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2004 chevy diesel smog problems.

spectra bash

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Ihave a 2004 chevy diesel. will not pass smog due to pcm when plugged in says egr N/A. When i bought the truck 5 years ago it had a tuner installed. I had problems smogging it. I plugged in and set back to factory settings then it passed . fast forward to now i never put tuner back and smog wont pass. My mechanic tried flashing the computer and same readings pop up. He used computer from identical truck and it showed good so i ordered a rebuilt computer to my vin and finally showed up. After install it reads same as my old computer. Today i took it to chevy and they see same thing and say it has chip and they cant do anything with it. Now tags are expired but paid but cant get it to pass smog. Any shops you think could figure it out? Thanks.
 

SBMech

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Do you have the tuner? So you had it tuned, then it would not pass smog, then you restored to stock and it passed, now it won't pass again without you ever reapplying the tune?

What exactly is missing, the monitor for EGR to run and it shows as N/A?

If the tune was the issue I would think that a reman ECU would have fixed that if it was the tune blocking the monitor from running. Are you getting a code?
 

sintax

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Google “finger stick duramax”

These were used to send an “all clear” signal to the computer when the EGR was bypassed. Maybe this can fix your problem?

not too sure if you can even get these anymore. I know they were like to 04-10 era duramax tech, but there’s prob 10’s of thousands out in the wild.
 
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robby dmax

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Google “finger stick duramax”

These were used to send an “all clear” signal to the computer when the EGR was bypassed. Maybe this can fix your problem?
Is this an LB7 or LLY?
The Fingerstick was for the LLY and above.
 

spectra bash

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Do you have the tuner? So you had it tuned, then it would not pass smog, then you restored to stock and it passed, now it won't pass again without you ever reapplying the tune?

What exactly is missing, the monitor for EGR to run and it shows as N/A?

If the tune was the issue I would think that a reman ECU would have fixed that if it was the tune blocking the monitor from running. Are you getting a code?
No codes. Only egr N/A. reman computer read the same. Now that i took it to chevy it is also red flagged whatever that means.
 

4Waters

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No codes. Only egr N/A. reman computer read the same. Now that i took it to chevy it is also red flagged whatever that means.
What it means is don't phony a smog, you and the smog tech will get caught, it has to get repaired, no fingerstick.
 

MSum661

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No codes. Only egr N/A. reman computer read the same. Now that i took it to chevy it is also red flagged whatever that means.
I would make an appointment with a smog ref. Its possible they let it go since your throwing no codes.
Done it before and was glad I did.
 

spectra bash

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My truck also has no CAT just large exhaust all the way back. Could this bring this up? Cat was off since ive owned it. I do have the cat.
 

floatn turd

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For what it's worth.

I had a shit time with my 06 F250 this year ad well.
I also had some EGR crap going on.

Never had a problem before, but this year I did.
Took me a few months to finally get the Computer to complete its "run cycle" or whatever it's called and reset everything.

I followed the same steps as I always do.
And went to the same smog guy as previous years.....but this particular year i had a horrible time.

Who knows 🤔
But good luck.
 

Joe mama

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This smog shit for the older diesels is bullshit. I never had to have my 03 smog checked, then all the sudden many years later it needs some bullshit test just to get my money. I’m about to drive mine off a cliff and have a new 2021 sticker I haven’t put on. How much will you pay for the sticker ? Lol
 

SBMech

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My truck also has no CAT just large exhaust all the way back. Could this bring this up? Cat was off since ive owned it. I do have the cat.
The monitors won't run when equipment is missing, it's looking for other monitors to set before it will run the next. You having no codes, with no cats, can mean it's possible the tune is blocking those monitors from running.

The fact that you replaced the ECU with a reman, and still have a problem on the monitors? Either your mechanic tried to tune it again, or it was programmed incorrectly.

Lots of people report having issues with setting the monitor, and it randomly saying N/A. Remove tool and look again until it shows it as not ready.

I have had success trying this before to set the EGR monitor : Assuming that everything in the system is working properly :

1. Start it (DO NOT hit the accelerator at all). Do not have anything on.
2. Let it idle at 640 - 820 rpms for a 1/2hr to 45 minutes until it reaches coolant temperature of 140* - 206*. The dash temp gauge will be a bit higher than the coolant temp so its better let it get higher than the 160* mark.
3. Shut it off and check it to see if it set the EGR.

It's not a simple system, there are many pieces besides the valve that make up the EGR system on your diesel. You still have the vacuum pump installed and it works right?
 

