Delphi EG10099 Exhaust Gas Recirculation (EGR) Valve

Works great on my 95 tahoe. Fixed problem.

I have a 1992 K2500 with a 305. I was getting a 32 code for a bad EGR and I tested the diaphragm on the EGR valve. It would not hold a vacuum, so it was bad. The one coming off of the vehicle was PN 17087194. It also has "N" stamped on it. According to my research, this means that it is a negative pressure valve. A positive pressure valve won't work where a negative pressure valve is required. Here's some info from an internet article: "When vacuum is applied to the negative backpressure EGR valve, it opens. Once the pintle is lifted it is affected by the negative pressure of the intake manifold. This negative pressure travels up the pintle shaft and begins to pull down on the lower diaphragm. When the negative pressure overcomes the tension of the lower spring, the lower diaphragm moves downward. This opens the center hole creating a path to the hole which is open to the atmosphere. This results in a break of the vacuum seal. Since there is no longer a sealed chamber, the upper diaphragm falls. This causes the pintle to lower on its seat, thus shutting off EGR flow." This is what the internet says about positive pressure valves: "A positive-backpressure EGR valve can be identified by the letter “P” stamped next to the part number and date code. Positive-backpressure EGR valves are used in simple vacuum-controlled systems, as well as more complex pulse-width-modulated applications. A positive-backpressure EGR valve’s hollow pintle shaft is much thicker than that of the single-diaphragm type. The hollow design allows exhaust gases to flow into the shaft and push up on it. When positive backpressure in the exhaust system is sufficient, the shaft raises and seals the built-in control valve. Once the control valve is closed, it allows applied vacuum to pull up on the diaphragm. Without backpressure to lift the hollow shaft and close the control valve opening, vacuum is bled off to the atmosphere. "So, there is a difference between a negative and positive valve. Many reviews state the one they got was a positive pressure valve and it would not work, causing the engine to sputter and die. The Delphi catalog says this is a negative pressure valve, which is correct for my application. At first, I thought it was OK, but now I have a habitual hesitation at starting off from a stop which I didn't have before and which I don't have if I block the vacuum line going to the diaphragm. Trouble is, I get the check engine light if I plug the vacuum line.Once in a while, I get the sputtering that others talk about, but always have the hesitation at least. I think it is just not the right part. Wrong spring, positive or negative, I can't say, but it has created a hesitation that was not there before. It did cause the check engine light to not come on after 7 or so miles at highway speed, but it creates what I consider to be a safety hazard by causing a stumble when pulling out into traffic. I've checked the controlling solenoid to make sure it works properly, and it does. There is simply something wrong with this valve in this application.Edit: I've been fooling around with this thing for a while now. I've even contacted Delphi regarding the sputtering issue and of course they didn't respond. So zero stars Delphi if you're listening. I do think, however, I may have tripped over a solution. I went to the junkyard to pick up an oem version of the valve. I got one that I thought was okay because I couldn't suck much through the vacuum port. Turns out the reason I couldn't was that the thing was corroded so badly that rusted plugged it. So I cut it apart. The diaphragm is fine; it is the pot metal that they riveted to the moving assembly that's the problem. And for some reason these things must just load up with water. I have no idea why, but the one from the junkyard was just crusty with all sorts of rust. Mine was not that bad. In any event, I cleaned the control solenoid and determined that it is working properly. I started to wonder if the restriction in the vacuum port on the EGR valve could have been used to slow the accumulation of vacuum to the valve while under light acceleration. So I cut the vacuum port with restrictor off of the junkyard one and put it in line with the vacuum line running from the solenoid to the EGR valve. This solved 80 to 90% of the hesitation issue. There is a slight hesitation under light load from a start. If you're driving on a 20 mile an hour road, you can feel it. Starting up from a traffic signal and getting up to 30 or 40 miles an hour in traffic, you don't feel the same hesitation. I got the car well used, so I don't know what it was like when it was new, but it could have had this issue from the factory. Without the EGR hooked up it's a nice linear acceleration at any speed. With EGR hooked up with the in-line restriction, there is the slight hesitation described. Also, and looking at the junkyard EGR that I cut open it seems to me that the rivets are the weak point that allow the vacuum leak. I'm going to try siliconing up the underside of the rivets on my old valve and see if it'll hold vacuum and compare it to this Delphi and see if the hesitation is the same. I'm including some pictures of the junkyard rusty EGR valve innards so you can get an idea of its construction. It's not the diaphragm that goes; it's that crappy pot metal. I never would have thought the restriction would have made a difference, but the guy who noted that in his review appears to have been on the mark.

This valve is definitely a better option compared to the aftermarket egr parts stores are selling. If the egr valve is actually the cause of a problem affecting quality of idles or causing spark knock or failed emissions. This part will address those problems. There's a few reviews stating the valve is junk but I'm not sure the people who wrote those reviews are professional mechanics with 20 yrs of experience. And actually now how to properly diagnose drivability issues with fuel injection or emissions related repairs on any vehicle.

The product is good and working fine.

This is a nicely built valve, but further research shows this to be a "positive pressure" type, not suitable for most 87-95 GM TBI trucks, which came with "negative pressure" type valves. Cars often used a positive type. Prior to discovering this, truck ran worse after installing Delphi and had me puzzled. I plugged off EGR vacuum hose and it ran great again, hence the research as to why. Although Delphi catalog shows this # to be correct, ACDelco shows two different types for my 1988 Suburban, so I returned Delphi and ordered correct AC.

Worked great on my 95 C1500 5.7tbi. Just make sure you match your Vin to the correct part.

Valve was either damaged when it arrived or wasn't made correctly. The plunger would stick at first, thought it was ok after moving by hand several times. Installed it and l thought it was fine. Noticed vehicle would run poorly after longer trips. I finally replaced it with the original one and all problems were solved. I think it was sticking open and causing vacuum leak. The body on the part seems flimsy compared to the old one. Was just doing some preventative maintenance and caused a problem 🙄.

The EGR valve corrected the check engine light on my truck. Before the original EGR valve failed, my truck had a hesitation under light throttle for years. Since I replace the original with this valve the check engine light and the hesitation are both gone.