jtarp

is it safe to run my car with the egr deleted and without a tune or do i have to get it tuned also?

Injuneer

No problem. You will get one or two codes/SES light - definitely one for the missing vacuum solenoid (put a resistor in the harness connector) and possibly one for no EGR flow (the OBD-I diagnostic is not very sensitive and usually does not detect the missing flow). The "tune" would eliminate the codes.

jtarp

thanks man. i really appreciate your help.

Severous01

why you want to delete it? it doesnt really give you HP. EGR actually helps keep the burn temps down. you're taking a chance at hot spots on the piston by deleting.

any reason? got new headers or got a cracked pipe? maybe the solenoid is extremely expensive and it went out????

jtarp

The solenoid went out so i figured i'd go ahead and delete it. Plus i've seen so many other people delete it without problems so i figure why not.

SlowMoComotion

Hello,

First I would like to apologize for bringing back an old post but it is directly related to what information I am after.

I have a 1994 trans am and just deleted the egr and AIR. The problem is I am getting a ses light. I scanned for the code and it is the solenoid. I simply unplugged the connector and did not put in a resistor. Injuneer mentioned tuning or putting in a resistor. I do not know how to do either and ask any one here to point me in the right direction. I would rather go with the resistor route due to the fact it sounds much easier. What kind of resistor do i need and where do you get one the plugs into that type of connector? Thanks for your time.

NJ-LE

SlowMoComotion:
To satisfy the PCM I believe I used a 200 ohm resistor. Just fold the ends (to make them thicker for a better grip) and push them into the female connectors in the plug. Be aware that the PCM does add up to 5 degrees of advance to the base timing when it activates EGR. This is to compensensate for the diluted cylinder charge. In TunerCATS the values can be found in a table called "EGR Spark Correction vs Vacuum vs RPM"

MTL_Z28

So I just got a new mail order tune from Bryan @ PCMforless, and he forgot to tune out the EGR. I do have the EGR block off plate to cap the port at the back of the intake manifold though so he said it is not a problem and I should not worry about it.

However I have logged a few runs with Datamaster and notice in the logs that the EGR duty cycle activtes somtimes... Are you saying that in these instances the PCM adds timing? If so then I should probably tune it out right??

SlowMoComotion

Thanks for the quick reply. So even if I put in the resistor I still have to tune it out due to the spark advance?

well i bought tunercat a while back ... time to start learning it.

NJ-LE

If the PCM believes it has powered up the EGR solenoid, it will apply whatever advance it thinks is needed. The resistor will complete the circuit and present a load similar to the solenoid valve's coil. The PCM will think it has opened the EGR valve, no SES light or code will be generated for EGR
The advance table could be 'zeroed out' so any correction would be zero or the 'EGR Enable' RPMs and/or Temps could be set higher than your operating maximums. RPM constant max set appears to be 6375 and Temp max set appears to be 151°C.
If you only pull the plug the circuit will not be complete, EGR open won't be successful, SES will light (only during the time the PCM thinks it should be enabling EGR) and a code will be stored but no advance correction should be applied.
When cruising the interstate with only the EGR blocked or solenoid resistor applied, the PCM applying the stock correction table conditions will probably trigger the knock sensor circuit at times (hills, etc) and actually retard enough timing to cause poor highway fuel mileage.
----------------------------- stock 1995 PCM values --------------------

EGR Spark Advance Correction Vs Vacuum Vs RPM

RPM Vacuum
70 65 60 55 50 45 40 35 30 25 20 15 10 5 0
800 0.0 0.0 5.0 5.0 5.0 4.0 4.0 3.0 2.0 1.0 0.0 0.0 0.0 0.0 0.0
1200 0.0 0.0 5.0 5.0 5.0 4.0 4.0 3.0 2.0 1.0 0.0 0.0 0.0 0.0 0.0
1600 0.0 0.0 5.0 5.0 5.0 4.0 4.0 3.0 2.0 1.0 0.0 0.0 0.0 0.0 0.0
2000 0.0 0.0 5.0 5.0 5.0 4.0 4.0 3.0 2.0 1.0 0.0 0.0 0.0 0.0 0.0
-------------------------------------------------------------------------
There are EGR related items in the ECM Constants:

EGR Enable, Min. MAP 36.2 Kpa
EGR Enable, Min RPM 900 RPM
EGR Enable, Max RPM 2100 RPM
EGR Enable Cool. Temp (Hi Startup MAT) 50 Deg. C
EGR Enable Cool. Temp (Low Startup MAT) 82.25 Deg. C
-------------------------------------------------------------------------

cthomson21

I noticed that you are from Nashville. I don't know if they test for NOX there (they don't in sumner county anyway), but that could be a problem also for emissions testing. It will give you a higher CH and NOX value at idle with the delete. Just a point to bring to your attention if that is a concern.

MTL_Z28

Would it be hard to edit these with TunerCATS? I just got my unlocked version not too long ago and was looking through it myself to see how to do it but couldn't figure it out.

So basically I would just set EGR enable min. RPM to 6350 and max. RPM to 6400 for example.

NJ-LE

MTL_Z28:
From "Tables" goto "ECM constant table". The EGR rpm enable values are the 24th and 25th items. Use the arrows or slider on their lines or enter new numbers in the box to change the values. I think just setting the "EGR enable, max rpm" to zero also will prevent the PCM from ever turning it on. Remember the EGR system is to help protect against light load, low rpm cruise detonation. When the PCM is programmed to NOT let the EGR system work, the protection isn't there anymore. Since you've got 4.10 gearing you won't have as much exposure as someone with stock rear ratios. When the EGR is mechanically disabled (block plate) but the PCM still thinks it's opened the valve, the extra EGR advance the PCM will add makes the situation worse. "Happy Motoring!"

MTL_Z28

Thanks NJ-LE

shoebox

Why would that be, since it does not operate at idle?