LT-4 failed emissions... wtf
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Reading the archives I see this P0300 code set mostly by bad plug wires followed by the opti and a few others. Many times it was a struggle to nail it down.Why I am searching on this code since my car does not have it is beyond me...... mabey the OP should have checked there.
Thread Starter
Racer
Joined: Mar 2005
Posts: 379
Likes: 95
From: Ingersoll Ontario
....maybe my desire to have personal one on one attention far exceeds my desire to do yet another search, maybe my feelings that this is more than just an archive site and that people my have some personal NEW information or experience to share other than "Bob's Vette threw a P0300 in 2004". I now realize why I post less more and more everyday. Unless my sarcasm quota is getting low, then I log on for some punishment.
yes, I did a search.
yes, I have a FSM.
yes, I wave.
yes, I try to use proper grammar and proof read my posts.
no, I don't believe C5's have a fat azz, nor do I think other generations suck.
no, I would never take my car to the dealer for service work, I use my FSM and occasionally this site. Although it seems the friendliest place on here now is the lonely halls of the archives.
I'll keep you all posted on how my car fares with it's problem... for the archives sake at least.
yes, I did a search.
yes, I have a FSM.
yes, I wave.
yes, I try to use proper grammar and proof read my posts.
no, I don't believe C5's have a fat azz, nor do I think other generations suck.
no, I would never take my car to the dealer for service work, I use my FSM and occasionally this site. Although it seems the friendliest place on here now is the lonely halls of the archives.
I'll keep you all posted on how my car fares with it's problem... for the archives sake at least.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Well it failed again, even worse this time. Failed everything in the driving test by a mile. Here is what I've done so far in this order:
1) Cleaned K&N and TB
2) Seafoam in the intake and gas tank and drove for 1 hour at highway speeds. Then added 3/4 tank of fresh fuel.
3) Changed oil and plugs to NGK TR55 platinum's
4) I had a random misfire code P0300 before I did all this but have not had it since.
The car actually seems to be running worse since I did all of this, it smells rich. The old plugs didn't look too bad, nice color, all pucks still there, gap was good. I noticed the biggest difference after I changed them (rich smell), but I am getting no new codes. I'm getting it scanned at a buddy's place next Wednesday, any suggestions before then? The car has decent power in first gear but seems to bog a bit going into second if I get on it. I'm going to do a thorough check for VAC leaks tonight, although I don't think there are any. Any constructive comments are welcome. Thanks
1) Cleaned K&N and TB
2) Seafoam in the intake and gas tank and drove for 1 hour at highway speeds. Then added 3/4 tank of fresh fuel.
3) Changed oil and plugs to NGK TR55 platinum's
4) I had a random misfire code P0300 before I did all this but have not had it since.
The car actually seems to be running worse since I did all of this, it smells rich. The old plugs didn't look too bad, nice color, all pucks still there, gap was good. I noticed the biggest difference after I changed them (rich smell), but I am getting no new codes. I'm getting it scanned at a buddy's place next Wednesday, any suggestions before then? The car has decent power in first gear but seems to bog a bit going into second if I get on it. I'm going to do a thorough check for VAC leaks tonight, although I don't think there are any. Any constructive comments are welcome. Thanks
A good spraying brought things back to normal.
Jake
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
I already told him to clean the MAF but he does not seem to be doing much to fix his trouble besides complaining.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Not true I found a lot of P0300 codes on LT4s mentioned.By the way it does not matter P0300 on LT1 or LT4 are the same and the causes are the same.
Last edited by Redeasysport; Jun 23, 2008 at 03:56 PM.
Thread Starter
Racer
Joined: Mar 2005
Posts: 379
Likes: 95
From: Ingersoll Ontario
If this isn't sarcasm I don't know what is. I have listed the steps I have taken so far and yes I forgot to mention that I did clean the MAF. I also said that the car is going for a scan on Wednesday, if that isn't helping to solve my problem I don't know what is. As for the P0300 I haven't had it since I cleared it as said in my original post and I have put a full tank of fuel through it since. After reading the FSM for awhile last night I'm going to go through and check out the fuel system tonight. I'll try to post the #'s from both e-tests later when I get home.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
If the P0300 is gone it will probably pass emissions. Not sure how yours work but usually here in the states if a OBDII code is present it will fail automatically. There is a whole rash of things that can cause this generic code some listed in the FSM some not. My comment was a reflection of your" I did not find a thing spare me the search advice" you get what you give. If you do do a search and read all of the posts on the P0300 you will have somewhere to look at curing your problem. Mabey the thing that caused the code is better but not well and not bad enough to toss another code. You are correct a scan with Datamaster and a laptop might help narrow things down.
