Ok guys,

So i have a 1986 carb'ed z28 with a 305 and manual transmission.

I live in CA, and recently went for smog, here are my numbers:

When I took it to get it smogged after a 30 min drive, all of the numbers were High:

Comprehensive Visual Inspection:PASS
Functional Check: FAIL
Emissions test: FAIL

15MPH
HC (PPM)
MAX:126
AVE:41
MEAS:158

CO(%)
MAX:0.79
AVE:0.13
MEAS:0.84

No (PPM)
MAX:1097
AVE:399
MEAS:1050



25MPH
HC (PPM)
MAX:101
AVE:29
MEAS:101

CO(%)
MAX:0.59
AVE:0.11
MEAS:0.55

No (PPM)
MAX:927
AVE:332
MEAS:777


Only thing it failed was the "IGNITION TIMING"

and at the bottom it said
"This vehicle has failed the ignition timing check due to engine RPM being to high"

If by "engine RPM" they mean idle, then yes, it was about 1000...Im not sure why, I had tuned it to between 600-700 but for some reason it sits around 1000 now...Come to think of it, I fixed a MAP sensor problem after tuning the RPM...could that be the case?

Now i DID HAVE THE FAN ON the entire time, and the temperature was about 160* on the gauge.

I was advised that that was the problem, and that if I fix my stock fan switch and go use my free retest, that I would most likely pass, as the engine constantly thought it was in warm up mode, thus polluting more. So i replaced the fan switch with a 215* switch, and all runs fine now, heats up, cools down, and repeats (although it seems to work around 230* according to the stock gauges).

Does this sound true? i don't want to waste my re-test if im going to fail again. What would you all suggest?

 

cold running engine could well be the culprit - I'd get that timing/idle issue resolved and try again.

wouldn't hurt anything to dump a can of the $9 guaranteed emmission inspection stuff in the tank as well - on the shelf at any auto parts store.

 

if you changed the sensor after tuning that could be your problem i would retune the idle and then like he said ^ get a bottle of injector carb cleaner i passed emissions in jersey but i simply installed a full msd and it cut my emissions in half if not more

 

Ok, I might have to make a new post for this, but I figured Id ask herejust to see if it gets answered.

So last night, I was up all night replacing the fan sensor, I ahd to do it from the top of the engine because I had no way underneith....ANYWAY, PITA...but it got done, and when I pulled it out, a LOT LOT LOT of collant poured out everywhere

Anyway, long story short, I installed the new one, took off the thermostat housing and double checked what thermostat I had (195*), and I now have a 215* fan switch...

Now at first I thought it wasnt working, cause on the gauge it was getting about 240* before it colled back down, but then I found out the gauges seem to be inaccurate...so whatever.. I also topped everything off with coolant.

Now the next day, I am ready to drive for an hour and head to the smog place. So I fire the car up, and it goes to about 1500 RPM..and was really bumpy...it actually kinda felt like it did when I had my firing order off (but I checked all the spark plugs, thinking I might have hit one removing the fan switch, but they were good)....not BAD BAD but you could tell it was no longer running smooth...

I figured it was warming up, but after it warmed up it dropped down to 1100 rpm... I decided to take it for a drive anyway, and went about 20 miles on the freeway and pull back into my place...I noticed that above 2000 rpm, the bumpiness seems to become smooth...but after that long drive it was still doing that...

Now I look under the car and see its leaking coolant...which looks like it was from the CAT??? I figured it was still drip off from the fan switch being pulled out...but now that seems inaccurate as this was over 36 hours after I ahd replaced the switch...then it started pouring rain...

ANyway, I tiried to adjust the idle, but even when turning the screw it doesnt make a difference...its so weird...You can see the rpm needle bump too, it jumps by anywhere from a centimeter to a quarter of an inch at a time, and when Im cruising at idle in first gear, you can FEEL that...lurching forward, and such...

First off, was there anything I could have done to do this? it was running beautifully smooth before this...

Today was the last day for My free retest and my car acts up

 

The fan switch plugs into the water jacket on the passenger side head, that's why you lost so much coolant. You should have drained about half your cooland first, that would have prevented that problem. Second, your fan coming on early will help keep the car cool, though if you run a 195* thermostat, your car shouldn't run that much colder than the 195 with the fan on, especially if it's warm out or you've driven it a long distance because the car won't cycle alot of coolant at less than what the thermostat opens at. Now, couple a low temp fan switch with a 160* thermostat andy eah, you'll have a cold running engine which will bump up your emissions problem. For the rough running....I'm not real sure. Can't say I've heard of that happening from anything that you did.

 

Sounds to me like you knocked a plug wire off or loose, since you attacked it from the top. Check all the plug wires making sure they are all tight on the plugs.