1986 Service Engine Soon Light
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
If you disconnect the ECM connector near the brake booster codes will be cleared but the ECM not otherwise effected. If you can't/don't find the ECM connector remove the neg battery terminal. It really won't make that much difference.
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
On back of the passenger side engine,is a metal tube that has a foil looking wrap around it,it comes off the exhaust manifold and curves up over the valve cover and bolts to the back of the intake manifold.Thats the egr feed tube.
On that pipe,on top of it near the distibutor cap,theres a white switch with a black wire...thats the egr temp switch.They can crack and twist out some and throw the code.
The wire itself is screwed into the switch...the switch is screwed into the pipe...you should not be able to unscrew the wire from the switch if its not cracked..if the wire is loose inside the white part of the switch,thats a sure sign its bad too.
On that pipe,on top of it near the distibutor cap,theres a white switch with a black wire...thats the egr temp switch.They can crack and twist out some and throw the code.
The wire itself is screwed into the switch...the switch is screwed into the pipe...you should not be able to unscrew the wire from the switch if its not cracked..if the wire is loose inside the white part of the switch,thats a sure sign its bad too.
4th Gear
Joined: Jul 2018
Posts: 4
Likes: 0
i have same issue the service engine doon light came on for few minutes then i accelarate and went off , could be the ecu aranged the fault because it didint came on agine or there was high emmisions and it was cleared , thanks
Cruising
Joined: Jul 2018
Posts: 11
Likes: 0
Hard start
I had the intake gasket replaced and I get the same problem. Hard start when first starting and the light comes on. I drive it for a while, shut it off, then restart and the light is off and starts good.
Any Answers?
Any Answers?
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Ses light
I have the same thing. 86 early.
changed the pump relay for hard start, Nothing changed.
put gauge on fuel rail, it was 40, going to zero when shut off. then changed fuel press diaphragm and now it does that.
took diaphragm back, got another new one, still hard start first start of the day.
pressure 42, pull vac hose, 48.
irregular idle.
dropped pressure to 38, and idles better, doesn’t take as long to start,
but i noticed there’s no pressure at gas cap when getting gas.
so i ordered a fuel tank pressure regulator.
all tjis stuff is rubber or plastic.
it doesn’t last forever
changed the pump relay for hard start, Nothing changed.
put gauge on fuel rail, it was 40, going to zero when shut off. then changed fuel press diaphragm and now it does that.
took diaphragm back, got another new one, still hard start first start of the day.
pressure 42, pull vac hose, 48.
irregular idle.
dropped pressure to 38, and idles better, doesn’t take as long to start,
but i noticed there’s no pressure at gas cap when getting gas.
so i ordered a fuel tank pressure regulator.
all tjis stuff is rubber or plastic.
it doesn’t last forever
