Help needed Failed smog test

[icemaneric1]

Ok take it easy on me guys as I'm still learning this TBI system, don't flame me if I ask a stupid question when I'm done.

So I failed the CA smog test. I passed the NO test with plenty of room to spare. The hydrocarbons, now that was a different story.

Alright onto the truck, its a 91 K5 350 CA truck
Rebuilt engine maybe 150 miles on it. New Plugs, wires, cap, rotor, coolant sensor, water temp sensor for gauge, new T-Stat new oil pressure sensor, TBI gasket, intake manifold gasket. before assembling I cleaned out the egr passages.


All of the above items but had a lower Temp T-Stat (175)
first test I passed the emissions part failed the visual.
@15mph HC max 112 measured 112
@25mph HC Max 92 measured 92

Second test. All of the above items with a new T-Stat (192) Used ignition control module, used electronic spark control module, used map sensor and a used TPS sensor but still have high HC readings.
@15mph HC max 112 Measured 114
@25mph HC max 92 Measured 88

Smog tech said it also failed for not having a specific cat. Looks like a hanger to me but he said its an air injection pump tube.

Anyhow, I have checked for codes and it only gives two codes 12 and 42 EST circuit.

I was doubtful of a vacuum leak being that the Nitric oxide NO readings were low, but I went on a head and checked for vacuum leaks. Unplugged one hose at a time, then all together installing one at a time but no dice.
I had a spare ignition control module and map sensor so of course I popped those in. I also tried two different electronic spark control module from a 92 and 94 but not change.

Here are the symptoms. While driving for over 15 minutes the service engine light comes on and stays on until you restart the truck. It doesn't idle smooth like a V8, it feels. The exhaust note sounds like its running lean. If you push the gas pedal revs pick up and idles smooth with no hesitation. Push on the gas pedal just enough for the rpm's to change and they increase but seems to stumble for a second or soo. I replaced the TPS with a spare used sensor because of this but that also did not change.

My questions How common is it for the electronic spark control module, ignition control module, or a map sensor to go bad? Could those parts cause high HC but not effect the NO (PPM) test? Could a incorrect cat cause high HC but have low NO?

Is there someone local who could help me. I'm in Modesto CA about 1.5 hours south of Sacramento, or 1.5 hours east of San Francisco.


Sorry for such a long rant, but I'm getting desperate here.

 

[icemaneric1]

Not sure if this makes a difference, but it idles smooth when the engine is cold RPM's do drop once the coolant reaches operating temperature.

New O2 sensor and a new knock sensor were installed with the fresh engine.

The wires in the wring harness looked good. The the wire looms were all dry and falling apart so it got new ones, I even payed extra attention near the knock sensor wire since its so close to the exhaust manifold, it looked good though.

 

[icemaneric1]

OK so before I throw parts at the truck, I will attempt to test some things. I remembered a while back on how to test the TPS, so of course I did a search and found it again.

Onto the test results for the TPS
Tool used Digital volt meter (I don't have an analog meter)
Battery voltage was 12.5
Reference signal gray wire was 5 volts exactly
At idle the dark blue wire was 0.54 volts and @ WOT 4.5 volts
The volt meter ground wire was connected onto the black wire on the TPS connector.

I think that rules out the TPS sensor.

Next step will be to replace the electronic spark control module. I would like the AC delco module, but my local parts store only warranties it for a year. There is a lifetime warranty on a BWD Automotive module. Are the BWD garbage is it common for the delco parts to go bad? Any suggestions on testing this part.

Come on guys throw me a frickin bone here!

 

[p0ps45]

Check your EGR valve. It can cause stumble and/or check engine light.

Check out this thread: http://coloradok5.com/forums/showthread.php?t=289118&page=3. See post #30 for troubleshooting chart.

 

[icemaneric1]

Check your EGR valve. It can cause stumble and/or check engine light.

Check out this thread: http://coloradok5.com/forums/showthread.php?t=289118&page=3. See post #30 for troubleshooting chart.

Thanks for the advice p0ps34

Hopefully my test procedure was correct.

First thing was to disconnect the hose between the EGR valve and the egr vacuum solenoid. There was no vacuum coming out of the solenoid to the valve at idle. There is vacuum from the TBI to the solenoid with the KEOR. Onto the EGR valve. If I apply vacuum to the valve while the engine is of the diaphragm moves freely and holds vacuum. If the engine is running and I apply vacuum, the diaphragm doesn't seem to move. If I push the diaphragm with my fingers it opens and the engine stalls.

Does that make any sense?
According to my test the EGR valve is working, what do you guys think?

 

[RootBreaker]

out here i still have to take the low idle emissions test.. when i failed.. i was like crap.. the guy told me that there are things i can do to get my truck to run cleaner.. but he wasnt allowed to say it.. but he was staring at a bottle on the counter up high.... called

Guaranteed to Pass

well i used it.. $7.. followed what it said on the directions...
went back and viola flew through with flying colors...

then i went and was working on my truck... while it was running.. for some reason i looked down the throats.. .and it was POURING fuel down the secondaries.. i had my float wrong....

so it got me to pass when i was way out of adjustment..

not sure if you can run that on your motor or if it will work for ya... i just know my truck wont go through inspection without it...

