Failed Emissions
Thread Starter
On The Tree
Joined: Dec 2006
Posts: 121
Likes: 1
From: Aloha, OR
Failed Emissions ...miserably. So right now I'm at...
Idle: HC: 703 CO: 0.9304
2500rpm HC: 596 CO: 2.1117
HC needs to be below 220ppm and CO needs to be below 1.0
And this is after I replaced: spark plugs, spark plug wires, cap, rotor, oil, O2 sensor, PCV valve, and I put the cat back on. Timing is at 6*, TPS voltage is spot on. Disconnected CSI. I even put a can of denatured alcohol in with a 1/4 tank of gas. Car was above normal operating temperature too. I'm out of ideas. Why would my car be running so incredibly rich?
The engine is a stock '87 LB9.
BTW my tags expired at the end of august so time is of the essence.
Idle: HC: 703 CO: 0.9304
2500rpm HC: 596 CO: 2.1117
HC needs to be below 220ppm and CO needs to be below 1.0
And this is after I replaced: spark plugs, spark plug wires, cap, rotor, oil, O2 sensor, PCV valve, and I put the cat back on. Timing is at 6*, TPS voltage is spot on. Disconnected CSI. I even put a can of denatured alcohol in with a 1/4 tank of gas. Car was above normal operating temperature too. I'm out of ideas. Why would my car be running so incredibly rich?
The engine is a stock '87 LB9.
BTW my tags expired at the end of august so time is of the essence.
6 & 8 Second Club
Joined: Aug 2006
Posts: 2,284
Likes: 0
From: Illinois, RT 66 dragway area
.
Don't know how to fix it. I do have some big trucks that won't pass.
I run them down near empty before going in. I put a few gal's of E-85 in and go straight over.
After I finish testing, I fill up with premium, to dilute the alcohol. Worked every time so far.
Before everyone bitches about cheating the system. I put a brand new bigger & stronger engine in.
They will not take that into account, so I have no way to get the lower readings required.
The new engine is perfect, and tuned perfectly. The added inches and added power put it over the minimum.
.
what is CSI?
http://www.type2.com/library/exhaust/comix.htm
CO = incomplete combustion, due to lack of oxygen,
HC = unburnt fuel and possibly oil introduced into the combustion chamber,
the catalytic converter is responsible for reducing the CO and HC to CO2 and H20,
I don't know anything about the LB9 TPI (tuned port injection) so I don't know what to tell you,
I initially mentioned (but edited out) that you should be running around 12-14 dBTDC timing at idle but I didn't see you mentioned it was an LB9 engine, I was thinking typical SBC. You might try advancing the timing a little, that may help, otherwise the general conclusion to this scenario is a mixture problem which could be bad injector spray pattern, or leaky injectors...
And I wouldn't conclude that it is running rich because of the HC reading,
you need to measure the A/F ratio with a wideband O2 to determine if it's rich or lean,
the HC is simply unburnt fuel (gas and/or oil) in the exhaust which can be caused by other things not just too much fuel being injected.
Do a compression test, and a leak down test if possible, poor compression and bad valve seats can cause the HC and CO readings. Other than that, is it possible the catalytic converter is bad? It may be as simple as needing a new cat if it's the original which has many miles on it where the engine burnt pre API-SL oil having higher phosphorus additives which poisons the converter.
http://www.type2.com/library/exhaust/comix.htm
CO = incomplete combustion, due to lack of oxygen,
HC = unburnt fuel and possibly oil introduced into the combustion chamber,
the catalytic converter is responsible for reducing the CO and HC to CO2 and H20,
I don't know anything about the LB9 TPI (tuned port injection) so I don't know what to tell you,
I initially mentioned (but edited out) that you should be running around 12-14 dBTDC timing at idle but I didn't see you mentioned it was an LB9 engine, I was thinking typical SBC. You might try advancing the timing a little, that may help, otherwise the general conclusion to this scenario is a mixture problem which could be bad injector spray pattern, or leaky injectors...
And I wouldn't conclude that it is running rich because of the HC reading,
you need to measure the A/F ratio with a wideband O2 to determine if it's rich or lean,
the HC is simply unburnt fuel (gas and/or oil) in the exhaust which can be caused by other things not just too much fuel being injected.
