NOS too high?

[timstoyz]

I am having trouble getting my 89 Ranger to pass the Ohio e,check. The NOS level is too high. I have replaced:

Plugs
Wires
Cap
Rotor
Gone to synthetic oil (which did the most to lower level)

I have also checked everything including vacuum hoses, wires, sensors, etc.

Any suggestions?

 

[low_five]

does it have an EGR system? if so read this about how EGR lowers NOx
http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

you may have to repair your EGR system

 

[timstoyz]

According to the manual, the 89 dose not have an EGR system. I cant find any kind of exhaust return on the truck. I will (if all else fails) either buy a code reader or take it to someone who has one. Im thinking it has to have some kind of m.o. though.

Printing volt meter test procedure and trying now

 

[timstoyz]

tested for codes

I tested the truck for codes and its all good. code 1-1 or 11 Still leaves me with a missing solution. A high NOS (or NOx as it appears in the link above) is due to gas burning too hot. Can anyone verify this? I am considering closing the gap on plugs a few thousandths. Anyone?

 

[Wicked_Sludge]

NOX are produced at combustion chamber temperatures over 2,800 degrees. if your NOX levels are off the chart, you need to lower cumbustion temps. what kind of shape is your cooling system in? are you running the proper thermostat? when was the last time it was changed?

lean air/fuel ratios will also cause high combustion temps, so look for vacuum leaks, clogged fuel filters, old/slow O2 sensors, etc. whats your HC PPM?

 

[timstoyz]

HC is 72.6 ppm 201.0 is limit
CO is 0.86 % 2.51 is limit
NOX is 1383.5 ppm and 1316 is the limit

The NOx has been as high as 1618 on a test a while back. The engine was swapped by the previous owner and it had the wrong radiator fan. i switched it out and it brought it down to 1523 ppm. I then put synthetic oil in it and its down to 1383.5 ppm. it dose have a new thermostat and a new over sized radiator in it. it runs under the first notch on the gauge. I am seriously considering the O2 sensor the more i read. I have a few extra vehicles around to pull one off of.

 

[Wicked_Sludge]

only 67 PPM to go...thats close.

what temp. is your t-stat? i wouldnt go lower than 180 (stock is 195). but if your above 180 now, swapping in a 180 might be just enough to pass.

your HC count sounds about right. i dont think its running lean, but it might not be a bad idea to check out your fuel system anyway, just to be sure.

 

[low_five]

backing your timing off will lower nox a bit

 

[97ranger xlt]

do you run a cat? high NOX = bad cat.

 

[MAKG]

High NOx can also be caused by a vacuum leak.

Base timing is very often part of an emissions inspection, but if it isn't, look there. Advanced base timing will lead to higher NOx.

A cat is pretty easy to check with an IR thermometer. Exhaust temperature should go up through each bed of the cat.

 

[tbirdsps]

Read you plugs. Very white you're running too lean which will produce hight NOX. The 89's do in fact have an egr system unless someone has removed it. That system functioning will lower combustion temps when working properly thus lowering NOX.

 

[MAKG]

Of the Bronco IIs, only the 1986-87 versions have EGR. And they all came from the factory with 2.9L V6s after 1985.

 

[timstoyz]

Defiantly no EGR as according to the repair manual. Neither of my 89's or my 90 have it. California emissions may be different.
my other 89 passed with a 678, and the 90 with a 547 NOX reading. also according to the Ohio EPA 65 % of all vehicles failing are Fords and there is some kind of extended warranty on some models. I'm guessing now the m.o. is warn out ford equipment. I really do love my toyz so im going to start from the bottom up and start swapping parts. Old cat and O2 sensor from other 89 first.

 

[Psychopete]

Any luck?

California emissions may be different.

FWIW, My '90 Cali PCM has no provision for EGR either..

Pete

 

[rickcdewitt]

ask the techs to make sure the cat/truck is all the way warmed up.that was all natedog needed to get his 2.9 to lower nox enough?

BTW there is no EGR on any spec 88-92 2.9