 

[icemaneric1]

out here i still have to take the low idle emissions test.. when i failed.. i was like crap.. the guy told me that there are things i can do to get my truck to run cleaner.. but he wasnt allowed to say it.. but he was staring at a bottle on the counter up high.... called

Guaranteed to Pass

well i used it.. $7.. followed what it said on the directions...
went back and viola flew through with flying colors...

then i went and was working on my truck... while it was running.. for some reason i looked down the throats.. .and it was POURING fuel down the secondaries.. i had my float wrong....

so it got me to pass when i was way out of adjustment..

not sure if you can run that on your motor or if it will work for ya... i just know my truck wont go through inspection without it...

I was thinking of something along those line. Someone said alcohol would lower the HC levels, not sure what type of alcohol though.
Anyone have experience with those type of chemicals on a TBI system?

I did look at the injectors thinking one was plugged. Both have a even cone shaped pattern to them. Maybe its a bad cat after all?

 

[RootBreaker]

I was thinking of something along those line. Someone said alcohol would lower the HC levels, not sure what type of alcohol though.
Anyone have experience with those type of chemicals on a TBI system?

I did look at the injectors thinking one was plugged. Both have a even cone shaped pattern to them. Maybe its a bad cat after all?

fyi.. this is exactly what i use...

http://www.google.com/products/cata...a=X&ei=SCOfTsi6HsSO0QHQguTGCQ&ved=0CCwQ8wIwAA

 

[icemaneric1]

Thanks for the info RootBreaker, I will give it a shot.

 

[goathearder]

I was struggling with nearly the same exact thing 2 years ago with a 93 cherokee with fuel injection. I tried all the "tricks" like guarneteed to pass, denatured alcohol in the gas tank, sea foam, water in the intake manifold and nothing worked.

I finally put a new cat on and it passed. Not saying its the same situation but a new cat was the only thing that worked for me.

 

[icemaneric1]

I was struggling with nearly the same exact thing 2 years ago with a 93 cherokee with fuel injection. I tried all the "tricks" like guarneteed to pass, denatured alcohol in the gas tank, sea foam, water in the intake manifold and nothing worked.

I finally put a new cat on and it passed. Not saying its the same situation but a new cat was the only thing that worked for me.

I have a feeling thats what my issue is to, infact I orderd a magnaflow unversal cat (part#39009) yesterday.
The truck runs good, its issues are high HC and a little bit of a rough idle, not bad. Maybe its me expecting this TBI system to idle like a sequential port fuel injected V8.

I had store credit, and figured a catalytic converter would be a good bet. I will be going back to retest some time next week.

 

[Keitha]

I have a feeling thats what my issue is to, infact I orderd a magnaflow unversal cat (part#39009) yesterday.
....

I am not sure that a "universal" cat will pass the visual in California. I think it may have to be an OEM or OEM certified cat.

 

[icemaneric1]

I am not sure that a "universal" cat will pass the visual in California. I think it may have to be an OEM or OEM certified cat.

You can use a unviversal cat on any car in CA as long as it has Executive orded for given vehicle. This one has a EO number d-193-85, Magnaflow shows its covers my K5. I will give an update once its welded in place and head off to the smog shop.

 

[4X4HIGH]

A new CAT will fix the HC numbers no problem.

 

[scouthead]

feel you on this one... just got mine to pass with different problem.
but i would take your egr off the intake and inspect the ports on the intake. ive had several trucks where the ports were fouled and blocked, and had to knock out the burned up drap with a hammer and screwdriver...
doesnt matter if the egr works if the ports are clogged.


mine passed tailpipe with flying colors... then they charged me an extra 11 bucks, pressurized my gastank, and failed me. awesome.

 

[icemaneric1]

I would take your egr off the intake and inspect the ports on the intake. ive had several trucks where the ports were fouled and blocked, and had to knock out the burned up drap with a hammer and screwdriver...
doesnt matter if the egr works if the ports are clogged.

All the EGR ports were cleaned on the intake manifold when I rebuilt the engine. They where majorly plugged.

I had a new cat installed on Friday, truck passed but not by much.
First test with the old cat.

@15 MPH HC (Max) 112 (Meas) 114 (Fail)
@25 MPH HC (Max) 92 (Meas) 94 (Fail)

Second smog test with a new cat
@15 MPH HC (Meas) 110 (Pass)
@25 MPH HC (Meas) 57 (Pass)

I'm guessing the HC dropped with the egr opening at higher RPM's, so I would assume the EGR is working. Any how I'm leaning to the knock sensor, EST module or wiring itself. It keeps spiting out a code 42. It also seems to retard or advance the timing where it loses power. Also thinking of having someone else have a crack at fixing it.

 

[pmpski_1]

I was struggling with nearly the same exact thing 2 years ago with a 93 cherokee with fuel injection. I tried all the "tricks" like guarneteed to pass, denatured alcohol in the gas tank, sea foam, water in the intake manifold and nothing worked.

I finally put a new cat on and it passed. Not saying its the same situation but a new cat was the only thing that worked for me.

Same here. Magnaflow, 390009.

 

[RootBreaker]

what do you do if you dont have a cat? i just failed but didnt do the guaranteed to pass like i always do.. i was 500 co% where you can only be 300.... or something like that... i know it was supposed to be 3 and i was 5.. not sure if hundreds....

everything says carb air fuel screws... so will do that.. but i know we did that. but the temp changed...

 

[bp71k5]

If a TBI system is showing codes, you can't expect decent performance until the problem is fixed. If it's the EST, then you have a bad knock or something wrong with the ignition system. Double check the base timing and make sure it's 0 degrees.


-Brian