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EGR Valve

ericcarney

ericcarney

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I am getting a 3-2 trouble code for a problem with my EGR Valve. It seems to be all hooked up right, but apparently its not. The issue is that I notice a difference in engine performance as soon as the Service Engine light comes on. Now I am wondering, is the light coming on because the engine isn't acting right, or is the engine not acting right because the service engine light is coming on? It doesn't seem like the EGR valve would cause a difference in engine performance, since its purpose is to reduce emissions.
 
Code 32 is either EGR circuit or MAP sensor circuit (open circuit). I would lay money on something wrong with the MAP sensor long before the EGR circuit. If the EGR valve is sticking it will make the engine run bad as then it is a vacuum leak when there shouldn't be.
 
What year and model do you have, does it have By-pass egr of or just regular egr. either way yes it makes a huge difference in performance. The EGR cools the combustion burn, there by reducing N0X. if EGR is open at the wrong time it cause hesitation, stalling, poor fuel economy (relative)
 
I took a look at his profile and it says he has an 88 blazer which uses a negative back pressure EGR.
 
I would first check the vacuum hose to the MAP sensor and make sure the hose isn't split somewhere and that it is free and clear and that it's hooked up to the proper location (rear center of TBI unit). Then i would make sure the electrical connector is clean and tightly attached.
 
Wow, those are the hard ones to diagnose. But, not impossible.
Attach a vacuum pump (hand held) run engine at idle. apply vacuum. should be no change at idle. use vacuum gauge to see if vacuum is present at idle and at 2000 rpm.
NBPegr should only open on hard acceleration above about 1500 rpm. then close again as vacuum rises to a near normal (cruise) level if that does not happen then yes EGR valve is the problem. but, do the easier stuff first. check for vacuum leaks, fuel pressure levels, timing all that first.
 
I have the instructions on how to test each part of the EGR system from All Data if you need it. Don't forget that there is an electric solenoid that controls the EGR function.
 
I am going to check all the easy problems tomorrow, and hopefully find a cracked vacuum hose or find one disconnected. But i am gonna have to see if somebody has a vacuum pump to test the other stuff. The MAP sensor is the one directly connected to the EGR valve, right?
 
ericcarney said:
I am going to check all the easy problems tomorrow, and hopefully find a cracked vacuum hose or find one disconnected. But i am gonna have to see if somebody has a vacuum pump to test the other stuff. The MAP sensor is the one directly connected to the EGR valve, right?
Click to expand...

No, the MAP sensor is mounted on a bracket to the passenger side of the TBI and has a vacuum hose that connects to the rear of the TBI and has a 3 wire connector on it as well.
 
4X4HIGH said:
I have the instructions on how to test each part of the EGR system from All Data if you need it. Don't forget that there is an electric solenoid that controls the EGR function.
Click to expand...

Yeah, that would help me out alot. I am trying to take a trip to the river this weekend in the K5 and I want it to be running well for the 2.5 hour trip
 
Not that yours is surely bad, but every year now for the last 3 years I've had to replace the NBPEGR valve on my 89 TBI 350. the damn things just like to die on my motor. I don't know why it just won't pass an NOX test until I do.
 
ericcarney said:
Yeah, that would help me out alot. I am trying to take a trip to the river this weekend in the K5 and I want it to be running well for the 2.5 hour trip
Click to expand...

(1) Check vacuum source to EGR solenoid (if not ok, repair)
Ignition "OFF"
Disconnect EGR solenoid vacuum harness (hose)
Install hand held vacuum pump on manifold side of solenoid.
Apply vacuum. (does the solenoid hold vacuum?)

If yes

(2) Ignition "ON" engine stopped.
Does vacuum drop?

If no

(3) Ground diagnostic test terminal.
Does vacuum drop?

If yes

(4) Remove ground from diagnostic test terminal
Ignition "OFF"
Connect a vacuum pump to EGR side of vacuum harness (EGR side of solenoid)
Using a mirror, observe EGR diaphram while applying vacuum
Diaphram should move freely and hold vacuum for at least 20 seconds.

If Ok

(5) Apply vacuum to EGR valve.
Start engine and immediately observe vacuum and valve position.
Valve is good if valve moves to seated position (valve closed) and vacuum dropped while starting engine.

If Ok

(6) A/T (auto trans) check P/N switch (park nuetral saftey switch)

If Ok no trouble found.

If any of this shows different than what i just described then let me know and i'll post the NO's and what to check for.
 
Did you ever find the root cause?
Why is the NBPegr supposed to return to closed position with vacuum applied and engine running?
I don't have a vacuum pump, but when I apply engine vacuum to the egr valve the engine really starts to struggle to idle.
 
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