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Username Post: how do i check the egr solenoid for operation?        (Topic#226701)
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
09-27-09 01:30 PM - Post#1779163    

can someone tell me if it is a vacuum test or an electrical test to see if it is operating? i have unhooked the vacuum and the electrical connector and no code comes up for it?

oops, it's a 1989 GMC Suburban, 5.7L.
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


Edited by kartracer46 on 09-27-09 01:33 PM. Reason for edit: No reason given.

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2964

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
09-27-09 04:41 PM - Post#1779265    
    In response to kartracer46

Specific criteria / driving conditions must be met for a code 32 to get set.

I have seen a vehicle with the EGR passages totally blocked with carbon, and the vehicle owner said the light only comes on about once a week.

Does the vehicle have a pinging problem?

You could disconnect the EGR valve and attach a vacuum gauge to the EGR side of the solenoid and drive the vehicle and see if you get a vacuum reading.
For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
09-28-09 05:59 PM - Post#1779917    
    In response to Chevytech

Chevytech,

Today I disconnected the vacuum line to the EGR valve and attached a vacuum gauge and if you accelerate it does show signs of vacuum. I also left it plugged in, but took all the vacuum supply away by blocking the port on the throttle body and drove it. i did not get any SES light that way. any ideas on what i need to make it operate properly?

PS: It doesn't have a pinging problem either.
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


Edited by kartracer46 on 09-28-09 06:01 PM. Reason for edit: No reason given.

 
someotherguy 
Moderator
Posts: 25478
someotherguy
Age: 44
Loc: Texas
Reg: 08-01-03
09-28-09 06:27 PM - Post#1779949    
    In response to kartracer46

Here's pics (sorry, my scanner sucks so I just take pics with the d-cam) of the two pages in the '94 factory service manual for a code 32; what it does do is explain the thresholds for the ECM to run the EGR test. Page 2 is the troubleshooting flowchart.

http://www.someotherplace.com/info/code32_1.jpg

http://www.someotherplace.com/info/code32_2.jpg

These pics are large so your browser may auto-shrink them and make them look crunchy; try printing it out and it should be totally legible.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2964

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
09-28-09 07:01 PM - Post#1779974    
    In response to kartracer46

The EGR is only tested under specific conditions, and it will only set a code if it fails self tests. If you dive the vehicle without meeting specific criteria, there is be no code set even if the EGR is disconnected.


Here is a test you can do to see if the passages are plugged:
If you lift the EGR diaphragm with your fingers, with the engine idling, (being careful not to burn yourself or get your fingers caught in the EGR valve) you should hear a definite difference in the way it runs and the engine will most likely stall. If there is no difference you should look for plugged passages.

Do you have a hand vacuum pump for testing?
For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
09-29-09 05:37 PM - Post#1780426    
    In response to Chevytech

Yes, I have a Mighty Vac. I just had no idea how much vacuum was required to open the valve. usually all I need are the test parameters and/or any go or no go information.

I really miss my GM Shop manual and Mitchell manuals. If I had them I wouldn't have to ask to many questions.
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
09-29-09 05:40 PM - Post#1780429    
    In response to someotherguy

Thank you, That should help me out.
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2964

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
09-30-09 07:23 AM - Post#1780711    
    In response to Chevytech


Do this test in the quote first and if it passes the test go on to the information below and determine which type of EGR it has and do the appropriate test.

  • Chevytech Said:
Here is a test you can do to see if the passages are plugged:
If you lift the EGR diaphragm with your fingers, with the engine idling, (being careful not to burn yourself or get your fingers caught in the EGR valve) you should hear a definite difference in the way it runs and the engine will most likely stall. If there is no difference you should look for plugged passages.






There are multiple types of EGR valves. To test it I need to know which kind of EGR it has.

TBI trucks are generally Negative pressure EGR or Port EGR systems, except California emission 4.3 TBI trucks had Linear EGR valves.

Negative pressure EGR valves - Should have an “N” after the last numbers on the valve. The pressure in the exhaust system effects (modulates) how much the valve opens.

Port EGR Valves – The EGR solenoid pulses like a mixture control solenoid/fuel injector to control vacuum supply. Port valves have no “P” or “N” and it is blank after the last numbers on the valve.

Both port EGR valves and Negative backpressure EGR valves should open if vacuum is applied to them with a hand vacuum pump with the engine not running.

Negative backpressure valves should hold vacuum with the engine off. When the engine is started the valve should bleed vacuum. The slightest pulse of pressure in the exhaust system will modulate recirculation (close the valve at least some). A good test for these is to put a hand vacuum pump on the EGR valve and apply vacuum with the engine off and it should hold vacuum. Leaving the vacuum on it, start the engine, and the valve should close.

On negative backpressure EGR systems the ECM powers the EGR solenoid when the engine might need EGR operation and it is the internal mechanism in the Negative backpressure EGR valve that modulates how much the EGR valve opens.


Here is a site with a good illustration of a negative backpressure EGR valve.
http://shbox.com/1/EGR_valve.jpg

This is a site that has a photo and an illustration about EGR vale numbers which should help you determine which type of valve your vehicle has.

http://shbox.com/1/EGR_ID.jpg

If you find it does need an EGR valve, I would suggest only using a general motors OEM (Original equipment manufacturer) replacement EGR valve.

