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CIS question (non turbo)

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 Post subject: CIS question (non turbo)
PostPosted: Thu May 28, 2020 10:34 pm 
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I sprinkle rubber on my Cherios

Joined: Wed Jun 01, 2016 9:27 am
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Car is an 86 coupe with a KV engine.

I was having fuel leaking from under the fuel distributer into the airbox and the fuel was leaking out from the steel plate in the air box. I read that their was no fix for it so I replaced the entire top filter housing complete with CIS system from an identical parts car I have which the engine started right up, idled and ran fine.
Except for the fuel leak the car started righted up and ran fairly well

Now with that system on the driver car it starts harder, idle hunts until warmed up but the car definately runs smoother now. That may be cause of no more leaking but I dont know.

Any ideas what to check or adjust. Like I said the system was just fine on the donor car.


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 Post subject: Re: CIS question (non turbo)
PostPosted: Fri May 29, 2020 6:10 am 
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kickin' tires'n lightin fires

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make sure you didnt knock any air lines off or possibly crack the intake boot.
you can try adjusting the mixture by looking at differential pressure valve value cant remember what its suppose to be, or disconnect the o2 once its warmed up and see what your value is at, i think around .7-.8v? Try adjusting the mixture accordingly, small steps remember where you started so you can go back. verify no air leaks and the o2 functions before adjusting your mixture.


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 Post subject: Re: CIS question (non turbo)
PostPosted: Fri May 29, 2020 6:19 am 
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I sprinkle rubber on my Cherios

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Thanks Dustin.

I was planning on rechecking everything this weekend. I was very careful about hooking everytgibg back up ut it was getting late and I was getting tired. Would you believe I had it all together and then saw the air filter sitting in the valve cover!


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 Post subject: Re: CIS question (non turbo)
PostPosted: Wed Jun 03, 2020 7:32 pm 
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I sprinkle rubber on my Cherios

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Dustin,
I did a quick check over the weekend and all looked good and still had trouble starting. Yesterday (monday) started right up and no problem hot or cold since then. Maybe there was still some air in the system. Idle hunts for about 30 seconds but then settles down at just over 1k. Good enough for now :)


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 Post subject: Re: CIS question (non turbo)
PostPosted: Thu Jun 04, 2020 8:58 pm 
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Fix any vacuum leaks, replace injector seals if they haven't been done, clean ISV, new O2 sensor if it's old, and verify all temp sensors are working (along with the cold start valve). After that you can follow the procedure in the Bentley for setting the idle RPM and mixture. Then starting issues and idle hunt will go away.

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 Post subject: Re: CIS question (non turbo)
PostPosted: Thu Jun 04, 2020 9:17 pm 
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I sprinkle rubber on my Cherios

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alxdgr8 wrote:
Fix any vacuum leaks, replace injector seals if they haven't been done, clean ISV, new O2 sensor if it's old, and verify all temp sensors are working (along with the cold start valve). After that you can follow the procedure in the Bentley for setting the idle RPM and mixture. Then starting issues and idle hunt will go away.


I was planning on going through it this weekend. I have a question on the 02 sensor. The light was on when I got the car and was doing some research on it. I reset the the light on the cluster to turn it off. I read that everybody just takes the bulb out because the bulb coming on is just based on mileage. That's why there is a reset in the cluster and the earlier cars had the reset in the intermediate speedo box. I read from multiple sources that the computer does nothing in relation to the 02 sensor. The system is after all a CIS


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 Post subject: Re: CIS question (non turbo)
PostPosted: Fri Jun 05, 2020 10:34 am 
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The computer uses the 02 sensor to maintain stoichiometric AFR by modulating the electro-hydraulic actuator on the CIS-E metering head during idle and cruise. BTW your high idle problem is often a symptom of a non-operational idle stabilizer valve. The ISV should buzz/vibrate when the ignition is on and it should idle at like 800 rpm. The 4000/CGT ISV is very prone to failure due to pitting of the electircal contacts inside the unit.

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