ORM Mod circuit

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

ATXKJ wrote:

isn't the flow control valve - a engine turn off valve - (a safety feature to prevent runaway engines?)

So no worries at all about a runaway diesel with the AFC disconnected? I just had thoughts of me driving tomorrow with it unplugged and I goto slow down and it wont and then I approach town and what do I do? Ride the brakes till its slow enough to ditch or jump out?

Jeger · **Posted:** Wed May 30, 2007 11:51 am

bbertram wrote:

ATXKJ wrote:

isn't the flow control valve - a engine turn off valve - (a safety feature to prevent runaway engines?)

So no worries at all about a runaway diesel with the AFC disconnected? I just had thoughts of me driving tomorrow with it unplugged and I goto slow down and it wont and then I approach town and what do I do? Ride the brakes till its slow enough to ditch or jump out?

No more concern than with the droves of other diesels on the road without FCV valves. I suppose if you wanted to you could rig up a safety shutoff switch that would close the valve when activated. Or even rig up a cable to operate the valve, but that would require some surgery.

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Cool, then its safe to do this mod, woot.

ATXKJ · **Posted:** Wed May 30, 2007 1:24 pm

The runaway diesel would be a failure of something else - i.e. blown Turbo seals providing a oil source to keep the engine running - a couple of folks were making jokes about the big diesels that did that.

I don't think it's a big risk - but the possibility exists.

skywarn · **Posted:** Wed May 30, 2007 2:16 pm

bbertram wrote:

Cool, then its safe to do this mod, woot.

WOOT!!

did you say WOOT??? :shock:

i hadnt checked the woot site in a few days.. so today i check in and...

they are having a "woot-off" today!!!!

www.woot.com.

ok thats my spam for the day!

stevesmith7 · **Posted:** Wed May 30, 2007 2:17 pm

Turbo Tim wrote:

For the EGR (Exhaust Gas Recirculator) to work there has to be a vacuum on the intake so the engine can suck in the exhaust. On a diesel, there is no vacuum, in fact, with the turbo pushing air down the intake, the EGR by itself won't work. So, what some clever engineer did to make it work was to add this AFC valve on the entry point of the intake manifold. Now when the engine CPU says to add EGR, this valve closes part way (choking the engine), thus creating a vacuum so the EGR valve can dump exhaust in right behind this valve.

So thinking out loud here. Would it be possible to get the benifits of no EGR just by defeating the AFC? No vacuum, little to no exhaust gas in intake.

Simple solutions are best.

Steve

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Went out to look at my jeep, I'm pretty sure I tracked down the EGR but I can't find the AFC. Any pictures or help would be appreciated, would like to test this out tomorrow.

dgeist · **Posted:** Wed May 30, 2007 4:57 pm

stevesmith7 wrote:

Turbo Tim wrote:

For the EGR (Exhaust Gas Recirculator) to work there has to be a vacuum on the intake so the engine can suck in the exhaust. On a diesel, there is no vacuum, in fact, with the turbo pushing air down the intake, the EGR by itself won't work. So, what some clever engineer did to make it work was to add this AFC valve on the entry point of the intake manifold. Now when the engine CPU says to add EGR, this valve closes part way (choking the engine), thus creating a vacuum so the EGR valve can dump exhaust in right behind this valve.

So thinking out loud here. Would it be possible to get the benifits of no EGR just by defeating the AFC? No vacuum, little to no exhaust gas in intake.

Simple solutions are best.

Steve

Indeed. The KISS method appeals to me, too. The big question in that regard is if the EGR will throw trouble codes if it doesn't actuate or if it WILL actuate and just do a really BAD job

TT, you mentioned that with the traditional ORM in place, there was still small voltages across the FCM and EGR. In your oppinion, were these just control signals polling the devices or were they actuating to some degree? i.e. was the FCV actuating even though the MAF was unplugged. Was the "unplug everything and lay rubber" what occurs if your REALLY shut off the egr? Ideally, I'd actually like the FCV to operate in engine shutdown, just not along with the egr. I suppose there's always the TCM P/N sense pin.

Man, would I love a brick that plugs inline to the harness right at the ECM and "edits" the signals (as opposed to the mid-wire solution).... it could even have a manual bypass for on-road lab-abidedness

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

I just drove 300 miles and I used 10.2 gallons of B 20 it is now hard to keep the tires from spinning it drives much better. no side effects at all

Stan Wright · **Posted:** Wed May 30, 2007 9:09 pm

Is it possible to unplug the EGR wires without removing a bunch of stuff. Is it a 2-wire plug? The flow control was easy to unplug, but I've been fighting with the EGR for 30 minutes now.

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Can you guys unplugging the AFC please give me a few hints at where it is. I dont know what it looks like. I can't find any manuals online or parts diagrams. Would really love to test this mod out tomorrow on the road and see how it affects driveability and mileage.

