First off Hi everybody! I`m new to the forum In fact this is my first post. I know this has come up on the forum somewhere but I had no luck searching. any way i have a 85 (C4) that does not want to idle when it`s warmed up. I put new plugs in,new cap rotor,new idle air control,Cleaned the MAP sensor...
I`m thinking that the problem may be with the EGR. Okay now here we go... A well known Local Vett Guru tells me to just block it off with a plate. Then I see on you-tube this guy says you have to have a new chip burnt or it will run to hot. So I`m thinking alright I`m just going to replace it.Then I here no all the EGR valves they say will fit WONT! I was told that they don`t make one that will replace it anymore. Is this true? Has anyone went through this and have an issue?
Given a choice I would like to just eliminate it and clean up the engine compartment. So any advise from someone who`s " been there" would be greatly appreciated.

 

Hello and welcome, I am also fairly new to this forum but have found it helpful as well. What does it do when its warmed up? does the idle fluctuate or will it just not run? I have put new heads on my 84 vette that do not have egr ports on there. I still have the Egr in tho (haven't bothered getting a block off plate).

"I see on you-tube this guy says you have to have a new chip burnt or it will run to hot"
like I said I have new heads that don't have egr ports and mine doesn't run hot, do have a new all aluminum radiator and 180 thermostat. The only reason that I know of that you would need to get it prom "burnt" is to keep the check engine light on after its removed.

As for the new one not fitting properly, I'm not sure but I would think it should fit. Could always go to your local parts store and buy one, if it doesn't fit or look the same you can return it.

Like I said you can buy a block off plate and get the prom reprogramed to work properly without the egr but I haven't been able to find many reputable website to get one reprogrammed.

 

Welcome to the forum!

Does your car idle well when cold and get progressively worse as the car warms?

If so you want to check the coolant sensor. If the coolant sensor is off, it will tell the computer that it is still cold when it is actually warm causing it to run rich and idle poorly.

 

let us know a little more about how it runs when warm

 

Are you getting any check engine lights and have you done a minimum idle adjust. I noticed with a up and down idle that my tps sensor was bad. Try a minimum idle adjust it is the first step.
The chip isnt a fix, and blocking off egr also.
http://www.digitalcorvettes.com/foru...ad.php?t=58873

 

You need a chip so you don't get the Code 32

 

That procedure works ONLY if there are no issues with anything and everything is in perfect order. Kinda why I don't use it. I prefer to set it with IAC counts which helps me to check if there is an air leak.

 

If he is deleting egr then yes I suppose a chip deleting will do the trick, I thought he was not sure about deleting egr.

 

Hell did say that he wanted to delete if possible

 

He said he thought the problem was with the egr, I was just suggesting keep it until a code is thrown.
It doesnt really hinder performance. If there are no codes, mabey clean all the connectors for starters.
Good luck

 

not sure i'm understanding the whole problem, but taking advice from the local vette guru, especially when they talk about deleting emissions hardware, modifying this and modifying that, IMO, is not the answer. an idle issue, when warm, could relate to something closed loop. i'd start there. not sure i'm getting the full picture concerning codes (if any), but i'd look into the O2 sensor. another thing, the OP indicated a new IAC valve, but did he give the throttle body a thorough cleaning? I don't understand why folks when they have some problem, the first thing they want to do is remove the EGR valve or anything related to that "evil" emissions system. let's not fix it, lets just rip it out! (just my 2-cents)

 

Not getting any codes and it idles fine when cold. Changing the plugs and cap made a big difference as I had a heck of a miss. Just to throw a little more information out there...
I just got the car a bit over a month ago. I think that is has been sitting for awhile. It does have over 150,000 miles.
The first thing I did was to clean the throttle body and put in a new idle air control valve so no I`m not one of these guy`s who would rather rip it out or block it off. I`ll do what I need to do to get things right I just want to find out what`s what.
I have no problem buying a new EGR But before I tear the car down and have everything in pieces I need to know if the new one is going to work. This "Guru" I`m talking about has been Building and repairing Corvettes for over 30 years so when he say`s something like " hey be careful..... " I listen.
Thanks much for all the advise people and please Keep it coming! I will for sure let you know when (or if) I get to the bottom of all this.
I have the day off today so maybe I`ll go out and do some more snooping around. Maybe check some grounds,wires,vacuum lines...

 

With the Idle Air Control valve, did you replace the gaskets when you took the TB and IAC housing off for cleaning up the passages?

 

Thanks Much! I will check that.

 

That is interesting that he said EGRs are not a one size fits all. I would also recommend taking it to a shop that can plug a scanner into it. It might not be throwing any codes but you can data stream and see if all the sensors are working properly being having it pull them out and replace. I had a problem last year with my truck, o2 sensor went bad but it didn't throw a code, ran like crap when it did run, destroyed cats. Only figured out it was o2 after looking at all the sensors with scanner.

 

You'd need a scanner to see what the ECM sees as a temperature and an infra red gun to see what the sensor temp actually is

 

Isnt the temp sensor used for the digital display read out?

 

Hello there,
I am going to put my 2 cents in here.

The EGR is not a bad thing to have on your car. When mine failed it made a huge mess because I did not know it at the time. I was at the emissions station and then I learned my NOX was so high that my car could not get approval.
I came home and tore into it. My EGR was replaced after much work to the entire intake manifold system. In the process of fixing my car I ended up rebuilding my fuel pressure regulator and finally found the reason my EGR failed in the first place. The little solenoid that attaches at the thermostat housing had failed. The Vacuum lines were very brittle as well. So after installing a new throttle body, EGR, the EGR Solenoid and the Cold Start Valve I had learned a lot. I also changed all the old vacuum hoses and now even my Cruise Control works great.

I live in Northern Virginia and a car's emissions have to be tested every two years until the car is 25 years old. My car does not need to be tested but I still go through the process anyway. I like to know if my emissions systems are working, I want them to work properly. For $18 I get a pretty good checkup on my car and its engine's emissions system.

There are a lot of people that like removing things they consider detrimental to all-out performance. I am not one of them. I will keep my car running with the systems it was designed with. My emissions are now within the bounds of the laws here and my car runs strong and CLEAN.

I wish you the very best in getting your Corvette fixed right.

 

1985's EGR is a little different from the rest of the L98s, so that must be kept in mind when buying parts and troubleshooting it. Solenoid control is different, the valve mounting is buried under the plenum with the temp switch as well, if memory serves.

Reading the data with a scanner is also a little different than the years that followed, since it has a simpler ECM, but this should be done.

Idling poorly when warm points me towards a closed loop sensor having a problem. O2 or MAF would get my attention, and vacuum leaks. EGR does not function at idle speed, or its not supposed to.

 

This info might be helpful (especially in regard to the "special" nature of Corvette EGR valves):

http://www.tomco-inc.com/Tech_Tips/ttt26.pdf