Can A Disconnected Egr Cause Misfire?

[Mustanger]

I recently replaced my stock fuel regulator with a bbk adjustable. I placed the guage on the guage port of the regulator but then I could'nt plug back my EGR plug. The car has a hesitation at low cruising speeds it feels like minor breaking up or misfiring. Can this be caused by the EGR being unplugged.

[Capri306]

By "unplugged" do you mean the vacuum line, or the EVP sensor connector? BTW, a year/model/engine list, with any major modifications, would help.

Typically a disabled EGR system will cause detonation, a hotter-running engine, and a loss of fuel economy. None of these are good. Figure out what's wrong here and get it working again.

[Mustanger]

I mean the EVP Connector. It's a 93 notchback with a 306, windsor jr heads, e-cam, holley systemax intake, bbk headers, stock injectors, t-5 and 373's.

[skiwesser]

Originally Posted by Capri306

By "unplugged" do you mean the vacuum line, or the EVP sensor connector? BTW, a year/model/engine list, with any major modifications, would help.

Typically a disabled EGR system will cause detonation, a hotter-running engine, and a loss of fuel economy. None of these are good. Figure out what's wrong here and get it working again.

When I blocked off the riser in intake, pluged back of heads, bypassed coolant to EGR, mine started backfiring, is this why?
Smog pump's been gone for years, as has tube going to H-pipe.
It started running hot too, only while driving not when idleing?
Hooked tube to radiator overflow and stuck it in a jug of water and it blew bubbles, which I thought meant blown head gasket but no evidence of this when we took it apart??

[mpj76]

I removed my smog pump, I'm running an off road X-pipe with no smog tube, plugged the AIR tube from the heads, disconnected the charcoal canister, but have kept the EGR valve in place. My car runs great (as far as I know) and gets the best mileage it ever has. No pinging. Temp gauge on first line from bottom with stock Thermostat. Feel free to chime in if you notice any mistakes with the above as far as useless stuff still being connected. Sounds like you may possibly have a vacuum leak if it stumbles or hesitates during low RPM cruising in high gear, especially when you teeter between the gas pedal being barely pressed and coasting.

[Dark_5.0]

I totaly removed and blocked off my EGR 3 years ago with no trouble at all.

[Capri306]

The "problem" is that that part of the EEC-IV instructions include the use of EGR in its programmed strategy for a/f ratio. It is programmed to 'anticipate' (for lack of a better term) the dilution of the a/f mixture by inert exhaust gas. This is the reason for many people with disabled or malfunctioning EGR experiencing higher temperatures (because it runs leaner than it should), pinging (again, due to lean mixture), and cruising problems. Now theoretically the EEC should be able to correct for this using the HEGO, but most of the time it's not using that signal for mild- to WOT-acceleration; it's more-heavily relying on other inputs.

I'm going to maintain my stance that it's to your engine's and your own benefit to keep EGR attached and operational. There is absolutely no reason to remove a functioning EGR system on an EEC-IV-equipped street-duty vehicle, other than your mind playing tricks on you.