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1994 chrysler new yorker 3.5l v6 failed emissions. Edited post

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Aug 8, 2016, 5:59 PM

Post #1 of 13 (2782 views)
1994 chrysler new yorker 3.5l v6 failed emissions. Edited post Sign In

looking for help to try to solve a 2 failed emissions tests. Only failed the CO portion, at both idle and cruise. Prior to 2nd test I changed out PCV valve, (which was nasty and gummed up), plug wires, air filter, and plugs. Found one plug that appeared impacted. Ceramic was half gone, center post was gone and spark arm was bent to the side about 45 but was not buried in the plug (one would think a lower upward impact would bury it, especially with ceramic damage. After work done started car and ran it. Pulled the plug, and no damage. Hoped that was the reason for the fail. Obviously not. Is it possible car wasnt driven far enough to clean out all the build up from bad plug/pcv valve, or get catalytic to temp? Alsp why did the CO go up after the tune up. Expected ot to go down. Owner about to drop a couple bills to a shop, and would hate to see that happen if preventable. Test results are below. Any help would be appreciated.

Cruise limit. 400. 3.00. NA. NA. 2750
Test 1. 243. 3.99. 16.19. 0.6. 2260
Test 2. 197. 4.92. 16.64. 0.5. 2430
Results P. F. NA. NA. NA

Idle limit. 400 3.00. NA. NA. 1100
Test 1. 284. 3.48. 15.75. 1.1. 980
Test 2. 221. 4.39. 16.22. 1.0. 800
Results. P. F. NA. NA. NA


(This post was edited by Rob0107 on Aug 9, 2016, 1:24 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 9, 2016, 12:14 AM

Post #2 of 13 (2770 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

? Found broken plug and gummed up PCV which you can usually just clean out - new fine but question is why? Usually improper vacuum supply to it via hose not sealing, terrible oil change history, poor quality oil, worn engine and overheat ongoing or in it's history.

Codes will be limited for 1994 for help but try.
With finding the smashed plug probably should do a compression test on that cylinder if alone or just the whole job to compare it.

This probably ran like crap for too long as well harming cat converter. Might be time to really check engine health in general to see where you really stand and if a 1994 is just plain worn and may need more than it's worth.

For just high CO only that much over it's possible a good highway run once running well will clean it all up then test again.

EGR if inoperable/defeated would set off higher CO.

IDK - would probably check whole engine for health of it in general including all tune up items,



Aug 9, 2016, 1:43 AM

Post #3 of 13 (2766 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Just edited the post adding both test results. Not my car, helping a friend. She changed pcv before my involvement. No overheating. Checked with oreilleys or auto zone.. I forget which and they said it was too old to put on their code spitter. I also inquired about doing a compression test, and was advised that it wouldn't really assist. Basically said cylinder over travel is only thing that would cause that and bearings and caps would have to be checked by oil pan removal. There was something liquid in that cylinder (i assume fuel) and upon checking new plug.. Cylinder was dry. Would the cylinder not have over traveled at start up damaging new plug?

So vacuum line check to pcv valve.
EGR and CAT (can I test these somehow)

I really want to have her go drive it longer (how long?) on freeway and spend the 15 for a retest ... Especially since CO went up after tune-up. If I can test those components I will do that first.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 9, 2016, 3:21 AM

Post #4 of 13 (2759 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

We'll be at some loss as it's not your car with second hand info now. Guess you can' t know of an overheating history.
Please realize that place like the chain parts outlets are not mechanics they are there to sell parts and that's their job.

Broken plug isn't from cylinder over travel or if bearings could allow that much it's game over for that engine and wouldn't hold any oil pressure now and already be seized up - plain wrong.

Plug could be wrong type, dropped or damaged before purchase or during installation and either an overheat or blast of something too much (cold) into intake just a sudden shock of temp change? Parts would bounce around, could bent or break plug more, valve issue or score cylinder wall so of course you would want to know.

Who could drive this thing with one plug (if it was just one) running that poorly and not seriously complain something was wrong?
You or someone said sludged up PCV strongly suggest oil problems or abuse. Again overheating sludge oil too.

So, you are trying to help and be the nice guy and are. Careful not to be the one blamed when this engine could be declared in serious trouble old as it is from what seems like neglect.

Sludge: Look around for other evidence of it. Once seriously sludge up it's usually all over sooner or later for that engine with areas one by one starved of oil at all.

The reason for a drive is to really heat it up, work the thing so converter if it can burn up junk if it works at all from being run with a dead cylinder that junk has to be cleared out, parts replaced or find it's too much to be worth it. It's a '94 so someone took good care of it for a long time along its life.

