Weird idle, cold power issues --- Imagine that!
05-02-2017, 10:23 AM
#1
Rennlist Member
Thread Starter
Weird idle, cold power issues --- Imagine that!
On my 86 951...
So, this isn't the hugest deal, it's more a "it's not right and drives my OCD about this stuff nuts" kinda thing.
Car starts fine, cold or warm. When it's cold it will idle fine, about 1k-1.1k and hold it for as long as I have the patience to let it. When warm, it's a bit more ruff idle. Not hunting really, just ruff. New plugs, wires, rotor. New injectors, new fuel components. New fuel filter. New vac lines. The works.
When it's cold, as soon as I touch the gas, it goes to running ruff. I've also noticed I have low and very surgy power till it warms up some. It takes 20-25 mins to get to the first mark on the temp gauge in this 40-50 degree weather, but it starts sorting itself out after about 5 mins and has more constant and normal power.
Back in the day, I'd just say it's cold natured. But this is (old but still) computer control fuel injection. It should compensate and run the same cold or warm. Most of the things I've found by searching would be causing much worse problems than I'm having. Really don't think it could be DME temp sensor, then it wouldn't run cold at all. Can't be vacuum, would start and idle worse.
The two main weird things are the fact it idles normal unless I blip the gas, then it goes to more like idling like it does when hot. And the surgy power when cold. I get a small amount of that when warm, just a tad. But it's bad when cold...
Course I'm missing an exhaust stud, and have an exhaust leak I can hear when cold, and it goes away it seems when warm... at least at idle. Could an exhaust leak on one tube cause it to surge like that? Like maybe the exhaust gas is venting to atmosphere (somewhat) instead of making it's way to the turbo, causing surging? I also thought maybe the turbo just needs to warm up?
Would kinda make sense if it's the leak, it could still be leaking somewhat hot when there is pressure in the exhaust, just not as bad as it is when cold. Don't think that could effect my idle though, unless it's playing with the O2 sensor.
I got the new exhaust stud in the mail and will be testing to see if the threads are stripped, if it's got one broken off in it, or somehow someone just "forgot" that last stud in the past. But any ideas?
So, this isn't the hugest deal, it's more a "it's not right and drives my OCD about this stuff nuts" kinda thing.
Car starts fine, cold or warm. When it's cold it will idle fine, about 1k-1.1k and hold it for as long as I have the patience to let it. When warm, it's a bit more ruff idle. Not hunting really, just ruff. New plugs, wires, rotor. New injectors, new fuel components. New fuel filter. New vac lines. The works.
When it's cold, as soon as I touch the gas, it goes to running ruff. I've also noticed I have low and very surgy power till it warms up some. It takes 20-25 mins to get to the first mark on the temp gauge in this 40-50 degree weather, but it starts sorting itself out after about 5 mins and has more constant and normal power.
Back in the day, I'd just say it's cold natured. But this is (old but still) computer control fuel injection. It should compensate and run the same cold or warm. Most of the things I've found by searching would be causing much worse problems than I'm having. Really don't think it could be DME temp sensor, then it wouldn't run cold at all. Can't be vacuum, would start and idle worse.
The two main weird things are the fact it idles normal unless I blip the gas, then it goes to more like idling like it does when hot. And the surgy power when cold. I get a small amount of that when warm, just a tad. But it's bad when cold...
Course I'm missing an exhaust stud, and have an exhaust leak I can hear when cold, and it goes away it seems when warm... at least at idle. Could an exhaust leak on one tube cause it to surge like that? Like maybe the exhaust gas is venting to atmosphere (somewhat) instead of making it's way to the turbo, causing surging? I also thought maybe the turbo just needs to warm up?
Would kinda make sense if it's the leak, it could still be leaking somewhat hot when there is pressure in the exhaust, just not as bad as it is when cold. Don't think that could effect my idle though, unless it's playing with the O2 sensor.
I got the new exhaust stud in the mail and will be testing to see if the threads are stripped, if it's got one broken off in it, or somehow someone just "forgot" that last stud in the past. But any ideas?
05-02-2017, 12:12 PM
#2
Rainman
Rennlist Member
Rennlist Member
check the DME temp sensor even though you wouldnt think so.
bad sensor won't stop the car from running as long as its putting out "some" reading but a faulty reading could mean car goes lean which makes cold driving suck.
bad sensor won't stop the car from running as long as its putting out "some" reading but a faulty reading could mean car goes lean which makes cold driving suck.