Thread: Cam stumbles off idle. Is this normal?

I just pulled the trigger on my S1X cammed L32. I noticed that I have a consistent stumble off-idle when launching. It only lasts a second then smooths right out.

I scanned my PCM and saw 500+ history misfires on cylinder #6. I have tried new plugs and wires with no effect.

Is this normal with a cam or am I missing something?

Not normal at all. I could understand random multiples if you didn't disable code P0300.

Did you happen to forget to plug in an injector? Believe it or not, these motors will idle and run halfway decent on 4-5 cylinders until you get on it (forgot to plug two in one time after a blower swap...)

Sent from my SkyRocket

I'm super sure that I connected all the injectors. I'd expect a code to set before too long with anything disconnected. To be absolutely sure, I'll disconnect each one, one at a time and listen for a change in idle. It could very well be that I have a broken wire or a bad connection somewhere.

I never did get a proper CPS variation learn. I attempted it several times and I did complete the process, but each time my PowerTuner reported that the test had failed. I'm going to do a full flash in the morning and try the case learn again.

I just wonder if I should raise my idle at all to accommodate the cam? It's set at 715 RPM while in gear and does idle smoothly. It just chokes for a second when I step on it.

Absolutely right! This was NOT normal. And it took some troubleshooting but I figured out that it was the fault of my old stock injectors. I saw that I had hundreds of misfires in cylinder #6 and the ceramic on the spark plug was bright white after hundreds of miles of normal driving. I pulled the fuel rail and all three of the rear cylinders had cracked disks. #6 was cracked so badly that the disk was no longer continuous and was allowing air to seep past the o-ring.

A new set of Siemens 60 pounders from ZZP fixed the problem immediately. They were super easy to tune in also. I just reduced the stock IFR table to 60% of original and had single digit fuel trims right away. The idle is smooth as stock even with an S1X cam.

My old stock injectors were topping 18 msec at 6500 rpm with 11.3:1 fueling. Same conditions now require pulses smaller than 10 msec. Mileage seems about exactly the same too.