EGR Woes...or somethin'.

[Tim-E]

Hey everybody,

I need some expertise very badly!!

A few days back, I removed my EGR valve from my otherwise fine running '83 I6 w/ MC2100. It seemed the EGR was sucking in a small amount of air in the low to mid-rpm range, and I wasn't using it anyway, so off it went.

I plugged the port where the EGR was, and the port where the EGR tube went into the intake manifold. The engine now refuses to idle, or stay running at all. I can get it running only by holding it above 1500rpm, and even then the engine surges and won't stay at a constant RPM, when I let off the gas it dies.

I've been looking all around for vacuum leaks, and have found none. Even with the engine warm, it won't start when choked, so that may rule out any massive vacuum leaks. Even it were choked, it would still get air from the problem causing leak, right?

Timing is set around 8*, I rebuilt the carb. earlier today, and still no luck. The float bowl is staying full the entire time. I crank it and it runs for 3 seconds and then dies...all since I removed/plugged the EGR on Tues.

Anyone out there have some advice for me?
Thanks for reading!!
Tim

[LEVE]

If it wasn't something you did that was related to the EGR removal, then it was something you did that you're not aware you did. Get a friend over and retrace the activity of removing the EGR. It could have been as simple as fracturing a vacuum line. I sure seems like a vacuum problem. If you have the engine running can you choke it off by putting your hands over the carb throat (use gloves), or can you spritz water or Carb cleaner around everything to see if the RPM changes whe it's sucked into a vacuum leak?

[Tim-E]

Yeah LEVE, I sprayed carb cleaner around any suspected leaking areas, but the RPMs are so erratic without any carb. cleaner being introduced, this test has given me little to no feedback.

The only vacuum lines I've got going are the dist. advance off the pass. side of the carb, and the PCV, and the brake booster of course. They all appear to be in good shape. I've got a bunch of new vacuum plugs for all the other ports. The carb to manifold gaskets are new. Besides, even with small vacuum leaks like a cracked hose my rig has run, just poorly. Now it won't run at all under 1500-2000rpms...

I removed the EGR valve from the flange that bolts to the manifold, and installed a brass plug in the ERG flange, and another brass plug directly below the EGR valve, where the EGR tube came in.

However, I plugged the EGR flange BEFORE I removed the EGR tube, so for a few cranks, exhaust was feeding back into the intake. I thought that was causing my grief, so I disconnected the EGR tube and plugged that port, thinking that would solve the issue, but NO!!

I've tried choking it with a rag, and that doesn't help it run any better, so maybe it's not a vacuum leak, although to me as well, it sure seems like one.
With the engine warm and choke closed, no start....wouldn't a vacuum leak let in air from SOMEWHERE to allow the engine to run?

Thanks for reading LEVE. I've been doing a lot searching on this forum, and you're always on the spot and really helpful. That's quite nice of you.

[Pete88YJ]

Take the plugs out and put the EGR valve back on? See if it runs again?

Pete

[LEVE]

Pull the Brake Booster Vacuum and plug the Carb and see what happens.

[Tim-E]

Originally Posted by Pete88YJ

Take the plugs out and put the EGR valve back on? See if it runs again?

Pete

Um, yeah...I broke the EGR valve during removal. I figured I wasn't using it anyway, so I was kinda rough with it. I wish I could put it back on see what happens, but I was kinda reckless.
A new one is around $50, but why would I buy a part that I'm not even using? I figure it's not a imperative part of the combustion process, so I'm gonna try to go without it.

Originally Posted by LEVE

Pull the Brake Booster Vacuum and plug the Carb and see what happens.

This is what I was thinking too... I'm gonna try this in a little while when the rain stops...after happy hour!

[RRich]

To prove - or NOT prove it's EGR related - a simple test:

Advance the timing at idle way up - to 20 or more. If it smoothes out, runs better, it's exhaust gasses getting in the intake - your patch/plugs are not really sealing it.

If that doesn't make it run better, put the timing back to where it was and find
what you messed up. Plug wires got switched?

[Tim-E]

Here's the latest:
-Plugging the booster vac didn't help.
-Advancing the timing didn't make it run better.
-The plug wires are in their correct spots.

The engine will only run if I constantly rev it. If I stay at a constant RPM, even a high RPM, it dies.

I'm soooo stumped.

[RRich]

WOW - not a lean condition, not an inadvertent EGR, what's left? Ignition?

Try to find out WHICH cylinders aren't running right - hold the R's up and disconnect each plug wire, one at a time. Find the one - or more - cylinders that are not working.
Pull that/those plugs and have a look.

Possibly removing the valve knocked a small chunk of carbon loose in the intake, then it got stuck in a plug gap?

I know the EGR is on the other side, but did you touch the distributor or wiring?

No doubt it's something stupid, but it's smarter than us.

[LEVE]

Drop back to basics and pull the plugs. Then ground them ALL so you can see them fire. Now turn the ignition to RUN and see if they all fire as you rotate the engine by hand. Note the:

• Firing order
• Degree at which spark occurs
• Quality/robust look of spark
• Is this repeatable for several revolutions of the engine.

If the sparks are

• weak, or
• intermittent, or
• not at correct time

then I'd look at the ignition module. Just out of curiosity, have you cleaned the dist. cap? I'm still thinking it's a vacuum leak. It has the classic signs. Did you ever get a friend to look things over? Sometimes a fresh look will find problems when you're looking for a problem, but thinking two or three steps ahead... and overlook the actual problem.