Running lean & no response from the egr

[ratesheet]

He's baaaccccckkkkkk....Ok team, got another issue, I can't find the solution....yet.

As I said a bit ago...failed cal. smog...too high NOx reading...everything else is fine, great actually...plugs are white and running lean no matter what I have done...timing is spot on, truck starts instantly, idles a tad rough though...I have checked the vacuum lines and everything appears fine, I pulled off the intake manifold and scrubbed out the egr passages and also through the cylinder head, my cleaning rod came out of the #4 cyl exhaust port...here's one thing I can't figure out...I removed the egr valve, put a vacuum line and sucked on the line, egr held vacuum, both small ports on the top of the egr held vacuum, when I run the truck at idle no response from the egr which is normal, when I rev the motor, still no response from the egr...It should respond by opening, when I depress the egr manually at idle...nothing, the motor continues to idle normally, it should stumble and/or stall right?...I have this feeling this is something I'm just overlooking or considering...give me a heads up.

[camoit]

does it have a carb? If so you need to pull the slider at the same time.

[geezer101]

The EGR crap can carbon up badly - I mean 'the stuff looks like coal' bad. The gallery through the inlet manifold can coke up rock solid and the ports into and out of the valve body can do the same thing too. Remove the EGR valve body from the manifold and blast it with carb cleaner. You will more than likely need to physically dig the coke out of it. Spray the piston body and into the ports of the EGR with WD40 and manually actuate the piston - get your fingers under the vac housing and squeeze it up and down a few times. This will free it up and get it fully opening under vacuum. This should be more than enough to ensure your D-50 passes emissions. If you're wondering how bad an inlet manifold can get fouled up - http://i1089.photobucket.com/albums/i351/geezer1011/L200%20Express/L200Express221_zpsed194cc9.jpg
^that's from 180,000 kms, not miles...

[ratesheet]

Camoit...it's a carb'd motor but, educate me, what/where is the slider?....Geezer 101...the egr operates correctly off the manifold...I hooked up a vacuum line and sucked on it and the diaphragm collapsed and held vacuum...it moves very easily and does not stick...I did this on both openings...I have done a very good job of clearing out the carbon...the egr is showing more metal than carbon inside...I was able to run a piece of silver solder through the egr port in the cylinder head that is under #3 cylinder and it came out the #4 exhaust port, I am relatively confident plugged egr ports are not the significant problem...here is a question I still have, if the exhaust is returned to the combustion through the egr and the process is to dilute the fuel charge in the combustion chamber shouldn't each exhaust port have an egr port to distribute the spent exhaust into each cylinder? here's what else I found since I posted last...when I put the parts back on the engine I noticed a small spring that had broken and both pieces were laying together, then I thought about it and the springs were laying just below where I let the fuel pump hang inside the engine bay....so I pulled off the fuel pump (again!) and the small return spring that actuates the lever that operates the diaphragm inside the fuel pump was not there...I'm thinking AHH...HAA!!!...its not getting enough fuel, low float level, lean condition...so I buy a new fuel pump install it....crap!!......I still have the lean condition, that wasn't it...but it's raining now and the truck is outside so I have some time to think and read more about what is the cause of this issue and I eagerly await any and all suggestions...thanks to everyone for taking the time to provide additional suggestions and insight.

[geezer101]

Can you feed a thin, stiff wire through the manifold to the EGR gallery under #4 inlet? This is a difficult gallery to clean out as it bends all over the place around the outer edge of the manifold. If your fuel level is low I'm going to recommend you pull the bowl cover off and check the needle, seat and float (grrr, sorry 'bout that - but it is easy to adjust). Also, how clean is your carb? A fully or partially blocked jet will obviously mess with your mixture reading. And I think it will also mess with your NOx reading but not in the way you'd expect. I'll take a bet either way that the lean mixture is the culprit of your higher NOx output.

[camoit]

Ok on the carb you should see a plunger on the drivers side. It has an arm or linkage connected to it. It is round about 1/2 inch or so. It will open up with the throttle via the linkage. The idea behind it was to better control the flow of EGR gas. So the EGR will open and then allow the gas to flow to the carb where the slider can regulate the amount. So in order to check the operation of the EGR you need to pull a vacuum on the EGR valve to make it open. Then pull out the slider. Then the engine will start to run like crap showing the gas passages are open and working.
The EGR is to reduce the NOx the combustion process makes. Put a vacuum gauge on the intake and get a manifold vacuum reading for us. We want a nice steady needle not whipping back and forth.

