88 5.0 failed emmisions.

Hey all! You probably have been seeing all my recent posts about the use 88

5.0 with t-tops that I just bought. I took it today to get the emmisions tested and failed (Tennessee). HC: 1446 (max allowable 220) CO: 2.35 (max allowable 1.20)

I emailed the guy I bought it from and asked him if he had done any mods or disconnected anything that might cause me to be dumping so much gas. I'm getting about 30-40miles for half a tank. He said he "put a 160 degree t-stat in it for more power. That keeps it in openloop at idle which is a very rich condition. Try putting in a 180 or 190."

Would just the thermostat cause it to dump hat much fuel and get readings that bad? What is the stock thermostat rated for and I'll pick one of those up at autozone? I have been driving it out in the hot sun with the AC on and I haven't notice it running any hotter than my other mustang.

If the t-stat woldnt cause this much of a bad reading then I can take it to the local BP shop and for $70 they said they can debug the vehicle and tell me exactly whats wrong that is causing me to fail.

Thanks!

--Cameron

Reply to
Cameron
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The computer will cause the engine to run rich until the normal engine operating temperature is reached which is approximately 190 degrees. Running rich will definitely affect the emissions readings. Also, running the engine cooler causes more wear on metal parts and bearing surfaces. You should change back to the OEM thermostat for this reason alone. It could very well solve your emissions problems too. Until the thermostat is replaced I wouldn't even bother with running the codes. If it still fails the test then run the codes.

Reply to
Michael Johnson, PE

Thanks for that info. I will 100% be slapping a new $5 thermostat from autozone in there today. I was just wondering if that alone could cause such a drastic bad reading?

Is there any way a regular guy like me could tell if it's helping alot, once I put the stat in, before I take it back to the emissions place?

I figure I will dump some fuel injector cleaner in there while I'm at it and maybe change all the spark plugs. Then I'll fill the tank back up and cruise around for a bit. If I drive 20 miles and dont use much gas then I can assume it's better and I'll try the emissions test again tomorrow.

Reply to
Cameron

If a car is running rich you will see black smoke coming out of the tail pipes and/or have a faint oder of gasoline. Other than this you will need the emissions test to be sure.

An improvement in gas mileage could be another indicator. As for fuel injector cleaner, I suggest getting a can of BG fuel injector cleaner. It is a little pricey at $20/can but it works much better than the cheap brands sold at auto parts stores.

Reply to
Michael Johnson, PE

So if I run the car at idle in tmy driveway with the bunk thermostat in I should see a little smoke and maybe smell some gas?

I havnt notice any driv>> Thanks for that info. I will 100% be slapping a new $5 thermostat from

Reply to
Cameron

If it is running very rich you should.

One other thing to do is disconnect the battery for 30 minutes while changing the thermostat. This will clear the computer buffer and allow it to relearn your driving habits based on the new operating temperatures. Drive it around a few days before doing the emissions test.

Reply to
Michael Johnson, PE

160 is too low, you can do a 180, water will still get up to 210. The thermostat just opens at 180, dosent keep the engine @180 it is just when it opens the engine will still climb on up in temperature.

Not that much, oil has almost the same properties over a 50 degree range.

Reply to
Zmegile

If the cooling system is operating properly the temperature doesn't fluctuate much at all. It should be very near the thermostat rating under most driving conditions.

It isn't the oil as much as it is the temperature of the metal. Tolerances are set assuming the engine will operate at certain temperatures.

Reply to
Michael Johnson, PE

try measuring it, instead of guessing.

When metal heats up it expands, not contract, therefore clearance will be fine from 160 to 220 range. How much will it expand ? less than 0.01 thousandth of an inch for steel. People measure clearances when engine is cold.

Reply to
Zmegile

I have. A properly functioning cooling system will see little fluctuation under most operating conditions.

Clearances between dissimilar metals vary with temperature because they expand at different rates. The engine was designed to operate at a specific temperature. For an older 302 the tolerances were more forgiving but in todays engines tolerances are tighter and operating at the specified temperature is more critical. Also, running the engine rich washes down the cylinder walls so there is less oil available for lubrication. Over time, this can increase wear on the cylinder walls.

Reply to
Michael Johnson, PE

I've changed the 160 stat out with a stock 190 one. We will see tomorrow morning when I get it tested again what my results are. :-)

Reply to
Cameron

With 160 stat: HC: 1446 (max allowable 220) CO: 2.35 (max allowable 1.20)

With 190stat today: HC: 651 (max allowable 220) FAIL CO: 0.22 (max allowable 1.20) PASS

The stat makes a gigantic difference. The guy at the emissions place said that I should just run a bottle of "Guaranteed to Pass" through. So I have bought a bottle of that crap for $10 and will run it trough most of a tank today. I asked the guy at Advanced Auto and he thinks it will pass too by using that.

Anyone had luck with that type of a product? Worst case I'm out $10 and have to still get it checked out by a mechanic.

Reply to
Cameron

Huh! I sure am glad I live in Henderson county! No smog tests here, yet. Not that it's a concern on either of ours, but the expense and hassle is what I hated

Kate

Reply to
Kate

Did you disconnect the computer and drive the car for a couple hundred miles before the test?

Reply to
Michael Johnson, PE

Reply to
Michael Johnson, PE

No I did not. I am not even sure what you mean by "the computer". I did not leave the battery unhooked before the test. The don't hook into a computer on a 88 for the emissions test, they put a thing in the tailpipe.

I'm not sure how I would drive it a couple hundred miles either without getting harassed by the fuz.

Reply to
Cameron

The computer stores information obtained while driving in a memory buffer that it uses to anticipate your driving habits. Since the engine was running very rich the buffer probably contains data that isn't up to date now the thermostat has be changed. Disconnecting the battery for

30 minutes clears all the stored data and allows the computer to recompile it based on the current operating parameters. You should do this before the next test. I'm not telling you these things just to send you on a wild goose chase. ;)

Can't help you on this one.

Reply to
Michael Johnson, PE

Oh, if thats all it takes then I'll leave the battery unhooked before I run out the half tank of gas left in it. Then tomorrow I'll fill her up and go over for my next test.

If I still fail (h>>> Did you disconnect the computer and drive the car for a couple hundred

Reply to
Cameron

The posters keep trying but here are steps again (with reasons for each)

  1. disconnect battery or pull computer fuse for 10-15 minutes. This erases computer memory.
  2. Drive car at least 20-30 mins normal driving cycle. Stop/go, city streets, some 55mph+. This causes the computer to reprogram itself to the input it is getting from various sensors (temp, O2 probe, knock sensor, MAF, etc) and adjust ignition and fuel injection for most efficient operation

Both of these steps are important. If you just clear the computer then it starts of in what might best be called a "fail safe mode" which is rather inefficient and may result in increased emmissions.

Best of luck Howard

1989 5.0
Reply to
Howard Nelson

Failed. Today I drove it for about 30 minutes after unhooking the battery for 30 minutes. I also filled up a new tank of gas after the tank with the "Guaranteed not to pass" was almost empty.

The HC was 691 where yesterday it was 651 and the CO was .44 where yesterday it was .22. I drove downdown to the FREE mechanic paid by the state that will tell you whats wrong. What a waste of time, he couldnt tell me anything. But at that place my HC reading was back in the 1300s and the CO was 2.0.

I have the mustang now at a local mechanic that says for $70 he can tell me whats wrong, or whats leaking, etc. If that fails I guess anyone that wants a nice t-top mustang that will never pass emissions can buy one on ebay from me.

--C

Reply to
Cameron

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