2001 Chevy Express EGR

2001 CHEVROLET EXPRESS
330,000 MILES • V8 • 2WD • AUTOMATIC
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
My van all of a sudden started stumbling and showing a loss of power (only at mid-upper rpms). Check engine light came on, so I took it to autozone and they gave me p0401. I have researched this and researched this, changed out the egr valve. I have read about vacuum lines being clogged-I believe mine does not run on vacuum. I read about carbon build-up--I saw some, but only around outside edges, didn't seem bad to me. I am guessing that it might be the sensor for the egr valve, but don't wanna play change this, change that. I have a fluke voltmeter, if it can be used to check the sensor, but don't know how to check it. This van has 330k on it, and I want it to see 1000k because I am a poor floorman that cannot afford a new van; so i do my very best at fixing/maintaining it. I have some training from UTI also, but like I said I am a floorman now. Your input is greatly appreciated.
Edit Post
Oct 18, 2010 at 1:06 PM
Advertisement
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
The code is for insufficient air flow. Even though it wasn't plugged, are you sure the valve is working properly?
Oct 18, 2010 at 1:45 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
I am "pretty sure" that the Egr valve is working because I bought and installed a new one with the same results.
Oct 18, 2010 at 1:50 PM
Advertisement
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
That code is insufficient EGR flow but I doubt it has anything to do with your symptoms. This EGR system is self contained within the EGR valve so there are no other components. The most likely problem is the passage between the EGR valve and the throttle body is plugged up with carbon. You should be able to clean it with some carb cleaner and a coathanger.
As I said though, it's doubtful that will make it run any better.
Oct 18, 2010 at 1:51 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
So what you are implying is that I need to disregard the problem code and use the basic engine troubleshooting techniques to identify my problem? ie:checking for proper spark, compression, fuel flow etc.?
Oct 18, 2010 at 2:04 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
No, not exactly. You still need to resolve that code but you will likely have other issues to resolve after that.
A scan tool would be helpful to analyze all the sensor data during the failure.
Oct 18, 2010 at 2:14 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
i am going to try and return the new egr that wasn't the problem and trade it for a scanner. Hopefully this won't kill me, but make me stronger.
Oct 18, 2010 at 2:17 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Ok, so I got a scanner. First I cleared the prior code, which never came back. I recorded live data during idle, cruising at 55, acceleration, and deceleration. I am clueless at this point. I could not record the full acceleration at 3/4 throttle because it started pinging severely, which worried me, so I let off of it. I did get a 1/2 throttle acceleration though.
Oct 18, 2010 at 6:23 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
That's the EGR problem causing the pinging. Fix that first.
Oct 18, 2010 at 6:26 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
So then, since the new egr valve did not correct that problem, what am to do? And thank you for all of your advice so far.
Oct 18, 2010 at 6:30 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
I already covered that.
Oct 18, 2010 at 6:33 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
So since i am mostly sure it is not the egr valve itself, then I need to simply spray a bunch of carb cleaner into the passageways involved in the egr process and scratch it out with a coat hanger? What about the residual particles that will break off during this process? Will they simply evaporate with the cleaner? i don't want to get stuff in my chambers. I only want to understand the process.
Oct 18, 2010 at 6:48 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
Blow them out with compressed air. they won't hurt anything. Just make sure you get all the way through the passage to both ends.
Oct 18, 2010 at 6:54 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
You might have to remove the throttle body to access the small hole o that end.
Oct 18, 2010 at 7:04 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Ok. I will do that tomorrow morning. Good thing I have no work to do currently. Will it be ok for me to clean the valve in the same manner?
Oct 18, 2010 at 7:31 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
No need to do anything to the valve as long as the pintle is fully seated.
Oct 18, 2010 at 7:39 PM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
I started with you and have been watching the progress since. I agree with him that where the EGR mounts can be clogged. That was going to be one of my suggestions, but...

