Breakin' [California smog test limits] 2: Electric Boogaloo.
 

So my car [1994 Geo Prizm with 1.6L 4A-FE and 5 speed manual] failed smog like it always does. I would like some feedback on what I should do.
Background info: 270k on the body, unknown mileage on engine since engine is out of a 1995. Did timing belt a year ago, top end did not have anything wrong with it then as far as I can tell, but that was 11,000 miles ago.
Spark plugs: NGK BKR5EYA replaced 2k ago.
Cap, rotor, wires: Ebay stuff installed 27k ago.
Oxygen sensor: Replaced 20k ago after I failed the smog test in 2013. Installed a DENSO 234-1053 Oxygen Sensor.
Air filter: Replaced 5K ago.
Motor oil: Mobil 1 EP 10W30 with 5k on it. Mobil 1 claims it is good for 15k with their filter but I'll want to change it soon since I'm not able to run an automotive history check on the engine's VIN and the body's VIN, thus I don't know the actual mileage of the engine.
PCV valve: Replaced 23k ago. Cleaned out 5k ago. May still be suspect.
Steam cleaning: Never done in the ~30k I have had the car.
Thermostat: Not OEM, I don't have heat on downhill sections of my commute when I need heat (30F-40F outside).
EDIT: Thermostat has 16k on it. Replaced in in jan 2014.
Catalytic converters: Need to check both converters, I have a USB boroscope and an automotive lift. There is a rattling noise from one of the cats. I ran over a bucket earlier this year while doing 60 MPH, rear cat may have broken up even more. Never replaced.
Fuel economy: Averaging 35 MPG. Got ~34 MPG averaging 65 MPH on highway legs of a trip that was 100 miles each way.
Fuel filter: Never replaced.
Compression check: Need to do.
Injectors: Never messed with.
Intake manifold cleaned: Never, only squirted some throttle body cleaner into throttle body 23k ago.
EGR: Never cleaned.
Vacuum hoses: Never replaced.

Currently using the intake for automatic equipped models since my manual transmission intake hose cracked this spring (difference is that manual transmission one has larger resonator and resonator opening), I still have manual transmission intake and resonator in case I need to use that to pass smog. I can't seem to find a new manual transmission intake hose.
First test done with max smog allowed 13 degrees base timing:
http://i.imgur.com/5ECjoLr.jpg
I then drove to a parking structure and set base ignition timing to the minimum allowed value of 7 degrees and took it back to the smog station (free retests as long as you are actually trying to fix it).
Second test: Dyno printout only.
http://i.imgur.com/T6IUzrm.jpg

Past smog tests. Order from top to bottom: Smog test PO did in june 2012 at 1PM at 242k, done with base timing set at ~7 degrees; Passing smog test I did October 2013 at noon with 13 degrees of base timing and a new oxygen sensor. Failing smog test I did late September 2013 at noon with 13 degrees of base timing.
http://i.imgur.com/uH4AxVW.jpg

I think I'd want to try to figure out what temp the thermostat is actually running, especially if the lack of heat at times is a new symptom since last test.

EDIT: Thermostat has 16k on it. Replaced in in jan 2014.
The downhill part of my commute I'm talking about is the stretch from 1600 ft to 244 ft. About 9 miles long. Speed limit is 45 so over most of it and I'm alternating between coasting in gear with engine in fuel cut and coasting in neutral (no EOC because I can't bump start for the life of me). By the time I'm on the second downhill grade, it is closer to 50 or 60F.
http://i.imgur.com/bQsxEgh.png

The results as I see it show very low NOx and high HC, which indicates it is running rich. If it is running cold, you'd get this result. Is the thermostat stuck open?

Got the car up on a lift (friend owns a lift) and found a chunk of substrate blocking the exhaust.
Front face of rear cat with chunks of precat littering it. Has sounded that way for ages.
http://i.imgur.com/1sJ1bOB.jpg
Blockage.
http://i.imgur.com/XDRJxZ1.jpg

Front face of rear cat.
http://i.imgur.com/Op07UND.jpg
Not shown: Melted down precat and chunk of wayward substrate liberated from exhaust.
Think this may have been part of my problem?
I'll check compression and sensors tomorrow, it was 105F today.

Replacing the cat should help. I would think you're still running a bit rich, as Nimblemotors said. With a new cat (s?) you stand a decent chance of getting the numbers good enough to pass. If they aren't, then suspect the thermostat.

If you can get ahold of a wide-band O2 meter, you may be able to use that to see what your mixture is like. You probably want a little bit lean for economy, but generally the best emissions are right at 14.7:1, because the catalysts work best there.

The EGR shouldn't be an issue, as the NOx numbers are OK, or at least OK-ish.

Yeah, I'd replace the cats and see if I passed.

-soD

No engine off coasting with engine getting so cold the heat won't work = thermostat stuck open and it could be a contributing factor to the damaged catalyst.

regards
mech

I though that it was normal to lose heat on that long of a downhill grade when in DFCO half the time?

