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I have a 79zx that won't run well until warm. It starts up pretty easy, but after starting, rpms drop to 500 or so, it lopes like it has a vacuum leak, feels like it is missing. after the car is warm, engine runs good idle is 1000 rpm or so. It blows a lot of black smoke above 4000 rpm, so could be running pretty rich, maybe left over carbon from starting? I noticed some posts in archives about temp sensors. also found one about a dashpot. I thought it was the cold start valve, but it tested ok. I can't find any obvious vacuum leaks. I saw a post earlier about a 78 z with similar problems. I was wondering if he came up with a resolution for it. Any advice would be greatly appreciated.
 

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> I have a 79zx that won't run well until
> warm. It starts up pretty easy, but after
> starting, rpms drop to 500 or so, it lopes
> like it has a vacuum leak, feels like it is
> missing. after the car is warm, engine runs
> good idle is 1000 rpm or so. It blows a lot
> of black smoke above 4000 rpm, so could be
> running pretty rich, maybe left over carbon
> from starting? I noticed some posts in
> archives about temp sensors. also found one
> about a dashpot. I thought it was the cold
> start valve, but it tested ok. I can't find
> any obvious vacuum leaks. I saw a post
> earlier about a 78 z with similar problems.
> I was wondering if he came up with a
> resolution for it. Any advice would be
> greatly appreciated.

This may solve your problem because I have the same problem. Just pulled the hose on the air regulator and checked the regulator door ---- it's frozen shut. Air regulator is like a choke that helps out in cold engine conditions. Door opens when cold and the computor inriches the mixture to compensate ---- as the engine warms up the door slowly closes and everything goes back to normal. Hope this helps Jerry 83 280Z
 

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179 Posts
> I have a 79zx that won't run well until
> warm. It starts up pretty easy, but after
> starting, rpms drop to 500 or so, it lopes
> like it has a vacuum leak, feels like it is
> missing. after the car is warm, engine runs
> good idle is 1000 rpm or so. It blows a lot
> of black smoke above 4000 rpm, so could be
> running pretty rich, maybe left over carbon
> from starting? I noticed some posts in
> archives about temp sensors. also found one
> about a dashpot. I thought it was the cold
> start valve, but it tested ok. I can't find
> any obvious vacuum leaks. I saw a post
> earlier about a 78 z with similar problems.
> I was wondering if he came up with a
> resolution for it. Any advice would be
> greatly appreciated.

Just finished up the air regulator --cleaned all electrical connections with contact cleaner from Radio Shack ---- put on new hoses --- fired up like a dream ---- idled nicely at slightly higher rpm then very shortly dropped down 1000 rpm's -- perfect -- hope you have as good a luck Jerry 83 280
 

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My 78 280 z was doing that, but after changing everything out it was the tempeture sensor that was cutting on an off and making the car run without any power. I jiggled it and the car ran fine until it moved back into it's orginal position----But TRy the temp. sensor.
 
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