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Drifting
Joined: Jul 2007
Posts: 1,293
Likes: 36
Don't worry. . . a lot of people share your sentiments.. . and suffer in silence. I concentrate on the good solid folks who would never post garbage like that. And it is garbage.
After a while you ignore the ego maniacs and get whatever you can get from CF
. You need tough skin on CF.
After a while you ignore the ego maniacs and get whatever you can get from CF . You need tough skin on CF.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Don't worry. . . a lot of people share your sentiments.. . and suffer in silence. I concentrate on the good solid folks who would never post garbage like that. And it is garbage. After a while you ignore the ego maniacs and get whatever you can get from CF . You need tough skin on CF.
After a while you ignore the ego maniacs and get whatever you can get from CF . You need tough skin on CF.
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
Lernt dat yesterday!
Stored a car with a code.
Shame.If there was moisture [water], it ain't gonna' dilute just cause you put gas in.
What additional codes do you have now?
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
If this isn't sarcasm I don't know what is. I have listed the steps I have taken so far and yes I forgot to mention that I did clean the MAF. I also said that the car is going for a scan on Wednesday, if that isn't helping to solve my problem I don't know what is. As for the P0300 I haven't had it since I cleared it as said in my original post and I have put a full tank of fuel through it since. After reading the FSM for awhile last night I'm going to go through and check out the fuel system tonight. I'll try to post the #'s from both e-tests later when I get home.
A gas problem would show AFTER the fire, at the o2's ...
Thread Starter
Racer
Joined: Mar 2005
Posts: 379
Likes: 95
From: Ingersoll Ontario
1st test:
Driving HC limit: 57ppm Reading:25ppm PASS
CO limit:0.32% Reading:0.20% PASS
NO limit:421ppm Reading:570ppm FAIL
Idle HC limit: 200ppm Reading:73ppm PASS
CO limit: 1.00% Reading:0.97% PASS
NO N/A
2nd Test:
Driving HC limit:57ppm Reading:133ppm FAIL
CO limit:0.32% Reading:0.48% FAIL
NO limit:421ppm Reading:1518ppm FAIL
Idle HC limit:200ppm Reading:110 PASS
CO limit:1.00% Reading:0.62% PASS
NO N/A
** I did find a Vacuum leak last night on the left side of the intake by the PCV valve, after I fixed it the rich smell went away. Hopefully that was my problem, but the scan on Wed should shed some more light. I cleared the P0300 code myself with a code reader, it is not stored in the history, and it has not returned, nor have any other codes appeared. I have 44lbs of fuel pressure with the key on, engine off. Engine running I have 42-43lbs. When I shut it down the pressure did not go down it stayed at 44lbs for an hour before I removed the gauge.
Driving HC limit: 57ppm Reading:25ppm PASS
CO limit:0.32% Reading:0.20% PASS
NO limit:421ppm Reading:570ppm FAIL
Idle HC limit: 200ppm Reading:73ppm PASS
CO limit: 1.00% Reading:0.97% PASS
NO N/A
2nd Test:
Driving HC limit:57ppm Reading:133ppm FAIL
CO limit:0.32% Reading:0.48% FAIL
NO limit:421ppm Reading:1518ppm FAIL
Idle HC limit:200ppm Reading:110 PASS
CO limit:1.00% Reading:0.62% PASS
NO N/A
** I did find a Vacuum leak last night on the left side of the intake by the PCV valve, after I fixed it the rich smell went away. Hopefully that was my problem, but the scan on Wed should shed some more light. I cleared the P0300 code myself with a code reader, it is not stored in the history, and it has not returned, nor have any other codes appeared. I have 44lbs of fuel pressure with the key on, engine off. Engine running I have 42-43lbs. When I shut it down the pressure did not go down it stayed at 44lbs for an hour before I removed the gauge.
Thread Starter
Racer
Joined: Mar 2005
Posts: 379
Likes: 95
From: Ingersoll Ontario
It idles very smooth and even better now that I fixed the Vac leak. I pulled the tube off and could hear the engine rev up a bit and then back down, like it was compensating for the problem. I could hear just a tiny bit of a stumble at the tail pipes when the tube was off and a rich smell would come after about 30 seconds. Hopefully my problem is solved.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If the 300 is gone, fixing the vacuum leak probably fixed the problem. The air that gets sucked in through the leak is not measured by the MAF and it runs lean which sets up the lean misfire, which sends combustion temps up, which creates NOX. Scanning should now show that fuel delivery is correct for the air the MAF says it's getting. If so, it should pass (or it needs a new CAT).
