3.0 is Running Rich

[WutUp Clegg]

This is an issue I haven't seen yet. The truck idles great, but when I give it gas, it starts to run rich. On the computer, it looks as though it's reading a tremendous amount of air coming into the engine, but obviously there isn't, due to it running rich. I replaced the MAS, and it still shows the same issue.

It is a 2004 Ranger with a 3.0L. The heads were ported, it has equal length headers, and a K&N cold air intake. There are no vacuum leaks, and I can't see any other issues.

Have any of you experienced this issue before?

 

[franklin2]

This problem just popped up one day? Or it came about right after the engine modifications?

 

[Curious Hound]

Have you checked diagnostic codes? Get a Bluetooth OBD II code reader and download Torque Lite to your phone. The app is free.

your oxygen sensors tell the computer whether it’s running rich or lean. If they are connected wrong or not functioning, that will have an affect. Also check TPS, IAC, IAT and fuel pressure. A stuck open injector could also cause it to run rich, but that’s probably the last thing to check.

 

[WutUp Clegg]

Thank you. I'll recheck the scanner for more readings.

 

[WutUp Clegg]

This problem just popped up one day? Or it came about right after the engine modifications?

I bought the truck this way. I knew it would be a project, but not this much. Still, I obtained it at a pretty good deal.

 

[franklin2]

I think you are going to have to go over the whole engine and make sure everything is stock. The first thing I would do is check the injectors. Make sure they are stock. They may have put over sized ones in, and I wonder if it's over fueling the engine. I would also check the fuel pressure, make sure it's normal and not too high.

P.S. I just said all that above, but that doesn't make sense when it idles good. I think I would still monitor the fuel pressure when you rev the engine.

 

[WutUp Clegg]

I think you are going to have to go over the whole engine and make sure everything is stock. The first thing I would do is check the injectors. Make sure they are stock. They may have put over sized ones in, and I wonder if it's over fueling the engine. I would also check the fuel pressure, make sure it's normal and not too high.

P.S. I just said all that above, but that doesn't make sense when it idles good. I think I would still monitor the fuel pressure when you rev the engine.

Funny you said all that, because I was thinking the same exact things last night while laying in bed. I will check those this week.

 

[WutUp Clegg]

Okay,
changed O2 sensors, fuel injectors, MAF sensor, no vacuum leaks, cleaned throttle body, installed new CATs, fuel pressure is good, and it's still running rich. Any other tips?

Also, the intake manifold has been ported. Would this cause it to run rich? I would think it would run lean, if anything. How can I tell if a tuner remapped the fuel system?

 

[franklin2]

You are really going to have to play detective. Does it have the correct computer in it?

 

[bobbywalter]

intake ported? define that.....custom cam too? what is the actual vacuum at idle and tip in?

 

[WutUp Clegg]

You are really going to have to play detective. Does it have the correct computer in it?

It looks to be the correct computer. However, that is one of the things on my list to check. The problem is, If I get a new computer, I will have to reprogram the key to it, and that can cost as much as the computer. I'm would like to make a list of items before I continue to throw parts at it. I'm already at $2000 in parts to track down the rich issue.

 

[WutUp Clegg]

intake ported? define that.....custom cam too? what is the actual vacuum at idle and tip in?

The lower intake manifold had the intake holes bored out. I will check on the cam, but wouldn't that do the same as boring out the intake manifold due to the truck being fuel injected? It would only inject the gas to meet the air input? I don't know... It idles and runs perfect. After a few about 10 minutes of driving, the Check Engine light comes on due to running rich.

I know the mechanic checked the vacuum, and he said it's great. Doesn't appear to be any issues. I texted him for the codes, so hopefully I will get that tomorrow.

 

[WutUp Clegg]

By the way, how can I tell if my camshaft is stock or aftermarket? Are there markings on it?

 

[bobbywalter]

degree it and measure lift

 

[WutUp Clegg]

Okay. We found the problems. It was combination of a handful of issues.

• Loose connection at main harness plug.
• Wrong Y-Pipe. Wasn't CARB compliant and only had 3-O2 sensors instead of 4.
• Leak between lower intake and heads.
• BCM had the old programming in it. We had to update it.
• Wrong fuel injectors. They came as a set from Autozone, but 2 were a 3-hole version, 3 were a 4-hole version and 1 was a 1-hole version. Don't ask why, I have no idea why. I think someone put the wrong ones back in the box.

Each time we replaced/fixed something, the truck ran better with less black smoke blowing out of it.

The truck is now running clean and has passed smog.