's a new motor with new plugs, leads, and coils stock tuned. My 2 cents.
VodeAN is on the money with his suggestions. Those are the most commonly overlooked items on a swap.
Injectors are cleaned and flow tested.
Checked the plug leads yesterday and now I'm down to coils, pcm wiring harness or the pcm itself.
Is there any way to check if the coil is ok?
The way I test coils is with a stress tester it's a simple tool that you set a gap and see if the spark can jump the gap.
Any comments on the log files?
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