CSUS_Dude

About 18 months ago I was given an '88 V-6 5-speed that needed some work. It has 106k miles and I've just finished getting it road worthy. In order to get the car registered, I need to get it to pass smog here in CA. The car has been basically sitting in my yard for the last 18 months except for an occasional trip down the driveway. I replaced the plugs, wires, and air filter and the car runs pretty good. I got a smog pre test and both the Hydrocarbons and CO were too high:

Hydrocarbons allowed at idle=120
Actual=270
Hydrocarbons allowed at 2500=140
Actual=225
CO allowed at idle=1%
Actual=3.13%
CO allowed at 2500=1%
Actual=1.76%

The timing is set at 12BTDC, which they said is in spec. They said its probably running too rich and it could be caused by an ignition problem. Also, the car likes to "buck" anywhere under 2000rpms at about 1/2 throttle when its under a load. What can I test/replace? I'm not very familiar with Chevy's injections systems.

Thanks in advance,

Brandon

FAST RS

Put it at 10BTC on the timeing that will help some. Also do the cap and rotor look ok? put some emmision stuff in it like 104 emission i think its called or auto zone sells some stuff in a little red bottle 10 bucks its suspost do wonder i "herd". did you put Fresh gas in? check for vacume leaks replace the O2 sensor and fuel filter and spray throtle body cleanr in it. pretty much do a FULL tune up. i think tom p has a list of what to do. and jsut go over that and do what you havent done

TomP

High HC tells you the combustion process isn't completing. This usually points to a bad ignition system (bad plug wire, overgapped plugs (spec= 0.045" gap), etc). One misfiring cylinder can shoot the HC's off the chart enough to cover 20 properly-running cars!

High CO tells you the engine's not getting enough air as it should. Usually all this requires for a fix is to change the air filter with a new one. If you have a K&N, put a new $6 K-mart one in, and take it back out after inspection. Call it your smog filter if you want

The combination of high HC and high CO screams out "running rich!" In contrast, high HC and normal CO would mean "running lean!"

Also FastRS is right; try it with your timing at stock spec. Emissions stations are "allowed" to pass a car if the timing's a bit off... that's what the guy meant by "in spec"- "in the allowed range".

I just figured I'd cover the emissions tech for ya; FastRS is right in what you've gotta do. I used "G2P: Guaranteed To Pass Emissions Additive" in my tank before the NJ dyno-test, which is close to the CA test.

------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited January 24, 2001).]

CaliCamaroRS

maybe the previous owner gutted the catalytic converter. that would make the sniffer think you are running rich.(and it would fail you)

------------------
Dan
1990 3.1L RS
80 Series Flowmaster
It's fast(er than a 3 cyl metro)

CSUS_Dude

Thanks for the advice! The air filters are brand new "K-Mart" ones and I replaced and regapped the plugs and replaced the wires. I know the cat's not hollow because I just had the whole exhaust system out to get some work done to it. That doesn't mean its good, but its not hollow. How do I check the computer for error codes? Is there a website that will tell me what they mean?

Thanks,
Brandon

Grim Reaper

What are your mods to the motor? Relocated MAT, TB Bypass, aftermarket chip, cranked up fuel pressure or low temp T-stat are all mechanical methods that could cause you to run rich. Of course a faulty cat would too.

Also a faulty O2 sensor or taking the car into the station and idling for prolonged periods will kick you out of "closed" loop which can cause you to fail if your VE tables in your eprom are not "bang on" for your engine.

Lots of possible reasons to fail. But if you state your "mods", or check for their proper operation will shed some light.

Grim Reaper

If your SES light is not on, you don't have a bad sensor... but you could have a "flaky" one. A "flaky" sensor will not necessarily trigger an SES code, you really need a Scan Tool to see the operation of the sensors an ensure they are operating normally.

Of course, if you have no idea of whether or not they are operating properly, then having a Scan Tool is of no use.

Hate to say this, but it might be best to take it to a GM Dealer and have them do a diagnostic scan on the engine...you just want them to see if there is anything amiss.. and you can do the work yourself if you wish. Often, this is the smart thing to do, especially if you don't have a scan tool and know how to interpret the readings. The LAST thing you want to do is replace sensor, after sensor, after sensor... hoping to hit the right one.

But, if I was to guess as a sensor to replace...I would go with the O2 sensor. Frankly, if it is doing it's job and your engine is in closed loop, you SHOULD be able to pass as the ecm is very forgiving in compensating for mods to the engine. The dyno test should have your engine in "closed loop" while it is operating. The only one that can be a problem is the prolonged idling. All you have to do is keep "blipping" the throttle while your are waiting every couple of minutes. That should put you back in "closed loop" if you accidentally drop into "open loop".

AND DO NOT TURN OFF THE ENGINE. IF you do, it takes 3-4 minutes to go back into closed loop.

But, if you have to change anything, go for the O2 sensor.

CSUS_Dude

Thanks everyone. I'm gonna start with a new cap and rotor, and set the timing at 10 degrees. The car has absolutely no mods. I'm just trying to do this as cheaply as possible because the car isn't in great shape. I'm trying to sell it and make the best profit I can so I can buy a nicer 'maro.

Brandon

KED85

You failed as you have a worn timing chain.
It's allowing your engine to run poor.
Test this.
Take distributor, crank toward radiator and go for a ride.
I'll bet it'll smooth out!
I did this to my 2.8.
Worked wonders.
I had timing up to about 20.
I did NOT use the way to time in the books, I just cranked it toward radiator.
You can do this!

