My Jeep has always ran rich and gotten horrible gas mileage. Today I decided to "Reset the ECU" by touching the positive battery cable to ground for 30 seconds then doing the headlight thing. Started the Jeep up and it ran like crap... idled VERY smooth (Which it normally doesn't) blew white smoke out of the exhaust (unburnt fuel), smelled extremely rich, and every time I gave it gas it would spit, sputter, and load itself up with fuel. I then tried to move it from the street into the driveway to check it out and it stalled on me and flooded itself out. I let it sit for five minutes and tried to start it again..... still flooded. Knowing that it's fuel injected I held the throttle to the floor and cranked it. It started right up and ran perfect. Now that's the only way it will start..... What's the deal? This has me all types of confused........

 

Nobody at all?

 

After resetting the ECU the engine will run poorly untill the ECU learns the new parameters. Should start running better after a few warm up cycles.



Resetting the ECU = key off, disconnect both battery cables for 30 seconds, touch positive and negative cables together for 30 seconds, reconnect cables to battery, key on engine off (2nd position, just before starter engages), headlights on then off, turn key off.

The ECU has now been reset to its factory settings. For the next 50 warm-up periods the ECU will re-learn the engine and driving habits for your driving conditions and the newly installed parts.

 

White smoke? that signals coolant being burned, Black smoke is rich. Anyways, pull the plugs one at a time to inspect them to rule out if all cylinders are running rich, sounds like possible injector sticking.

 

CEL?

 

I am aware of that, but the fact that the Jeep will not start unless I hold it at WOT has be a bit thrown off. If I try to start it without the throttle fully open it will spit and sputter until it turns over, then stall itself out in under a minute.

A lot of vehicles that run rich blow white smoke at idle and black under load. Our Mustang used to do it all the time. There was no smell of coolant in the exhaust, just pure unburnt gas. A sticking injector wouldn't surprise me to be honest; I've had problems with these injectors ever since I put them in.

No CEL was tripped, but I'm not entirely sure mine works. The light will turn on when turning the key, but it doesn't function as it should. It's only ever turned on for "air/fuel ratio at limit" two or three times, but the code never sticks. Every time I check for codes (OBD1 ignition trick) it will bring up code 12 which is something about the memory being cleared within the last 100 miles. This code comes up whether the battery has been disconnected within 100 miles or not. I have run the Jeep without the o2 sensor hooked up a few times without any CEL or changes in it's running characteristics.

 

What trouble have you had with the injectors?

 

Well I will start out by saying I've heat soaked them multiple times. I don't know why it happens so often other than my exhaust is extremely hot. The stainless steel manifold I used to have was blue all the way back, which I think is pretty impressive with a stock motor and the length of the manifold.

Besides heat soaking them often (atleast once a week in the summer to the point that it stalls itself out) I have had a lot of problems with them sticking just a tiny bit (freed them up with injector cleaner kits) and the plastic that covers the wires on both my fuel rail and the wires for the o2 sensor are constantly melting causing them to short out.

My engine runs warm, but not in the range of overheating (usually run consistant at about 220) but that doesn't explain why I melted exhaust repair wrap on my exhaust manifold. My exhaust is way too hot.

** sorry if this sounds kind of jumbled.... I took my sleeping meds about 20 mins ago. If any of you have taken prescription sleeping meds before, you will understand. I apologize for the inconvenience.

 

It sounds like the melted wires may be causing your run rich/flooded condition.
member tjwalker has often suggested adding a timer to the electric fan to run a short time after engine shut down to cure heat soak. Your engine bay temps sound extreme so you may also need louvers on the hood to vent the excess heat. Why is it so hot in your engine bay??

 

That would make sense. I've thought about louvers several times, but with the weather where I live I would need to install drip pans. I don't know of a clean way to do drip pans without the use of a welder. Every time I go water fording I lose my oil pressure sender.... I'd hate to see what sensors would quit on me with louvers allowing rain/melted snow water under the hood. (You just reminded me I wanted to pick up a fuel rail/o2 sensor harness at the junkyard this morning...... )

I honestly have no idea why my under hood temps are so hot. Back a few years ago when I was battling a cracked exhaust manifold I tried a ton of exhaust repair products ranging from jb weld to full fledged exhaust manifold repair wrap... Every one of them burned away during the "trial run/warmup" in the driveway. I then bought a stainless steel manifold which turned blue all the way back (Which was cool and all, but not right for a stock motor). That manifold was destroyed by a broken front driveshaft so now I'm running a plain steel manifold with flex bevels in it.



Earlier this week I deleted my mechanical fan that had an absolutely whooped bearing. Could the reduced drag from removing that bad bearing have caused the computer to run rich? (Since the computer would have previously compensated for that bad bearing and ran a little richer to make up for the drag on the motor... now that drag is gone and it's just running rich.) This was the first time the Jeep was run since that fan was removed.

 

The only time I have observed extremely hot exhaust manifold temperatures was a case of badly retarded timing in an old 6 cylinder Nova. It was so bad that the cast iron exhaust manifold was actually glowing red. My assumption is that the fuel/air charge wasn't being ignited by the spark plugs until the exhaust valve was opening.

I'm not sure how this could happen with a modern computer controlled engine, but it might be a possibility.

 

My Jeep recently developed a slight tick that will go away if you turn the engine off and immediately fire it back up. That sounds like bad timing to me. I don't know much about these computer controlled systems though. I just thank god every day that it's OBD1 lol.