- Thread starter
- #41
60 mi test drive and no Check light 
kurt
kurt
Its back...Code71 (1 Viewer)
- Thread starter landtoy80
- Start date
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Let's think this through a bit....
1. Kurt says the VSV tested bad (resistance *way* too high)
2. Vehicle was run for several months with a faulty VSV
3. EGR temp sensor is coated with carbon
4. EGR modulator has sand sized carbon (in filter?)
Is it possible the VSV failed first, then the system did not open the valve causing less (no) exhaust gas to "burn off" the carbon on the temp sensor... or maybe the carbon started forming after the VSV failed. Once the carbon got thick the temp sensor had trouble measuring the EGR flow after the VSV was repaired.
The rationale for this is the only part that failed the tests was the VSV. It's possible the other pieces (i.e. the temp sensor and the modulator) began to develop high carbon levels after the VSV failed.
Just a theory to explain what Kurt experienced. Sound reasonable?
-B-
1. Kurt says the VSV tested bad (resistance *way* too high)
2. Vehicle was run for several months with a faulty VSV
3. EGR temp sensor is coated with carbon
4. EGR modulator has sand sized carbon (in filter?)
Is it possible the VSV failed first, then the system did not open the valve causing less (no) exhaust gas to "burn off" the carbon on the temp sensor... or maybe the carbon started forming after the VSV failed. Once the carbon got thick the temp sensor had trouble measuring the EGR flow after the VSV was repaired.
The rationale for this is the only part that failed the tests was the VSV. It's possible the other pieces (i.e. the temp sensor and the modulator) began to develop high carbon levels after the VSV failed.
Just a theory to explain what Kurt experienced. Sound reasonable?
-B-
- Thread starter
- #43
To add to the list, In May 03, I cleaned out the carbon build up in the intake chamber. So the exhaust flow would of been very low before cleaning. After cleaning, I would of had full flow of exhaust gas. I did clean out the modulator in April 03. When I blew out the modulator this time, I got blasted like it was a sand blaster.
kurt
kurt
Kurt,
>> I would of had full flow of exhaust gas. <<
You should of had full flow of exhaust gas after the cleaning. If the VSV wasn't opening then you were getting no flow of exhaust gas into the intake; clean or not.
-B-
>> I would of had full flow of exhaust gas. <<
You should of had full flow of exhaust gas after the cleaning. If the VSV wasn't opening then you were getting no flow of exhaust gas into the intake; clean or not.
-B-
That's great Kurt but I was under the impression that you would need 2 trips to be sure that the problem was fixed. Again this is from the 96 manual but it wouldn't fault until that second trip.
Do you guys let your truck warm up before driving it?
Do you guys let your truck warm up before driving it?
In the winter, sometimes. Not in the summer.
- Thread starter
- #47
I drove 35 mi. Ate supper,gassed up and the wife did her thing at Wmart. Then drove home.
The light would of come on at least 2 times when I drove that far.
I am going 50 mi to doctor and returning home taday.
kurt
The light would of come on at least 2 times when I drove that far.
I am going 50 mi to doctor and returning home taday.
kurt
Kurt,
The "EGR Flow Insufficient" is a two trip logic and the vehicle has to reach a specified speed for a specified period of time. IIRC, the speed is 50MPH and the time is 2 minutes.
-B-
The "EGR Flow Insufficient" is a two trip logic and the vehicle has to reach a specified speed for a specified period of time. IIRC, the speed is 50MPH and the time is 2 minutes.
-B-
I know code P0401 is a two trip logic, but are you sure the pre-OBDII code 71 is?
That may be where the two of you are conflicting.
That may be where the two of you are conflicting.
I am not sure about the Code 71 but it seems that this wouldn't change much from year to year. It's possible the pre-OBD-II ECU's weren't as picky about the number of trips, vehicle speed, coolant temp, etc. We have seen very few pre-OBD-II's with EGR problems.
-B-
-B-
- Thread starter
- #51
230+mi in all traffic driving conditions and no light
kurt
kurt
