B18Cr sudden idle problem??

[EM1_nic]

So i had my car not moving for the winter in the driveway since november. Id start it from time to time and let it sit on idle for 10-20 mins until it was at peak temp then close it. never had a problem till yesterday, i do same thing as usual and everything is fine but i decide to rev it once its at its peak temp, revved it to 3k 3 times and once to 5.5k rpm let it sit for couple mins then shut car off and everything was fine. 5 minutes later i turn it back on and it bucks and idle is fluctuating(200-1.3k rpm) and car shakes a bit and is really really rough, it also has no CEL. I let it sit there for the night and started it again the next day and everything is fine till the idle drops at lower rpms then it bucks again and runs very rough. Haven't tried driving with it as i have no clue why it does this. could the revving have broken something even though it was at its peak temp? I need help the car was running great since i have swapped it a year ago. no CEL light on and everything was running fine until i turned it off and back on....

info on car: stock block b18cr, only mods are I/H/E, stock p73 obd2a ecu

 

[XpL0d3r]

Try cleaning the IACV, if you haven't yet it could just be very dirty and starting to cake / clog up.

 

[EM1_nic]

i had cleaned it previously even though it was already clean, I'm kinda astounded by this, could revving the warm engine have caused this? its the only thing i did differently and last thing i did before this happened....

 

[lethal6]

Rule of thumb, a car sitting at idle isn't efficient to keep the charging system charging no matter how long it is left running. Your car needs to be at road rpms for the system to be charging correctly.

Also revving it without a load is not a good thing if done a lot.

Neither of these have any relation to your problem though, but the first one will cut the batteries life significantly short unless you keep a battery tender plugged in while it is sitting to keep the charge up to 100%.

It is possible that the cold took out a sensor or revving it knocked a connector loose? Without having the car in front of me to test and diag, there isn't much I can do without full information. Sounds like there might be a vacuum leak somewhere just off the information you have given.

 

[EM1_nic]

This was the first time I revved it and only brought it to 3k rpm twice and 5.5k once that's it. The thing is when I start the car everything is fine and sounds fine, the problem starts once it gets to 1.5k rpm or lower it starts doing the weird symptoms of bucking, rpm fluctuating with sounds like missfire and car shakes a bit.. It was checked for vacuum leaks previously also before winter but I will recheck, every wire and connector seemed in place and solid

 

[lethal6]

Cold weather sitting can be hell to vehicles. I would check everything thoroughly to see if anything is loose, check the air filter and housing if factory. Some critter could have made a nest in there and it is mucking up the intake "parameters". How long ago was the car gone completely over tune up wise?

 

[EM1_nic]

Last tune up was about 6 months ago and 3000miles. I will have to wait to check the car out again as it isn't accessible anymore

 

[EM1_nic]

Alright so I got access to the car and checked the engine bay and I think I found my problem I noticed the ground wire from the engine was snapped in 2 and isnt touching metal. is it possible this is the source of my problem and changing it will make everything run right again? I will check my fuses and stuff

 

[R3dline]

yeah, grounds make a differnce