Captron

how do you test?

Captron

This thread kinda dried up, but for anyone reading here is an update. After reinstalling the original coils, but leaving in new plugs and replacing a really dirty air filter........I thought I had gotten lucky and fixed it but....
After driving it around town now and on the freeway, I have 0 codes, all monitors except evap complete and ready, and the car was driving great with no further rough idle at traffic lights. Then suddenly without explanation, wham, the car sitting at a red light and started the very rough idle again. I smooth it out with rpm in neutral and continue driving. When I got in my driveway, I left in gear with foot on brake to get it to rough idle again and it complied. Read the OBD in this idling condition and still no codes at all, not even misfire. That's where I'm at.

donbrew

Check the fuel pressure when it is happening.

Oldblue

X2^^^^^^ what Donbrew said!

Captron

I shall. Is there an inline fuel filter on this car between the tank and the injectors, or is it just part of the pump in the tank? also, what do I want to see on fuel pressure at idle?

Oldblue

Nope, no fuel filter outside the fuel tank, 55 to 65 psi and it should hold pressure for about 5 minutes.

RJ_RS_SS_350

Perhaps there is a vaccum leak at the brake booster. Sometimes the plastic hose fitting cracks.