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Another 85T fails nox, flux warmup idle+exh leak (long)
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Posted by JBB [Email] (more from JBB) on Tue, 21 Jun 2005 11:20:33 Share Post by Email
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85 900T, 191992 miles. Replaced brake boo$ter, AIC, O2 sen$or, CAT(unneces$arily, it turns out), plug$, cap, rotor, oil, air filter (not fuel filter). Found leaking check valve at charcoal canni$ter, so dummied (plugged) the vacuum line from cannister. Found and replaced cracked vac hoses, including cruise control ones under dash. Found APC wiring harness at box under back seat to be not fully mated = a bit loose.

Car now drives STRONG & gets full way strong boost to the end of the yellow with 87 octane. Fails CA smog miserably with very low everything but 2x NOX at 15 & 25 mph, NOX actually went UP with new cat, aftermarket, from The Cat House (gotta love the biz name). The guy there has been there for 30 yrs, all the local mechs recommend him, and I really want to think he didnt give me a 2-way vs. a 3-way cat. I am now a Gross Polluter with a new cat and must go to a test-only station or a Gold Shield Station, certified mechanic of some sort.

Test results:
Test RPM CO2% 02% HC:Max |Meas CO:Max|Meas NO:Max|Meas Result
15 mph 1776 13.90 1.66 135|22 .83|0.01 1136|2331 GrossP!
25 mph 2928 14.00 1.60 110|14 .63|0.01 966|1394 Fail

Previous test before new cat:
Test RPM CO2% 02% HC:Max |Meas CO:Max|Meas NO:Max|Meas Result
15 mph 1775 14.34 0.92 135|80 .83|0.41 1136|1914 Fail
25 mph 1957 14.67 0.72 110|50 .63|0.10 966|1577 Fail


Remaining symptoms and questions:

1. Turbo bearings/seals are putting oil into the intake manifolds and there is oil in vacuum lines. Would this contribute to high nox, or as my indy claims, should this stuff burn up once inside the combutstion chamber and so not be a part of my Nox problems?

2. After doing a short in-the-driveway "internal steam clean" with windshield wiper hose attached to vacuum point for charcoal cannister (at butterfly throttle body) and then the 2 way nipple further back on the side there, to get water to back 2 cylinders. Water also seen in bottom frame near battery...then I see it: LEAKING EXHAUST at engine/manifold interface AND at manifold to turbo interface, where the outermost bolt was actually spinning. Drove to indy who helped me crank it down a bit, but he says that this would not make me fail NOX.

How hard is it to pull/replace exh manifold and replace gaskets? I hate wrestling with old hard to get to bolts...and apparently so does my indy.

Could someone please explain how exh. leak affects O2 sensor and why 02 sensor doesnt see lean and then put more fuel in?

I have the same when-warming-up-from-dead-cold fluctuating idle as does Jonathan in this morning's post. Happened to me this am pulling out of 62 degree garage. Idle never surges high, just runs for a bit then stalls or dies.

Could my exh. leak be part of my cold start fluctuating idle?

I have been thinking AMM, but my indy says if AMM was bad then car wouldnt run so well. I'll check resistance and hot glowing wire test when car gets up to temp after a drive later today.

For the past few months I have used nothing but 76 ethanol-ed 87 octane, thinking it would help me pass. Yesterday I have put some "environmentally friendly" top end cleaner into the engine with 3 gal of premium. Ran hard up a hill yesterday on the way home and got a juttering boost. Wondering if the engine doesnt like the cleaner or if that means cleaner is doing its job.

Could someone verify that lower octane fuel burns cooler and helps lower NOX? Or does low octane fuel actually burn hotter and lower HC's and raise NOX? I've read thru as many posts as I can but I am still confused.

Considering hardwiring fan to run full time for test next time I go in. Should I consider coolant flush and replace as well?

I am throwing a lot of money at a car I love and which drives better than it has in a long time - the boost yesterday, pre-cleaner, was simply amazing, but it isnt getting any more CA-legal.

Oh, and btw, I cant retard ignition anymore. In CA, you can be off from recommended (16deg) by +/- 3 degrees UNTIL you go to a test-only station, where it must be correct.

Sorry for the long one. Thanks for any insight.

posted by 66.245.2...
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