Erratic idle - poor fuel mileage?

[Fairlaniac]

Over the winter my beater truck (’89 2.3 x-cab) went from about 24 MPG to 18 MPG. So as the weather is getting better I took some time to investigate. I ran my code reader and got a 33 and 77. The 33 is an EGR and the 77 apparently is some error I did? Anyhow since then and I didn’t make any adjustments I am having idle issues. When it’s all warm and I’m driving along I go to stop, throw in the clutch and the idle goes to 1500-ish RPM. Then after about 5 seconds it comes down to 700-ish RPM, tap the gas and it shoots to 1500 and another 5 seconds or so it drops to 700. I didn’t get any error on a TPS but I wonder? Any ideas on the erratic idle? I still need to figure out my gas mileage. I didn’t think and EGR would drop it like that, would it?

Thanks,

 

[gw33gp]

I don't know much about the 2.3 engines but I would guess the Idle Control Valve needs to be cleaned or replaced.

I like your Fairlane. I have a 69 Fairlane Cobra myself. Quite a blast to drive.

 

[lethal-threat-b288]

mine idles like it has a freakin cam in it

 

[Fairlaniac]

I don't know much about the 2.3 engines but I would guess the Idle Control Valve needs to be cleaned or replaced.

I like your Fairlane. I have a 69 Fairlane Cobra myself. Quite a blast to drive.

I had a '69 428CJ Torino GT years ago, Gulfstream Aqua with black "C" stripe. It was a blast. My '66 if fun too!

I replaced the IAC valve with a brand new one I had. No difference in my idle. It hangs around 1500 RPM when I throw the clutch in and after a few seconds it drops to to the 750 RPM range. I don't get an error code for the Throttle Position Sensor but I may stick a new one on as I have one of those in my box of new parts. More of a PITA to change.

 

[06RangerXLT]

Over the winter my beater truck (’89 2.3 x-cab) went from about 24 MPG to 18 MPG. So as the weather is getting better I took some time to investigate. I ran my code reader and got a 33 and 77. The 33 is an EGR and the 77 apparently is some error I did? Anyhow since then and I didn’t make any adjustments I am having idle issues. When it’s all warm and I’m driving along I go to stop, throw in the clutch and the idle goes to 1500-ish RPM. Then after about 5 seconds it comes down to 700-ish RPM, tap the gas and it shoots to 1500 and another 5 seconds or so it drops to 700. I didn’t get any error on a TPS but I wonder? Any ideas on the erratic idle? I still need to figure out my gas mileage. I didn’t think and EGR would drop it like that, would it?

Thanks,

your supposed to idle around 700. they aren't sport bike engines

 

[Fairlaniac]

your supposed to idle around 700. they aren't sport bike engines

My problem is when I get out of the gas it only drops to 1500 RPM or so. When I get off the highway for instance I may be doing 2000 RPM and go to downshift and it only drops to 1500 and pulling up to a stop it hovers at 1500 for a few seconds or so then drops to 700. It's not dropping to idle as quick as it did a few months ago and fuel mileage has dropped 25% or so.

Here's an anology you'll understand, I'm cruising the highway at 7000 RPM on a "sport bike" and when I pull up to the stop sign and throw in the clutch, it hovers around 2500 RPM. The RPM doesn't drop to proper idle speed. Ya got my point now?

Thanks!