New to GMT400 from Oregon

[PlayingWithTBI]

Your intake manifold passages for the EGR can be clogged up too. That means you'll have to pull the manifold and clean them out. Normally a bad EGR will fail NOx especially if you have an old 2-way Cat. The newer 3-way Cats help with NOx.

EGR in feed from exhaust in red arrow, EGR cleaning ports in blue arrows

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[Steve Cunningham]

Welcome to the forum g00se.

 

[g00se]

Thanks guys! Quick question, would a clogged EGR manifold passage contribute to high HC? Right now, I'm not getting anymore EGR codes (or any codes --since I removed and cleaned the EGR valve). The only problem (I think) going on now is high HC. I have some time today --I think I'll try 'checking' the timing and take it in for the sniff test to see how it changes the numbers.

 

[g00se]

Welp...I backed off the timing 'and it seemed' to not smell as rich so I headed out to have it checked. There was a line all the way down the street at the DEQ, ---probably a dozen cars waiting to pull in from the street and that was just from my direction. Too long to wait --I'm sure it was more than a half hour just to get to the gate.

I'm glad I didn't wait because halfway on the way back --I the truck threw another CEL. If I had waited in line at the DEQ it would have taken a long time to get back to the street with that check engine light on (and it was low on fuel...)

Plugged in my trusty paper clip when I got home and got a code 32 (sigh..!) Yeah, the EGR code. I may be pulling the intake soon--just too cold today. Question; my Y-pipe looks a little smashed --as if the truck had bottomed out on one of its previous journeys.. --would that restriction be related to the issues (high HC and/or a EGR code 32?)

It also had a code 42 --which could have been caused by my temporary tweaking of the timing..?

 

[PlayingWithTBI]

It also had a code 42 --which could have been caused by my temporary tweaking of the timing..?

That's normal when you disconnect the (Black/Tan) EST bypass wire. I wouldn't think a little dent in the Y pipe would cause issues with the EGR valve besides, it's downstream from the O2 sensor.

 

[g00se]

That's normal when you disconnect the (Black/Tan) EST bypass wire. I wouldn't think a little dent in the Y pipe would cause issues with the EGR valve besides, it's downstream from the O2 sensor.

Quick follow up --I haven't been able to work on the truck much due to the weather and not having time but I did set the timing back to zero with the bypass disconnected and then reconnected it. CEL lights are all clear again.

On my 94 --the O2 sensor is on the Y pipe just before the CAT --not on the exhaust manifold. So the dent is actually upstream to the O2 sensor in this case and on the drivers side of the exhaust flow (of the Y pipe).

I'll try to post up a picture of my dented y pipe since the weather is looking good and I have the day off..

Quick ALDL cable and TunerPro question on the INT/BLM (short term and long term fuel trims). What should I be looking for --they look to be 124-133 range..?
Also, the O2 sensor changes from 920 when cold and 60 when hot (I don't really know what these mean and what they should be..

 

[PlayingWithTBI]

Quick ALDL cable and TunerPro question on the INT/BLM (short term and long term fuel trims). What should I be looking for --they look to be 124-133 range..?

That's normal, stoich is 128, below is rich and above is lean. You're within 5 which is good.

Also, the O2 sensor changes from 920 when cold and 60 when hot (I don't really know what these mean and what they should be..

When the engine is cold the PCM ignores the O2 sensor and runs in OL off the VE tables. The O2 sensor won't start working until it gets warmed up. Then it should go into CL and fluctuate over/under .45V from .1 - .95 or thereabouts when cruising at ~2000 RPM. You should see "Cross Counts" in your data log. If it doesn't cross over .45V within 30 seconds you'll get a MALF code, either code 44 for lean or 45 for rich.

 

[Osteoblast]

Welcome!

 

[jhornsby3]

Goose, I have the fix to get this thing registered. It works 100% of the time. And I promise it will work for you. No, I'm not going to say to call car shield because your warranty is outdated.

Use my address. 100% problem solved. I am 1 mile south of the Yamhill county line in rural Joke county (polk). No checks and no issues. Currently the oldest vehicle is our 98 Burb and no issues with any DEQ checks. Just the check to the dmv and done.

 

[g00se]

When the engine is cold the PCM ignores the O2 sensor and runs in OL off the VE tables. The O2 sensor won't start working until it gets warmed up. Then it should go into CL and fluctuate over/under .45V from .1 - .95 or thereabouts when cruising at ~2000 RPM. You should see "Cross Counts" in your data log. If it doesn't cross over .45V within 30 seconds you'll get a MALF code, either code 44 for lean or 45 for rich.

Thanks TBI! I should mention I put in a heated O2 sensor --and I do see it go from OL to CL (not sure how to read the O2 range units in voltage in TunerPro yet) --but glad the INT/BLM look to be functioning properly. I don't know yet but Cross Counts may be listed in TunerPro as RiCH/LEAN transition counter..? I'm not getting any codes (at the moment) so it seems that the truck is running and functioning properly --with the exception of high HC at the sniff test.. I haven't found my laser temp thing tool, may pick one up this weekend to check the temp range on the cat..

Goose, I have the fix to get this thing registered. It works 100% of the time. And I promise it will work for you. No, I'm not going to say to call car shield because your warranty is outdated.

Use my address. 100% problem solved. I am 1 mile south of the Yamhill county line in rural Joke county (polk). No checks and no issues. Currently the oldest vehicle is our 98 Burb and no issues with any DEQ checks. Just the check to the dmv and done.

LOL J3! I like your solution! Moving is an option I have looked at --and keeping open. The SH*T show around these parts go far beyond the mandated sniff test on my old 94... Beautiful area --I grew up in Polk and moved north for the work.