sylviaboy34

Hello all,
I'm getting ready to make a repair on my ol' 96 k1500 truck and well.. I'm not exactly what some would call "hands on." I mainly am looking for advice regarding the part I choose (I've narrowed it down to two parts but am open to any other suggestions!) and on the actual replacement job itself.

So the issue at hand is that my truck has a rough idle. When in park, the idle sits around 900-1100 rpm depending on the given day. When in drive, the idle can go as high as 2k. After researching the problem online, I think one of the more reasonable first steps is to test the EGR valve (planning on doing it this Sunday, weather and life permitting).

So I've been doing some looking around online and have narrowed it down to two brands: AC-Delco #2141080 and DELPHI #EG10026. The reason I'm asking for any advice in the parts is because I am choosing to buy the parts from an online retailer (helps a college undergrad save some money) and the description for the AC-Delco is.. well.. more extensive that the Delphi. For example, it mentions the blade type, the genders of the connector and fitting, etc (have I mentioned I'm really not hands on?). Both parts show an exact-fit so I'm sure either works, and I know that it could just be that the retailer hasn't included all of the characteristics of the DELPHI as they did the AC-Delco. I've already also noted that the AC-Delco doesn't come with the gasket whereas the DELPHI does. Basically, any recommendations to these two parts (or suggestions of another part) would be appreciated!

Last bit of business would be any advice in the actual repair itself. Seeing as I'm not sure if it is the EGR valve, my plan first was to test the EGR valve. I found this guide for testing the EGR valve (https://axleaddict.com/auto-repair/H...mple-Procedure), but any additional insight is appreciated and welcome! I also know that the task itself to replace the valve is straightforward enough (looked up a few videos).

Thanks again everyone!

Sabino56

I typically buy AC Delco but don't have any experience on whether Delphi is good/bad. I'd stay away from the really cheap brands - but even those may be made in same factory in China, so who knows.

As far as checking - if same as my 93 C1500, my memory is you can get your fingers on the diaphragm under the steel top cover where the vacuum line goes in. You should be able to move it up/down. That won't tell you if diaphragm is OK - just that it's not stuck. Rev'ing engine and dropping throttle like link said should create vacuum that you could try to see if diaphragm is moving but it's kinda a pain and not fun to have hands/head into engine bay while someone rev'ing engine. Easier & better - I have a little plastic hand vacuum pump, can't remember where I got it but was only about $20. Easy to put onto EGR and suck down - you can see if diaphragm moves with fingers and also see if it holds a vacuum.

sylviaboy34

So, been a bit busy so I haven't been able to post anything. Managed to successfully pull out the EGR valve from my truck and visually inspect it (have pictures and I may post them incase anyone doesn't know what it is and has a similar issue). The EGR valve didn't have any carbon build up that I saw, and the gasket itself seems to be in good condition. I flipped the valve over and tested the valve stem manually. The stem sprung back out a without any hesistation.

In regards to testing the valve, well, I found out something useful: the 96 was the first year that GM decided to switch from the vacuum EGR system to the electronic system. I probably should have realized that as soon as I opened the hood, but I digress. I went to the local auto part start and purchased a voltmeter. I found a reference for any who, like me, have little idea of what they are doing (https://easyautodiagnostics.com/gm/4...-valve-tests-1). So at some point, I'm going to go through the steps (albeit, some of the steps I have inadvertently completed by pulling out the EGR valve) to test each of the 5 lines and the solenoid itself.

Of course... provided I find the issue in the wiring, I'll still have to fix the wiring

sylviaboy34

Here are the pictures of my EGR valve. Side note: I decided to run a little experiment on the way to work today. I unplugged the EGR connector for my truck to see how it would idle on the way to work. Naturally, the RPM's were higher than normal and the check engine light remained. However, I noticed that the idle didn't improve.. if anything it got worse. So I'm thinking, and please correct me if I'm wrong, but I'm thinking that my EGR valve is stuck on open?

I'm planning on testing the 5 different circuits tonight.

sylviaboy34

So, I got the following measurements when I tested the individual circuits:
B - 11.9 V
C - .896 V
D - 5.0 V
E - 11.62 V

The resistance I got was 8.5 ohms. I neglected to do the test where I removed the EGR valve and tested the voltage with the pindle pressed mainly because all the other tests checked out.

So, not seeing an issue, I decided to make my way down to the local auto parts store and see what code the check engine light returned (probably shoulda started with that). When I got it tested, it returned the P1406 code - no DTC definition found. When I looked it up online, it points to a piece of carbon is blocking the pintle from seating properly. This also would support what I found by disconnecting the EGR electrical connector... seems like the EGR valve is stuck open. So it looks like I'll have to take my EGR valve off and try spraying it with some carb cleaner I suppose. Out of curiousity, though, would it be smart to replace the gasket when I clean the valve? Or should I just try cleaning it first, and if the problem continues, then just replace the valve altogether?

sylviaboy34

Decided I just wanted tp get this little project done today. Went to the auto part store and started with a new gasket. Went home from there and took out the valve. I noticed when I took off the old gasket that it was starting to really fall apart on the side that touches the valve. Took some carb cleaner and a wire wheel brush to it, then used a toothbrush to finish it off. Then I cleaned the actual hosing in a similar manner. Took the truck for a little drive around the nieghborhood and still had the same issue (the truck actually stalled, but it was colder than it has been in New England, and I hadn't let the truck warm up at all before driving it). Went back to the auto part store and bought a BWD valve for $150. Went back home, spent a little more time cleaning the housing itself inside the truck, put some never-seize on the bolts for the valve and threw it in the truck. I noticed that for the first few seconds (no more than 10) the truck still had a rough idle. After than, the RPM normalized and held steady. I took the truck for a ride through town (less than 15 minutes) and then let it idle in the driveway. No issues. The check engine light is still on (I may have to clear it).. but the plan is to take it for a longer drive tomorrow after work (I got a 12 hour shift ahead of me, so I may not post till the following day. I'm hopeful that the issue is solved though, and I can start working on my next job: brakes

sylviaboy34

For those wondering/following, the check engine light came on briefly after I took the truck for a ride, but since then it has come off and stayed off (to date). The truck still has a rough as hell idle though (well, rougher than I would like), especially when it's cold... so I'm thinking it's a vacuum leak. I'll have to address it afterwards.. cause the clamp for my radiator hose is leaking and that is taking priority.. ... anyway. I'm going to consider this case closed as the engine light is off and the idle has improved.