Topic: Smog Help Failed 25 mph UPDATE Failed 15 mph

[854x4]

My 1985 22re Truck passed everything except 25 mph NO (ppm) test the max is 1222 and mine was 1270. Ive read through the how to pass smog now that I have failed. I didnt no untill I was there that my timing was at 6 degrees could this cause the problem? My plan is to readjust my valves retard timing down to 4 degrees and retest will this help or am I just burning my retest? Any Help for a poor broke redneck

[MiniSimp]

Put bigger tires on.

[Steve_925]

next time you go drive the crap out of it for like half an hour to get the cat really hot, should help. did the trick for me atleast

[DCabTaco]

my 85 22re failed with high NO in both 15 and 25 mph and with just a tad bit retard it passed with flying colors.  I am 99.9 % confident that you will pass as well.  Now do as previously suggested as well.  Make sure you CAT is hot.  No need to adjust valves unless they are ticking or you're sure they need it.  Just retard the timing, raise idle, and warm up really good before you take it in for the retest.

[854x4 [OP]]

I adjusted the valves awhile back and I need to again there ticking. How high should I bring the idle up to? 1200 and retard down to 3 or 4?

[jimbo74]

yeah, they check the timing though... if it isnt timed right, you get an automatic fail..... he gave me a fail for advanced timing (said 20*) but it was perfect @ 0 and low idle (did idle @ 396 rpm) but mine passed all the dyno emissions.....

[emsvitil]

Timing allowance is +/- 3 degrees, so time it at 2.5 BTDC instead of 5 BTDC

While you're waiting in line, keep the AC on and use your foot to keep it at 1500 rpm to keep CAT hot.....

BTW I need to get my 86 EFI smogged tomorrow........

[854x4 [OP]]

Well the truck failed again, this time at the 15 mph test. I retarded the timing and drove the hell out of it and at the 25 mph test it brought my NOX level down from 1270 on the first test to 514 on the second test it Passed. But on the 15 mph it made my NOX level go up from 1129 on the first test to 1467 on the second test the limit is 1136 so it Failed. I applied for the cap program and if I'm awarded I will take it to a shop and let them worry about it but if not my plan is to seafoam the motor, remove and clean the egr system, put guaranteed to pass in the tank, retard the timing, drive it to hell and back, and then retest. What does everyone think?

[emsvitil]

At 15, there's more load on the engine  (ASM 5015 means 50% and 15mph, ASM 2525 is 25% and 25mph)...   With more load, combustion temperature goes up.

Didn't realize with your first post that the 15mph test was so close (1129 / 1136) so the first time you just squeaked through.

Most likely it's the EGR system.   Valve, modulator, or clogged passages.

BTW, I just squeaked thru with my test at 25 mph (15 was good).     Still believe the 22REs have a problem with NOx........

[SQUIRREL MONSTER]

yea... always run your truck down the highway for abotu 20 minutes with your foot in it. helps get that cat get as hot as possible to burn off as much as it can. did it to mine and it passed without a hitch.

those numbers however sound exactly what my 85 2wd was doing before i changed the egr. also, if you havent changed the oil in the truck... do that first! they always pass cleaner with fresh oil in em.

[superyota]

i thought if you retard the timing, your exhaust temp. goes up.  isn't NOx due to high exhaust temps?my cousin's building a 90 4runner with a 22re(its in the projects and builds section) and just failed smog due to high NOx.  i told him to advance the timing and poor a bottle of rubbing alcohol in it.  please correct if i'm wrong.  he hasn't gone back to retest yet should probably let him know if i'm heading him in the wrong direction.

[DCabTaco]

read #3 here:
http://board.marlincrawler.com/index.php?topic=1119.0

[superyota]

this doesn't make sense to me.  i know everyone is saying to retard your timing and it will clean up your exhaust if you have a problem with the HC's, but how does it help with your NOx level?  bigmike says it will decrease your cylinder pressure, and that makes sense, but how does that lower your NOx?  i've retarded my timing before and my manifold and exhaust start to glow red.  wouldn't that increase NOx?  i'm all confused.

BIG MKE.....HELP US!!!

[DCabTaco]

http://www.smogsearch.com/index.php?page=faq

number 1 reason for High NOx failure midway down:

Nitrogen Oxides (NOx)*
NOx is formed inside the combustion chamber when excessive heat is present.

A list of common causes of NOx related smog check failure:

1. As usual check the timing first. Advanced timing can cause extra NOx.

If it is too advanced it will increase the likelihood of detonation and increase both temp and pressure.  As you retard(to a certain point of course) it decreases pressure which in turn decreases temp(they are interrelated)

[emsvitil]

NOx is formed from high peak combustion temperatures, nothing to due with exhaust temperature.

Retarding timing / Adding EGR  = lower peak combustion temperatues

Advanced timing / No EGR = higher peak combustion temperatures (NOx forms)

Rich Mixture = cooler peak combustion temp, HC and CO, less likelyhood of NOx
Lean Mixture = higher peak combustion temp, NOx, less likelyhood of HC and CO