I can't guess with things you don't know and suggestions from fast food parts outlets mean nothing IMO. Just ignore anything but rest results in writing then decide what to do - not them.

Sorry - I caught up with why PCV was noted as sludge up and what that might mean for the engine as a whole. Just a new one isn't the fix you need to know why in the first place and if hose(s) involved are any good.

Any engine that isn't running properly isn't going to pass an emissions test. Most places that require that exempt this age vehicle unless there's visible discharge of smoke for example alone it would fail. By machine test that close you would get a time period to fix and if otherwise OK (general inspection pass) and spent enough (not that much) get a year more to drive it or sometimes start the game all over again if still running by then.

There are other ways to determine compression but doesn't allow you to see each plug new now or not what they look like and also do a "wet" test if one or more is lower that spec.

This bearing thing isn't/can't be that worn without insane wild noise.

You/we may not know why the plug broke and if it was from any part traveling too much would do it again right away so that fairy tale just sunk.

Not my call for you but how far do YOU personally want to get involved with this, that is NOT your vehicle?



Aug 9, 2016, 5:00 AM

Post #5 of 13 (2751 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

she has had the car about a month. prior owner shared nothing notable as far as problems, and has not overheated on her.

I completely agree with everything you have said. compression test and other engine health diagnostics need to be done. I also understand that the emission test does hinge on engine health.

I needed to see if those emission results beore and after the tune up, along with lack of drive time made anyone in the community believe certain sensors or components could be easily tested, or a longer drive time made another test for 15.00 sound plausible before she dumps a couple hundred into the shop. Her thoughts for that are the waiver. With this being the last test before exemption. . would just hate to see them take advantage, or her wasye money.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 9, 2016, 5:50 AM

Post #6 of 13 (2745 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Ick! She's only owned it a month - so real good info on this all missing. Off on the wrong track already as the car should have been totally checked out before buying it.

You can bet the seller (I can smell thru this computer) knew of problem which is why it was sold. May be beating on a dead horse type thing and should have been scraped but we don't know that yet.

Already said, the broken plug and sludge tell too much already. Yup, you can fake some stuff to hide chronic overheating but not enough time yet for that to occur again if so.

Just understand sludge some: Oil, older oil and heat cause that. Oil lost additive by time and miles and can't take it like butter in a red hot frying pan. Then it clogs small ports or even large ports like a valve cover can't even return oil to pan fast enough, other items run so long dry of any but very limited.

People will either try canned magic crap or knowingly use it to cover a problem and some does for a very short time then almost always causes much more trouble later.

It may have been engine flushed so aggressively it choked on something put in throttle body or oil changed with essentially kerosene to clear it out doesn't help a thing but might for a short while. Cooling system, head gaskets some crap in a bottle will stop those but not for long then harder to do right.

Take all that if possible on a 1994 vehicle - any. IDK - I don't like this picture and sorry but don't think there's much good news. If engine is plain abused you can't expect it's sensors and controls to get accurate information to run properly new parts or not the source problem is always there to just do it again.

I really smell a rat with this. It probably should have gone to salvage (a guess right now) and seller just found some way to make it run well enough to sell it and just get more than its scrap value. Hope not but a lot of checking now would help wasting $$ on a lost cause we don't know yet. That is what folks should do BEFORE buying anything not after.

Guess my suggestion is to find out what you can and spend as little $$ as possible to cut losses on what might be the lost cause value wise to make it really useable again and dependable.

Keep checking what you can find.
Refresh: The Parts places are in biz to sell parts - not diagnose what you should need - you make that call,


Hammer Time
Ultimate Carjunky / Moderator
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Aug 9, 2016, 6:20 AM

Post #7 of 13 (2742 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Before you go looking for the cause of this, you need to understand what CO is.

To put it in simple terms..........

HC is basically unburned fuel so you would be looking for causes like misfire, timing, vacuum leaks, etc.

CO is basically burned fuel, just too much of it so you are looking for things that would cause a rich mixture or possible Converter issues but that would usually set a P0420 code.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.


Aug 9, 2016, 8:35 AM

Post #8 of 13 (2727 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Everything you stated is precisely why I came here. I will never know for sure anything that was done and covered up. I just want to get it through emissions without a shop.

I knew it was rich.. However was unaware that unburned fuel was HC. Blows me away it passed HC with that bad cylinder. So I have to lower the amount of fuel going into cylinders. Timing is not adjustable. Is there a control unit for the fuel injectors or somethng like that? The P0420 code could be there, have to get it on a code spitter. Any other things like type of gas, or an additive that can clean it up a little temporarily? Just gotta get that CO down for a few minutes.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 9, 2016, 9:05 AM

Post #9 of 13 (2724 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Oh boy. Mopars I'm just not strong in. Does this run perfectly or seem like it now just a must be tail-pipe exhaust check for the sticker.

