1985 grand marquis CFI rough idle

[85tanmarq]

so i have a CFI 302 car ive changed injectors all sensors tuned it up set idle, removed cats and egr valve, i have a rough idle sometimes i was thinking timing but most people say check vacum? any trouble spots this is the first CFi i have had, i aslo was wondering do you have to remove the distribuer to remove the intake?

[phayzer5]

Id check for vac leaks. Those old rubber caps/hoses and plastic lines get real brittle with underhood heat and age. You might also want to check resistance on those plug wires. You could have one that's got a flaky break in the conductor.

[gadget73]

Replace all of the vacuum lines and see what that does for you. Also check the timing to make sure its where it belongs. The timing chains are known to stretch, and the 85 and older cars have really lousy timing sets that have been known to jump.

[phayzer5]

... and yes, you can remove the intake without touching the dist. Though you'll probably want to unplug the TFI module to keep those wires out of the way.

While you're in the engine bay, the heater bypass hose on the t-stat housing would be a good thing to check too (not that it's related to the problem, they just like to develop cracks on the underside of the bend and fail at the worst time).

[gadget73]

you can get the intake out without pulling the distributor, but honestly for as much bother as it is to shuffle that thing in and out of there around the dizzy, its really not worth it. Takes minutes to pop the distributor out, and then you can use guide pins to plant the intake back on without risking pushing the gasket out of position. If its the cast iron intake instead of the aluminum one, its even more of a pain in the ass because of the weight.

[85tanmarq]

phayzer 5 i did replace that hose t stat and water outlet housing i know all about them pesky things thanks for all the advice, do you think the ford racing wires would be bad already?

[85tanmarq]

One more question can i change the timing from the plastic gear to a metal one?

[sly]

all replacement timing sets use metal gears. You can't get plastic. So yes.

Ford racing wires should be good for the long haul. I've never heard of a set being bad that wasn't severely jacked with or bad out of the box.

[85tanmarq]

Ok so i changed vacum lines idle got better checked timimg it was 20 degrees BDC sticker told me to set to 10 degrees BDC now runs great idles good except when u sit at stoplight for longer than 10 secs it gets rough but other than that runs silky smooth? any ideas

[85tanmarq]

Oh and one more thing i found a disconnected wire that was red and white goes with the wire cluster behind the alternator cant find where it goes anybody go a decent wiring schematic for these old cfi's?

[gadget73]

did you unhook the spout connector when setting the timing? If not, you probably put it 10 degrees retarded from where it belongs. The connector is the single wire round connector right next to the distributor, in the harness coming off the ignition module.


red/white wire behind the alternator could be the temperature sensor. It lives right behind the alternator. See if there is already a wire on it. If not that, don't know.

[85tanmarq]

I didnt see a wire like that do you have a pic all i could find was the wire that hooked to the ignition module?

[85tanmarq]

Well first week driving gas mileage is on the rise car pulls awesome and the rough idle is gone so if i retarded the timing too much it runs to good to advance unless u think it would be harming the engine?

[johnunit]

It could cause some long-term issues, but I'd get a timing light on it with the spout connector disconnected before I made any decisions about 'too far'.

[gadget73]

The 85 module and wiring ought to look like this:



Pete is holding the SPOUT connector that you'd need to unplug in order to set the timing.