As far as the noise you get at full throttle, is it valve ping?
Oct 18, 2010 at 8:00 PM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
Ignition "ping" would be an expected symptom of not having EGR flow. Get the EGR working and that will go away.
Oct 18, 2010 at 8:05 PM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
Would you please PM me.
Oct 18, 2010 at 8:17 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
I believe it is ignition ping, but at 3/4 throttle it did sound like there was some kind of noise from the valves or rockers also. Not completely sure about that though. I am certain about the ignition ping. I am wondering if this whole situation is just bad gas. I cannot PM until I post a couple more.
Oct 19, 2010 at 9:28 AM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Here is a snapshot from the scan tool during the pinging:
DTC_CNT 0
FUELSYS1 CL
FUELSYS2 CL
LOAD_PCT(%) 40.0
ETC(°F) 199
SHRTFT1(%) -21.9
LONGFT1(%) -0.8
SHRTFT2(%) 16.4
LONGFT2(%) 12.5
MAP(inHg) 26.9
RPM(/min) 2890
VSS(mph) 42
SPARKADV(°) 20
IAT(°F) 97
MAF(lb/min) 12.146
TP(%) 44.7
O2S B1S12--B2S12--
O2B1S1(V) 0.095
SHRTFTB1S1(%)-19.5
O2B1S2(V) 0.045
O2B2S1(V) 0.705
SHRTFTB2S1(%) 8.6
O2B2S2(V) 0.745
OBD OBD1
Oct 19, 2010 at 9:46 AM
Avatar
WRENCHTECH
  • CERTIFIED EXPERT
  • 20,761 POSTS
That is one of the main purposes of the EGR system is to eliminate ignition ping by lowering combustion temperatures so fix the EGR and that will go away.
Oct 19, 2010 at 10:16 AM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Let me see if I remember correctly: is the catalytic converter part of the egr system? I cleaned the upper end of the egr system and have the same results.
Oct 19, 2010 at 11:44 AM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
I want you to remove the knock sensor and inspect it. It is on the right side of the motor.


https://www.2carpros.com/forum/automotive_pictures/249084_5_88.jpg

Let me know its condition. Joe
Oct 19, 2010 at 1:42 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Right side as in passenger side?
Oct 19, 2010 at 1:58 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Am I to take it completely from the block or just unhook it? I loosened it and oil started coming out. will i lose a bunch of oil? If I remove it from the block, to I clean it out with carb cleaner to inspect?
Oct 19, 2010 at 2:26 PM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
You won't loose a lot.
Oct 19, 2010 at 9:51 PM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
Ok, I did not check it because I was waiting for a reply and it is dark out now. But I had a thought about looking at my ignition system in the dark. It looked like a christmas tree. I saw two for sure arcs in the plug wires. But it seemed to me that all of the wires were lighting up (seemed like inside the wire) all in the same places, for example where they might be near another wire but not touching. This was at idle. When I gave it some throttle it seemed as if it would go away in all places. Are the wires bad if they light up like that? I have tested my ignition stuff like this before, but never remember seeing wires act like that.
Oct 20, 2010 at 12:05 AM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
I would be happy if this was the issue and angry at the same time because it hasn't been long since I changed them and I thought I did a pretty good job.
Oct 20, 2010 at 12:12 AM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
Oh my god... That is the problem. You shouldn't get any arcing.
Oct 20, 2010 at 8:01 AM
Avatar
SMETZ
  • MEMBER
  • 16 POSTS
So what makes the wires light up internally? I have never seen this before. And should I have been able to see the spark plugs lighting up too? Maybe I was just seeing the glow through the porcelain I dunno. I could not see all the plugs to make sure that it wasn't just the ones I was seeing, which was two out of two. I think the wires are still under warranty, hopefully they will let me swap and pay the difference for better ones.
Oct 20, 2010 at 10:49 AM
Avatar
JACOBANDNICKOLAS
  • CERTIFIED EXPERT
  • 110,175 POSTS
You are seeing the spark from the ignition system. You shouldn't see any at all. The only place there should be spark is inside the engine at the end of the spark plug. You are losing all the power from the arcing.
Oct 20, 2010 at 11:01 AM