I have a 1995 Bronco + 1995 5.0-specific ECU (WAY1) + 1996 5.8L engine... it runs rough. Not so rough that you'd be upset, but it ain't right.
I've been trying to figure out why the exhaust smells strongly when at wide throttle going up a hill, under heavy load. Speeding down the highway you don't smell it as much. Chugging up a hill, it smells like a rotten egg factory.


It ain't the cat converter. I just replaced it. That must mean it's running rich.


Okay, how could it be running rich? It's a brand new engine - new *everything*, so whatever you're going to suggest replacing, it ain't that. Even the oxy sensor. Even the injectors were revamped.


Reasons I could think of for running rich:
1. unmetered air entering or exiting intake
2. oxy sensor not working (it was replaced), but perhaps a ground fault, power issue, corrosion somewhere in the wiring, etc.
3. 5.0L ECU isn't compensating fully for 5.8L engine, and I need to get the BIO0.
4. MAF isn't working right


Did I say something about the MAF?! :-) I just remembered, I stuck my 95-based 5.0L MAF on top of the housing (collar?) for the 96 5.8L MAF intake, because my 5.0L intake was all scrungy inside. This is my question: could that be a problem?

 

gosh man your all over the place. Being a 96 motor should have nothing to do with any of this. the motor is physically the same as the 95 5.8 motor with the exception of the crank position sensor ring. the WAY1 ECU is doesn't care about displacement either. are you running stock 19# injectors still? have you ruled out vacuum leaks? Where did you buy the O2 sensors and are they located in the stock location? Have you pulled codes? have you checked fuel pressure at the rail? are you running the stock FPR? all the smog equipment still intact.

 

I guess I didn't spell this out: I'm asking all this because it WAS a 5.0L engine, and I put a 5.8L into it. Yerp! Sorry! Still running stock injectors, I'm pretty sure there are no vacuum leaks, period. I bought the O2 sensor at O'Reilly (it's a Bosch), and it's at the joint of the cat converter where the two pipes come into it. I had to buy a new cat, and it didn't have the cross-bridge, so I had them add one, same diameter as the old one. I've pulled the codes and ran a cyl balance test - no codes show up at all except 311 (missing secondary O2, I pulled the smog pump and blocked the TAB and TAD, since my heads didn't have inlet ports for the secondary O2, they might be marine heads). I checked fuel pressure on the rail, it's standard (I think about 40psi?). I checked the timing again, and it's all working normally, advances nicely when it needs to.

Thanks

 

if your ECU is looking for a second o2 sensor that is your issue. where is the second sensor located?
You must keep the harness plugged into the TAB/TAD solenoid, is your EGR still hooked up?

what heads are you running? Timing should be 10*btdc with spout connector removed.

 

I kept the same harness & ECU. The WAY1 (5.0L) only had 1 oxy sensor, at the Y junction on the cat. I still have the same WAY1. The harness is still plugged into the TAD/TAB, they're just plugged off on the vacuum side. My EGR is still hooked up, yeah.

I'm running the heads that came off the 5.8L, but I got it out of the junkyard. Since it's a 96, the 96's didn't have secondary air into the heads (or so I was told), or they're marine heads. Either way, they don't have ports for the secondary air.

Yeah, the timing is right at 10BTC, and it advances when I stomp on the throttle (with the spout connector inserted). The spark plugs themselves are a nice tan color when I take them out.

I gotta question: "closed loop" means it's looking at the oxy sensor. I'm assuming under closed loop the MAF and oxy sensor will calibrate whatever's going on so it's as close to right as it can get. If I'm pressing on the gas, not fully WOT, but about 1/2 to 3/4 the way down, and I'm chugging up a hill, is it in open or closed loop? If it's open loop (not using oxy sensor), then if I understand right, it uses the long term fuel trim calculations (from closed loop) + it's internal tables to determine the air/fuel ratio. This is the only time I smell the rotten egg smell. Maybe it's open-loop only that is the problem here, and that's because I'm using the 5.0's ECU? It drives FINE when I'm just putt-putting down the road, it's only going up a hill or putting it under load that it acts funny and smells horrible.

 

Are you saying you put the 5.0 MAF sensor(the plastic bit the harness plugs into) into the MAF meter housing(roundish aluminum bit) that mounts near the air box? If so that could be your problem right there so I'd suggest putting all the original 5.0 MAF parts back together(clean the MAF housing with some carb cleaner first).