CEL comes on after about 5 min of driving

[NEp8ntballer]

When I first start up the SHO it has no codes but after about five minutes the CEL comes on. I could probably set my watch by how long it takes to turn on. If you shut the car off while hot and then turn it back on the code goes away and then comes back on in a few minutes. After checking the codes it shows that it is running lean. The O2s have less than 100 miles on them so I doubt that they're the issue. I pulled a plug and it's running AC Delco(648 I believe) plugs. I checked vacuum and it has between 14-16 inches of Mercury at idle and quickly climbs to 20+ if the revs kick up to about 2k. The plug is starting to get some white on it so it is indeed running hot/lean. I cleaned the MAF already but it be that the MAF is faulty. The fuel pump also seems to be a little loud but I'm comparing it to my Jeep as opposed to another SHO. It's also currently on a diet of Shell V power with a little bit of the old gas mixed in along with a bottle of fuel injector cleaner.

Power also seems to vary at times. Sometimes in second you can really feel the secondaries when they open and at other times it feels and sounds like they didn't open. It kinda looks like the vac line to the front secondaries is pinched and not routed properly.

any other ideas/comments/etc.?

 

[sperold]

You don't want to hear this, but it is the 02 sensors.
In my experience, they have to be Motorcraft (Rockauto source) and try not to drop them.

 

[hawkeye18]

If the CEL comes on after 5 minutes, it is the O2s. Sorry bub, but new parts are bad sometimes. I've learned the hard way that you can't simply trust new parts to be good.

You did plug them back in, right? I've seen a couple of people that go through all the work of installing new O2 sensors and forget to plug them in.

 

[NEp8ntballer]

If the CEL comes on after 5 minutes, it is the O2s. Sorry bub, but new parts are bad sometimes. I've learned the hard way that you can't simply trust new parts to be good.

You did plug them back in, right? I've seen a couple of people that go through all the work of installing new O2 sensors and forget to plug them in.

I've installed and removed that y pipe multiple times. they're hooked up. and they're Bosch O2s and not some fly by night company.

 

[Phoenix]

If the CEL comes on after 5 minutes, it is the O2s. Sorry bub, but new parts are bad sometimes. I've learned the hard way that you can't simply trust new parts to be good.

You did plug them back in, right? I've seen a couple of people that go through all the work of installing new O2 sensors and forget to plug them in.

Times 2

Been there done that with a reman water pump on my explorer. It lasted 2 days and it was more screwed then my previous one I replaced it with.

 

[zblackbeast]

When i owned the car it did the same thing... I figured the new o2's would fix it.. I hope thats all it is.. Chris, i still have the 02's off my factory y-pipe if youd like to swap um out and see if the code goes away. I know they are good cause i never got a lean code with them..

 

[NEp8ntballer]

When i owned the car it did the same thing... I figured the new o2's would fix it.. I hope thats all it is.. Chris, i still have the 02's off my factory y-pipe if youd like to swap um out and see if the code goes away. I know they are good cause i never got a lean code with them..

I have the O2s off of the old y pipe as well, but what I would like to borrow is the MAF off your parts SHO and I guess I could borrow your old O2s and see what happens. I'd replace the MAF first since it's easier to get to.

 

[zblackbeast]

Thats fine.. Like i said, it was doing the same thing when i had it with those o2's.. remember me cussing at in on our little test drive when i forgot to plug in the TPS? IF i remember tonight ill throw the parts by my bag for school and bring um tomorrow!

 

[projectSHO89]

What are the EXACT fault codes (not a "description" of them)?

 

[NEp8ntballer]

What are the EXACT fault codes (not a "description" of them)?

HEGO - Lean. I don't remember the numbers and I'm not up to counting CEL flashes.

 

[NEp8ntballer]

code 172 and 136. hego lean, one bank always lean

 

[hawkeye18]

code 172 and 136. hego lean, one bank always lean

Well if it's only one bank, then it's not the MAF, as that would make it both banks. It's got to either be a vacuum leak or a bad O2. But if it's reading lean and it's showing lean... that kinda makes me think it's not the O2 since if it were bad it would be reading lean and showing rich (wet plugs, etc.). Sounds like you got a mystery on your hands.

Regarding bad new parts, its brand means nothing. We have had parts come in from Lockheed Martin (also not a fly-by-night organization) come in bad. Like, $2.6 million parts. Stuff gets dropped during shipping. IIRC O2s are fairly sensitive to that. Stuff gets exposed to high heat and humidity. Stuff just simply slips by a sleepy QC tech. I'm just saying, it's always possible. Just because you paid more for it doesn't mean you can rule it out.

 

[NEp8ntballer]

the plan at the moment is to try the MAF just for ***** and giggles, check fuel pressure and injector function, probably replace a good amount of vac hoses since some of them are starting to deteriorate, check power to the sensor and then swap in a known good O2.

 

[NEp8ntballer]

UPDATE: FP at the schrader valve checks good but that's pretty much all I've done aside from driving it. It got 22MPG on the last tank which is better than my Jeep but not as good as I think it can be, although I stick the skinny pedal into the firewall at least once or twice a drive but I think it has more mileage in it.

I'm planning on doing some work on it tomorrow before I leave for Colorado for a couple days so I'll pull the intake, bypass the throttle body, change the plugs to Iridium, and check injector function. At this stage I'm thinking it's a vac leak or a few injectors aren't pushing as much fuel as they're supposed to. Every time the lean code comes on is on an upshift or when I'm coasting. I've never had it come on when my foot's in it.

 

[NEp8ntballer]

front bank is definitely running lean(front bank is on bottom in photo, plugs have about 1k on them):


hmmmmmm, found this guy disconnected. It's by the front left cylinder if you are looking at the motor from the front, aka cylinder #4:



injectors all work as well...

 

[NEp8ntballer]

problem solved. reconnected O2 grounds and either the bulb burned out or it's working. it feels like it's working better.

 

[yamahaSHO]

Bring the car over today and we'll see how it's running. I can throw the code scanner on it and run a balance test.

 

[sperold]

Good news.
The O2 sensors turn on a lot of CEL lights, all across the continent. And sometimes they don't turn them on as soon as they should.
I thought the price of our sensors was high (yours was ground problem) until I looked up a Suzuki XL7, there are a pile of o2 sensors and some are hundreds of dollars.

 

[firstgen89sho]

I have run into that ground either being off or not grounding properly, and that is the cause of a few CEL's with lean codes.

the ground runs your O2 Heaters.