3800 Scan parameter suggestions..."too lean" code...

[imported_Theautoguy]

I installed the ported manifolds and downpipe this past weekend and I started throwing a "too lean" code. I plan on scanning the car on the way to work tomorrow with a LS1M Palm Scanner and I'd like some suggestions as to what parameters I should do.

Scan interpretation is a little foreign to me but I really don't want to lean the motor out and blow it. Help!

Don

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[imported_Theautoguy]

Someone suggested that an exhaust leak may pop the code. If so, would this show in a scan as well?

Would a small exhaust leak actually produce a "lean" condition or just trigger the code and prompt the computer to richen the mixture even though it's actually fine?

 

[xttc2000]

an exhaust leak would actually trigger a rich condition if its before the upstream o2.
its kind of backwards, it sees the AF from the combustion then a bunch of air gets sucked in cuasing the o2 sensor to read lean and the pcm will richen the hell out of it but it wont do any good because the o2 is still getting that false air from the leak.

 

[imported_Theautoguy]

That makes sense. I detect NO noise from the manifolds when the car is idleing or running under a low load. However, under a moderate to high load I can hear what sounds like a leak...but others have noted that it could very well be the harmonics from the downpipe creating the infamous "tick" noise. The code tripped twice yesterday after I pulled into traffic under a moderate load.

I'm guessing on the parameters to scan for on the way to work this morning and hope something stands out.

I'm sorry for whoring this thread but I don't want to cause any damage to the "one good car".

 

[imported_Theautoguy]

I checked the EGR tube to the rear manifold. Perhaps tonight I'll pull it off again and seal it on the outside with some high temp red RTV. I'm wondering if this may be a source of a leak.

Further, on the way to work today, I had seen O2 readings all over the board. It seems that it will scan at 450 a couple of times (this may be it's normal cycle) and then go up to 850-935'ish. There seemed to be a couple of 550 and 775 readings thrown in there as well. It threw the P0171"system too lean (Bank 1)" code twice this morning

Under normal driving it hovers around 915-945 once it's warmed up.

I'll post portions of the scans tonight.

 

[xttc2000]

a lean code can be thrown from a bad maf sometimes too- have you checked that?

 

[imported_Theautoguy]

Originally posted by xttc2000@May 17 2005, 01:14 PM
a lean code can be thrown from a bad maf sometimes too- have you checked that?

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How can I check for this? I would be surprised if it were because this didn't come up until after the PM and DP install but at the same time I wouldn't be surprised because of my luck lately.

 

[CoolGTX]

make sure the wiring isnt burnt or touching anything extremely hot

 

[imported_Theautoguy]

Well, I had enough. When I got home I yanked the rear manifold and downpipe off. I found some discoloration in the downpipe to manifold flange gasket but found absolutely no indication of an exhaust leak. I'm going to religiously clean the mating surfaces tomorrow and instal a new O2 sensor. I think I'm going to throw some more wrap on the downpipe too.

As for the O2 readings, when I started the scan after the car sat for an hour after an errand the readings were around 850. It took 8 more minutes of easy normal driving before they finally started to creep into the 900 range. By the time I got home, a total of 20 minutes of easy normal driving, the readings were hovering around 945-950.

Could the O2 sensor itself be craping out on me?

I hope I can get this figured out and back together before Saturday, I'd really like to bring the Regal out to the Mod Day.