Stan Wright · **Posted:** Wed May 30, 2007 9:36 pm

The AFC is right behind the alternator. A large black rubber hose connects to an aluminum piece. The connector is on top and easy to get to.

On the other hand, I'm still fighting with that d@mn EGR connector.

Turbo Tim · **Posted:** Thu May 31, 2007 12:58 am

This test is something you all can do right now by just unplugging all three, the MAF, EGR, and AFC. All that will happen is that you will get a big smile on your face when you step into it, and you will now have 5 CEL codes (that can be cleared if your worried when you plug everything back in).

This is as good as it gets as far as KISS (Keeping it simple), but you will have to live with the CEL light.
What I am trying to do is exactly the same as above, but keep the CEL light off by fooling the CPU. However, to insert the "Sprinkler Timer Mod Circuit" you will have to cut into the wiring harness and splice in your own connector. Getting factory type connectors to just plug into is not going to happen, plus, the cost on even finding a male/female set of CPU connectors will probably get you a set of new tires!

As far as the CPU polling the sensors, the AFC is an active sensor, meaning that it has power, ground and then the trigger wire from the CPU. As far as resistance goes, it measures open. From what I saw on the O'scope, the only feedback the CPU gets is apparently from the MAF. When it starts to choke the motor, the MAF voltage drops fast.

The EGR however measures 9 Ohms, so when it gets pulsed, the CPU expects to see current in the circuit and a drop in MAF voltage too.
Both sensors (EGR & AFC) have about a 5 - 10% signal on them all the time with the MAF unplugged.

The whole idea here it to keep everything in place, no re-plumbing, and just a quick connector plug-in to swap all sensors back in for any inspections. Will all the sensors unplugged, they won't gum or get plugged up as they won't be working, but they will be ready to go back in service for use on the road.

I hope all of this is making sense.......

By the way Dgeist, you mentioned that you don't need all 3 signals from the TCM CPU to get the Park logic? Please explain as for some may want to switch back in the AFC for shutdown. This signal would make it possible. Thanks......

dgeist · **Posted:** Thu May 31, 2007 11:15 am

Turbo Tim wrote:

By the way Dgeist, you mentioned that you don't need all 3 signals from the TCM CPU to get the Park logic? Please explain as for some may want to switch back in the AFC for shutdown. This signal would make it possible. Thanks......

From the thread's first post, pin 41 is closed when the tranny is in P/N and is otherwise open. It closes to ground.

Dan

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Didn't have time to unplug them this morning, went on my trip with a full tank. Filled up at my desitination, unplugged EGR and AFC while waiting for the computers to finish updating. I will drive back with a full tank along the same road and same speed with them off. I will report the difference when I get back later this afternoon or evening.

My EHM likes to blow white smoke, its funny.

GilaMonster · **Posted:** Thu May 31, 2007 3:50 pm

Just wondering why the EGR plug needs to be unplugged when the MAF controls its function via the computer. Can't one simply just unplug the MAF and AFC plugs and get the same results as unplugging all three?

BiodieselJeep.com · **Posted:** Thu May 31, 2007 4:06 pm

Alternately, if one just unplugs the AFC, do you get the same amount of "un EGR-nesss" as when you unplug the MAF? Is there more "un EGR-ness" with them both unplugged?

And do you get a code when you unplug the AFC only?

plugging away....

Stan Wright · **Posted:** Thu May 31, 2007 5:05 pm

BiodieselJeep.com wrote:

Alternately, if one just unplugs the AFC, do you get the same amount of "un EGR-nesss" as when you unplug the MAF? Is there more "un EGR-ness" with them both unplugged?

Good question.

BiodieselJeep.com wrote:

And do you get a code when you unplug the AFC only?

P1140. Did it just last night.

Cowcatcher · **Posted:** Thu May 31, 2007 5:15 pm

On a lunchtime errand today I got hit by that "Jam the throttle to get into the traffic" and have it slooooowly slog out while my pants fill. :oops:

Does this burn the tires fix eliminate the one thing I hate about my CRD?

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Mileage results are in. On my drive today through hilly twisty rainy +15c weather 85 kph highway I got:

ORM, EHM
170 kms at 18.8 liters this morning

Metric (Canada) 11.06 L/100KM
Metric (Europe) 9.04 KM/L
US Gallons 21.39 MPG
Imperial Gallons 25.55 MPG

ORM2, EHM
175 kms at 16.7 liters this afternoon

Metric (Canada) 9.54 L/100KM
Metric (Europe) 10.48 KM/L
US Gallons 24.79 MPG
Imperial Gallons 29.60 MPG

Last time I went this route I got 38 mpg but I think my filling up was wrong, I let someone else fill me up at one location and I dont think they put in the proper amount of fuel, never topped her up to the max. I also had alot more straight highway that really bumped up my mileage. But it looks likeI gained 4 mpg(cnd) and 3.3 mpg(usa.) Not to shabby. I didn't want to wreck my test by hammering it down in town to test the new power, I will try that some other day.

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