[ratesheet]

Camoit...the slider that you are referring to is what I thought but I wanted to make sure, I will do the test tomorrow, as it sits though, I put a vacuum gauge on the intake manifold and got a dead center needle reading in the green, no dancing, waivering, nothing...just steady reading at idle, when I raised the rpm the needle pegged at the top of the gauge then right back down to center green...Geezer...I ran a length of silver solder through the intake manifold egr mount to the outlet leading to the cylinder head then from the egr port in the cylinder/intake interface out through the #4 exhaust port, I cleared out a lot of carbon so I am confident the passages are clear enough...btw, silver solder comes in rods shaped like a small rectangle..about a 32nd thick and 1/8th wide usually made of brass and silver, it is hard enough to scrape the carbon and flexible enough to make mild bends...thanks again guys for the help, I'll keep everyone posted, we will get this solved.

[geezer101]

Good luck ratesheet. A major PITA that a reading is the only thing between you and the road...

[camoit]

Vac reading tells me the upper end is working fine no burnt Jet valve.

[ratesheet]

Thanks Geez....Camoit, a while back I read one of your responses to another member re: the jet valves, I posted a bit ago that my number 2 rocker broke off the jet valve tab, the broken tab was wedged in the recess area where the fuel pump rod goes through the cylinder head wall, plucked out the broken piece and removed the rest of the jet valve adjusters out of the rocker arms...now I have non op jet valves.

I spent half the day going over the motor and making certain that timing is right on...it is, every mark is covered, but I forgot to check the egr and slider you mentioned, that has to wait until tomorrow...but the truck starts perfectly, idles great but is a little rough for my liking, knowing these properly functioning engines are sewing machine smooth, after everything was buttoned up I went for a short drive, the truck ran damn near flawlessly but when I got back the plugs are still white...SO...I haven't replaced the O2 sensor yet, I don't think the guy I bought it from ever changed it, I'm betting it is the original, it will be in (ordered from O'Reillys)..tomorrow, if that doesn't fix it then it has to be the carb...

[camoit]

Are you sure it's running lean? Have you looked through the thread, how to read a spark plug (http://www.mightyram50.net/vbulletin/showwiki.php?title=Engine:How+to+read+a+spark+plug )?

[claych]

ratesheet,
could you post the readings from the Inspection report?
Thx

[ratesheet]

As requested...

At 15 MPH..

MAX GP MEAS

HC 137 326 89

CO (%) 0.94 2.24 0.00

NO (PPM) 1107 2081 3029......This is the issue, these numbers cause a fail and labeled a gross polluter

At 25 MPH

HC (PPM) 109 276 85

CO(%) 1.19 2.49 0.00

NO (PPM) 1163 2162 3444.....again, the measured is the number that crosses that gross polluter line...

So to me it looks like the engine is acceptable except that cylinder combustion chamber temperature causing the nox...let me ad to this; this morning I changed the O2 sensor, not much difference in performance or plug color, except it does appear that the plugs do have an ever so slight tan color to them now...Camoit, I reviewed the plug color link you suggested and my plugs look exactly like the picture... NORMAL...however, in my life I and everyone I know have agreed that a proper burning combustion chamber will leave a spark plug insulator the color of coffee with alot of cream...a very light brown or tan...to me the plugs are running lean (too much air or not enough fuel) or excessive advanced timing...so maybe I'm in the process of being re-educated regarding Mitsubishi engines...as always, thank you everyone for taking the time to comment and help/suggest...Also, this morning I did what Camoit suggested...with the engine idling I pulled out the slider on the carb and depressed the egr diaphragm and did get a small...change in engine idle and smoothness of engine running/idle...it began to run a little crappier...I think it should have idled a lot worse than it did, so now maybe I have to reconsider the egr valve, although it did operate normally by manually checking vacuum, it could be that the egr system is the issue..

[camoit]

Claych is a retired SMOG Ref or something like that, so he will chime in here soon. But you might want to check and clean the passage in the slider. They can fill up just like the other ports.
As for the EGR plumbing you should check and see if all the lines are hooked up the the proper order. The EGR should only get vacuum at a cruse. From there the slider does the rest.

[noahwins]

You're running extremely lean at 0.00% CO and high NOx. It should be closer to 0.30-0.40%. CO is the lean/rich indicator. NOx tends to go down as CO goes up and HC tends to go up as CO goes up.

