300zx's ELX work log

[KAinjection]

I reduced the timing to 8 BTDC and put in 3 gallons of E85 on top of about 2 gallons of gas left in the tank. Failed worse this time.

HC--1.0--.8 Allowed
CO--4.24--12.0 Allowed
NOX--2.42--2.0 Allowed

My CO's are lower this time. I hope a new cat will take care of this problem.

EDIT: I dont think a new cat will help much

Hot compression test is:

140 125 140 140. My "rebuilt" engine is worse then it was before. Combination of too much idling in the driveway before running it hard and an excessively leaking injector in cylinder 2.

[azgtx]

Try a bottle of HEET....that should take care of the nox and the super retarded timing should hit the hc's. To Get my GTX's to pass I crank in the timing to where it don't wanna run and push the idle up to 1400rpm's. Although I only need to pass an idle test with the AWD. My numbers show that it is nearly not even running and that is with the old oem cat that goes on for testing only.

[KAinjection]

I wish I only needed an idle test, but they put me on the dyno. The funny thing is that if the car was a 1993, I would have passed the initial test but since its a 1995 the standards are stricter and it didnt pass.

I am going to buy a quality cat for this thing and make the A/F ratio a little richer. From my current catalytic converter research it looks like the cheap aftermarket cats dont last even in the right conditions and there is a reason they are cheap. I found some that have a 5 year warranty on them for a decent price that are made to meet LEV/ULEV emissions standards so if that doesnt work, I will have to park the car and put some new rings in there.

[crazycanadian]

I wish I only needed an idle test, but they put me on the dyno. The funny thing is that if the car was a 1993, I would have passed the initial test but since its a 1995 the standards are stricter and it didnt pass.

I am going to buy a quality cat for this thing and make the A/F ratio a little richer. From my current catalytic converter research it looks like the cheap aftermarket cats dont last even in the right conditions and there is a reason they are cheap. I found some that have a 5 year warranty on them for a decent price that are made to meet LEV/ULEV emissions standards so if that doesnt work, I will have to park the car and put some new rings in there.

Look into a Walker CalCat... I run their Large body version... Its supposed to be one of the higher end aftermarket Cats..

[KAinjection]

I will check those. I was actually looking at the Bear river cats or Magnaflow. I am going to perform a wet compression test on this thing so I can decide what to do next as well. With that cylinder at 125psi and the rest at 140psi I am almost having doubts a new cat will get the numbers low enough, but regardless I need a new cat anyway......

[DuRWooD]

FYI: I just put a 3" magnaflow cat on my jetta. 2 months later, and I'm getting a cat efficiency code. I didn't buy the more expensive obdii version, so that may be why, but it did work fine for a bit.

Sent from my SAMSUNG-SGH-I717 using Tapatalk 2

[KAinjection]

Thats interesting news. From what I have been reading about cats there is a reason certain ones are more expensive. The rare metals inside that actually do the job of breaking down the exhaust gases are barely whats required to meet the EPA standards and they also use the least effective (cheaper) of the materials inside. Palladium is the cheapest, and Rhodium is the most expensive and most effective.

OEM cats are the best and contain the most precious metals and hence are the most expensive but also work best since they have to meet warranty requirements. I kind of wish I could find a cat from a full size chevy truck so it had a 3" in/out.

[crazycanadian]

Itss not just about cats meeting obd2 specs.. you want one that also meets California emissions specs..

magnaflow is in the market of making performance cats.. not oem quality. . I have not see one that lasts or doesn't throw cat efficiency codes after a year..

[KAinjection]

So I did the wet compression test this morning and the results are not good.
1- 180 vs 140
2- 170 vs 120
3- 190 vs 140
4- 190 vs 140

Question is now if a new cat will get me to pass or should I just tear the engine back apart put new rings in it and then a new cat.

I should also note that cylinder 2 appears to be slowly getting worse. My very first compression test got me 135 and now it reads 120.

[DuRWooD]

A brand new cat can probably get a pretty loose engine to pass, but the cat won't live long.

[crazycanadian]

Just like Durwood said... Its possible a brand new cat will help it pass, but it wont live long... Also its probably a little more then just rings, but you wont know until you tear it apart..

[KAinjection]

What else do you think it could be? I had the head checked, replaced all the stem seals, made sure every valve was lapped perfectly, head and block were skimmed so the surface was perfect, so unless the machine shop messed up on boring it then I cant see what else it could possibly be, especially considering the results of the wet compression test.

[DuRWooD]

Did you get new valves? Were they cut to the right length? HLAs perhaps. Most likely ring seat though.

Sent from my SAMSUNG-SGH-I717 using Tapatalk 2

[KAinjection]

Valves are original. Machine shop said they sealed good and the guides were good, and I installed brand new HLA's when I assembled everything.

[crazycanadian]

Its more likely a ring sealing issue.. you just have to hope the cylinder walls didnt get damaged during break in..