Do a compression test, and a leak down test if possible, poor compression and bad valve seats can cause the HC and CO readings. Other than that, is it possible the catalytic converter is bad? It may be as simple as needing a new cat if it's the original which has many miles on it where the engine burnt pre API-SL oil having higher phosphorus additives which poisons the converter.
Last edited by 1 FMF; Sep 4, 2009 at 02:50 PM. Reason: oops
Thread Starter
On The Tree
Joined: Dec 2006
Posts: 121
Likes: 1
From: Aloha, OR
I stated in my original post that I changed the oil.
The Cold Start Injector. Commonly prone to failure.
http://www.type2.com/library/exhaust/comix.htm
CO = incomplete combustion, due to lack of oxygen,
HC = unburnt fuel and possibly oil introduced into the combustion chamber,
the catalytic converter is responsible for reducing the CO and HC to CO2 and H20,
I don't know anything about the LB9 TPI (tuned port injection) so I don't know what to tell you,
I initially mentioned (but edited out) that you should be running around 12-14 dBTDC timing at idle but I didn't see you mentioned it was an LB9 engine, I was thinking typical SBC. You might try advancing the timing a little, that may help, otherwise the general conclusion to this scenario is a mixture problem which could be bad injector spray pattern, or leaky injectors... Factory timing is 6*, however, I've always been under the impression that you want to retard your timing as much as you could for better emissions results? How can you test for a leaky injector?
I concluded that for a good reason.
I'm 100% positive the cat is good. It was purchased new 2 years ago when I last did emissions and was taken off the car until a week ago. In other words, it has about 3 weeks of run time on the car. It only goes on for testing.
The Cold Start Injector. Commonly prone to failure.
http://www.type2.com/library/exhaust/comix.htm
CO = incomplete combustion, due to lack of oxygen,
HC = unburnt fuel and possibly oil introduced into the combustion chamber,
the catalytic converter is responsible for reducing the CO and HC to CO2 and H20,
I don't know anything about the LB9 TPI (tuned port injection) so I don't know what to tell you,
I initially mentioned (but edited out) that you should be running around 12-14 dBTDC timing at idle but I didn't see you mentioned it was an LB9 engine, I was thinking typical SBC. You might try advancing the timing a little, that may help, otherwise the general conclusion to this scenario is a mixture problem which could be bad injector spray pattern, or leaky injectors...
And I wouldn't conclude that it is running rich because of the HC reading,
you need to measure the A/F ratio with a wideband O2 to determine if it's rich or lean,
you need to measure the A/F ratio with a wideband O2 to determine if it's rich or lean,
the HC is simply unburnt fuel (gas and/or oil) in the exhaust which can be caused by other things not just too much fuel being injected.
Do a compression test, and a leak down test if possible, poor compression and bad valve seats can cause the HC and CO readings. Other than that, is it possible the catalytic converter is bad? It may be as simple as needing a new cat if it's the original which has many miles on it where the engine burnt pre API-SL oil having higher phosphorus additives which poisons the converter.
Do a compression test, and a leak down test if possible, poor compression and bad valve seats can cause the HC and CO readings. Other than that, is it possible the catalytic converter is bad? It may be as simple as needing a new cat if it's the original which has many miles on it where the engine burnt pre API-SL oil having higher phosphorus additives which poisons the converter.
to check for leaky injectors get a fuel pressure gauge on the fuel rail, turn the key to run and fuel pump should kick on and pressurize the fuel rail. Turn key off or have the fuel pump turn off, note if the pressure drops. If it drops significantly then that may be a leaky injector, it is not conclusive proof because the leak may be elsewhere. But as for injectors, generally you need to pull them and have them bench tested otherwise you're guessing.
you're A/F ratio is super rich across the board so it seems like something basic is screwed up. I kinda doubt injectors because it would have to be a few of them all having bad spray patterns otherwise you would be able to tell by fouled or gassy spark plugs on certain cylinders and not others. is there a mass air flow (MAF) sensor on that system? If so, then consider looking at cleaning/replacing that. Otherwise it could be the manifold absolute pressure (MAP) sensor which the computer needs, or the oxygen sensors if your system has O2 sensors. Those 3 are the only things i can think of that could cause a completely rich A/F ratio across the board like your pic showed, or you have a wiring short to ground or too much resistance to ground on a sensor and it's not providing a good signal. a problem like this is when you want to hook the engine computer up on the dealer's big diagnostic machine and see the pulse widths of every injector when it's happening to diagnose and pinpoint the problem. hope that helps.
