Gebert530

Just installed my new engine from S&J engines and it started right up. I broke it in at 1500-1800 RPMs for 20 minutes using Amsoil break in oil. I burped the cooling system with a coolant funnel and the engine still idles and the exhaust makes a poofing noise. Not a knock or tap or loud misfire but just bursts of air every couple seconds, only happens while idling and it can easily be felt from inside the vehicle. I have no idea where to start, does anyone have a similar experience? Can the Cam shaft position sensor be off just a little causing this issue? Could timing be off a little causing this issue?

dave1123

It sounds like an occasional misfire that can be caused by any number if things, like maybe a spark plug that's shorting out or a valve that's not quite seating properly. Maybe even a spot of carbon on a valve seat. Is the spark coil rail new? It could have a damaged plug boot that's arcing over. My rebuild engine had one cylinder that the rings took almost 2000 miles to fully seat and was causing an occasional miss only at idle. I could tell because it was using a bit of oil, not much, but some, and then stopped and the engine idled smoothly after that. It would throw a misfire code for #5 every so often after idling a while before that.

The cam position sensor controls injector timing and can be set to 0 with a scan tool. The computer can compensate to a certain degree + or -. The ignition timing is entirely controlled by the computer by reading the crank sensor and rpm, temp, MAP sensor, TPS, vehicle speed and load.

Griffyorcono

Hello,

A video of whatever is going on would be helpful.
I'm not a diagnostics expert so I'm just going off of what Dave has said. (!Cruiser where you at doe, its not a Renix but!). If it is a misfire check your plugs to see if their burns look different and take photos of that too, has the whole ignition been tuned-up or is anything original? Has the crank shaft position sensor been replaced? Just a more descriptive explaination I think will help the more educated people on here help you better.

Thank you and good luck with your problem.

Gebert530

Alright this case can be closed, went to adjust my cam shaft position sensor and when I pulled the first cylinder spark plug it had almost no gap on it. I think I crushed it somehow or dropped it. Also my camshaft position sensor was slightly turned towards the engine, and I mean slightly so I corrected that. So im confident the spark plug was my issue but the cam shaft position sensor probably helped too. This was a brand new engine install so thankfully I knew something was wrong and caught it quick.

dave1123

Yeah, too many people just take spark plugs out of the boxes and put them into the engine without checking the gap. People think they should be gapped properly for the engine they are made for, but no, not always. I've also found the gap can be closed by rough handling in shipment. Champions were known for this long ago because they were extended tip. I use NGKs in my jeeps since they are waste spark engines and they have plastic sleeves over the threads when you open the boxes. Yours should be NGK ZFR5N (3459)