Ok, I after 1 year of changing and cleaning parts I went and disconnected the vac line from the EGR valve to the solenoid (the unit bolted to the left of the Distributor). Startup the car with this line disconnected and WOWWWWWWWWWWWWw, no hesitation just off idle anymore!!!! My faith is restored! Now, Can I simply plug the EGR valve with a sealed vac tub (along with the other end at the solenoid...my emissions test just went through so I don't have to worry about it for two years (car will be stripped for resto by then).
Will I have any problems plugging this vac line up (or shall I just leave it unplugged and open?????????
Thanks for everyone's help!!

Steve

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89 GTA G92
305 TPI WC 5spd w/3.45
Accel Cap & 8mm Taylor's
Custom 4" Cold Air Induction
Jet Airfoil
K&N Airfilter
160 deg stat/fan switch TB Bypass - Steel Rad
Cat back 3" Exhaust w/Terminator Muff.
HiGh FlOw Dynomax Cat
Spohn LCA's - KYB GR-2's
Moroso Crank Bolt and roller pilot bearing.
New Fuel Pump!
Autometer Vac+Oil Temp
2000 Yamaha R1 150hp 385ibs

 

Maybe a SES light if anything. Some people get by without any annoying orange glowing lights, and some don't...just pray your one of the lucky ones.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes

 

Keep in mind that you may(will) have some detonation problems by running without EGR at all. I would say that you need to keep looking and find the ACTUAL problem and not try slapping a band aid on it. Those weak factory cast pistons do not like being detonated on much.

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Matt

1987 GTA L98 MD8 GW6

"Stop Lights timed for 35Mph are also timed for 140Mph"

 

Matt, then why do companies sell EGR cover plates and such to totally remove the EGR from the system. I have a feeling it's the solenoid which may be causing the EGR valve to open slightly off idle which is causing a lean condition at that point.
Does anyone know any testing procedures towards the EGR solenoid? I don't think it's the valve itself but I could be wrong. Car has 179,000KM and the EGR could be original but I'm not sure.
I also just passed emissions a couple of weeks back with the bog/hesitation problem...do you think this would eliminate the EGR valve from being the problem and point to the solenoid?
Just to clarify, the vac line from the solenoid to the EGR...is it connected to engine vac? 'cause when I disconnected this line, my vac reading is the same on my vac guage...
Thanks for all your help guys...
Steve

[This message has been edited by Steve89GTA (edited May 27, 2001).]

 

No, the line that goes from the solenoid to the actual valve only has vacuum sent to it when the ECM requests EGR to occur. That is what the solenoid does - opens up to allow vacuum to go the valve and supply EGR. Vacuum is constantly supplied to the solenoid, however.

The reason why companies sell block off plates and the such is because you CAN completely disable EGR, but you must make the requesite corrections to keep the timing tame enough to keep the engine from detonating. I have never dealt directly with a TPI setup that has had the EGR completely disabled so I am not sure what exactly needs to be altered in the EPROM calibrations but the car will need to be less aggressive with its timing due to the lack of an EGR system to keep detonation down. Cars that have been altered in this manner will almost always run high octane fuel (race gas) to aid in the prevention of detonation. These cars also eat oxygen sensors for breakfast, lunch, and dinner.

A car that does not have EGR and does not have the EPROM altered and run high octane fuel, will most definately detonate A LOT. This detonation can severly damage the pistons. I have heard of engines blowing holes in pistons, burning pistons, bending connecting rods, and burning valves due to excessive detonation (also referred to as preignition or pinging).

If your EGR solenoid is malfunctioning than replace it and retain the EGR functions. If you really dislike EGR that much, than you can have an EPROM setup for you that is EGR-less, run very high octane fuel($$$$), and remove your catalytic converter as it will most likely melt down from the use of race gas. I think you will be much happier in the long run by correcting the problem properly.

Good luck and I hope that covers most of your questions.

Laterzzzzzzzzzzzzzzzzzzzzz

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone and AFPR, TB bypass, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"

 

Diagnosing the EGR solenoid.

First off, it is probably more trouble than it's worth, because the solenoid is only like $20 or so. Just buy a new one unless you're really strapped for cash.

Basically hook up a vacuum gauge to the vacuum line FROM the solenoid TO the valve. Run the engine. At idle, the valve should get no vacuum, at part throttle it should get some vacuum (not sure how much) and at WOT it should get no vacuum. I'm pretty sure that's correct, a Chilton's will have a detailed flow chart of how to diagnose it (check out the section on diagnosing code 32).

 

It's weird cause the car never threw a code when the RPM was rough (or the hesitation or bog) was occuring. There are two vac lines running to the solenoid (which are an extreme bitch to take off). I guess I'll change it if the cost is around 20-30 bucks. The vac lines running to the solenoid look to be in good condition and I've hit that area with WD40 while it was running to find a possible vac leak but nothing happened (no change in idle).
I have a permanent vac guage set up in the car and I can notice a slight difference in the readings now with the vac line (from solenoid to EGR) disconnected (not plugged). This leads me to think that the valve is closed but the solenoid is faulty and opening the valve at the wrong time (or too much or too little).
What do you think?
Thanks again

 

Your description of the vacuum changes sound like they support your theory. However the car has a lot of vacuum operated componants that can mask small vacuum leaks by acting as reservoirs of sorts which make using general vacuum reading (not isolated to the componant in question's circuit) a less accurate diagnostic tool.

If you are noticing a vacuum reading at idle that is lower than normal with the line disconnected from the valve to the solenoid, than the solenoid probably is allowing vacuum to be sent to the valve (or in your case with the line off, to the atmosphere creating a vacuum leak). If that is what is happening than the valve must be malfunctioning as it should not be supplying EGR at idle.

I would suggest that you get a quality service manual for your car and trace the troubleshooting chart completely to determine the absolute cause of the problem. You will want to have a service manual for your car eventually anyway - they are essential for a true enthusiast. I would suggest finding a GM one as they seem to have better make-specific data and troublshooting aids in them than the aftermarket ones (Chilton, Haynes, etc...).

Good luck again.....

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone and AFPR, TB bypass, AirFoil, !AIR, !A/C, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"

 

I've got the Haynes book and have used it for years. It's been great for general help (used it to change my first timing chain 2 years ago). The Vac at Idle is the same as before, the difference is now when I press the throttle I notice that the VAC doens't drop down as much when on the highway and city driving along (it takes more gas and accelerating harder to bring it down to 5 or so.) which makes the engine feel stronger and I think I'm getting better fuel economy as well. I have a feeling it may be the valve itself. What is need to get the upper plenum off parts wise? (some gaskets for the upper runners and new solenoid and EGR valve..that's about it correct? Do you think the EGR is stuck open a little due to the solenoid causing a drop in VAC pressure when driving? The idle is perfect so I think the EGR is fully closed then.
hmmm...
Steve