RPM Drop slowing
 

Installed LT2 intake manifold and Roto Fab now getting CEL p0106 and when I come to a stop and slow down the RPMs drop quickly to 500 and then go right back up to 1k. What is going on? Torqued to 89in/lbs and looks as if all my intake tubes are sealed. Seems to drive fine but almost tries to stall at the slow down.

sounds like you need to check the wiring and connections on the map sensor. disconnect everything, inspect it thoroughly, reconnect. if everything is good, perhaps you have a faulty extension. which one are you using?

GPI is the extension I’m using. Came with the intake manifold

Did you disconnect power when you installed the intake? I didn’t, and I had goofy problems until I disconnected and let it rest for 30 minutes or so. After that all codes cleared and runs good. Same setup here, LT2 and Rotofab

I had it disconnected. Maybe it is just relearning the air flow? Just the RPM drop when slowing down confused me. Drops to under 500 then jumps right back to 750-1k in a split second after.

Do you need to get the tune adjusted for manifold volume and MAF characteristics?

Shouldn't many owners do it without a tune so im just not sure if I have a vacuum leak or what could have happened it hard to find a leak specifically. Might take the foam out from under the IM and try it that way.

Is your hood compressing that PCV line? Others have installed a 45 deg fitting to prevent hose crush. If PCV is getting pinched it could alter manifold pressure. the P0106 code is unexpected change in manifold pressure.

Just ordered a 90 degree to see if it is that but still not sure where else vacuum leaks could be. I'll remove foam from under IM and check the brake booster fitting with some brake cleaner and see if engine revs.

Good ideas.
Do you have a scan tool which lets you monitor the MAP reading? Would be nice to know if it is going up or down to throw the code and/or vehicle coming to a stop.

That I do not only OBD scanner nothing MAP specific

took foam out still did not help. When i get on the gas real hard it shuts off the power to reduced engine power and shuts the car off....anything i should check now

Anytime I've had idle speed anomalies (usually idle will stay high and be slow to drop, I admit), it has been due to an air/vacuum leak. I've got the MSD IM, and they also prescribed 89 in/lbs, but they were specific about raising the torque sequentially (at least 3 passes) and in specific order. I left out the foam also without adverse effect.

I'm sure you know your stuff, but here's MSD's install instructs- https://documents.holley.com/2700.pdf

yeah I torqued them in order