Need help.. engine rpms drop right after cold start-up

[T4Rscott]

Hi all,

I recently replaced the injector in #4 cylinder with a good used one. This cured the misfire, however, now the rpms drop immediately after the engine fires. They come back up after a few seconds.

I have since received 5 reconditioned injectors back from Gordon at Witch Hunter Performance, ( the injector from cyl#4 had a bad coil winding) the condition still persists. The engine runs fine and is good on a hot start, only on a cold start such as first thing in the morning that it does this.

I did not replace the used injector in #4 since it cured the misfire. Also I cleaned the idle speed sensor and TB.

Could this be related to the fuel pressure regulator, or something else?

Any help would be great.

Thanks, Scott

 

[T4Rscott]

anyone????

 

[jgue467]

Bad fuel? bad #4?

My only similar experience is when mine would stumble just a moment when I started to accelerate for the first time after a cold startup. Just a momentary stumble but it bothered me. So, I read around here and heard of startron. used it per instructions (2 oz first tankful, 1 thereafter) and it cleared up by the next day and stayed away.

Got kinda confused on ur #4, replaced, not replaced, bad winding, whats all that about? :banana:

 

[T4Rscott]

Instead of sending all 6 original injectors to Witch Hunter, I bought 6 from a wrecking yard. I put one of the best of those 6 into cyl#4. I then sent the other 5 and my original from that cylinder to be reconditioned.

 

[Kanoe]

Just a thought.

The morning cold start idle speed is affected by the IAC valve. Less(or no) effect on a hot start I believe.

You mentioned you also cleaned Throttle body and Idle Speed sensor (IAC valve maybe??).

Is it possible the IAC is acting up as a result of the cleaning??

Just wondering..