EGR emissions system question/opinion

[wink84fj60]

Need your opinion. I got a carb from Jim C. Had to adjust the mixture screw one full turn to make it run richer. I am trying to find out why. I went through the emissions manuel and found outi found that a bvsv and a vsv were broken. Both are the one's specific to the EGR system. Could these 2 little broken parts make the carb need to run on a richer mixture? My thinking is these 2 little parts are not working which is allowing too much exhaust gas into the sytem so the carb needs a richer mixture. Figured I asked before I drop more cash on parts.

 

[dogboy2]

First off, Jim C. builds a mean carb. If by mixture screw, you mean low speed idle, and had to increase the idle speed in order for your truck to idle smoother, then yes, you are not alone. I did too but here's a possible explanation:

Jim hot tests his rebuilds on a 2F and I'll bet you bucks that motor is extremely well tuned so his adjustments should be dead on given that your motor is in an equal state of operation. Each motor is a little different and as you've already discovered, the EGR system can wreak havoc on the running condition of your motor. If every component of your engine was operating to spec, chances are you wouldn't have had to touch Jim's settings. In my case, his carb rebuild exposed another issue with my 2F (TBD) that was being masked by the poor condition of my carb prior to rebuild.

Replace the failed BVSV and VSV with new OEM parts. They are integral to the proper functioning of the EGR system. Since you're replacing the one BVSV, replace the other too at the same time so you don't have to go back in again later. They aren't too expensive and you will address a known part failure. Make sure your EGR Vacuum Modulator and the EGR valve itself are functioning properly. I don't think you are off in your logic but then again, I'm not a mechanic by trade but rather one of necessity.

Straighten out your EGR system and I'll bet you can restore the carb to Jim C's setting or at least discover a "new" issue with your motor

HTH,
-dogboy- '87 FJ60

 

[FJ40Jim]

Jim hot tests his rebuilds on a 2F and I'll bet you bucks that motor is extremely well tuned so his adjustments should be dead on given that your motor is in an equal state of operation. Each motor is a little different and as you've already discovered, the EGR system can wreak havoc on the running condition of your motor. If every component of your engine was operating to spec, chances are you wouldn't have had to touch Jim's settings.

True Dat!

The truck in question has a recent history of running issues, and the carb was certainly one source of trouble. But there may be (probably are) other issues.

As a testing method, I suggest completely disabling the EGR vacuum system.
simply pull the hoses off the EGR modulator, BVSV and VSV, then plug them w/ golf tees. Now test drive the vehicle.

If it runs good, then the problem is in the EGR system.

If it still runs like poo, then the problem lies elsewhere in the engine management systems.

 

[High Desert]

JIM..

If it runs right with the EGR lines plugged...

What harm is done to the engine if you leave the EGR by-passed, like, forever?

 

[cruiser88]

it all freaking trash .ive got a nice full trash can to prove it

 

[Shinichi]

Jim C, I am ready for a pully and a rebuild. Please PM me with your info

Thanks
Jamie

 

[FJ40Jim]

If it runs right with the EGR lines plugged...

What harm is done to the engine if you leave the EGR by-passed, like, forever?

If there is no EGR, the engine will stay cleaner internally, last longer, get better fuel economy, produce less GHG, make more power...

All bad things, AFAIK ;p

 

[Pluton]

If there is no EGR, the engine will stay cleaner internally, last longer, get better fuel economy, produce less GHG, make more power...

All bad things, AFAIK ;p

When I disconnected the EGR(with everything else hooked up and functioning normally) the engine pinged like crazy...does this mean that I'd have to retard the advance to stop the pinging? Any suggestions, Mr FJ40Jim?

 

[dogboy2]

oh yes, the 2F will run like a champ with the EGR system taken out of the loop, BUT.... you'll never get it to pass emissions if your state has stringent test procedures.

not that I've tried to pass emissions with the EGR system disabled or anything....me? never....

-dogboy- '87 FJ60

 

[FJ40Jim]

When I disconnected the EGR(with everything else hooked up and functioning normally) the engine pinged like crazy...does this mean that I'd have to retard the advance to stop the pinging?

Yes, you'll need to retard the timing, or recurve the dissy so it doesn't get too much advance at too low an RPM.
Or connect the vac advance hose to the sub-advancer (the HAC fitting). Main vac advance gives something like 18*, sub gives 6-7*.

 

[Pluton]

Jim, connecting the advancer hose to the secondary advance on the dist worked perfectly. Engine runs nice and smooth w/o that pesky EGR. Thank you for the suggestion.

 

[Slow N Steady]

Jim,

Thanks for the explanation. You did my carb some time back - I put it on after rebuilding the most of the motor (everything except rings and main bearings) and since then I've had a stumble and stutter during the warm up that's had me baffled! (Great Cold, Good Hot, In between - stumble and stutter for about two minutes as it warms) Following your suggestion, I grabbed my Toy Emissions Manual, traced the plumbing and unplugged and capped the EGR modulator output to the EGR Valve. I now have a SPORT Truck! Amazing difference! Ran into pinging and detenoation aftwards (as described above), rerouted the VAC Advance and sorted that issue. Thanks!!!

Question is - what's the downside of this? I have heard the exhaust temps may run a little higher as a result - possibly causing warpage of the manifolds, etc. Are there any long term issues? Truck is stock will all other emissions present and accounted for. I'm really inclined to leave it like this!

Thanks!

 

[FJ40Jim]

The only downside to EGR removal is that the engine will put out more NOx gas, which can be a precursor to smog under certain conditions, and can also be a contributor to acid rain.

Yes, the exhaust temps will come up to normal, which will help the efficiency of the cat, and keeps the plugs cleaner.