*Smog help!*

[XJ Wheeler]

^^^ Just some of the reasons i couldn't live in cali. Shame such a beautiful place is so messed up!

Sent via messenger pigeon - i talk, he types.

[rm2406]

question... when i was replacing a few parts for maintenence to my jeep and possibly help smog test i developed a new problem.... i think. ok ive replaced alot but these are the things i last replaced before this happened. o2 sensor (denso- same as previous one installed). fuel pressure regulator.changed spark plugs (champion oem's) gapped .035"
PROBLEM: when i start the jeep for the first time in the morning it idles perfect then if i give it light throttle the engine stumbles or kinda like chokes but NEVER dies or even start to die.immediately after letting off the pedal it idles like nothing is going on then i give it light throttle and it does it stumbles again. then i left off the pedal and it still idles good. this only lasts no more than 10secs then after that its GREAT ALL DAY til i park it for awhile or til morning. did i do something wrong maybe??

[4.3LXJ]

Hard to say on that. TPS may be getting a little worn out

[rm2406]

the only reason i havent looked at anything else is because it only happened after those changes.. but wouldnt the TPS remain like that for the whole drive? or interfere with shifting? which it shifts GREAT! and it ONLY happens if it sits for maybe 4hrs or mornings...

[4.3LXJ]

I really don't know. That is the only thing I can think of. If it only happens for a few seconds, see if it works itself out. Might be the computer has to relearn.

[rm2406]

did a computer relearn.. so far it still bogs down when i tap the throttle but it doesnt last as long anymore.. idle in morning is low though. not real low just low for a morning start up. normally morning start ups have a bit higher rpm to warm up engine. maybe relearn procedure needs more time to smooth out.

[4.3LXJ]

It takes the computers awhile. They are slow learners. Give it a couple of weeks

[rm2406]

if the computer doesnt smooth it out, what controls morning start ups? (high idle to warm engine on cold days)

[4.3LXJ]

Have you tried running a tank of premium in it yet?

[rm2406]

i have chevron in my tank now. before that i ran berrymans b12 with regular gas..everything else runs great except the morning or cold start up.. every cold start my engine idles as if its warmed up already only its not. i switched out my old ect sensor with new one and still the same problem.

[rm2406]

i read also that a faulty heated o2 sensor can cause cold start problems. sensor itself can be in good range but heater on sensor can malfunction on its own causing my problem.. this is also something i just replaced RIGHT when my problem occured. (what was changed right before problem- MAP SENSOR,ENGINE COOLANT TEMP SENSOR,O2 SENSOR). before this idle at cold start was perfect.

[4.3LXJ]

I suppose that could be it

[JeepFreak]

The sensors may be slightly off on the voltages they give out. Between .5v-4.5v is normal but lets say the voltages coming from the sensors are slightly higher .7 or so. The computer is getting the voltage correctly but it's interpreting a slightly higher 'normal' voltage as not normal so it tries to counteract it but never can because the highs and lows of the voltages don't match. It can cause problems due to the resistances. Kinda like how I was saying with my coolant temp gauge lol it reads higher than it is but it's normal. The voltages are higher than the computer determines as 'normal' even though the sensor is functioning perfectly.

[rm2406]

well so far idle at cold morning starts has seem to go back to normal as 4.3LXJ stated "It takes the computers awhile. They are slow learners. Give it a couple of weeks"
being that i did a ecu reset... so far its getting better every time i start it.. ok back to the original problem of failing NOx emissions.. as i said my last test NOx was reduced by enough to pass after changing multiple parts and using berrymans b12 in tank.. i continue to use fuel injection cleaner to clean up as much as i can before my 4th last free emissions test. im almost certain my high NOx is due to combustion chamber carboned up alot.. i do alot of short trips... emissions guy said change my CAT and it will pass but my CAT is good and i dont want to only mask whats causing high NOx, i want to fix it. and after MUCH parts being replaced just for regular maintenence i beleive i benifitted the most from "berrymans b12". i checked my combustion chamber after running 1 tank of that cleaner and it definetly cleaned alot out as well as giving me a slight boost in mpg's.. last test will be done tomorrow so i will report back my results and compare them to my first test and whats helped out.. thanks all!

[rm2406]

FAILED NOX AGAIN @ 25MPH run. Ran numbers through lambda and got these results. Attached.
Can anyone tell me if anything looks wrong please?