I think if I coasted down a hill that long in my car in DFCO that I would probably lose heat too. I know some much shoter hills where DFCO brings my engine temp readings down 10 and 20 degrees.

You are right, I was wrong.

regards
mech

I have never had much of a downhill where I could coast without building up too much speed. In my Prelude, I used to coast down a canyon, hit 90+ MPH, and coast back up the other side, but I stopped doing that before anything bad happened.

I'd hit 90 MPH if I didn't use DFCO on some hills. Terminal velocity on this hill that I have in my commute would have a terminal velocity around 65-70 MPH in a 45 zone.

More oxygen means incomplete burn, more co means incomplete burn, more hydrocarbons means fuel in the exhaust. Running rich has destroyed your cat. I think you know the general problem, just need to diagnose why its running rich. The oxy sensor should be correcting it... unless it is sending bad data. Edit: i see you replaced that.

Any news on compression test? Are you burning oil? Is the timing in spec? Ignition coil? Idk...

Map sensor? Those are pretty typical for failing.

Xposted on another forum, DannoXYZ seems to answer why the O2 can only correct so much bad info from other sensors. (thread here: Breakin' [California smog test limits] 2: Electric Boogaloo. - Toyota Nation Forum : Toyota Car and Truck Forums )


Got the car up on a lift (friend owns a lift) and found a chunk of substrate blocking the exhaust.
Front face of rear cat with chunks of precat littering it. Has sounded that way for ages.
http://i.imgur.com/1sJ1bOB.jpg
Blockage.
http://i.imgur.com/XDRJxZ1.jpg

Front face of rear cat.
http://i.imgur.com/Op07UND.jpg
Not shown: Melted down precat and chunk of wayward substrate liberated from exhaust.
Think this may have been part of my problem?
I'll check compression and sensors tomorrow, it was 105F today.

NEXT BIT OF DIAGNOSTIC INFO

Okay, did a compression check and a shallow sensor test (I can't get to the backside of the ECU so I'll have to rig something up to test the MAP. I'm an EE major, shouldn't be an issue [famous last words].
TPS:
VC-E2: 3.42k
VTA-E2
WOT: 2.75k
67*: 2.3k
45* 1.7k
23* 1k
0* .5k
IDL-E2: within specs
Coolant temp sensor: 1300 at 35C, 480 at 67C. Will revisit when I have a gasket for it.
IAT: Meter reads it as being in spec. I'll have to check again because I didn't write down the reading.


Compression test. Written as first 3 puffs and then about where I ended the test. First time running a compression test so I may not have cranked long enough, I only cranked ~5-6 times instead of the 7 my hayes said to do.
#1 : 120, 150, 180, 205
#2 : 120, 150, 180, 205
#3 : 120, 150, 180, 205
#4 : 120, 150, 180, 210


Spark plug wires:
#1 : 3.41k
#2 : 3.08k
#3 : 2.44k
#4 : 2.15k

Rear catalyst surface temps at idle:
Front was something like 130C, outlet was 160C. Couldn't get close enough to get a better reading but the exhaust seems hotter now that it used to be so it seems like my cat may be working now that that exhaust blockage isn't making the exhaust cool down before the cat.

I have some boroscope pics on another computer, I'll post them later.

NEXT diagnostic info:

Do you know what the mechanical limit for the ignition advance is? I'm thinking that if my timing belt jumped a tooth (unlikely, but possible) my maximum ignition advance with TE1 shorted to E1 will not be the same as an engine that hasn't jumped time.
Did more data gathering:

MAP voltage from sensor pin to ground:
24.5" HG: 1.48 (initially read at 1.2v but then all my readings seemed to have shifted up .3v)
22.5" HG: 1.65
22" HG: 1.69
21"HG: 1.8v
engine off~ 3.56v.
Idle: needle vibrating at around 24.5" HG.
I drove around with a multi meter watching the oxygen sensor, as it cooled down outside the engine seemed to be on the rich side of .5v more and more.

I need to find somewhere that has enough vac line that I can watch the MAP from the cabin.

I am doing some looking and it looks like I should be idling at 1.2V and not 1.48. Would this be a likely culprit?

EDIT: Okay, double checked the vacuum readings and it seems that I'm still .3v high. I'm guessing that my MAP sensor is a POS.
Readings are taken by putting a sewing pin into the signal pin of the connector and the same for the ground pin on the connector.

I'm suspecting that the MAP may be erratic about readings. It initially read out at 3.4v then suddenly went to 3.56v.

I think I'll go to the scrapyard tomorrow and try to find a working sensor.

EDIT: IF the limit is 17 degrees or thereabout, that is about what I can set my timing to as max. I'll double check it, it may be closer to 20. I remember looking at another thread and it looks like that a jumped tooth will throw off camshaft timing by 7.5 degrees.

