1990 5.8L idle drops...

[Dan 2663]

First I want to say that I have the EGR blocked off with a plate I made to check the opeation of the EGR, with out the plate and having the EGR mounted correctly the Idle drops suddenly and returns, almost like a stall but with it blocked off I get a smooth idle most of the time and I get hesitation during accelration. NOW if I unplug the SPOUT connector the motor runs perfect.. I have check and replaced just abpout every sensor and the one that remained checked out to be good. I think it might be the vaccum canister cause there seems to be no vaccum on all the EGR lines ect. Also is there a sensor in the E4OD tranny cause when it shifts into OD if I am coasting its fine but as soon as I touch the gas the E4OD bucks and chuggs but with the SPOUT connector unplugged it runs beautiful..

Please...please has someone ever run into this problem before...

Dan

 

[Seabronc]

From what I understand;

1. disabling the EGR with the Spout connector hooked up the engine runs OK.

2. with the EGR normally hooked up and the Spout connector removed the engine works OK.

With the Spout connector disconnected the timing runs at a default setting. With it in the EEC controls the timing. As far as the EGR vacuum goes you should have no vacuum at idle and when the engine is cold. When the engine is at normal warm, the EGR is controlled by several factors, such as vacuum, engine speed, coolant temperature, throttle angle, and backpressure.

From the sound of what you said, the EGR is introducing exhaust into the system at the wrong time or in the wrong amount. That is the reason that it runs smoothly when disabled. It takes both vacuum and backpressure to operate the EGR.

A common problem with EGRs is that the valve doesn't seat properly because of carbon in the seat area. The electronic EGRs are not considered servicable if they carbon up. What you have done with the plate is the same as the EGR seat test, and it is suggested that you replace the valve.

Good luck,

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