I just finished installing a new 350 in my 91 TA. I previously had a 305. I installed the same intake(along with the 19lb/hr injectors. At 50 psi) same everything. Its an LO5 shortblock with stock 350 tpi heads. The cam on this thing is beyond just mild. The engine has 35 miles on it and is failing for carbon and I belive Nitrates of oxygen. (I havent seen the report yet). The cat is relatively new but it has been run on the old 305 that was blown to hell. Could anyone please explain what is going on, or theorize. I'm at a loss and cant spend anymore money.

 

Did you change the prom from the 305 to a 350 one?....If not do so, also to pass emissions you could lower your fuel pressure and run it lean, just to pass!

 

PROBLEM #1 ecm's do not recognize engine size,you are asking it to feed a larger engine with the original configuration.#2 50 psi sounds a bit rch even though you are using 19lb/hr instead of the 22lb/hr injectors.two things to correct it.either swap back to a mild cam an go with the 350 injectors and prom or have a prom burnt for your application using the 19lb/hr injectors.they theoretically should be able to support 300hp so you might be able to use them.post your specs on the cam(lsa,in./exh. duration #'s)either way you are gonna spend a few bucks more to figure it out.

------------------
87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch&t-stat,tb bypass,accel supercoil,cap& rotor,slp 3in. catbcak,a/c delete.

SHE IS GONE BUT I KNOW THE GUY WILL GIVE HER A GOOD HOME.

best e/t:
3653lbs./full tank+ driver.
14.10@96.53mph 2.01 60'

 

Sorry I typed my last post way too fast. I meant this cam is really mild. Its the stock LO5 cam. Its not just mild its supermild. I have been told on a couple occasions that The chip/computer is no different between 305 and 350. Also wont leaning it our too far make emissions worse? Heres my results.
<table border=1>
<tr><td> </td><th colspan=3>15 mph</th><th colspan=3>25 mph</th></tr>
<tr><td> </td><td>limit</td><td>reading</td><td>result</td><td>limit</td><td>reading</td><td>result</td></tr>
<tr><th>HC ppm</th><td>128</td><td>161</td><td>FAIL</td><td>123</td><td>166</td><td>FAIL</td></tr>
<tr><th>CO%</th><td>0.71</td><td>0.36</td><td>PASS</td><td>0.69</td><td>0.57</td><td>PASS</td></tr>
<tr><th>NO ppm</th><td>970</td><td>3129</td><td>FAIL</td><td>878</td><td>2535</td><td>FAIL</td></tr>
</table>

Hope that will help somebody figure this one out.

[This message has been edited by nebulous (edited October 19, 2001).]

 

8 5.7 MD8 A/Trans Prom codes, 4307ANJF,4312ANJA,1350AUJP
8 5.0 TPI MD8 A/Trans Prom codes, 8210ANHY,5672ATNY,9521ANJB,
6212AWLT,3164AXYD 305&350 PROMS ARE DIFFERENT!!!!!

 

what do you have the timing set at??? also do you have the other gasses for the test??? if the last engine was misfiring bad enough it could take out the cat in a short time... seeing the other gasses would help alot though (co2 and o2)...

zroc

 

Timing was set at 6degress but it creeped a couple degrees retarded by the time it was tightened down I think. The chip in it is some performance one that the previous owner installed. As far as other gasses, thats all thats the inspector gave me on the DEQ sheet. So maybe those arent checked??? Well the old engine was on this cat for about 500 miles. Two of its rings were blown, but it got around for a while. Would you say that would kill a cat?

 

This might sound stupid but it is the easiest way to pass. Just give the inspector $20. I know of several people in my area who will do it. I am sure there will be people in your area who will do the same.

Good Luck to you

------------------
1989 GTA Trans Am
350 5.7
-----------------
Hypertech Stage 2Chip
Low Temp Thermostat

 

Speaking from experience (unfortunately), even as short a time as 15 minutes blowing oil smoke through a cat will do permanent damage.
Set the timing right, and reduce the fuel pressure to around 40 psi, then retest it, if it fails, then most likely the cat is toast.

Cheers

Richard

88GTA (same engine as the guy posting), 350, LO5 cam and heads, ported plenum, coolant bypass, no A.I.R, dynomax 3" intermediate pipe, hi flo cat (wonder why), flowmaster 80 series muffler, 98 T/A tips.

 

As for the $20 bit. Unfortuatly in my county the inspectors cant give out passes. The information from the government sniffer goes directly to a government computer facility to get passed/failed and the results are sent back. They not only have to be low enough they have to be in range for the car, so the only way that will work is to put a clean running thirdgen on the dyno and scan the barcode from my car.