------------------
Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

CSUS_Dude

Even if it does smooth out, the timing still has to be withing a few degrees to pass the visual part of the inspection. Also, I don't see how advancing the ignition timing would correct for "slow" valve timing caused by a worn timing chain. Plus, it seems like it would ping like crazy at 20 BTDC. Can anyone explain this?

Brandon

FAST RS

Mines advanced at 12 degrees right now im gona retard it bak to stock i liked it better then.

TomP

My car also seemed to perform best at a stock setting (10 advance). I had my car timed by a mech who was trying to diagnose my no-start/no-run problem (turned out to be a bad supply wire for the computer that -I- found- I had the car towed home). The mech didn't tighten my distributor-hold-down bolt enough; after 6 months or so the timing had advanced itself so far that I destroyed a plug due to detonation (pinging)! The center electrode was gone. (That cylinder now has the lowest compression out of all of them.) 20 deg advanced is probably way too much.

Have you checked your balancer out? The balancer's an innter steel core, with a middle rubber ring, and then a outer steel ring around that. The timing mark's on the outer ring. If the rubber's deteriorating, the outer ring (and balance mark) can spin a bit out of position.

To check, remove the #1 plug, and remove the distrib-to-coil wire. Put a breaker bar and socket on the center crankshaft bolt. Put a phillips-head screwdriver into the #1 plug hole, and turn the engine clockwise with the breaker bar. When the screwdriver raises no more (top dead center #1), the timing mark on the balancer should be at 0 degrees. If the timing mark is nowhere near the timing indicator, then you probably have TDC of the exhaust stroke. Turn the motor over one more complete rev so the phillip's head screwdriver drops all the way, then raises up all the way... this gets you to TDC of the compression stroke, where the balancer should read 0 deg BTC.

Oh the #1 cylinder (in case you didn't know) is the frontmost PASSENGER side. Yes, this is opposite of most other GM engines, which have their #1 on the driver's side.

I think a worn timing chain would result in bad performance, not poor emissions. I was passing emissions on my original chain somewhere around the 180,000 mile mark.


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

TomP

Ah- I thought of another way to test TDC, which lets you make sure you're on the compression stroke and NOT the exhaust stroke.

As before, with a cool engine, remove the #1 (frontmost passenger side) cylinder's plug. Next, remove the distrib-to-coil wire. Put a breaker bar and socket on the center crankshaft bolt. Now, you've got two choices:

(A) Now, place a clean rag slightly into the spark plug hole. The idea is not to wedge the rag in; but you want to seal the hole. A small rag (piece of towel) lightly pushed in with your finger usually does the trick.

(B) Put your finger over the #1 plug hole.

Spin the crankshaft clockwise with the breaker bar. When the piston starts it's compression stroke, two things will happen: If you did (A), the rag will blow out. If you did (B), you'll feel pressure in the spark plug hole with your finger. This means the piston's on it's compression stroke.

This means you can finish the "checking for TDC" procedure above, and not worry about finding TDC for the exhaust stroke:

Put a phillips-head screwdriver into the #1 plug hole, and turn the engine clockwise with the breaker bar. When the screwdriver raises no more (top dead center #1), you've found TDC (within a degree or two) of cyl #1.

If the balancer mark does not line up close to "0 degrees BTC" on the timing indicator, your balancer ring has shifted too much to be accurate. If the balancer mark is only 1/8 inch off the 0 degree mark, you probably could've gone a bit more with the breaker bar. 1/8 inch isn't much to worry about, 1/2 inch is.


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

psigourney

Definitely replace the o2 as part of your work. A new o2 sensor will always help the computer.
Also get the Guarateed to Pass stuff. the G2P brand gives you a 200% refund on it's price if you fail using it. Can't lose there.

-Patrick
Concord, CA

CSUS_Dude

Here's an update. I replaced plugs, wires, cap, rotor and it still had the same miss. Before spending more money on parts, I decided to have a mechanic diagnose it for me. The #5 injector is barely functioning. I feel stupid for not listening to them before bringing it in. Anyway, injectors are expensive and the car itself isn't worth that much.

Brandon

TomP

Wow, that's different... sorry we didn't think of that!

An injector's $60- the car's not worth it? From a junkyard, it should be much cheaper. Is it clogged? Rip all 6 out and send them to Rich at http://www.cruzinperformance.com for a professional (and low-cost!) flow-testing, disassembly/cleaning, and blueprinting.


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

CSUS_Dude

I got the car as a gift. Since then I've put about $750 into it trying to get it ready to sellable. I'm just not sure it's worth enough to put any more money into it at all. What do you think? It's an '88 5-speed with 106k miles. The interior is OK except the stereo has been ripped out and the dash board is severely cracked. The body is mostly straight but it needs paint badly. The brakes are squishy and work, but they need to be rebuilt. The mechanic also said the other injectors were probably on their way out, so it would be stupid to just replace 1. He also said it may need a new cat. I'm just not sure if I would be better off trying to sell it now, or getting it fixed/smogged, then selling it.

Brandon

CaliCamaroRS

hmmm well if you sell it, change of ownership requires a smog check anyways, right? but i'm not sure if it's the seller's or the buyers responsibility to smog it. but if YOU have to smog it then you might be up a creek....if you know what i mean.

------------------
Dan
1990 3.1L RS
80 Series Flowmaster
It's fast(er than a 3 cyl metro)

CSUS_Dude

You're correct. It is the seller's responsibility to smog it before selling it. That's why this is so hard. A free gift may turn into a big loss. I'm trying to figure out if there is any way you can LEGALLY sell a car without a smog cert. For now I think I'll run down to the junk yard this weekend and pull a set of injectors and give that a try. Thanks for everyone who has put in their 2 cents on this post. I'll keep you updated.

Brandon