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Old 06-11-2009, 03:13 PM   #1
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Default Reroute EGR delete weirdness. Explanations?

So last week I installed my BEGI coolant reroute. On my 94 I had to delete the EGR pipe across the back of the motor. I blocked off the fitting on the mani and screwed a plate over the fitting at the inlet below the EGR valve. That was the only change.

Immediately my VE's were pig rich. I had to drop nearly the entire table by 10%. Another change was overboosting. All of a sudden I'm running into over boost protection. I fiddled in MS with boost control but couldn't seem to get the boost scaled back.

Earlier this week I go in and remove the EGR valve, all the related plumbing and the charcoal canister. Opened up a lot of space. (Holy crap there are some razor sharp edges around the egr valve!) I fabbed another plate and blocked off the EGR valve spot. Now I'm lean and had to add that 10% back in!

WTF? Any ideas what or why the dramatic VE changes would be related to my EGR system? Any idea of what path to follow to diagnose this? Still overboosting too. I don't know if the overboost has anything to do with the VE changes. Could be a completely separate issue. Haven't disconected EBC yet to try spring only. Have to try that.

Any thoughts on either issue?

94 1.8. BEGI s4 system. MSPNP.
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Old 06-11-2009, 03:20 PM   #2
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Hmmm...Subscribed. Curious as I have just deleted the EGR tube on my 99 and wondered if it could be a cause for some of my tuning problems.
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Old 06-11-2009, 03:33 PM   #3
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From Rich to lean w/ only real difference being Charcoal canister between both EGR delete setups? I'll be following this as I have just deleted my cc. I have had the EGR tube deleted way back when while waiting for correct header to show up, but neither at the same time.
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Old 06-11-2009, 03:49 PM   #4
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First: It went rich when I removed the pipe and just blocked off both ends. All the EGR valve stuff was still intact. Wiring, vacuum hoses, solenoid, etc. (by going rich I figured it was running more efficiently somehow, therefore needing less fuel)

Second: When I removed the rest of the EGR system, fuel needs went back to where it was before removing the pipe.

My VE table has always seemed richer than most around here. I figured pulling 10% out was a good thing. Strange. I'd really like to know why it went up and back down. I'm guessing the charcoal canister is unrelated. It just happened to come out at the same time as the EGR valve itself and all the related wiring and plumbing. Vacuum leak before or after? Faulty EGR? Plugged EGR passages? I'd really like to get the VE table back down like it was briefly.
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Old 06-11-2009, 04:19 PM   #5
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Oh I see what you meant.....do you get idle surge too?
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Old 06-11-2009, 04:57 PM   #6
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Quote:
Originally Posted by Machismo View Post
Oh I see what you meant.....do you get idle surge too?
Mine is surges a bunch with the tube delete when cold. Not bad hot.
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Old 06-11-2009, 05:30 PM   #7
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I used have a really eradic idle surge, but replaced EGR. This doesn't help us then, because tube and CC were untouched. I do notice mine doesn't seem to idle as pig rich at idle with canister removed, but will have a slight lope when stopped at a light after sitting for a bit, and then it settles out.
I then would maybe think leaks, but at different locations but somewhat related. I seriously have been trying to source mine since I've owned the car for 4 years. I'm so used to it, I have just accepted it. But recent CC delete brought on the lope at idle while sitting after warm. IDK?
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Old 06-11-2009, 06:05 PM   #8
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I've dumbed down my idle. Disconnected the IAC. Mines pretty stable unless I'm using the AC.

Idle didn't move up or down significantly when I pulled the egr line, just the AFR's. The entire VE table was suddenly too rich. Pulled the EGR valve and related plumbing and everything was too lean.

Any big brains out there have a clue what could cause this?
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Old 06-13-2009, 01:25 PM   #9
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Overboosting turned out to be an easy explanation. In moving all the lines around doing the coolant reroute the vacuum line supplying the turbo actuator became porous. Heat from the mani had turned the rubber crunchy. The actuator wasn't seeing boost. Duh.

Still hoping for some insight on the other issues surrounding the EGR valve and significant changes in fuel requirements!
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Old 06-13-2009, 01:54 PM   #10
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Cueball, assuming your EGR system was functioning properly. If the EGR is disabled, the fuel mixtures will run leaner and require enrichment.

The EGR system introduces the spent, inert exhaust gas back into the intake manifold to "take up space in the combustion chamber". This reduces NOx (oxides of nitrogen) by decreasing peak combustion temperatures.
If you remove the EGR system from a vehicle, now the engine is taking in 100% air instead of the mix of air and spent exhaust gas. Since we have now have more air in the system, the engine will run leaner and require enrichment. Now, all of this happens at cruise speeds only. The EGR system is not operating at idle, WOT, or anytime the vehicle is not moving.


There was something else affecting your system to cause the opposite reaction.
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