Code 44 but it's running rich.

[Burbdood 74]

I've got a question for y'all.

I have an 88 Sub that has been giving me fits lately. I keep getting a code 44 every now and then which means it's a lean condition. But if you stand at the back of the truck when it's running, it's so rich that you get sick and your eyes burn. It's not chuffing out black smoke and my mileage hasn't gone down either.

About 75% of the time, the idle is real smooth, but if you blip the throttle, the idle drops and it surges. And, if you hold the throttle just above idle, (around 1500 rpm's or so), the idle surges then as well. Power is good on the road, but at an idle, this thing runs like a pig. What am I missing?

I should also mention that I have replaced the ICM under the dist. cap and there was no change. Please help me out here.

 

[y5mgisi]

From Chevythunder.com This is for TPI but it seems that most the stuff for TPI applies to TBI.

 

[y5mgisi]

Im thinking either EGR stuck open or bad o2 giving the computer a lean signal and the computer correcting it by adding fuel.

 

[Burbdood 74]

It's weird because the SES light comes on, but goes out right away and stays off for a couple of weeks and then comes on again. The EGR is relatively new as well, (just over 1 year old I believe). I even had a spare EGR and it did the same thing with the old one too. I had my fuel pump changed by a guy at a shop, but I'm wondering if he changed the rubber hose that comes off the pump because I've read enough threads to know that if the hose is bad, the pressure can go down just enough to give you issues but still make the car run.

Another thing it does, as you go down the road, if you just barely have your foot on the throttle, it bucks and lurches down the road.

 

[Burbdood 74]

Another thing I just thought of, I wonder if my throttle shaft on the TBI unit is worn out causing a vacuum leak and causing the linkage to stick.

That might explain how you can blip the throttle and cause it to run poorly and it would also explain the ECM fattening up the mixture.

 

[y5mgisi]

Thats possible. Im still betting EGR with the bucking condition you described. Just try capping the vacuum line that goes to it and see if that fixes the problem and go form there.

 

[eagle mark]

There's also a link in stickies to get your own pdf for checking engine codes.

Your nose is a terrible AFR gauge and if you can smell that much fuel I know you don't have a cat.

Lean condition can be caused by low fuel pressure and the ECM add's fuel in closed loop till it runs beyond it's capabilities. Then lean. Could be as simple as a clogged fuel filter.

Vacuum leak will also cause lean condition to O2 sensor because of the extra air.

Vacuum leak will also cause a drop in vacuum reading which the MAP will notice and add fuel thinking there is a load on engine.

If the EGR was sticking it would run bad all the time at or near idle. The EGR is not used at idle. But if a vacuum line involved with EGR is cracked it can cause a vacuum leak and improperly functional EGR.

If you have an issue with sticky linkage see if linkage is free with engine off, then start engine and see if it is now sticky off idle. If so it has probably worn the shafts a little or stop screw and the blades are to close or touching bores of throttle body, this causes a poor stable idle as well. Can pop cap off and give the torx screw half turn and retry. There is a proper min air setting procedure though.

 

[MT86K5]

Snuffy, we can hook it up to my computer this weekend if you want and see what is going on with it. I'll be out of town all week but will be home this weekend.

 

[Burbdood 74]

Snuffy, we can hook it up to my computer this weekend if you want and see what is going on with it. I'll be out of town all week but will be home this weekend.

If you're free next weekend that'd be out-damn-standing! I'll buy the beverages.

 

[GMC Truck]

I have had some issues like that... on my truck the vac lines rotted and caused crazy thing to happen. Remember that most vac leaks cause a high idle on TBI cause the ECM is seeing a drop at the map sensor. I also had a TBI motorhome run rich and it was pulling fuel out of the charcoal canister? Might check that??