93 Altima Emisson woes cont'd

Further to previous post, I installed a NEW Walker 3way cat and ALL the readings are now virtually UNCHANGED!!!!! NO idea what to do now.

Reply to
mark
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did you not go through the ignition stuff? you had high hydrocarbons and low CO2 - that means you had a failure to spark properly. either that or you have a burned valve.

Reply to
jim beam

mark wrote in news:k2ts74$lhc$ snipped-for-privacy@dont-email.me:

Then the cat was never the problem. Why did you replace it?

Reply to
who

probably because the code said so.

Reply to
m6onz5a

m6onz5a wrote in news: snipped-for-privacy@a19g2000yqd.googlegroups.com:

The code never says to replace the cat. It only says "P0420", which _might_ mean the cat needs replacing, depending on the results of some diagnostic testing.

OP would be wise to post ALL his numbers, both measured and mandated.

Reply to
who

Cat was the only probable device left, everything else has been changed and/ or checked. It's hard to believe a new cat would not change the readings significantly. Here are the scans:

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Reply to
mark

mark wrote in news:k313ro$m8k$ snipped-for-privacy@dont-email.me:

The graphs are blurry and hard to read. Is that what the test station gives you, or did you make those graphs yourself?

Does your test not involve fixed speeds, like idle,

15mph, 25mph, etc.?

Don't you have a simple chart that gives the readings at given speeds, plus the maximum allowable numbers?

- How long was the car driven before the test?

- Does the test give the vehicle "prep" time?

- Has the ignition timing ever been checked?

- Do you have EGR?

Reply to
Tegger

Go to aircare.ca , Inspection info / Test results and enter

1n4bu31c1pc166601 for the VIN

Car was driven several miles and fully warmed up.

No prep time

Timing was checked and retarded 10 degrees for the 8/24 test

EGR was repaired - Vac hose was leaking

Reply to
mark

mark wrote in news:k32tni$631$ snipped-for-privacy@dont-email.me:

I notice that the vehicle appears to have sat unused for at least 3 years. If so, this is significant. Lots of stuff can seize during the inactive interval.

Why wasn't it simply set correctly to begin with?

So it was inoperative but now it is, apparently, considered operative? Nobody's actually checked to make sure the passages are actually and truly clear? That the valve is actually opening up sufficiently when vacuum is applied? That exhaust gas is actually making it through the passages into the combustion chamber? And on ALL cylinders?

AirCare has a Web page intended to help with failures.

AirCare's documentation is jumbled and confusing, requiring you to assemble the needed information from different locations (did you vote for these bureaucrats?).

To compress and clarify the bureaucratic jumble, your HC is about 150% of the limit. your CO is about 40% of the limit. your NO is about 160% of the limit.

You're way high across the board, but mostly high on HC and NO. If it were me, I'd be investigating that EGR a bit more closely, plus resetting the timing back to where it ought to be.

Reply to
Tegger

Where did your replies disappear to Tegger?

Reply to
mark

mark wrote in news:k3do8v$g9c$ snipped-for-privacy@dont-email.me:

I sent two detailed replies on the 15th.

Reply to
Tegger

Yes, I read them and was going to respond today but they have disappeared, not even found in google groups search.

Anyways, he took it to an aircare specialist and was advised that the new cat was too small so he recommended to wrap the pipe from the manifold to the cat to increase heat so it would function better. The EGR was system has been repaired and all ignition parts checked. Will let you know what happens. About my vote for those bozos, I never vote and yes the whole program is a "make work project" and waste of time which luckily will be discontinued next year.

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Reply to
mark

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