Birdman66

Hi,

I just had my 93 Trans Am tested and it failed emissions. The only part I failed was the HC's.

To give you a heads up on what I have done to this car I have replaced the following components due to poor maintenance and due to the car being left under a flooded underpass.

1. New fuel pump, tank drained.
2. New opti (Delphi) new plugs (AC-Delco), wires, coil, ignition module.
3. All news sensors including O2, MAP, Knock, ECT, IAT, TPS, IAS.
4. New injectors from NAPA.
5. New cylinder heads due to broken exhaust manifold bolts. Note: heads from GM Parts Direct.
6. New exhaust manifolds as broken bolts caused manifolds to warp away from heads at rear of engine.
7. Intake manifold cleaned by NAPA to remove particles from EGR passages. New EGR valve.
8. New radiator, new coolant level sensor, new radiator hoses. Engine flushed to remove old coolant and any possible contaminants.
9. All new fuel lines from front to back including the nylon lines.

I hope this is a help so that I can narrow down the suspects of what is still wrong with this car.

As I said in the earlier part of the post I failed the HC's part of the test. I have uploaded to this post the two sheets from the testing facility.

Now for the conditions today when I had the car tested. It was 24 degrees out and I let the car warm up for twenty minutes and then drove it out east of town for twenty miles at 75 miles an hour. I then got on the toll road and headed to the emission center at 75 miles per hour. The whole time I was on the highway the temperature never went above the has mark between 100 degrees and the middle one at the top of the gauge. I think that is 220 if I am not mistake. The only time it hit the 220 mark is sitting in my driveway. Once it went a little beyond the fans kicked on and the temperature dropped back below 200.

When I got to the emission place the temp was still between 100 and the next has mark up. I only had to wait two minutes to get in. While waiting the short while it never got back up to where the fans would turn on.

I have done no modifications that would make the car stay cooler than normal. The thermostat is 180 degree, stock replacement water pump, and stock replacement radiator from NAPA.

I hope that the information I provided helps.

Thank you in advance.

Paul Bell

iTrader: (9)

Welcome to LS1tech!

You've certainly done a lot of work to this car. How many miles and what's it's condition?

How does it run? Is the check engine light on? Even if it's not, have you scanned for any codes?

You've replaced just about everything that could cause high HC's. A bad catalytic converter can cause high HC's and it's pretty much the one thing you haven't replaced.

LIQUIDZ28

+1 on the cats, thats the only thing on your car that filters hydrocarbons from your emmissions.

Paul Bell

iTrader: (9)

As you car is all stock, a Y-pipe with converter can generally be had for less than $300.00. And your old cat should get you like 50 bucks at a recycler.

Birdman66

Hi,

Thanks everybody for responding. The car has 129,930 miles on it. I would say it is in fair condition. It has rust, especially around the front and rear suspension components. That's why I don't drive it too far. I'm going to need lower and upper front control arms and lower control arms in back. I will also need the torsion bar, I think that is what it's called. It is rusted out.

The check engine light is not on, There was a code for the coolant sensor when I bought it, but the clown who owned it before me must have been pounding on something and smacked it and broke the plugin part of the sensor off. Since there was so much water and mud from it being left under a flooded overpass, I opted to replace all the sensors with new AC Delco sensors. As far as how it runs it ran horrible when I first replaced the oxygen sensors. Nobody at the time could get me AC Delco so I used Bosch. Big mistake. I killed every bug for twenty blocks and it set a rich condition.

Found the AC Delco's at Rock Auto put them in and that solved the rich condition. I forgot to mention in my original post, I did replace the entire exhaust. The Y-pipe and the cat are from Magnaflow and the rest is OEM Walker.

So I'm not sure why the HC's are high, though a guy did stop by my shop when he saw the T.A. and I told him what happened and he said that unless I get that beast hot, it won't get a complete burn and the HC's will be high.

I have a 180 degree thermostat, but something told me that 195 is the factory thermostat. I asked NAPA today and they said that 180 is the factory temperature. Monday it is supposed to be hot so I'll try again.

I think I'll set across the street from the emission station and idle and wait for the car to go to 220 and then slowly roll across the street and get in line.

Thanks everybody for your help and I hope that today's reply gives you enough info to formulate some ideas.

MertezWS6

iTrader: (8)

Welcome to the site! That sucks that Colorado has emissions wtf, I thought it was all tree's out there lol what are they worried about. If you have access to a scan tool you can always look at the front and rear O2's and see how efficient your cats are working. The rear O2 should switch slower if not at all compared to the front.

LIQUIDZ28

I actually retail Magnaflow and their cats arent as good as factory cats for keeping your carbons down. they are good for cars that have obdII where the emmissions guy just plugs in and says "your good" not for actual tailpipe readings, as they flow too quickly to filter as good as the stockers. ... sad face. find a county that does not do emmisions and register there, you may be able to register @ a po box in that county. (the cheap way). or replace the cats.

Birdman66

Hi,

Thanks LiquidZ28, I have heard both pros and cons for e testing with Magnaflow. I think I'll go to NAPA tomorrow and get the Walker factory setup that comes with y-pipe welded to cat.

Today my new intake elbow from Summit arrived. I purchased a new one because there was a tear in the bottom with a piece of rubber missing. Several people told me that this was allowing unmetered air into the engine and the computer was trying compensate. My engine has been idling a little rough but not as bad as before when I had the Bosch O2 sensors. When I put the new elbow on and tightened everything up and plugged in the IAT sensor, I started the car and what little rough idle had been there was gone. Now this car idles like Cadillac and has even better throttle response than before.

Once I get the new y-pipe and cat on this weekend, I'll go back to the e-test facility and try again. Since I was way under in CO but only .08 off in HC's, this will definitely help.

Thanks everyone for the comments and help.

One other thing, not as critical, but I need to replace my upper and lower controls up front as mine are rusted and have stress cracks in them.

Can anybody recommend a brand, and specifically a brand that comes with hardware?

Price is not a problem.

Thanks again everybody!

LIQUIDZ28

http://www.bmrsuspension.com/?page=p...&productid=347

Birdman66

Hi everyone,

Just got back the other day from the state diagnostic center and found out what was causing high hydrocarbons. The filler neck on the gas tank had a gash in it from being bent too much and fumes were collecting right near the exhaust pipe and when the emission guys hooked up the collector, they were going right into the machine. So order a new gas tank with filler neck.

So thanks to everyone who commented, it has been a long road just to find that simple problem that even i overlooked. And to think had that tank out and didn't see that. Hmmm