Fastdadtsmith

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My dad lives at the river. Could i just add his name and register it in AZ?
As long as he's in an area that doesn't require smog test, then yes you could. But, that doesn't solve your problem if you plan to keep and drive it in an area that does. Eventually it will bite you for being registered out of state.
 

spectra bash

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The monitors won't run when equipment is missing, it's looking for other monitors to set before it will run the next. You having no codes, with no cats, can mean it's possible the tune is blocking those monitors from running.

The fact that you replaced the ECU with a reman, and still have a problem on the monitors? Either your mechanic tried to tune it again, or it was programmed incorrectly.

Lots of people report having issues with setting the monitor, and it randomly saying N/A. Remove tool and look again until it shows it as not ready.

I have had success trying this before to set the EGR monitor : Assuming that everything in the system is working properly :

1. Start it (DO NOT hit the accelerator at all). Do not have anything on.
2. Let it idle at 640 - 820 rpms for a 1/2hr to 45 minutes until it reaches coolant temperature of 140* - 206*. The dash temp gauge will be a bit higher than the coolant temp so its better let it get higher than the 160* mark.
3. Shut it off and check it to see if it set the EGR.

It's not a simple system, there are many pieces besides the valve that make up the EGR system on your diesel. You still have the vacuum pump installed and it works right?
Should i put the cat back on?
 

SBMech

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Should i put the cat back on?
It will need to be equipped to pass eventually, the fact that you are not getting Cat codes is weird, indicating a chip or tune is blocking or bypassing the monitor IMO.

Who is doing the programming and tuning?
 

spectra bash

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It will need to be equipped to pass eventually, the fact that you are not getting Cat codes is weird, indicating a chip or tune is blocking or bypassing the monitor IMO.

Who is doing the programming and tuning?
I set the ppe settings back to factory 2 years ago.
 

SBMech

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I set the ppe settings back to factory 2 years ago.
IF it was your tune that is causing issues, there should have been a shit load of codes generated from the missing cat, the EGR delete etc when you installed a reman ECU.

You never answered my question if you deleted the vacuum pump as well?

Since it appears you are still running the ECU with the tune on it (even though you reverted it to stock) I would have to guess that it's corrupted somehow, or the tuner is unable to return it to factory settings, even though it has the option.

You might be further ahead to just remove it from CA and reg it in AZ, went through this last year with an Audi that came to me fully tuned/cat delete etc.....

Ended up costing the customer 5k for a "free" vehicle to make it CA legal.....
 
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4Waters

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IF it was your tune that is causing issues, there should have been a shit load of codes generated from the missing cat, the EGR delete etc when you installed a reman ECU.

You never answered my question if you deleted the vacuum pump as well?

Since it appears you are still running the ECU with the tune on it (even though you reverted it to stock) I would have to guess that it's corrupted somehow, or the tuner is unable to return it to factory settings, even though it has the option.

You might be further ahead to just remove it from CA and reg it in AZ, went through this last year with an Audi that came to me fully tuned/cat delete etc.....

Ended up costing the customer 5k for a "free" vehicle to make it CA legal.....
Free shit is expensive
 

motormonkey

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If you put in a new computer, you need to go thru several key on/drive cycles. And if your computer is stock it will show several pendings.
The procedure SBMech mentioned should have been done with the new computer start up.
Try resetting and start over and you have to drive it after it goes thru the procedure SBMech mentioned of running to temp and key off. Then it needs to be driven several times after setting for several hours or overnight coolant for temp low. Once it goes thru some of those cycles it will go from pending to showing what's reported. If you have anything deleted after it reports, then turn them off with programer and drive it.
I find some computers only like to get reflashed so many times before they start ghosting old programs and can brick out of nowhere.
 
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Ace in the Hole

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As long as he's in an area that doesn't require smog test, then yes you could. But, that doesn't solve your problem if you plan to keep and drive it in an area that does. Eventually it will bite you for being registered out of state.
3 cars in my driveway, 3 different states plates (MT, AZ, TX)...all corp registrations.. Never had an issue. Depends where he lives and if the cops want to be dicks. I'd switch it and be done with it. A basic plausible story is all he needs if stopped. Mine is simple..I don't own it.;)
 

monkeyswrench

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@spectra bash , I'd see if somehow you got a "Federal Emissions" computer somehow. A 2004 LB7 from Cali has an egr and some other BS...kind of a bastard. 2004 LB7's from other states did not have the programming to facilitate the use of the egr, and the harness was different as well.

