I have a small problem that I would like to get straightened around. The engine I have is a 351w EFI with the dual thermactor system and EGR in header system. The engine has the stock manifolds and I want to put on some long tube headers. Of course these wont have any emissions ports except for the welded on O2 bung. Can I remove all emissions without effecting the computer system? Not thinking I called Jegs last week to order the headers anyway and the tech I talked to said as long as you don't have emissons testing, removing the EGR wouldn't affect the computer in any way. I have heard of people removing the thermactor without any side affects, but not EGR. If you can remove the EGR, what do you do with the EGR sensor so the computer will not read an error code for the EGR being missing? If for anything else, I would simply like my engine compartment cleaner so I even possibly conceal a 6 pack without worry. lol

I have thought of just capping the EGR pipe off and leaving the whole EGR setup intact, or running a filter on the end to suck in straight air, or reroute it all the way to were the headers meet the exaust pipe and just weld in an adapter. But if I could simply remove the whole system that would be much less confusion in my mind right now.

 

You cannot remove the egr system or the O2 sensor. Both are required to be operational for the computer to function at any level beyond 5mpg.

The catalytic converters (thermactors) are another matter. They can be removed as long as you don't have to pass emissions again, as in leaving the country for good.

Regards, Robert.

 

The EGR doesn't affect mileage, but I agree that you should keep it (& everything else) working.

 

If the pcm doesn't see egr valve movement, it will turn on the check engine lite and go open loop, due to the fire hazard from the catalytic converters. It may be possible to leave the egr valve itself hanging somewhere just so the pcm knows it's there, then the egr hole could be plugged off. I don't know, I haven't tried this.

Regards, Robert.

 

The EGR isn't part of the catalytic converter system, so it has no effect on their temperature. It's totally self-contained and only affects combustion chamber temperatures.

The cats' temp is controlled by the amount of fresh air pumped in by the smog pump, and THAT is controlled by the TAB & TAD solenoid valves thru the combination bypass/diverter valve.

 

My cats were removed long ago before I owned the truck so im pretty sure the EGR doesn't have much to do with the cats. I would actually rather keep the EGR like Steve suggested but I see no way around it at this point. So just as long as removing this stuff doesn't result in any drivability issues It would sure help out a bunch. hmmmmmmmmm, would it help at all if I ran the truck with mass air instead of SD? I am thinking it wouldn't matter though if the EGR will in fact cause the PCM to trigger a code. In theory, it should happen irregardless how the intake air is measured.

 

You're saying fixing the EGR is too much trouble, but you wanna swap in MAF?

 

actually i never said anything about fixing the EGR, it runs great.........I want to get rid of the EGR so I can use headers. That is the whole mayhem behind the madness! lol

 

I swapped in Long Tubes on my 302, and still have my air pump, and EGR setup running. All I ended up doing was routing the line from the air pump back to my hi-flow cat. In your case I guess you could just have it routed to the exhaust pipe. I did that for about 6-9 months before I got my cat installed. I thought it was a cake walk and have absolutely no problems with it since.

Luke

 

Are you sure you don't mean the AIR injection system? Are you talking about about a bunch of little tubes running to the manifolds?

AFAIK, the EGR has nothing to do with the exhaust manifolds. The EGR sits right infront of the intake manifold. EGR recurculates exhaust gas into the intake for "less emissions". What I have seen done and have done to other vehicles is restrict the EGR flow into the intake.

Basically you take a thin piece of aluminum and drill a small hole in it versus the gaping hold the OE EGR provides. This will keep intake temps down (slightly), reduce carbon build up, and yield slightly more power and milage.

If the hole is too small just keep going slightly larger to keep the EEC-IV happy. I have done this to my Z71 (as have many others) and works fine. Next time I catch up with my truck I am going to be doing this mod.

 

On some V8s, the EGR supply comes off the front of the R exhaust manifold. Others take it from the center of the intake manifold in the exhaust crossover journal. Cars get it from there, but take it up thru the plenum in a special journal between the intake runners - no external tube.

 

Steve 83...As my smog pump is just there spinning with nothing to pump to (my check valves and such are gone) I would like to clean up my vac lines.

Could I simply ditch the vac lines that run from the TAB/TAD and leave those solenoids there? The diverter valves and pipe between the heads is gone too.

Now that is something I would like to see, do ya have any pics of this EGR setup? My Chevy has it coming off the passanger side manifold too. I thought Ford's late '80s to mid 90's trucks power and emissions stuff was pretty much the same, but I guess not!


gamehunter...If that is the case, I'd consider adapting the center EGR system so you can go with LT's. EGR works slightly to decrease NOx's I believe. I would sure try to keep this are you are OBD-I and probably have to pass an acutal tail pipe sniffer...and your computer would have a fit if that was missing.

By the way, what LT's did you go with? lexluthr69 and myself both have Hooker's...and they work very well.

 

The egr system injects exhaust into the throttle body to reduce combustion temperatures which prevents or lowers the formation of NOx compounds. By reducing combustion temperatures, the catalytic converters can be placed closer to the engine without overheating.

By removing the egr system and raising combustion temperatures (which will also lead directly to "pinging") the operating temperature of the catalytic converter is raised substantially. If this condition is coupled with any ignition failure which sends unburned fuel down the exhaust pipe, catalytic converter temperatures of 1200deg to 1400deg, or more, can result, making the possibility of a fire very real. If you drive your truck long enough, you will have an ignition failure eventually.

If you remove the egr system, you must also remove the cats. As a result of the higher combustion temperatures, the timing will also have to be adjusted to prevent excessive pinging.

Regards, Robert.

 

gamehunter,
where does your EGR line pick up it's exhaust gas supply? If it's from the manifold, you can pull the fittings and measure them. (They're probably metric, the ones on the 300 I6 are either DIN or BSPP, I forget which) It's no real problem to get a matching bung machined up and welded to the collector on one of your headers. Then you need to make up a new tube, again not a big deal. A Parker or Aeroquip fittings catalog will go a long way in helping you tofigure it out.

 

Here are the thumbnails - I won't put the fullsize images here. The album is at this link.