73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: frogman68 on November 01, 2008, 01:31:37 pm
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I hate emissions :) That being said I am at a total loss on a 88 Blazer 350 TBI either 97 or 197k on the engine.
Took it to emissions it failed with the following.
Hydro Carbons 7.0335 allowed is 2.4 Carbon Monoxide 9.5826 allowed 80 Oxides of Nitrogen 4.3030 allowed 4.2
Took it home and did the little computer check it gave error 13 for 20 bucks I just replaced the O2 sensor. While I was at it I changed the plugs checked the cap and rotor (less than 500 miles on this stuff) and did adjust the timing .
This truck is seldom used till my son starts driving. So before taking it back I ran it a few days seems ok rechecked the timing this morning and took it back.
Today it failed again
Hydro Carbons 11.4070 allowed is 2.4 Carbon Monoxide 18.1414 allowed 80 Oxides of Nitrogen 3.4058 allowed 4.2
Now it passed two of three but the CO2 has doubled and the hydrocarbons still are high since its TBI I can't adjust it not sure what to do to it next besides register it Historic and be done with it :)
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Exactly; i was going to suggest historic plates. Much cheaper too.
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Do you have the CO2 and O2 readings also? If you do I can point you in the right direction.
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Do you have the CO2 and O2 readings also? If you do I can point you in the right direction.
no they dont give that to ya just CO HC and NO
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What are your results in?
HC? PPM?
CO %?
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What are your results in?
HC? PPM?
CO %?
Hc first test was 7.0335 gpm allowed is 2.4 gpm second test 11.4070 gpm
co first test 9.5826 gpm allowed is 80 gpm second test 18.1414 gpm
Both times CO passed but for the second test it doubled and that is after a new set of plugs oxygen sensor and timing adjustment.
Thinking since this thing is 20 just change the Cat and see if that helps :) .
Might just be me but the exhaust feels hotter than "usual" for a chevy no scientific things just a feeling
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I would suggest this.....rather than throwing parts at it (cat alone is going to be couple hundred installed), I would fing a reputable shop that has a scope, not just a scanner. Around here there are a few shops that have a computerized scope and the average cost for diagnosis is $70 (about an hours work). If you're not sure who to go to, I would suggest calling 1 of 2 people to find out. Your local NAPA would know possibly (not just any parts store but NAPA because a good shop is primarily going to be using quality parts like NAPA). Or the other would be the local Snap-On guy and ask him who has a scope.
I wold love to offer ideas based on numbers you can recite but changing one thing can alter others and without a scope you really can't see whats going on. If you want more info let me know.
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Without the 5 gas readings I can't tell you what the most likely cause is. Well at least the HC, CO, CO2 and O2. If you can give us scan data also at operating temp that will help us otherwise like Jiggy said, you'll just be throwing parts at it.
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And make sure the engine is hot when you take it to the emissions place. These engines don't run real clean when they're cold.
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how did you set the timing?
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how did you set the timing?
Let the truck run for about 30 minutes (outside temp about 50 degrees Fahrenheit) hook the timing light up and disconnected the EST (Think that is what its called Brown/Black wire by the master cylinder) and set it to 0 degree's
this truck is seldom used I think I am going to run it this week to see if that will clear it up
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I thought 8 degrees was the factory setting? I used to set mine at 10 -- made it run better.
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I thought 8 degrees was the factory setting? I used to set mine at 10 -- made it run better.
It's a TBI engine so the timing is set differently.
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AHH!
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What is it called ?
I did a vacuum test I get 0 at 2000 Rpm at the EGR valve when I traced it back it goes to I have no idea what it is called but it has vacuum on the inlet ??? from the carb but nothing coming out on the side that has the EGR there is wires there not sure if its the EGR Solenoid (the pic from Autozone doesnt look like it). Of course the camera is dead and no batteries and its Thanksgiving so I cant get any today :(
Btw when I push up on the EGR valve at idle it does want to die
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That's EGR solenoid and you shouldn't have vacuum to the EGR valve only to the solenoid.
