Yet another dreaded 401 thread....(few diag questions)

[superjuice]

I just finished replacing my VSV without taking off the the intake. It took about 2 hours from start to finish but no doubt easier than removing the intake and replacing the seals. Although a bit frustrating, with some patience its a simple task. Just hoping i finally rid myself of the god forsaken p0401 code. Actually its the first time i ever m*o&^ther(*%ed mr. T for putting something so out of reach. I just kept telling myself and my knuckels its worth it to drive a cruiser and no doubt it is...

 

[NorCalDoug]

subscribing...need to read up on the P0401 sagas...

 

[The Moe]

Great info. Well, I have joined the 401 club a couple of months ago with my 97 '80. I cleared the code 2 times so far and it managed to come back a couple of hundred miles after each time.

A dumb question: Is there a sure or an overkill fix to this problem without disableing or replacing the entire system's hardware? Anything that involve cleaning with minimal parts replacing ?

 

[98 SNAKE EATER]

Great info. Well, I have joined the 401 club a couple of months ago with my 97 '80. I cleared the code 2 times so far and it managed to come back a couple of hundred miles after each time.

A dumb question: Is there a sure or an overkill fix to this problem without disableing or replacing the entire system's hardware? Anything that involve cleaning with minimal parts replacing ?

An "overkill fix" would be replacing the entire system's hardware

Just follow the FSM's guideline for testing each part related to the EGR system and repair or replace only what is needed

I haven't had an MIL since I replaced the faulty modulator almost 2 years ago

 

[THEJOCKER]

Question?

Hi Guys,

I just trying to determinate what's the problem with my 94 TLC, I just put out the intake to have better access to my vsv. I followed the instructions to test it, but when I tried the first one (blow air from G to E according to FSM) the air doesn't come out.

The other steps, put voltage 12V to the terminals, the vsv make a tic sound and the air doesn't come out.

My question is definitely I need replaced it? or I have another step to test it?

Thank you

 

[george_tlc]

Make sure you blow from G to E as per the FSM - the inside of the VSV has a bunch of seals and flaps and stuff. I'm not sure if air can be blown from either direction.

Here's the guts of my dead VSV (the coil was open circuit):

cheers,
george.

 

[THEJOCKER]

Thanks George,

I tried both sides but nothing.. I just trying to check it because I have a low idle frequently, the engine sound is like wants shut off...actually when I checked the intake had a lot carbon on the egr valve section and inside the intake, I don't know if the vsv can be produced this issue, i'll appreciate your help.

Thank you

 

[jatree]

I wish I had seen this thread before making one of almost the same title lol. Anyway, I see the same EGR tests in multiple threads but want to confirm that I did the test right AND next step if it fails

With truck idling
- Disconnected vac hose from Modulator output (Q), and connected vacuum pump
- Pulled vacuum -> no effect on idle

So, should I be doing it from the DS of the EGR Valve? Or as above but with the DS pinched?

If none of these cause the engine to stumble, is the valve definitely bad or could it be dirty? Or could the same condition be caused by dirty passages?

TIA