1993 Mustang 2.3l Already Done Tune-Up Ect..., Rough Idle?

Buddhahb · 10-21-2007

I just got a 93 Convertable with the 2.3l engine... It's rough when it idles and SLOW on take-off... I have already done a tune-up (Plugs, Wires, Air Filter and PCV Valve) I have a fuel filter, But I'm running some fuel system cleaner through before I cange it... I have changed the ICM (Ignition Control Module) and it is still having the same problems...

It never dies, but setting still the rpms drop below 1000 and it studders and it's just slow till you get to 45 then it's ok untill you get to 60 or so then it's slow again... The transmission shifts fine... the rpms while driving it's hard to get between 3000 and 4000 rpms...

I know that is a lot, but I wanted to fit as many detail in as I can...

What should I try next?

87ConvLX · 10-21-2007

I'm jumping on board with this one. I'm right there with you. Almost the exact same problem, same car '93 2.3l vert with auto (I have couple of others that's why my sig is 87ConvLX).
750rpm idle, but I think that's okay. On takeoff I have a random chance of being stranded in front of oncoming traffic as the engine tries to play catch up with my expectation of forward movement. This is an intermittent problem, but happens more than 75% of the time. General sluggishness up to 55. Occassionally, this car has run great, but the performance and fuel economy have been poor.
I've done the following:
Tune up: Plugs, new plug wires, air filter, fuel filter, pcv.
New EDIS to cure dead tach and check engine light.
Checked codes and it keeps coming back with passing codes everytime. I should be happy about that.
Did the MAF, IAC, TPS tests per Probst and everything checks okay.

The only things left (I think) are the O2 sensor, ECT and/or injectors.

87ConvLX · 10-28-2007

FIXED!

A new O2 sensor made everything perfect. I think this is what it must have felt like when brand new. Seriously...

fox81 · 10-30-2007

I may sound like a fool on this one. But where is the o2 sensor located? Cause my 2.3 does almost the same thing and I was getting ready to change the coil (it's the original from 1980 and I just replaced the original plug wires also from 1980) to see if that would help. Also what kind of "poor" milage were you getting? I'm getting around 19 city/highway.

87ConvLX · 10-30-2007

I'm not an expert on your year (okay I probably can't legitimately call myself an expert on any year), but your O2 sensor should be on the header. On some years it's on the top of the header where you can easily get to it, or like on the 93, it's on the bottom of the header where only several socket extensions and a lot of cussing can get to it.

AutoZone or PepBoys, etc, sells an 02 sensor socket that you'll want. It has a groove that clears the wires so you don't have to struggle with a wrench. The O2 sensors can be frozen and a pain to move using a wrench. Even with a socket you stand a chance of not being able to budge it.

By bad mileage I mean ~19 like you're getting. I haven't gone through a full tank yet, but I'm guestimating that I'm in the mid-high 20's now.

fox81 · 10-30-2007

I would have never guessed the o2 sensor. Never would assume that a senor could make it run like crap and eat mileage. Thats on my to do list. How often are they supposed to be changed?

87ConvLX · 10-30-2007

Well... I've heard they should be changed out every 60K on our cars. I think that might be too much.

As I understand it from reading Probst, the O2 sensor becomes less sensitive to changes in A/F ratio as it ages until it gets to a point where it loses all sensitivity and basically sends a useless signal to the EEC. Maybe its like a relationship where the guy is the O2 sensor, attentive to his girl (EEC) at first, but as the relationship goes on the only signal he give is "yes dear, yes dear, whatever." In other words, he's less sensitive now.

I think if the EEC is expecting a signal from the O2 sensor and all it's getting is garbage, then the signal it sends for fuel delivery is garbage (GIGO = Garbage In, Garbage Out). I suppose it's possible that the engine could run lean, but I think the default is to run rich which could result in excess fuel consumption. Since the O2 sensor isn't the sole source of info for the EEC (MAF, ECT, others) it's possible that you could have a bad O2 sensor without it being obvious.

EEC Experts, please feel free to correct any mistakes I made here....

fox81 · 10-30-2007

I like that analogy. Went out and checked where my sensor is. Lucky me it's on the top. Plus I can pretty much do it by taking off the air cleaner. So it shouldn't be to hard but it's probably siezed.

But I have my fingers crossed that this will fix it.

flash gordon · 11-01-2007

Ignition Control Module?

fox81 · 11-01-2007

That would be my next assumption but I will change the o2 sensor and see how it responds.
How much do the ICMs cost?

fionndruinne · 11-02-2007

Hmm, my '89 2.3l may be having those problems; its mileage is not as good, for sure. Do '89 models have the same/similar sensor? I'm pretty sure mine hasn't been replaced in a long while.

87ConvLX · 11-02-2007

Your sensor would be on the top of the exhaust header near the header/downpipe junction.

fox81 · 11-02-2007

Picked up o2 sensor this morning. Gonna change it first thing saturday. Hope I don't break the plug taking it off. Will let you guys know how if it solves my problems.

fox81 · 11-04-2007

HOLY CRAP!
The new o2 sensor made a big difference. I can tell just by the way its idling. Can't wait to get it out on the highway to see of it makes a difference in my milage.

HghStrng · 11-13-2007

Ok, guys, guess I am the next to get the 02 sensor. I have the 2.3 vert and auto and it runs pretty rich and only getting 15-19mpg. My engine light came on then off this morning and tonight stayed on.
HMMMM.