As for the oil smoke misfortune. 500 miles of oil smoke might kill it then? The reason I would be really pissed off about that is I did something stupid when I first got It welded and the next day I had to go get it rewelded. If Ive got to pay for that again... WEll I think I might rather just kill myself.

 

Make sure the timing is right, and the balancer hasnt slipped. Also check for any vacuum leaks.

 

There was one possible small leak. I need to drive it around at 15 and 25mph to see if the RPM numbers match with when they tested it.

 

I know in New Jersey the inspector must enter the engine size for the car. If you have already inspeced the car before the information for your car may be already saved the comuter may be using 305 standards instead of 350 standards. I know when i went from a 2.8 to a 5.7 they didn't recheck the engine size and tested it under the 2.8 standards. I failed miserably. I don't know if you used all knew emission parts but the egr valve has a lot to do with Nox. If that isn't working you will see nox numbers like that.

 

They were testing it as a 305, but a 350 isnt 400% worse in emissions than a 305. Most people I know have said that a 350 should be able to pass the 305's emissions test if its running properly. I ordered a new chip made for a 350, checked the timing, and fixed a couple odds and ends related to vacuum. We'll see.

 

Throw him a 20 most likely he will pass you, if he's smart he knows the trick, he'll go inside the car and while its got the thing stuck in the tailpipe he'll turn the steering wheel from side to side. Almost every guy in las vegas will take a 20 to pass you so i think it'd work for you.

 

nebulous,
Up here in MA we've got a similar insp. system as you do. You're right, it's not as easy as just slipping the inspector a $20. That might work for some safety items, but for emissions it's beyond the inspector's control. (Gee, thanks Big Brother! )

I was an inspector for roughly a year and learned a little bit about what causes emissions failures. Your NOX readings are WAY WAY too high. From what I understand, NOX is high when cyl. temp is high. What kind of emissions test is it? Is it a two-speed idle or is it a transient test (on a dyno)? I'm guessing it's a transient test since you included MPH in the chart. Did the inspector put a fan in front of the vehicle during the test? I've seen cars (MY 87 IROC) fail for NOX simply because there wasn't a fan in front of it during the test. That might not be the whole problem, but it'll probably make a difference. Like 88GTA305 said, double check your ign. timing, turn back your fuel pressure and seriously consider getting a new cat as well.

Make sure the inspector enters your engine size as a 350 instead of a 305 also. Again, that certainly won't solve the problem, but it won't hurt.

Either that, or just move to a state where they don't check emissions!

Rick

 

Well the engine is higher compression. I suppose that would raise combustion temps. Its 9.6:1 rather than the stock (I think 9.2 or so?). I called the DEQ(virginia official tree huggers) and they said I can get a 350 emissions sticker from my dealer if the engine I put in was available in my year. It of course was not. I called my dealer anyway and they said the emissions sticker for that car had been discontinued. Sounds like a load of crap to me but thats what they said. Ok I'm about to suggest a really stupid idea so be warned: What would happen if I just unplugged four of my injectors or something? Would that be cleaner or way more dirty from the extra load?

[This message has been edited by nebulous (edited October 31, 2001).]

 

I put the same L05 in my 87 Formula, TPI, and previous 305. Everything is the same except I put in an LT1 cam from GMPP. Computer is same as 305 and fuel pressure is stock. I passed Ohio emissions as follows:
HC 103.6 Limit 148
CO .58 Limit .94
While the Ohio test seems less strict as compared to VA, these numbers are much lower than yours. My catalytic converter is original from 1987. I set my timing as far as advanced as possible until in knocked, and then backed off a degree. It sits aprox 12deg, but thats a guess. I bet you engine, converter and timing is ok. Something in the fuel delivery is off, possibly bad infector, MAF etc.
Good Luck

 

I too put that same L05 long block in my '89 TA with all the original 305 electronics and intake (with the exception of the knock sensor). The original chip and injectors work fine for the engine. Not only did I pass emissions here in washington, but it also passed just fine in the SF bay area (where i moved here from). This would suggest a problem with a periferal (such as a cat!).

PS - does anyone have information on the stock L05 cam? I can't find any info online and GM won't tell me anything. Any recommendations for a better (though not too aggressive) cam?

------------------
'89 TA - 5.7 TPI (L05, was originally a 305TPI), T5-WC, 3.08 Posi (Drum)

 

Turned out to be the cat. Although that was two years ago and I failed again, but not nearly as bad. Think I just need a tuneup. As for the LO5 cam specs. I emailed Scoggin Dickey's tech department and they sent me this...

lift is .350 intake and .385 exhaust. The duration is under 200 degrees
at .050.