A long time ago I replaced my Egr sensor and it's quite possible I got the wrong one. Back then I didn't know a lot about the truck, so there's no way to know.

I know there are two different ones, same signals but different gauge length.

Anyways, been throwing 33 for a while. EGR valve, solenoid and sensor are new (third new sensor) and it's also making me throw a lean code when EGR tries to open (light consistent throttle, low speed, 30mph and under usually). I've been chasing this one for a LONG time as I'm sure some of you know.

If anyone has info on where the gauge needle for the sensor should sit on the EGR valve I'd appreciate it. Is it pressed a tad in when bolted in? does it just touch the top of the valve or is there space between it?
and what readings should I get from the sensor with EGR closed completely?

just wanna rule out the sensor once and for all.. if I can test it at closed position, then see if it outputs correctly when I put vacuum on the valve. If not, I want ot be able to grind the tip to get it to read correctly.

at this point I'm also suspecting computer, but we'll see after I run these tests.

Thanks guys

 

I think I found my answers, so nevermind. If I have more questions I'll ask.. gonna go ahead and test to see if I find anything.

 

Well, reading 3600 resist at closed, 450 at open

.4v at closed, 4.5v at open

They're technically within range, but i dunno.

Also can't get it straight on whether 33 is stuck open or that it means it isn't opening. Different sources say it means different things depending on car/truck. Anyone have the straight and forward on this?

 

0.40 VDC is indeed the bottom end (fully closed) reading. At 3.90 VDC the valve should be fully open.

Code 33 - EGR valve did not open (Translation: The voltage going back to the ECM did not get above the minimum voltage return from the EVP sensor... which is 0.40 VDC).

 

grey, so people saying for trucks 33 means it didn't close, that's a load of bull? I trust you more than just about anyone on this subject

I wish I had a better understanding of the programming in this truck. I wish it were higher at closed and lower at open, however, the computer might take these variances into account and I just don't know it.

 

Ok, easy rule of thumb when dealing with EEC-IV. Just about every sensor is sent +5 VDC from the computer. The sensors then alter this voltage in some way and the voltage returning to the computer is then compared to the +5VDC (VREF) by the computer. Variances are then used to determine what changes to make.

And yes, Code 33 is triggered when the computer gets a reading at the bottom of the "acceptable range", in this case 0.40 is the voltage the computer "expects" to see when the valve is fully closed. If it does NOT see anything higher than 0.40 VDC it triggers Code 33.

Code 35 is triggered if the valve is stuck fully open

Code 32 is triggered if the voltage remains just above the fully closed voltage which typically indicates that the pintle has not fully seated in valve.

Code 31 is triggered if the voltage received is below 0.40 VDC.

Code 34 is triggered if the voltage received is above 3.90 VDC.

 

Yeah, I did a little reading about reference voltages the other day when learning about.. ugh, some sensor, i forget which one, but I went out of my way to check reference and make sure it was okay.. it's always 5v, so that's good at least.

So I wonder what would intermittently cause EGR to not open or not read as open? Since it's only sometimes, there's no real way to troubleshoot. It could be anything from low vacuum moments to computer to the solenoid, sensor or valve itself.

guess my next step is to put vacuum between EGR and solenoid and make sure that it isn't the solenoid that is failing while driving around over the course of a few days.

 

EGR is not always open. Operating temp, engine load, and a few other factors contribute to the trigger point for the valve to open. Its one of the reasons I always stress to folks troubleshooting EGR that they make absolutely certain that the vacuum supply to the EVP comes directly from the EVR solenoid and NOWHERE else.

 

that's why I'm wanting to run a split vacuum to the solenoid so I can watch it while cruising. when that check engine light comes on, I want to make sure that I was receiving vacuum.. if I am, I can rule out the solenoid and vacuum system, if not, then either vacuum drops to an unacceptable level, computer or the solenoid is shot.