It just seems weird that there is no communication to or from the egr. Usually they'll throw a code showing above or bellow range. Pretty odd that there's nothing.
 

SBMech

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@spectra bash , I'd see if somehow you got a "Federal Emissions" computer somehow. A 2004 LB7 from Cali has an egr and some other BS...kind of a bastard. 2004 LB7's from other states did not have the programming to facilitate the use of the egr, and the harness was different as well.

It just seems weird that there is no communication to or from the egr. Usually they'll throw a code showing above or bellow range. Pretty odd that there's nothing.
Ohh good catch MW! Forgot that EGR is CA only! I was asking about the vacuum pump because if it's not there it won't even look for the EGR yet.

A FED ECU would show it just like that too, N/A because it's not equipped or monitored. Maybe your tuner needs a CA flash to update from the FED version?
 

Bigbore500r

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It will need to be equipped to pass eventually, the fact that you are not getting Cat codes is weird, indicating a chip or tune is blocking or bypassing the monitor IMO.

Who is doing the programming and tuning?
I dont think those year diesels have a way of telling if the Cat is working (or present...). Gas motors have pre-post 02 and check for proper drop between the 2, but the LLY / LBZ don't have a way to tell?
 

Bigbore500r

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@spectra bash i'm not sure if you can still do it, but years ago it was possible to use HPT or EFI LIve and go into the GM ecm and set the IM monitors to basically read whatever you wanted. Options were "not reported", "N/A", "ready"....etc. Setting it to "ready" would cause it to report to the smog machine that the EGR is present and self testing is complete. I.e - ready for smog. I hear the tuning companies were getting rid of those features by federal mandate, but old builds of these programs exist and can probably solve the problem
 

robby dmax

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Back when the lly came out people were removing the cat and doing the egr blocker plates that is when the finger stick came into play but not all trucks required the finger stick to fool the Ecm to not throw the check engine light.
So I don’t believe that if you put the cat back on it is going to fix your problem.
Sounds like you need to get ahold of one of the tuners to make sure everything that needs to be turned on is on and working correctly
 

spectra bash

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Thanks for replies. I will be checking things . I am getting exhaust fixed just so it will be easier to smog and if i can get it to pass maybe sell this thing.
 

sintax

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Which PPE tuner did you put on there? Do you still have access to it?

If I recall correctly the PPE standard disables the egr as well.

did CA change up their testing requirements lately? I know people who’ve had their PPE truck for 10+ years w/o smog issues.
 

sintax

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Thanks for replies. I will be checking things . I am getting exhaust fixed just so it will be easier to smog and if i can get it to pass maybe sell this thing.
yea the cat would likely be tough to overlook.
 

SBMech

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I dont think those year diesels have a way of telling if the Cat is working (or present...). Gas motors have pre-post 02 and check for proper drop between the 2, but the LLY / LBZ don't have a way to tell?
It's a visual inspection even if there is no monitoring via thermal or O2 sensors. CA is a "fine the fuck out of those who can afford it" state now lol....
 

ka0tyk

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i dont get why taking your ECU and flashing it back to stock with your vin would fail the EGR ready check unless it was being removed via a custom tune OR it was being defeated with a fingerstick. I'd inspect the wiring near your MAF to see if you have one installed. In order for it all to work together you're gonna need to toss the CAT back on the truck, possibly remove the fingerstick if installed, and tune the truck back to stock.
 

Bigbore500r

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It's a visual inspection even if there is no monitoring via thermal or O2 sensors. CA is a "fine the fuck out of those who can afford it" state now lol....
Oh yea, visual smog inspection would fail for sure.
 

SS-C

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He used computer from identical truck and it showed good so i ordered a rebuilt computer to my vin and finally showed up. After install it reads same as my old computer.
This makes no sense.
If the one he used worked properly, then why not get that exact same one?
 

monkeyswrench

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OK, if it is a vin matched Ca computer, and all good there, see if you can get it on a scan-tool. With it running, checkout the info, and see if it shows up under the feeds. If it shows 0% or something at all, computer is "Seeing" it as far as programming. Most of the scanners will also ID the ecm as a federal or Ca emissions when plugged in.

Two outcomes I can think of.
Jacked wiring (Driver side has contact issues...harness gets squished, causes weird crap sometimes. Also the connections. Loose pins in anything that's been messed with, or just straight corrosion)

The other one could be the seller of the current computer sent a fed one. The fed computers are more common, and cheaper. Could have been accidental, may have been intentional...may have been they didn't know. Honestly, I hadn't seen one with Ca emissions until I moved to Az.
 
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