California vs Federal Ranger Cats

[Calfmaster5000]

New to the forum, I’ve got a new to me 1998 4wd ranger with the 4.0. It is not a California car as per the vin. I was told that it had been partially decatted and it’s been running poor. Intermittent loss of power at low speed, but usually fixed by a heavy stomp on the throttle. Running pig rich, lots of white smoke/vapor on startup. Obd eleven shows p1131 and p1151 codes indicating a lean condition and the engine running in closed loop only. I checked for vacuum leaks with copious amounts of brakkleen and nothing. That being said, I did a data log for short term fuel trim vs rpm and the graph showed that it runs much better when on throttle (around 4%) vs at idle (north of 30% yikes!) This was why I originally thought vacuum leak or bad o2 sensors, but the o2 sensors read in spec so I figured the car was really sensitive to cats. And the guy I bought it from said it was partially decatted so I hopped on rockauto and saw that there’s 4 cats on these cars. Looked underneath, saw just two, inline with the muffler and I ordered one of the two options for the catted y pipe that rockauto offers. Well it didn’t fit. Not even close. Talked to rockauto and apparently both available y pipes they sell are for cali cars only. So I’m stuck with that, if anyone wants to buy it, hit me up. But this brings me to my question. Did the rest of the rangers that had to meet only fed epa regs come with a catted y pipe or just the two cats further down the line. I really appreciate any help, and yes, I searched the forum first.

 

[franklin2]

I wonder if the cats you have left are clogged?

 

[Calfmaster5000]

I wonder if the cats you have left are clogged?

Could be, should I have 2 or 4?

 

[Curious Hound]

I would expect it to have 4. But there should be evidence if some have been removed - maybe a section of pipe welded in where the missing cats were. How many O2 sensors do you have?

 

[Calfmaster5000]

I would expect it to have 4. But there should be evidence if some have been removed - maybe a section of pipe welded in where the missing cats were. How many O2 sensors do you have?

I have 2 in the y pipe, and I saw at least 1 further down before the other cats. Rockauto specifies upstream and downstream o2 sensors. The y pipe I took out had some ugly welds on it around the o2 sensor bungs. I’m hoping someone with the same truck can confirm how many cats they have.

 

[Robert Mangrum]

My 98 4x4 with 4.0 had 4 cats. I only remember because I replaced them all with straight pipe around 120k. I didn't have emissions in my small town. So I had them removed and replaced the whole exhaust. Shop did a custom dual with a H pipe. 2 were right up basically attached to the manifolds. Then 2 a little father down before the Y connection. It also had a large resonator before the muffler too I removed and had some Flowmasters.

 

[Calfmaster5000]

My 98 4x4 with 4.0 had 4 cats. I only remember because I replaced them all with straight pipe around 120k. I didn't have emissions in my small town. So I had them removed and replaced the whole exhaust. Shop did a custom dual with a H pipe. 2 were right up basically attached to the manifolds. Then 2 a little father down before the Y connection. It also had a large resonator before the muffler too I removed and had some Flowmasters.

Gotcha, and it ran fine without them? Not uber rich? Rockauto doesn’t even sell the non cali y pipe cats. Though ironically, rockauto can’t actually ship any cats to California anyway. So those will be in stock for a long time.

 

[Robert Mangrum]

Gotcha, and it ran fine without them? Not uber rich? Rockauto doesn’t even sell the non cali y pipe cats. Though ironically, rockauto can’t actually ship any cats to California anyway. So those will be in stock for a long time.

The shop welded the bungs in and installed the O2 sensors. I do remember it had a CEL on before i had the exhaust done so really wouldn't know if it threw another code then. As a redneck kid I didn't care haha. But yes it ran fine. If I remember it was running rich. But that was 20 years ago and I cant remember for sure. I drove for 2 years that way with no issues at all. It had a 2 inch body lift and 33s so it was never really fast to start with. But boy I thought it sounded awesome haha. Neighbors.....not so much.

 

[franklin2]

The shop welded the bungs in and installed the O2 sensors. I do remember it had a CEL on before i had the exhaust done so really wouldn't know if it threw another code then. As a redneck kid I didn't care haha. But yes it ran fine. If I remember it was running rich. But that was 20 years ago and I cant remember for sure. I drove for 2 years that way with no issues at all. It had a 2 inch body lift and 33s so it was never really fast to start with. But boy I thought it sounded awesome haha. Neighbors.....not so much.

When these emissions engines with cats are warming up, they all will run rich. You can smell it in the exhaust. But when they get fully warmed up, they should settle down and be normal IF you kept the forward most O2 sensors.

They run the engine rich to help it run when it's cold of course, though with fuel injection this is not as important as with a carb. But mainly what they do it for is to make the cats warm up and start working quicker. Figure that out. There is a lot of hokus pokus that goes on with this emissions stuff. The place I work has bought a bunch of these little diesel pickups from GM. Half the time I come into the shop, and I can't see where the door is for all the smoke. They will have a little diesel pickup sitting outside smoking like a freight train and sounding like it's going to blow up. I ask "what are you doing". They say, "cleaning the exhaust filter".

 

[Calfmaster5000]

When these emissions engines with cats are warming up, they all will run rich. You can smell it in the exhaust. But when they get fully warmed up, they should settle down and be normal IF you kept the forward most O2 sensors.

They run the engine rich to help it run when it's cold of course, though with fuel injection this is not as important as with a carb. But mainly what they do it for is to make the cats warm up and start working quicker. Figure that out. There is a lot of hokus pokus that goes on with this emissions stuff. The place I work has bought a bunch of these little diesel pickups from GM. Half the time I come into the shop, and I can't see where the door is for all the smoke. They will have a little diesel pickup sitting outside smoking like a freight train and sounding like it's going to blow up. I ask "what are you doing". They say, "cleaning the exhaust filter".

Yep, pretty much all engines run rich to begin with, but mine continues to do it even when up to temp. And yes, the ecm is reading the coolant temperature sensor correctly. The p1131 and p1151 codes intricate a lean condition is preventing it from running in open loop. So cold start tune all the time basically. What else besides a vacuum leak or faulty o2 sensors causes lean conditions? I suppose I should check fuel delivery. But I have no issues with surging.

 

[superj]

connectors are good? no corrosion or grease making a bad connection at the sensors?