Help w/ rough idle and poor gas mileage

Pepito opined in news:2004111819405616807%josephamadeusNSPAM@mindspringcom:

Do the thermostat WITH A 192 and come back then.

What's a 192?

It's a thermostat that opens at 192 degrees Fahrenheit to allow water from the block to flow through the radiator.

John opined

Sorry...it's the designed temp for the engine I ONLY said the number to state that there is NO advantage to going with a lower number and it is potentailly harmful..

and on that note... if the engine has been operating that way for any length of time, the inside is probably a mess and sludgy... check inside your filler and on your dipstick for wipeable deposits

Thanks for the info J

Could the temperature be the cause of rough idle and poor gas mileage?

I'd like to see a show of hands of those that did or did not understood you meant all that with "Do the thermostat WITH A 192 and come back then". It definitely went over my head.

JS

You've got the 2.3L engine, which means the fan is governed by the CCRM and ECM. Unless your model year is designed differently than the 93s, the fan should operate under the following conditions:

Engine temp reaches 221 degree threshold-->fan on Engine temp drops down to 200 degree threshold-->fan off

A/C on with lack of air flow due to vehicle speed; 43mph or lower-->fan on, and at 48mph-->fan off.

Note: All above operations are with the ignition switch to run position only.

If the fan starts instantly with a cold engine for instance, you may have a defective CCRM, ECM, ECM receiving false inputs or possibly the previous owner has modified the fan operation. I would first suspect the CCRM (constant control relay module). All of this might explain the engine having difficulties warming up, hence poor fuel economy among other things. Again, the fan is NOT suppose to constantly operate when the ignition is in the run position. This is the impression I'm getting from your post.

If the t-stat has been removed by the previous owner, you can check for max coolant flow after starting a cold engine. If replacement is needed, install a 192 degree t-stat like B/M already mentioned...HTH

-- Mike

Thanks for the output Mike, isn't the CCRM supposed to give me a computer error code if it was faulty? I have no error codes present at this moment. Looks like the fan is "set" to operate as soon as you open the ignition. A lot of people do that to their old cars in Florida when their fans start to fail.

My CCRM failed & no codes were set. I wired a switch to my fan... and I usually just leave it on.

-Mike

-- A happy kid behind the wheel of a 98 Mustang GT Cold air intake FRPP 3.73 gears Steeda Tri-Ax Shifter Full Boar turbo mufflers Hi-speed fan switch

Pepito

Looks like the thermostat is working fine, there is no flow through the radiator when the car is started cold, takes a couple of minutes for the engine to warm and lower the rpms.

Rough idle still there bothering the hell out of me and poor gas mileage anyone have an idea what can cause this problems?

I was thinking about replacing the spark plugs and wires, what is the "MIL"?

"Malfunction Indicator Light," AKA the check engine light.

X-No-archive:yes I just had the identical problem and was baffled for a long time until it got worse and I realized that I had a leaking manifold gasket.If I sprayed carb cleaner at the manifold the idle went up and smoothed out.I checked every possible leak source and found nothing so I replaced the(broken)intake mani gasket and all is smooth now.Will have to replace the Cat Conv.too as that was ruined (I thinks). I would check for vac.leaks and EGR valve malfuntion.

Thanks for the info Garth, no MIL or error codes present. If this helps, there's also a strong gas smell coming from the exaust, clear smoke but smelly.

Pepito opined

you said it took a long time for the engine to warm... does it, or not?

But your PROBLEM is not a manifold leak... it's PROBABLY a bad Fuel Pressure Regulator... if you disconnect the tubing (to the upper intake) from the little can attached to the fuel rail, I bet you'll find there's gas in it.

Even if there isnt change it anyway.. it WILL fail.

Must be the season... this is about the 4th I've seen on here and the ford group in a month.

This would account for a slighly longer warm-up than usual and often doesnt set the light because the leak is slight enough that the ECM adjusts.

The 88 didnt set lite for much of anything other than O2 errors anyway.

Thanks BM, the engine takes like 2 or 3 minutes to warm up. Where is the Fuel Pressure Regulator located?