Oil burn rate looks to be low.

Well that compression test, if it is correct, definitely shows a problem.

Actually compression is within 5%.

If it is an obd2 (post 95) an Elm 327 dongle can give you map and a bunch of other data on a Bluetooth device running " torque" free app.

There is no requirement for installed equipment except egr to work in CALI. it just has to be installed and look functional

Hmmmm...
Map seems to be ok, compression is quite good. Are those ignition components any particular brand or are they cheap chinese crap?

Yes, you are right. I read it too quickly and compared the 120 and 205. Gaa! Hate it when I do that!

I've noticed that my tailpipe is hotter now that I cleared out that substrate. I'll try to smog it tomorrow.

100% Chineseisum. What really stumps me is the fact that I'm beating the old EPA highway numbers.

Turns out that my exhaust manifold is leaking.

It could very well be that the restriction was causing really poor flow through the combustion chamber. The engine would require more power and thus fuel.

I smogged the car today. Failed with 120 HC, 15% CO2, .2% CO, 670 NOX, and 0% oxygen. Still rich or lazy cat?

Yes.
I would expect a new oem cat would return better results than one that has literally fallen apart. HOWEVER replacing a cat without resolving the cause for failure is an expensive road to go down.
I think I would want to drive the car with a scan tool and atleast monitor what the O2, and fuel trims are doing before getting serious about a cat.
I saw that the t-stat was replaced 16k ago, but didn't see what temperature it's running for you. (I've replaced the Stat in my Saturn twice, first replacement was down into the 170s after just a couple thousand miles, second one has been in there for probably 70k now)

http://ecomodder.com/forum/showthrea...age-27192.html

You are in luck, I can actually pull data off of the ECU to figure out what I'm dealing with.

I suspect the cracked manifold (being replaced tomorrow), an extremely lazy oxygen sensor, and the PO running it without a thermostat contributed to the melted down precat, I'll find out more when I have a chance to run the TDCL datalogger.

Changing the catalytic converter BEFORE knowing WHY the engine is running TOO RICH is sorta akin to slapping on a larger bandage™ to a hemorrhaging artery and expecting things to immediately get better.

tl;dr My car has ran well enough that this is the first time I've had to do troubleshooting besides replacing an old oxygen sensor or plugging my MAP sensor back in, as such I don't know what I'm doing the way a grizzled veteran would.
That is why I'm waiting. I was asking if it was running rich or if the cat was old, I think that it is still running rich but I haven't looked at tailpipe emissions results enough to be able to tell the difference TBH. I have until November to pass smog, I smogged it as early as possible so that if I fail smog, I can fix the car at a slower, more affordable pace. I don't have much experience dealing with EFI, most of my time wrenching on emission controls was done on feedback carbs trying to get my dad's car to pass. I don't know much about fighting EFI systems.

Because the engine's ECM controls everything in EFI systems, begin looking at the sensors providing "input" signals INTO the computer, such as wheel-sensor, manifold air density, catalyst hi & low, coolant temp, etc.

Do you have an OBD reader? Something to tell you what the ECM thinks is wrong and thus causing too rich A/F operation?

Yes and no. The ECU pretty much refuses to throw a code unless unplug something it can throw a code for, BUT I can watch live sensor data. See this thread: http://ecomodder.com/forum/showthrea...age-27192.html

I attached a datalog of what the ECU is outputting.

I'm using CarTester8000StableEdition_English, going to file-> view and viewing the .ctr extracted from the attached zip file.

PM me if you just want me to send you a dropbox link to the program.
OBD-1 Serial Interface - Toyota Wiki

Things that can make the ECM *think* the A/F mixture should be RICHER than normal:

1) Engine HOT, ie: high coolant temperature (sensor bad).
2) High engine LOAD, ie: high TORQUE loading (engine rpm does not match throttle position).
3) MAP sensor is dirty.
4) Front Cat-sensor bad, ie: ECM thinks cat isn't up to operating temperature yet.
5) Back Cat-sensor bad.
6) One (or more) fuel injector(s) partly stuck open.

Unburned fuel has decreased, unburned oxygen is decreased, more carbon dioxide (more fuel being burned), less carbon (soot), nox is still high (this is actually good, it means the combustion temperature is nice and hot).

I would do a once over on the spark plug gap, make sure the coolant temp sensor is ineed working properly. Replace the cat.

Or... http://ecomodder.com/forum/showthrea...-do-23483.html

I see you have have never cleaned the intake or injectors. At the minimum i would recommend buying a bottle of chevron injector cleaner. If you feel ambitious, remove the intake manifold and clean with a toothbrush and carb cleaner, or take a shortcut and just to the throttle body.

I'm waiting on gaskets so I can crack the intake open. DIY Intake Manifold Interior Cleaning - Toyota Nation Forum : Toyota Car and Truck Forums