I will be traveling over the next week, and will check this post on the road if I have the time.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
10-01-09 03:43 PM - Post#1781438    
    In response to Chevytech

Chevytech, it is a negative back pressure valve. It passed both the 20 second test with the engine off and a vacuum pump holding at 15. It also passed your test, all though this one has small round holes. I had to improvise and with the engine running, I used the vacuum pump and opened the valve and the engine shut off almost immediately.

I am starting to think maybe the ECU is at fault. I am thinking the quad driver in the ECU may be damaged. I don't have any manual to tell me how to perform a test to see if circuit 435 is open. What kind of leads me to believe this is the transmission shifts have also been a bit erratic. for example, you pull away from a stop light, you can feel the shift from 2nd to drive, then when you let off from acceleration and it slips into overdrive. once in overdrive it will act sluggish on acceleration until you depress the accelerator far enough to kick it down manually. I didn't feel any electronic shift back down to drive for the momentary need to maintain speed.

I may try a new/rebuilt ECU. they are about $83 at Autozone.

Let me know if you think there is something I may have missed or overlooked.

Thank you again,

Jay
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
10-01-09 05:56 PM - Post#1781502    
    In response to kartracer46

  • kartracer46 Said:
Chevytech, it is a negative back pressure valve. It passed both the 20 second test with the engine off and a vacuum pump holding at 15. It also passed your test, all though this one has small round holes. I had to improvise and with the engine running, I used the vacuum pump and opened the valve and the engine shut off almost immediately.

I am starting to think maybe the ECU is at fault. I am thinking the quad driver in the ECU may be damaged. I don't have any manual to tell me how to perform a test to see if circuit 435 is open. What kind of leads me to believe this is the transmission shifts have also been a bit erratic. for example, you pull away from a stop light, you can feel the shift from 2nd to drive, then when you let off from acceleration and it slips into overdrive. once in overdrive it will act sluggish on acceleration until you depress the accelerator far enough to kick it down manually. I didn't feel any electronic shift back down to drive for the momentary need to maintain speed.

I may try a new/rebuilt ECU. they are about $83 at Autozone.

Let me know if you think there is something I may have missed or overlooked.

Thank you again,

Jay



I also forgot to add that when I hook up the EGR valve and the EGR control solenoid complete I can drive about two or three blocks and the truck will run rough until I place it in park and allow it to idle. Once I do that it will clear up until I take off and it will start the process all over again. So I am driving with the port blocked at the throttle body till I can sort this all out. That was another reason that lead me to believe the quad-driver may be gone in the ECU.

I don't have a copy of the "ECM QDR check procedure" or I would attempt to trouble shoot it.
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


 
kartracer46 
Forum Newbie
Posts: 35
kartracer46
Loc: Norfolk, VA
Reg: 09-09-09
10-02-09 05:50 PM - Post#1782063    
    In response to kartracer46

chevytech,

here's an update:

ok, I replaced the ECU, coolant temp sensor and the TPS sensor today and my shift points are all good now, no more bogging down at low speed acceleration. It idles smoother, and it doesn't burn rich anymore. I guess 20 years will do that . I keep seeing the low mileage and forgetting that time and the elements play there toll on things. So now it runs good and no codes have come up since I replaced the above mentioned items.

however, I can still not run it with the EGR hooked up. So I am going to run the test on the EGR solenoid. I can't remember ever hearing it bleed off after I tested it the first time. And with all the other parts needing replaced, I figure it's a good place to start. A new one is less than $20 at NAPA. The EGR had been replaced prior to my ownership, and it just has the tag with the number written on it. It tested fine, so I know it is not the culprit. Once I sort it out I will let you know.

As always I really appreciated the nudge it the right direction.

Jay
Motorsport Junkie

My rides:
1989 GMC Suburban
1994 Chevrolet Suburban
1985 Chevy Suburban (Went to Bowtie Heaven)
2003 Nemesis Racing Kart


 
dlsweet 
Forum Newbie
Posts: 26

Reg: 10-05-10
10-24-10 09:02 PM - Post#1994492    
    In response to kartracer46

Jay, just read up on your posts and seems I have been experiencing the same problems on my 89 suburban 5.7. I have changed all electrical parts on top of the engine and throttle body and have also been thinking the ECU malfunctioning. My tranny is doing eratic things just exactly as yours has been explained. But why can't we hook up the EGR? When mine is hooked up I get the missing and stalling on low RPM takeoffs. Usually clears up after warmup and higher speeds. Let me know if you have got an answer by now.

 
someotherguy 
Moderator
Posts: 25478
someotherguy
Age: 44
Loc: Texas
Reg: 08-01-03
10-25-10 04:53 AM - Post#1994581    
    In response to dlsweet

Both of y'all look a little further up in this post, check out the EGR testing procedure that Chevytech describes.

I'll add that kartracer46's likely problem with the EGR is that it's a generic-type parts house unit. TBI engines do not like these. I suggest only using one from the dealer, or at the very least, a Delphi unit from the parts house.

The generic one-size-fits-many EGR's can be brand new, they can test fine, and they can still be the problem.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
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