What hurts is not knowing how long converter has been choking on too much raw fuel if that plug didn't work at all and probably didn't AND clogged if totally the PCV would alter "manifold- actual - vacuum" by all odds and wouldn't know how to self adjust a host of things - some will damage the engine left too long almost all would kill the converter if too long as well. I'm not sure how to tell if it's right running now to just drive it and see or start spending some bucks - right converter wont be cheap nor solve the way this runs for a 1994 I'm pretty sure.
Do you know you location's inspection rules? By that said earlier if you attempted to correct the problem and the car must pass all safety anything anyway you get a break and legit sticker to be able to use it or do where I am, Massachusetts - the world's most vicious place for stickers short of probably California.

It might be OK and self fix now with things found and done but hasn't had time or a good run to know for sure. That's why they allow the grace period only up to a point.

Again - if running real well now it could be on the mend just still overloaded with junk (raw fuel) and carbon still burning off. Actually surprised exhaust isn't restricted or parts so now. Check that.
This whole list of check could be quite lengthy.

2nd again: If running well now the sludge is still there. DO NOT FLUSH THAT OUT! I YOU know think this car can be ok someday just change out oil and filter real frequently so sludge will slowly dissolve and caught in filter not too fast. The additives in new oil proper type and rating are cleaners alone. Additives to do that are not a good idea IMO.

One would be use ATF for one qt of oil and only drive a few hours and dump that and still don't suggest that.

I feel for you, you don't know what someone really flucked up already making this a total nightmare now,


kev2 profile image

Aug 9, 2016, 10:01 AM

Post #10 of 13 (2715 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

wiith little history and a OBD1 system lets do BASICS.

plugs are they firing? correct plug? any looking fouled black or wet?
fuel pressure - then with KOEO observe pressure drop post results.
ECT, coolant temperature be sure its reaching temp, no removed t'stst. unplugged sensor etc.

then check for codes - did the failing emissions test station list any codes?
Is the o2 sensor 1 or 4 wire?
Reading the CHECK ENGINE Light
The "CHECK ENGINE'' lamp has two modes of operation. They are as follows:
  1. Diagnostic Mode — The SBEC can show fault codes by means of flashing the check engine lamp on the instrument cluster. To activate this function turn the ignition key on-off-on-off-on within five seconds. The check engine lamp will then come on for two seconds as a bulb check. Immediately following this it will display a fault code by flashing on and off. There is a short pause between flashes and a longer pause between digits. All codes displayed are two digit numbers with a four second pause between codes. An example of a code is as follows:
    1. Lamp on for two seconds, then turns off — lamp check.
    2. Lamp flashes 5 times, pauses, and then flashes once — code 51.
    3. Lamp pauses for four seconds, flashes five times, pauses and then flashes five times — code 55.
      The two codes are 51 and 55. Any number of codes can be displayed as long as they are in memory. The lamp will flash until all of them are displayed.

Ultimate Carjunky / Moderator
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Aug 9, 2016, 4:44 PM

Post #11 of 13 (2701 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

EGR doesn't come on at idle. Faulty EGR would cause high NOx. The CO is high because you have incomplete combustion of the fuel/air charge. Many things can cause that such as low manifold vacuum, faulty O2 sensor(s), ignition or timing issues, and ect. Someone is going to have to connect up a scan tool and look at some data stream information to figure out what is going on. An experienced tech should be able to isolate the problem.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Aug 9, 2016, 9:13 PM

Post #12 of 13 (2686 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

No known codes from smog technician, and it looks like the emission waiver is granted when she spends another 150, which it sounds like she is going to do tomorrow. It will then be granted emission immunity for life. Hopefully the techs will do the scope, and code scan first. I am thinking the list is gonna be a mile long, or almost nonexistant. I greatly appreciate all the time and information everyone has contributed to this. I will post the results when I get them.

EDIT... Had her run the key diagnostics and she has codes. However she only sent me 5 numbers so not sure if they are accurate as I dont lnow which ine she missed. She sent back 3 3 3 5 5

(This post was edited by Rob0107 on Aug 10, 2016, 2:30 PM)


Aug 11, 2016, 7:26 AM

Post #13 of 13 (2625 views)
Re: 1994 chrysler new yorker 3.5l v6 failed emissions. Sign In

Ok.. So she has to wait on shop do to finances. O need to get the other information about the number of wires on the sensor and such.. I do have this much so far though...

Plugs dry and did not appear fouled.. Gap was even good except impacted lookng plug, and one other had build up between the arc area... And now remebering that.. It lokely was not firing either.

3 codes... 12. 33. 55. Does that say much?

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