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That's EGR solenoid and you shouldn't have vacuum to the EGR valve only to the solenoid.
Thanks but how does the EGR valve open then ? I brought it up to 2500 Rpm and the EGR valve doesnt move no vacuum on the line that is suppose to go to it
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When the ECM energizes it. In closed loop operation.
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When the ECM energizes it. In closed loop operation.
When is the ECM suppose to energize the solenoid? Can I just bypass the solenoid and run vacuum to the EGR??
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Why would you want to do that? And no you can't. EGR should only come on when the engine is hot and when engine load is low. What are you trying to do?
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Why would you want to do that? And no you can't. EGR should only come on when the engine is hot and when engine load is low. What are you trying to do?
I was "troubleshooting" the emissions. The Egr valve would not open (putting hand on diaphragm) when warm and bringing engine up to 2500. I just replaced the Egr vacuum solenoid (16 bucks) now I get like 15 pounds of vacuum at 2500. I havent checked to see if the diaphragm is going up no one is home but could run the vacuum test.
Thanks Ville, trying to understand these computer trucks is driving me nuts
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Tuesday 12/9 is the "Big Day" the truck is going to Emissions Testing .
This time if it fails I will be registering it Historic.
If (hopefully I am getting ahead of myself) it fails I am thinking of doing one of two things.
one rip off all the emissions and put a carb set up on it
two put a 84 305/350 in it . with headers
Not sure if I should start a new thread if it comes down to it.
Questions are besides having to drop the tank and remove the fuel pump and running new line to the "older style" fuel pump what other issue might I run into ?
Pass or fail I am still thinking of pulling the engine over Xmas Break. Son wants this to be a stick and thinking it might be easier to pull the engine to do all the work putting the "Z" Bar and stuff in
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Don't do it! Keep it TBI and I would also keep it automatic personally.
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Don't do it! Keep it TBI and I would also keep it automatic personally.
But a truck to me is a stick, and not the fancy smancy hydraulic ones :) I like having to but some umph behind getting the clutch pedal to go in :)
If I register it Historic I know more about the Non TBI / Computer controlled engines so I wont be pulling my hair out .
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well send me up all the TBI stuff then cuz I could use an extra setup :P
Seriously though, sometimes you need to learn new things. TBI is so much better and you can always get help here.
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well send me up all the TBI stuff then cuz I could use an extra setup :P
Seriously though, sometimes you need to learn new things. TBI is so much better and you can always get help here.
Ville
I try and learn this Tbi setup and this site has taught me much but I don't want to be grey haired anytime soon :) . I am hoping it will pass on Tuesday and ripping the Tbi off will be a moot point .
Thanks Again
Brian
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FAILED AGAIN :(
It got better but still did not pass
Test Results
1st HC 7.0335 CO 9.5826 NO 4.3030
2nd HC 11.4070 CO 18.1414 NO 3.4058
3rd HC 5.4978 CO 156316 NO 1.5439
Allowed HC 2.4 CO 80.00 NO 4.20
Between 2nd and 3rd test complete tune up and timing replaced the Cat, Egr Solenoid and MAP sensor (tests failed for both Egr Solenoid and Map sensor) no more codes
Between 1st and second test Oxygen sensor replaced.
Anything else ? I am going to the shop to look at a non computer controlled 350 to see what its got and build a "nice" motor for this beast
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You could have brought it to a shop and had it diagnosed and fixed cheaper than the parts you are throwing at it. Without datastream and all of your gas #'s we really can't give you a difinitive answer on what's causing the problem.
Hi CO indicates rich
Hi HC indicates unburned fuel
Without O2 and CO2 we can't tell what's going on.
High Nox = high combustion temps
Make sure it isn't running lean. Check your engine coolant temp sensor, check your fuel pressure.