ZCar Forum banner
Status
Not open for further replies.
1 - 5 of 5 Posts

·
Registered
Joined
·
85 Posts
Discussion Starter · #1 ·
OK,
It is an 81 turbo and the engine idles erratically when cold and in drive(yes it is an automatic.) The thing is that when it warms up it idles fine, but then has less power. The engine just pulls like a champ when it is cold. So, what my question is if anyone can head me in the right direction without having to pull every sensor in this thing. I was personally thinking that it might be the water temp. sensor or possibly the Throttle valve switch, but am not sure if either of these sensors could cause these particular symptoms. All help is appreciated.
 

·
Registered
Joined
·
107,597 Posts
Tough one to call

> OK,
> It is an 81 turbo and the engine idles
> erratically when cold and in drive(yes it is
> an automatic.) The thing is that when it
> warms up it idles fine, but then has less
> power. The engine just pulls like a champ
> when it is cold. So, what my question is if
> anyone can head me in the right direction
> without having to pull every sensor in this
> thing. I was personally thinking that it
> might be the water temp. sensor or possibly
> the Throttle valve switch, but am not sure
> if either of these sensors could cause these
> particular symptoms. All help is
> appreciated.

My '83 zxt had a similar problem. I broke open the book and went step by step checking every sensor in the **** thing. Finaly after a couple of days I found a vacuum line with a very small hole in it - bought a new line and haven't had that problem again. The bad thing about an 80's car is that it isn't as simple to diagnose as a 70's 350. eratic idle can be - bad vacuum lines, egr, camshaft, exhaust sensor, or even a cloged air filter, and probably one of a billion other things I've never heard of.
This engine however does run great when they are cold - but when they warm up several bypass valves open and close to activate other components - making it hard to find a trend. Sorry I couldn't be of much help to you, but, there are a few billion people on this planet - and they are all smarter than me. So maybe we can solve this one.
Dave
 

·
Registered
Joined
·
107,597 Posts
wouldn't hurt to check the timing

> My '83 zxt had a similar problem. I broke
> open the book and went step by step checking
> every sensor in the **** thing. Finaly after
> a couple of days I found a vacuum line with
> a very small hole in it - bought a new line
> and haven't had that problem again. The bad
> thing about an 80's car is that it isn't as
> simple to diagnose as a 70's 350. eratic
> idle can be - bad vacuum lines, egr,
> camshaft, exhaust sensor, or even a cloged
> air filter, and probably one of a billion
> other things I've never heard of.
> This engine however does run great when they
> are cold - but when they warm up several
> bypass valves open and close to activate
> other components - making it hard to find a
> trend. Sorry I couldn't be of
> much help to you, but, there are a few
> billion people on this planet - and they are
> all smarter than me. So maybe we can solve
> this one.
> Dave
 

·
Registered
Joined
·
107,597 Posts
> OK,
> It is an 81 turbo and the engine idles
> erratically when cold and in drive(yes it is
> an automatic.) The thing is that when it
> warms up it idles fine, but then has less
> power. The engine just pulls like a champ
> when it is cold. So, what my question is if
> anyone can head me in the right direction
> without having to pull every sensor in this
> thing. I was personally thinking that it
> might be the water temp. sensor or possibly
> the Throttle valve switch, but am not sure
> if either of these sensors could cause these
> particular symptoms. All help is
> appreciated.
 

·
Registered
Joined
·
1,154 Posts
A guy I know who works in a local marina said he once called a boat owner up with bad news: Your boat has sunk in your slip. The guy said, That's funny, I was just down there yesterday working on the head (toilet) and it was fine.

The moral of the story is that many people do stuff to cars, then the cars run bad, and they immediately start checking every other system than the one they just worked on — which 99% of the time is where the problem is.

So the first question I'd ask is, Did you do anything to the car — anything at all — before it started idling badly? If the answer is yes, go back through everything you did and check for wires or vacuum hoses accidentally pulled loose. I manage to do this somehow almost every time I lift the hood on my car.

If the answer is no, check for back vacuum lines and electrical connections anyway. THEN start fiddling with sensors and stuff. If you START there, you'll drive yourself crazy. I am living proof of this.
 
1 - 5 of 5 Posts
Status
Not open for further replies.
Top