back together and still pinging

[TedC]

I think you are down to two issues. EGR not opening properly and carbon buildup in the heads messing up combustion. If we focus in on the EGR, you validated that the EGR ports are open and that the ECM is sending the signals causing the EGR vacuum feed to work when driving off idle. You tested your EGR and confirmed it does not open properly at lower vacuum pressures. My new EGR (reference point) starts to open at 2-3 Hg-In, while your EGR reguired 10 Hg-In. If the EGR vacuum feed is only sending 3-10 Hg-In off idle, I'm not sure how your EGR can properly operate (this EGR is not an on/off switch but has variable openings based on load). When I installed my new EGR, I ran a few tests to see how much impact it actually made on pinging. Bottomline, my L98 will ping regardless of gasoline octane used if the EGR is not fully functional.

 

[bigblack]

TedC I cant thank you enough for all your help.I think I am going to order a egr and give it a try.As for the carbon build up I aslo think you are right,just not sure how to go about that.I figure after I install the new egr I will try running a few tanks of good gas and see if that will help.I think the guy I got it from ran crappy gas and drove like a 95 year old lady.I will let you know what happens after I get the new egr and get it put on.Thanks soooooo much again.

 

[Hib Halverson]

Have you checked to see if the EGR passages are obstructed?

 

[bigblack]

yes I had the egr off and cleanned it up real good and even blew air through it with vac.pump pumped up and it let air pass through it. I do have another question that maybe someone may want to help with or give there .2 When I ran the sea foam through the car I sucked it through a vac line on the tune port part.I only ran like 1/4 of the can because I was real nervous about all the smoke that was pooring out.My question is should I run more though it,and how much should I let go through the car?Or is it bad to run that stuff through a older car??I have heard sooo many stories.Just dont want to do damage..hnoes

 

[John Robinson]

EGR

You don not say what you used to clean the EGR up with but in my recent experience with my EGR I had it off and used carb cleaner and then Brake cleaner and thought I had it clean. I don't know if the 89 EGR is the same as my 93 but I took it off again and it still was carboned up so I got some easy off oven cleaner and soaked it in that and let it sit for awhile. The next step was to run hot water through it to rinse out the carbon and I could not believe the amount of junk that came out the egr and the pintle. I repeated this process until the water did not wash out any more junk and then I reinstalled the EGR using two gaskets with a piece of stainless steel screen from a frying pan grease shield. I put this between the two gaskets over my square EGR opening (again I do not have any idea if your EGR is like mine or not but you get the idea of what to do.