quick question

[darnie1987]

So we got the new heads and intake on and the truck runs great! but when driving around town earlyer i got 2 check engine codes, one was p0701 ( bank one o2 sensor lean) and the other p0174.... i read about the 2nd one and it said to clean the MAF sensor, so we got some cleaner... i cleared the codes and they stayed off for awhile then we parked and started the truck again and same thing. code, cleared, and stayed off. now on the way back home i messed with the gas alittle and gave it about 1/3 throttle for about 2 seconds... afr 14-14.5 then let off the gas, afr-18.5-19 then we got on it 60-70 mph for a quick burst afr-10.5-11 then let off and it hit 19.... any ideas? the truck runs strong as hell just the afr and the codes? im gunna clean the MAF sensor once the truck cools and see if that helps?

[darnie1987]

Cleaned the MAF and the AFR still seems to be spiking? havent thrown a code yet tho idles at about 14.5-15.5 AFR or so

[farmtruc]

Those codes are set during idle and cruising, when in closed loop. This is when the ltrims are working. LTRIMS gives us a way to determine if the engine is getting too much or too little fuel.
If any unmetered air is entering the intake side without the maf knowing it and the o2's tell the pcm this, then the pcm will add fuel until it satisfies the fueling requirement.
The pcm can only add so much fuel, 25% positive ltrims, then it'll set a code after so many cycles.
So in this case, it could very well be a vacuum leak, which would make sense due to the mods the truck just got.
I've also seen a bad maf report to the pcm a false reading and cause the pcm to incorrectly add fuel.
Or it could be an o2 sensor reporting a false signal to the pcm, causing the pcm to add more fuel.

The a/f ratio is directly related to this. You're driving your truck around with positive ltrims, when you floor it, the pcm considers this a lean condition, then adds a lot of fuel during PE mode.
If the ltrims are positive during normal driving and just before PE mode, then the pcm will add that much more fuel on top of whatever it was tuned for.
SO that's where the rich condition is coming from.
The lean condition could be DFCO during no throttle and the fact that the pcm can't add anymore fuel past 25% ltrims, to compensate for the lean condition, so the a/f ratio meter is showing a lean condition.

[darnie1987]

So basically there's a vacuum leak? my main question i guess is it ok to be driving ? i know with the new intake id didnt come with a connection off the intake manifold for the tube coming off the passengers side manifold so i connected it to the intake tube. could that be the issue?

heres how i did it...



heres the old intake, you can see the tube, the nipple on the valve cover is now connected to the nipple on the intake tube. ?


heres how i have it set up now...

[farmtruc]

Did you cap off the vac port that hose came off of? Behind the throttle body?
Do this, pull that hose off the blue intake tube, cap off the intake tube.
Leave that hose from the valve cover open.
Go drive and see what's up.

It's not going to hurt anything, the truck is just getting more fuel than it should. As soon as you open the throttle body blade with your foot, if there's a vac leak, it become insignificant.

[darnie1987]

on the new intake " it a stock one ported ect from a 01 i believe'' it doesnt have a connection for the hose to connect to on the intake manifold, so didnt have to cap off.

the hose on the valve cover does it have to be connected to something? or can it just be capped off its self? if not there is another nipple on the drivers side of the intake manifold about middle ways back that i capped off could i run a hose to it instead? thanks for the help allen

[farmtruc]

The way you have it shouldn't cause any issues. The valve cover hose can be vented, don't cap it, the engine needs to vent under wot.
That hose is normally taken back to the throttle body, like you pictured, or to a catch can.
No need for a catch can.
If you had access to a smoke machine, that would help a lot

[darnie1987]

na i dont... i may just run a breather? but i did the cap on the intake and it still seemd to run the same, one thing i did do was put a freeze plug in the EGR hole on the intake, i used epoxy to keep it in, but it did take a long time to cure. so i wonder if it could have something to do with it? so i just loaded up the back end with a crap tone of silicone ?

[darnie1987]

ok i capped off the intake, then put a breather on the vaccum line on the intake manifold, also you can see were i put the silicone for the freeze plug. hope this helps....

[darnie1987]

well i had to move the truck, and started it up and it threw the codes again.... Is it ok to cruse around with it like it is? and also any other ideas on how to fix it. thanks for the help guys...