EGR question.

[Fett]

I don't have a CEL but I have an odd idle stumble at startup so I decided to pull my codes to see if I had any stored. Sure enough I had a code for an EGR hard fault. When the EEC4 tester was hooked up and I started the car, you could hear the EGR open(close?) because the tester was...well, testing it. When you heard it open(close?) the engine would jump to perfect idle for a few seconds, then the EGR would fall off and the idle would surge again. I am pretty sure the surge isn't due to an electrical issue, I upgraded all my grounds, and if it stumbles at startup, all I have to do is stomp on the gas real quick and the stumble goes away.

So I am thinking that the EGR is the reason for the stumble. Now, I could replace the EGR valve and sensor, but quite frankly I don't want to. I am thinking of just dumping it all together...but only if it would fix that issue. If removing the EGR itself wouldn't fix the idle...then I will just leave it as it is.

I have searched but I only find info debating the benefits of removing the EGR. I am NOT trying to "gain" anything by removing it. I would just like to "fix" an issue without spending good money on something that most people remove anyway.

Car: 88 Coupe 5.0 WC-T5. E-cam, gasketmatched/ported stock heads, stock bottom end, Edlebrock Performer intake, 24lb injectors/MAFS, 190lph fuel pump, smog pump deleted, 93 octane, 15* timing advance.

 

[myslo50]

i took the vacume line aff and pluged it off, left the connector pluged in. id check the iac, tps voltage, and adjust idle skrew. there is a thread about the surging idle checklist. get the egr delete kit off ebay for 25.00 and delete egr all together.

i had the same problem after i wired in my mass air. i replaced my iac and adjusted my tps. and now it runs like a raped ape.

 

[jrichker]

What was the code? There are five different ones (31,32,33,34,& 35) and they all have different causes & fixes. Post the code(s) and I will post the tests & fixes.

 

[Fett]

I had code 34.

 

[jrichker]

Code 34 Or 334 - EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1 ohm.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied. The EGR valve or sensor may cause the voltage to be above closed limits due to the manufacturing tolerances that cause the EGR sensor to rest at a higher position than it should.

This will affect idle quality by diluting the intake air charge

 

[93GTosu]

how about code 33?

 

[Fett]

Thanks jrichker, awesome info. I am going to follow that tomorrow and see where I am.

If I were to just remove it, with an eliminator, would that have any negative/postive effects on the car as it is now?

 

[Fett]

Sorry for bumping my one thread, but I didn't want to start a new one.

Which way would be better, fixing the EGR, or simply deleting it with one of those resistor "EGR delete" kits from eBay?

I was having a detonation problem at the track, which may have been due to a lot of other things....but I suppose a faulty EGR could also feed into that problem. I wasn't sure if fixing it or deleting it would be the better way to go.

The only reason I am thinking of deleting it is because of the cost to fix it. I would rather just delete it and save the money for something else....IF deleting it won't cause any issues.