New EGR valve and solenoid runs worse

[Cochise]

Tried to find something through searching but didn't have any luck.

Got the truck running like a top and all was good. Plugs looked perfect, no heating issues, idled fine etc..  I had the EGR blocked off and I thought I may have heard some pinging when I was in a strong head wind coming back from surf fishing (could have been a rattle, not sure), so I decide to fix up the EGR system and try the lower combustion temp theory.

 

I replaced the solenoid and valve, and had previously put in a new vacuum harness (which I had EGR lines plugged ). Hooked everything up and reset the ECU and took it for a run. It stumbled a little when I first backed out of the driveway and then it was fine. After it warmed up good it started to fall on it's face when I gave it throttle and started to idle really rough. I kept going thinking that the computer would correct itself but it didn't, so I plugged everything back up to be back where I started (no EGR). It still ran poorly and idled worse, so I reset the ECU again and all was good again.

 

The stalling and bad idle happened when I first hooked up the old EGR system after I got the truck, so I figured that part of it was bad and just plugged everything and moved on.

 

Now I put new EGR stuff and it acts the same way, maybe the old EGR stuff wasn't bad after all and it's something else,

 

Has anyone else experienced this?

[Marine1Texas]

I bet you blew a bunch of carbon in to your intake manifold. I capped my EGR off for good. All it did for me is blow carbon in to the intake. I used seafoam to clean up the carbon. another reason for stumble could be a bad vacuum line.

[Cochise]

When I removed the EGR valve there was  no carbon buildup in the intake, the valve must have been disconnected for alot of it's life. All vacuum lines are new and it runs fine with it disconnected.

 

The fact that it runs bad after I hook it up and then runs bad after I unhook it tells me it might be computer related, after I reset the ECU (with EGR disconnected)  it runs fine again.

 

Could it possibly be a sensor?, Did I not run it long enough for the computer to adjust?

[Ωhm]

Are the vacuum lines at the EGR solenoid connected correctly? YR? ENG?

[Marine1Texas]

The EGR valve should only open up at cruising speed, after engine is warm and vacuum is 35 psi or better. Never at idle should it be on. I think either your EGR valve is stuck open, or the electronic valve on the driver side fire wall is not functioning proper.

The ECU is hard coded to send single to electronic valve when all criteria's are met. 1st The temp from you temp sensor is at operation temp 195 and up, you RPMs over 1500, map vacuum saying vacuum is up at 35 psi or better, then it should get a signal to open. It should not open any other time.

 

I would first check to make sure the EGR is not stuck open, 2nd make sure your make sure the vacuum lines hooked right. the electric switch has 3 vacuum openings . The one by it self that faces front of engine is vacuum from manifold, and it should be hooked to the ported valve on the manifold. Then you have two valve on the other side of electric switch. the most rear one is a relief valve. the one closer to the vlave in the back goes to your egr.

 

If everything is hooked up right, and no stuck EGR I would suspect a bad electronic switch. Simple test when engine on at idle disconnect egr valve vacuum line. if rpm goes up, due to vacuum leak it is staying open and faulty or getting current it should not have there. 2nd same test but disconnect the wiring connector as well as EGR vacuum line if the rpms go up again you valve is 4 sure bad.

[Cochise]

All good advise, all was connected as it should be, the mystery to me is the fact that after I disconnect the EGR it continues to run bad until I reset the ECU.

 

Also a mystery is that it did the same exact thing when I originally hooked up the old system, this and the fact that there was no sign of carbon behind the EGR valve when it was removed.

 

This problem may have been there for a long time, hence the lack of carbon from being disconnected for so long.

 

Solenoid is new and valve is new but I will do some more checking per your advise, curious that at cruising speed it needs to see 35 inHg vacuum.

[Cochise]

Well, the Gods of Good have smiled on me (at least for now), decided to hook the EGR back up and took it for a test drive. All went well as I cruised a few long Texas back roads and let the ECU do it's learning thing, even at temp it was good. One difference between this time and last time, I didn't reset the ECU after hooking it back up, it was running good so I left it alone.

 

Maybe I didn't let it learn long enough or maybe it doesn't have anything to do with the computer at all, maybe it's not the God of Good but the Boss of Bad that's setting me up for another letdown, we'll see. (balls crossed just in case)

 

 

[Cochise]

All is well for now, runs really good, thanks for the advise.

[Cochise]

"advise" yah, and thanks for the advice too

[omega_rugal]

renix ECU "learn"? they don`t even store error codes...