First thing to check is the EGR. Get a cheap vacuum pump from Harbor Freight and with the engine warmed up and idling, attach the hose to the vac nipple on the EGR top hat. Apply a few inches of vac (one squeeze on the handle). You should hear the engine stumble as the valve opens up. If not, either the EGR passageways are plugged or the diaphragm is broken.

[ratesheet]

Thanks again all...worked on the truck this morn but I took a break from the truck this afternoon, does anyone know if each exhaust port has its own exhaust channel from the main channel out of the intake manifold egr...like I posted earlier, I scrubbed out the intake egr and ran a proper size drill bit through the port that runs through the cylinder head into #4 exhaust port, it seems to me there would be individual egr ports into all other exhaust ports?...and as I look at the Chilton book I have I am beginning to think by the drawings I have a later model carb, possibly an 88 model year, tomorrow though I'll be back at it applying everyones suggestions and anything I think up on my own...maybe I'll just break down and buy a new egr valve...

[noahwins]

EGR system dumps the exhaust gas into #4 only. Don't ask me why they designed it that way.

[ratesheet]

Noahwins,

Thanks, at least I know I wont have to pull the cylinder head and scrub a bunch of inaccessable tunnels....the more I think about the process, in order to have the engine run lean it would need a lot more inert gas than what is being produced and sent into one cylinder...

[camoit]

If you don't have a vacuum leek causing it to run lean. Then try the old trick of revving the engine up with the air cleaner off. Then you put a waded up shop rag over the carb choking it. Then you pull it off and repeat a couple of times. This will flush fuel through every hole in the carb. So if there was some chunk of crap plugging something it will just suck it clean. Also try a new fuel filter just for fun.

[claych]

Thx ratesheet,
If I could trouble you further , on the inspection report
there should also be O/2 & C/02 readings, could You post
those as well?

[ratesheet]

Here are the additional numbers...

15 MPH rpm is 1857 %CO2 is 13.8 %O2 is 1.4

25 MPH rpm is 1883 %CO2 is 13.8 %O2 is 1.2

also, today I bought a vacuum pump, got the truck up to operating temp. put the vacuum line on one nipple on the egr, pumped and and got nothing....put it on the other nipple and pumped it up to 10 and the truck began to stumble and almost die, never quit though but idled very rough, slowly the vacuum blead off and the engine returned to it's normal idle. Noahwins said to give it one pump, when I did that no vacuum registered on the gauge on the pump, I had to pump it several times to get the needle to register...gonna try Camoit's suggestion and smother the carb with a rag and see if we can discover any hidden leaks...

[ratesheet]

Just followed Camoit's suggestion...pulled the air cleaner off, revved the engine, stuffed a rag in the carb....did this 4 or 5 times...pulled the number one plug it was nice and sooty black, hoping for the best, I took off, ran a nice flat 2 mile stretch WOT got up to a little over 80 mph...normally I can hit a little over 90 mph so I've somewhere lost a little top end....anyway...got the truck home, pulled the number one plug....and it is white again, nice pretty white....thanks again everyone for all the help, I'll keep trying and posting the results.

[ratesheet]

BINGO!!!....I found the problem...I went to a local pick n pull and found an 87 G63B...I pulled 2 jet valves and a rocker arm to replace the one that broke the tab that actuates the jet valve...disassembled the rocker assy. on my truck and pulled the #2 cyl. jet valve and there it was...the head of the inner jet valve shaft was gone!!!...there is my gigantic air leak...now the question is where is the little piece that broke off???...is it still bouncing around in the cylinder or did it manage to escape through the exhaust valve?...the truck runs really good as is, all cylinders firing, etc...it is now a bit of a crap shoot, I can put it back together and wait for it to die or....maybe it never will...so now it is back down to pick and pull to buy as many of the engine parts that I can to use...BTW everyone, I found out today that the exhaust manifold and jet valves for the 1st. generation engine are obsolete and longer available from the dealer....Mitsubishi or Chrysler...also, thanks to everyone for the help and advise...I'll keep you posted as I continue to fix up Mr. Truck.

[camoit]

Yon never told us it had a broken rocker. You should put in the delete kit and just do away with them.
But if it's missing the end of the valve then the vacuum reading you took the needle would have had movement. It should have been rock solid. It should have been a 4" shop gauge not a generic dash gauge.
But glad to here this. And another one to the MCA valve.

[ratesheet]

No confusion intended...I posted on 1-21-16 that the rocker jet actuator had broken, I thought I posted this earlier but I guess I didn't..Camoit...after what I found today, I agree....I just should have eliminated the jet valves and eliminated them as the source of the lean condition...