you're A/F ratio is super rich across the board so it seems like something basic is screwed up. I kinda doubt injectors because it would have to be a few of them all having bad spray patterns otherwise you would be able to tell by fouled or gassy spark plugs on certain cylinders and not others. is there a mass air flow (MAF) sensor on that system? If so, then consider looking at cleaning/replacing that. Otherwise it could be the manifold absolute pressure (MAP) sensor which the computer needs, or the oxygen sensors if your system has O2 sensors. Those 3 are the only things i can think of that could cause a completely rich A/F ratio across the board like your pic showed, or you have a wiring short to ground or too much resistance to ground on a sensor and it's not providing a good signal. a problem like this is when you want to hook the engine computer up on the dealer's big diagnostic machine and see the pulse widths of every injector when it's happening to diagnose and pinpoint the problem. hope that helps.
Thread Starter
On The Tree
Joined: Dec 2006
Posts: 121
Likes: 1
From: Aloha, OR
I replaced my O2 sensor last week to no avail, so I'll look into cleaning and possibly replacing the MAF. I also just replaced the coolant temperature sensor and fixed quite a few vacuum leaks. It brought down my HC a little but I'm still over twice the limit.
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Thread Starter
On The Tree
Joined: Dec 2006
Posts: 121
Likes: 1
From: Aloha, OR
I picked up a fuel pressure tester yesterday and did the dead head test. It read about 20PSI when the pump primed, never bled off after keying off. When running it read about 36-38PSI. While the engine was running, I started unplugging sensors. When I unplugged the IAC nothing happened. So I picked up a new one. Adjusted it to spec. I started my engine and it idled at 1600RPM. So I then adjusted my Minimum Air to 400RPM while the IAC was disconnected. I plugged it back in, then attempted to adjust my TPS. What had both Derek and I baffled was that the voltage continuously jumped around from say 0.36V to 4.85V and everywhere in between. We adjusted to 0.57V the best we could. It seemed to run fine and idled at around 600RPM once all this was done. I took the car for a test drive and it drove very well for the first half. halfway through the drive I noticed that the car would drive itself. I stuck it in neutral and it would idle at 1600RPM again. Once I got home, I checked all connections and checked the TPS while the engine was running. It never gave a steady reading. I shut off the car then restarted it, and it idled like normal at 600RPM.
I have no clue what was going on. I never changed anything during this whole "episode." Is my TPS bad? When I unplugged it while it was running, nothing happened. Should the voltage be jumping around like this?
I have no clue what was going on. I never changed anything during this whole "episode." Is my TPS bad? When I unplugged it while it was running, nothing happened. Should the voltage be jumping around like this?
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Not trying to start anything or offend anyone. But DAMN, that is why i have a carburetor on everything i have except my truck.
All my f bodys, even the 95 Z i just sold.
You need to get with the shady fella on the corner if you need to.
All my f bodys, even the 95 Z i just sold.
You need to get with the shady fella on the corner if you need to.
Thread Starter
On The Tree
Joined: Dec 2006
Posts: 121
Likes: 1
From: Aloha, OR
Tested again:
352ppm 0.1831%
368ppm 1.7063%
The best so far but this is getting extremely frustrating. I scanned the car today after I failed. There's a few things that have got me scratching my head. First off, my car has never shown any kind of trouble code, ever. Another thing I noticed is that the scanner was saying that 4th gear was "engaged"....while in PARK. Also, just about every time I connect a scanner to my car it starts running like crap, unplug the scanner, runs smooth, plug it back it, rough again. Any chance that my ECU might be taking a dive?
BTW my Block Learn was between 125-128
Idle Air Control was at 136
Would a leaky injector cause a rich condition when running and warmed up or would it just affect start up?
352ppm 0.1831%
368ppm 1.7063%
The best so far but this is getting extremely frustrating. I scanned the car today after I failed. There's a few things that have got me scratching my head. First off, my car has never shown any kind of trouble code, ever. Another thing I noticed is that the scanner was saying that 4th gear was "engaged"....while in PARK. Also, just about every time I connect a scanner to my car it starts running like crap, unplug the scanner, runs smooth, plug it back it, rough again. Any chance that my ECU might be taking a dive?
BTW my Block Learn was between 125-128
Idle Air Control was at 136
Would a leaky injector cause a rich condition when running and warmed up or would it just affect start up?
