I have a slight hesitation when taking off, I ran the codes in the computer and got a #33, EGR valve not opening(something like that). Truck idles fine and runs smooth. There was also the same code in the memory of the computer.

How do I fix this or where do I start to correct the problem?

 

here's what i did to check my egr. find a vacuum hose that has a strong vacuum at idle (my engine has a capped off port at the top of the manifold that i used). Hook up a vacuum hose to it at coonect the other end to the egr. when i did this the engine all of the sudden started running real rough, almost like it wanted to die. That told me the egr was opening. The next step is to go to this website



I got this from steve83. It's a chilton's manual online. This will have the instructions for testing the egr sensor itself.

Hope any of that helps.

 

You probably won't need to check the sensor. If the engine bogs, like he says, the valve is good, and the passage is good. It is possibly control solenoid, vacuum lines, or sensor. Usually if the sensor goes bad, it shows to be open all the time, not closed. The other common problem on these is the egr passage being plugged. If it doesn't bog, it could be the valve, or the passage. You can see the diaphram inside the valve. When you apply vacuum, if the diaphram moves, the valve is ok, it is the passage. If it doesn't move, the valve needs replaced, and with it off, it's a good idea to go ahead and clean the passages out with carb cleaner and compressed air. Watch out for your eyes!

 

Trust a parts man to suggest throwing money at it!

I can e-mail you a document that will explain how the EGR system works and how to test it using a vacuum pump (it's the MityVac manual). If you want it, send me a real e-mail that I can reply to with ~1.8M of data.

You should always start your diagnosis by making sure there's nothing OBVIOUSLY wrong, like a vacuum leak, an unplugged connector, a broken wire, or a broken/burnt/melted component. Then make sure you understand what the code is telling you - that particular code doesn't say ANYTHING needs to be replaced; only that the computer can't see the valve moving. There are 2 things to notice about THAT:

1) The computer doesn't actually detect the valve - it detects the EVP (Exhaust Valve Position) sensor on top of the valve, and the EVR (Exhaust Valve Regulator) solenoid valve that controls the vacuum signal to the EGR. It uses wires & connectors; all of which have to be in good condition, so you have to diagnose it electrically. The Haynes manual tells how to test the EVP & EVR.
2) The EGR is vacuum-operated, so it that's another system to diagnose. Make sure: there's a strong vacuum available to the EVR, the EVR is opening & venting, there's a good line from it to the EGR, & the EGR diaphragm is airtight. The EVR looks different from the TAB & TAD solenoid valves because it IS different. The Haynes & MityVac manuals describe how it works and what results you should get when applying vacuum to its ports.

By the time you've checked all that, you should have found the problem because the computer saw the problem and that's all the computer can see. On older EFIs (before ~'95), the computer couldn't tell if the movement of the EVP actually resulted in any exhaust flowing into the intake, so even if the passages were filled with JB Weld (or a blockoff plate), the computer would NOT throw a code. (That's why OBD-II vehicles use a different EGR control system: PFE.)

 

Thanks steve83,
I'll check it out this weekend, I read the Haynes manual at a store and I read the same thing you just told me for a code#33.
To check the EVR and the EGR, I'll let you know how it goes, Thanks again!

 

Hi steve83,
In order to check the EVR you told me to make sure there's a strong vacuum available to the EVR.
How do I check that?

Do I pull the hose off, the one that is going into the EVR, while the engine is running and feel to see if there is a good vacuum?

Also the hose going from the EVR to the EGR, How do I check that there is vacuum going that way?

I checked all the wires and hoses and they all seemed to be in good shape..

Here's my e-mail so you can send me that info on how the EGR system works: ivansilva(No Email Addresses In Posts!)

Thanks again!

 

Use a vacuum gauge to test for vacuum and leaks.

I've sent that document, but I don't know if a hotmail account will accept that much data.