Emissions failure questions

[spaceghost]

My '93 Eurovan recently failed Colorado emissions on both CO (barely) and NOx (by a decent margin). I took it in to a shop to have them look at it and the graphs the inspection place gave me.

The shop told me that the CO failure may be due to the fact that I'm using Bosch Platinum spark plugs, as the EVs "don't like platinum". I changed my plugs a little over a year ago, and got them from BusDepot.com, on their recommendation that the Bosch Platinums are as good as it gets for the EV. I've never heard of platinum spark plugs negatively impacting emissions, either. Is there any merit to this? Could spark plugs with platinum electrodes really cause increased carbon monoxide emissions?

They said the NOx failure was more likely due to a failing catalytic converter. I will have to sort that out as well. Are CARB-compliant cats physically different from EPA cats (i.e. is the problem simply that the van's current one is not CARB-compliant, and does the difference actually cause a noticeable change in the vehicle's emissions profile)?

[jjvincent]

A CARB or EPA typically look the same. It's one costs more and is different internally. In the end, if you have a non CARB EV, then get a non CARB CAT. From what it sounds like, you have a failing cat and thus why yours failed the tailpipe emissions. As for the plugs, I've never heard that before unless your plugs have a ton of miles on them and they are starting to misfire.

Since you have pre OBD2, then you don't have misfire detection along with failing CAT detection.

[spaceghost]

Thanks jjvincent. I ask about the CARB vs. non-CARB thing because Colorado now follows California regulations and if I buy one in-state, it has to be CARB-compliant, which made me think that maybe they base the emissions standards off of what a CARB cat-equipped vehicle should produce.

[rocknroj]

thats not the recommended plug for the ev.. Supposed to be ngk.

try fcpeuro for parts.. they know their stuff.. busdepot is for the old air cooled stuff. Spark plug temperature does matter so factory recommendations are best.

Spark plug wires are known failure point with intermittent arcing as they get old and bounce around.. You can test these in the dark with a water bottle, an insulated screwdriver and a bit of courage... plenty of web stuff on doing that.

Biggest problems with these cars is lack of required maintenance and bad workmanship by previous owners and/or their hires.

usually vacuum leaks, loose grounds, or other messed up wires.

quite a bit of info available online

access to the bentley guide and the vag com software is essential.. vag com enables you to read the signals that the ecu is getting so you can track down component issues. There are quite a few variations and mid year changes on the 1993 as well as CA vs 49 state versions..

rich conditions can be caused by many things. The ecu increases the fuel injector duration based on the readings it gets.. primarily engine temp and vacuum readings.. a failed o2 sensor is another culprit but check the wiring first.. once again the vag com software will tell you if these things are functioning correctly..

some of the ev's of that year have a co adjustment. the plug is sealed and messing with it is ill advised. It is located on the air intake temp sensor.. There was a mid year model change.. early vehicles have it later ones don't.. the ecu vesion number changed as well. If the plug is open and someone messed with it that's a clue.. I believe the cutoff on that is dec 1992 manufacture date after which that adjustment is gone..

wiring, especially grounds can impact operation as well as vacuum leaks as they can throw off the ecu and cause it to run rich... many things to check.. and plenty of write ups.. basically want to go through a thorough inspection on the grounds and vacuum lines as a start.. and get the proper plugs, perhaps change the ignition wires as they go bad, replace the vacuum lines all of them including the connector to the ECU.. a bit of a pain...and make sure the one way valve to the vacuum canister is working and oriented correctly.

check the connections at the o2 senor plug..typically the wires can wear and break where they go into the connection... or worse from morons that cut the insulation to backprobe...bad bad.. but often done..

there is a hidden ground that is tough to get to and tighten. and seldom discussed. Its on the passenger side down below the exhaust manifold.. Its a stud with a nut and a ring connector.. clearance is really tight and a stubby thirteen or a quality ratchet with a tight click (you can only move a few degrees at a time. You cannot see it from the top but can feel it if your arms are long enough. It provides the primary ground for the ect, tps, iat and perhaps others. Its called ground connection 1 and identified as number 94 in the bentley diagram.. Mine was loose from the previous owners mechanic, I am guessing for the reason cited above. Once I made that tight car ran way better...

Another thing to try is to clean the IAC. disconnect intake air hoses to keep the cleaner and gunk from going into the throttle body. spray with some brake cleaner, blow the air out, repeat.. open and close the valve by turning the ignition on and off, spray again... repeat.. make sure the black junk doesn't hit you in the face.. blow it out good before reinstallation.. I put a small amount of lubricant on the mechanism as well. The IAC blows extra air into the intake so if its not working effectively could make things rich. Cleaning it also helps with the stumble/die at stop light thing..


Make sure the car is properly warmed up before getting the smog check again.

[wannabecamper]

[spaceghost]

Thanks for your insight, wannabecamper, and for the thorough reply, rocknroj. I will check the vacuum lines and O2 sensor connections for sure.

[BatesEV]

Here is something you can try to help with the CO. I’ve been running ngk and have had good luck with the plugs. I know here in California depending on the smog tech if he sees a replacement part it must have a CARB number. I had to replace mine for a second time.

[spaceghost]

Interesting, thanks! Where is that screenshot from? It looks like a nice resource.

[BatesEV]

Here is the other screen shot. It was something done by the Canadian air resource board to solve the issue with the van emissions on the early models

[bcolins]

[SambaBurnsRed]