High idle problem after motor mount install
High idle problem after motor mount install Well, I just got my car back from the shop. I felt sorry for the guys because they spent 8 hours on my car but only billed me for 1.5, and that was just for the drivers side mount.
At first I was really happy that the one mount was able to cure my y-pipe ills, but I've noticed that my car doesn't idle the same anymore. It used to idle at 700 flat, no surges. Now it varies, but will start at 1100-1200 and the slowly come down. Once it gets to around 600 it will come up and float between 650 and 750. A tap of the throttle will send it back to over 1000 and then it will come down again.
I looked for a vac leak but couldn't find one. Is there anything else that the shop could have bumped or unhooked that would cause this? It was too hot to check, but would an unhooked O2 sensor act like that, or perhaps he plugged it into the unused rear plug?
My mods are lid, K&N, P&P TB, LS6 intake, longtubes, ORY, !EGR, !AIR
1999 Z28 M6
At first I was really happy that the one mount was able to cure my y-pipe ills, but I've noticed that my car doesn't idle the same anymore. It used to idle at 700 flat, no surges. Now it varies, but will start at 1100-1200 and the slowly come down. Once it gets to around 600 it will come up and float between 650 and 750. A tap of the throttle will send it back to over 1000 and then it will come down again.
I looked for a vac leak but couldn't find one. Is there anything else that the shop could have bumped or unhooked that would cause this? It was too hot to check, but would an unhooked O2 sensor act like that, or perhaps he plugged it into the unused rear plug?
My mods are lid, K&N, P&P TB, LS6 intake, longtubes, ORY, !EGR, !AIR
1999 Z28 M6
wow 8 hours is way to long to change the mounts on a ls1. I did it with a buddy in the drive way in less than half that time. My guess would be they jacked the motor up to high and possibly created a small vaccum leak at the back of the intake. There is one small vaccum line on the back side of the intake on the left and a large vaccum line in the middle/right side going to the booster. Make sure both of those lines are all the way on.
Well, in the shops defense, they are a tranny shop and this was the first motor mount the guy had done on a vehicle like this. I warned them, but they had no idea what they were in for. I felt bad that they only billed me for 1.5 hours because I knew how rough it was on the guy. Keep in mind that in 8 hours only ONE mount got put in, thankfully it was enough.
Anywho, I double checked the vac lines in the back and they both looked good, as did the PCV lines. I need to double check my catch can, but I didn't hear it earlier when I looked. Are there any other vac lines it could be or should I start looking elsewhere. It really feels like a vac leak, I just can't seem to find it.
Anywho, I double checked the vac lines in the back and they both looked good, as did the PCV lines. I need to double check my catch can, but I didn't hear it earlier when I looked. Are there any other vac lines it could be or should I start looking elsewhere. It really feels like a vac leak, I just can't seem to find it.
Originally Posted by BigDaddyBry
Did they disconnect the battery when they did the install? If so, you're just going through the idle re-learn procedure. Don't worry about it.
They did indeed. I was thinking the PCM had to be reset for that to happen, but given the fact that I can't find a leak, perhaps that's what it is. It didn't do it today on startup or on the way home, so perhaps this was a false alarm.
