my 1988 fuel injected 2.9L is failing NO at 15 and 25mph not by much
15mph max NO reading allowed 891.. I am running 990
25mph max NO reading allowed 1031 I am running 1068

all my books say its an EGR problem but my fuel injected 2.9L does not have a EGR?

the bronco has been in storage for over a year. plugs,wires,all replaced before starting storage. before storage it was maintained by the ford dealer

it runs well with a minor miss and feels a little low on power at full throttle.

any ideas?
steve

As far as I know all 2.9 FI have an EGR system. You will not pass the NOX test if it is missing or not functioning. You also will not pass if the vehicle is missing, or there is a bad O2 sensor. Do a tune up first, and if the O2 sensor has not been replaced, it might be worth changing.

As far as I know all 2.9 FI have an EGR system.  You also will not pass if the vehicle is missing, or there is a bad O2 sensor. Do a tune up first, and if the O2 sensor has not been replaced, it might be worth changing.

Wrong.....The 2.9 had EGR up to about mid-87. Some 87s had it and some didn't (my 87 does, a buddy's 87 does not). Those that did not have the EGR had a slightly less aggressive timing program in the ECM to compensate. The rest of the info is accurate, though.

Have you pulled the codes to see if the ECM is trying to tell ya what's up with it?

Mine did the same. I put in an o2 sensor - not the easiest as the plug is way up on the pass side where you can't get to it to release/clip the little plastic spring job that keeps it together.

But it's doable.

If you want to throw a part at it I'd try that & I like the Bosch.

I gave up and took it to a shop... HE claimed a bad cat converter so I installed a new one..during the replace the shop noted that there were two cat on this Bronco which is normal and that the rear cat converter is the one to replace.. so I did that.

also installed new plugs. but the old plugs were almost in perfect condition.
didn't bother with the wires as they look almost brand new same with the dist. cap.

now the NOx is worst... at 25MPH NOx is 1340?????????? and 1000 at 15MPH

everything else is well under all normal cars...

the guy at the shop now says bad gas due to it sitting for a year.. says to run a tank of gas or more through it... I have poured some fuel injector cleaner in the tank.. although I don't like that type of fix...

I am running it down to Bakersfield this weekend (about 200 miles) just to clean it out...

thanks for any help or ideas

been to Bakersfield and back. ran a tank of gas through it.

NOx now at 1700 @25mph

timming perfect
the Co readings say fuel mixture good.. (not lean)
water temp runing well within normal limits

everything I do seems to make it worst.

this is the last chance here over the weekend then I take it to the Ford dealer

thanks for all the views and ideas...

got any last ditch thoughts.

steve

In your tuning etc, did you change the oil and filter?
Look for any vacuum leaks along the way?
I know the wires are 'new' but they can also be an issue.
Any rubbing on anything can cause a leak.
Any corrosion on the wire terminals can cause a miss.
What about the distributor cab and button?
Were they also changed out recently or are they the same as the wires, done before sitting?
The terminals in the cap and on the rotor could be corroded also.

What about the other easily changed emmissions parts, like the air filter and the PCV valve? These can make a small but noticable difference in the output.

I reread this one and I remembered something we (the inspector and I) would do on my T/A to get it blowing right for a few years when I had it.

There was a vacuum leak in some of the heat/ac lines under the dash, so we would clamp the main line going from the intake into the dash with a set of vice grips. (the dash of an 88 T/A was a mother to get into to find and fix the line) Then we would adjust the timing to get the best reading possible before pouring a bottle of Emmision Pass in the fuel tank and run it at about 2000 rpms for a few minutes and take another sample reading. Our test machines allow for testing without sending data just for mechanics to diagnose issues etc. (I paid the labor charges for the time spent tweaking it, but well worth it and sometimes hard to find a shop that will work with you like this.)
This did great for a few years, then one day we couldn't get a good reading at all.
The problem for that was a pretty simple fix, pull the valve covers and clean out the oil passageways so the oil would drain out of the heads. They were blocked just enough to let the oil puddle above the valve seals and send a tad extra into the combustion chamber to get partially burned and some directly into the exhaust to get sent out not being burned at all. No visible smoke but enough to be read by the probe.

I also did some of the basic stuff before going to the shop those days, such as new plugs, rotor cap & button, new wires, oil change, air, oil (filters), pcv and the small breather filter inside the air cleaner housing, everything that can improve the reading was done.
Just as a side note, I bought that car when it had 125,000 miles on it and managed to get 267,000+ miles on it AND still passing emissions until it finally expired.

What about the other easily changed emmissions parts, like the air filter and the PCV valve? These can make a small but noticable difference in the output.

Definately change the PCV valve...they are about $4 and will help.

Thanks to all who posted.. I finally got it to pass... here's what happened

1. computer was not at fault.. no fault codes
2. engine had new wires,plugs,cap,PVC valve.
3. new engine oil and filter
4. new cat converter (back converter replaced.. front converter mty.. 3 different smog shops state that the front converter is not needed to pass)

the problem was N0x numbers were going up rather than going down as each
of the above corrections were complelted?

The problem boiled down to the 02 sensor was not bad enough to report a code
but was slow to respond to the engine and slow to report to the computer..

replacement of the 02 fixed the problem..

the suggestion to clean out the valve cover gullies is a great idea and was needed
... thanks.. I had to replace the gaskets so that was done while replacing those


final N0x reading at 25 mph..... 85

thanks to all
steve