Brand New D15Z1 - Lean Burn Stutter / Hesitation

[turbothrush]

Originally Posted by 94CivicVX

After checking out that link in the above post, I'm not too sure that those who are posting are very familiar with the VX exhaust system. Who knows though, when you get an O2 sensor thats good let us know how lean burn works with your hollowed out cat......

Except for a hollowed cat my exhaust is 100% vx . Leanburn works fine just incase someone is wondering.

[slownugly]

mine is hollowed on my z1 in the vlx as well and lean burn is smooth. its a vx manifold to vx cat and a vx downpipe and that bolts up to the lx converter (i would recomend doing this to your dx as well) that way you know the engine is getting the correct backpressure.

what kind of hesitation is it? does it stumble and carry on? or does it just bleed off like you are losing power?

[slownugly]

grab some numbers off of the 02 sensor. should have the ngk part number and then underneath that it should read A09 or A08 or A07 etc. the correct one is the A09.
the actual part numbers on the box are the same but different ones are made in different places and the federal vx calls for the A09. check out my thread for more info with pics.

http://ecomodder.com/forum/showthrea...5z1-23433.html

7th page has pics

[Rusty94cx]

I'm not sure that I will put an 02 on the car I might have a tuned ecu and either a 02 delete or calibrate the ecu to run a less expensive wideband. I have many ideas and options. But as you see a hodgepodge of exhaust will work as to weather or not the 02 will last I don't know. Today the tuner told me to move the 02 way past the cat downstream. As the heat kills them. The are just as accurate farther back if the exhaust is sealed properly???? So all the more ideas now.

[94CivicVX]

Originally Posted by Rusty94cx

I'm not sure that I will put an 02 on the car I might have a tuned ecu and either a 02 delete or calibrate the ecu to run a less expensive wideband. I have many ideas and options. But as you see a hodgepodge of exhaust will work as to weather or not the 02 will last I don't know. Today the tuner told me to move the 02 way past the cat downstream. As the heat kills them. The are just as accurate farther back if the exhaust is sealed properly???? So all the more ideas now.

You cannot tune the P07 ECU. I wouldn't mess with the O2 sensor location either, I'm sure Honda put it there for a reason.

My shift light started working again on the way to work this morning. Weird.

[Ryland]

your o2 sensor is where it is because it needs to be there to stay hot enough to work right, the vx's engine run slower and cooler so the exhaust doesn't get as hot, that is why the cat is close up to the engine block as well.

[94CivicVX]

Originally Posted by slownugly

grab some numbers off of the 02 sensor. should have the ngk part number and then underneath that it should read A09 or A08 or A07 etc. the correct one is the A09.
the actual part numbers on the box are the same but different ones are made in different places and the federal vx calls for the A09. check out my thread for more info with pics.

http://ecomodder.com/forum/showthrea...5z1-23433.html

7th page has pics

Thanks for the input I have tried two different O2 sensors and still had the same result. I am currenty running a brand new OEM Honda O2.

The car does go into closed loop but it hesitates a little, still maintains speed and all but it sputters and seems to have a dead spot at light throttle while in closed loop only. I ordered a VX mid pipe and am searching hard for a cat, then everything will be completely OEM and I will know for sure if that was the problem.

I know one thing, if the O2 needs some heat or proper exhaust pulsation to work properly like Ryland is suggesting and has seen by experience, then there are definitely issues with my 3" wide bypass pipe into a DX downpipe.

I will keep you all posted... in the meantime some pics of the motor pre install:

Brand new had never been started D15z1:

You can see the custom pipe (I since changed to new plug wires)

[Rusty94cx]

Lean is mean and generates alot of heat. You melt your pistons when you get to lean with a load. No I will not be tuning a p07 it's maps will be put into another ecu that us tunable.

[94CivicVX]

PROBLEM SOLVED!!!!...

So after going over everything again and again, I took off the valve cover and realized that the timing plates on the rocker arms were damaged. There are little tabs on the timing plates that sit on top of the primary rocker arms. The tabs butt up against a casting on the rocker arm caps. These tabs allow the car to disengage VTEC once it is engaged. The tabs on mine were all broken off!!

I had to change all the timing plates. (They must have been damaged by students since the engine spent it's entire life at a technical college). I didn't realize they were messed up when I originally put the engine together. When the valve cover was off I could see that the primary rocker arm pistons were all engaged into the secondary. A flick of the spring by hand disengaged the little pistons in the rocker arm, freeing the primary rocker arms from the secondarys.

So what was happening is that the engine was constantly in VTEC!! This caused it to run with a stumble in leanburn. It's surprising how well it ran overall considering this issue, but now it runs PERFECTLY.

Can't wait to see how the mileage will be!!!

Note: It doesn't look like a catalytic converter is necessary for proper leanburn operation. I have installed an innovate LM1 wideband 02 sensor right beside the OEM sensor and the car is entering leanburn just fine with no stuttering or problems. (I drilled and tapped the OEM manifold right beside the stock 02 sensor. )

Thanks to everyone for their suggestions!

[slownugly]

Could you post a pic of where you mounted the wideband on the manifold? I mounted my vlx one in the converter because it's gutted but I plan on putting one in my vx hatch and that converter is not gutted.

I used an innovat wideband as well. I love it