Failed emissions on a 951. 21 times the limit.
05-18-2005, 06:03 PM
#16
Hey Man
Rennlist Member
Rennlist Member
I've never really seen that section 24-13 in my turbo shop manual. That's great! My 951 just barely passed on CO last month, loaded runs on the dyno were much cleaner than idle. Thanks again for the info, it's a good thing to know.
05-18-2005, 09:22 PM
#17
Three Wheelin'
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Is the car leaking oil or burning the oil?
I know oil in the exhaust will show up as increased HC, but that CO is way out of line. The catalytic convertor is supposed to be like 80% effective reducing the HC and CO emissions.
I know oil in the exhaust will show up as increased HC, but that CO is way out of line. The catalytic convertor is supposed to be like 80% effective reducing the HC and CO emissions.
05-19-2005, 03:57 PM
#18
Three Wheelin'
Thread Starter
It's definately burning the oil. The car just sat for 10 months without a drop under it.
I just remembered that I put a bottle of fuel stabilizer in the car before I left and it probably was in the tank (though pretty well mixed. I had an empty tank with a full bottle of that stuff and ran it to about half a tank before I went to get tested). Would that cause these horrible readings?
I just remembered that I put a bottle of fuel stabilizer in the car before I left and it probably was in the tank (though pretty well mixed. I had an empty tank with a full bottle of that stuff and ran it to about half a tank before I went to get tested). Would that cause these horrible readings?
05-21-2005, 07:07 PM
#21
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Check that old O2 sensor is plugged in; if not, plug it in. If so, replace for $45. AF gauge should dither or sweep back and forth at warm idle and cruising, not just sit there. If that doesn't fix it, have AFM checked and adjusted as needed without removing the black cover as suggested, use the proper CO adjustment screw under the round metal cap on the top of AFM. If that still doesn't fix it, remove the four fuel injectors and send them in for cleaning and checking for about $50.
07-14-2005, 10:04 PM
#22
Three Wheelin'
Thread Starter
I put in a new O2 sensor, new plugs and new injector seals today. It seems to still surge on idle and the A/F meter is registering that the mixture is very rich now.
Is the O2 sensor supposed to flucuate on idle? I'm getting a very steady reading which I think might be part of the problem. They're supposed to run back and forth between lean and rich on idle, correct?
Part of the problem was caused by a dirty air filter, but that's been fixed. I'm searching for bad grounds and then I'm kind of at a loss. New TPS maybe, maybe try a different DME?
Is the O2 sensor supposed to flucuate on idle? I'm getting a very steady reading which I think might be part of the problem. They're supposed to run back and forth between lean and rich on idle, correct?
Part of the problem was caused by a dirty air filter, but that's been fixed. I'm searching for bad grounds and then I'm kind of at a loss. New TPS maybe, maybe try a different DME?
07-14-2005, 10:22 PM
#23
FR WIlk has a good tutorial on the AFM (along with a lot of other pertinent info on the Bosch DME system).
http://frwilk.com/944dme/
http://frwilk.com/944dme/
07-14-2005, 10:40 PM
#24
Three Wheelin'
Thread Starter
I've been thinking for some time that my turbo seals are gone. It's pushed a lot of oil through the pipes and seems to boil coolant down to a certain level. I'm still pulling 15psi and it pulls strong, but could a turbo with blown seals cause this type of problem?
07-15-2005, 01:21 AM
#27
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Nick,
A constant rich O2 indicates one of three things- the computer isn't reading the sensor so it can't compensate, the computer can't lean the car far enough to fix the problem and has "railed," or there is a mechanical/electrical problem causing one or more cylinder not to burn the fuel supplied.
The injector seals will fix a leak to the outside but won't fix a leaking injector. Try disconnecting the injectors one at a time and see if the problem relates to a specific cylinder. Remember, the computer only sees and average so a leaky injector will sound lean and read rich. A bad intake valve would cause a similar issue and also explain the low vacuum. A bad fuel pressure diaphram is another possibility.
Best bet- bribe the local gearhead to come over and help. Are you old enough to buy beer? Offer him a drive when he's done, hinting that he'll have more fun if it's running right. Better yet may be a run to his house since he probably has more tools than his ride will hold. Kind of like this:
http://home.comcast.net/~eastmanb1/newadds/Tools.htm
Good luck,
Bill
86 NA
A constant rich O2 indicates one of three things- the computer isn't reading the sensor so it can't compensate, the computer can't lean the car far enough to fix the problem and has "railed," or there is a mechanical/electrical problem causing one or more cylinder not to burn the fuel supplied.
The injector seals will fix a leak to the outside but won't fix a leaking injector. Try disconnecting the injectors one at a time and see if the problem relates to a specific cylinder. Remember, the computer only sees and average so a leaky injector will sound lean and read rich. A bad intake valve would cause a similar issue and also explain the low vacuum. A bad fuel pressure diaphram is another possibility.
Best bet- bribe the local gearhead to come over and help. Are you old enough to buy beer? Offer him a drive when he's done, hinting that he'll have more fun if it's running right. Better yet may be a run to his house since he probably has more tools than his ride will hold. Kind of like this:
http://home.comcast.net/~eastmanb1/newadds/Tools.htm
Good luck,
Bill
86 NA
07-15-2005, 05:12 AM
#29
Race Director
A lot of possible causes for your symptoms, you may have multiple problems here. The O2-sensor may be OK because it only has a small adjustment range that it can adjust and if your air-fuel ratios are outside of this range, the maximum adjustment will still be too rich and it won't dither. Also the high idle-speed IS a sign of a vacuum leak or mis-adjusted throttle-plate.
In order to get an engine to run at any particular RPM, you HAVE to flow a minimum CFM through it, there's no way around this. If you open the throttle, you let more CFM through and the engine-revs pick up. You let off the throttle and you limit the air-flow and the engine slows down. There's absolutely ZERO way to have an engine idle at 1400-1600rpm without flowing close to twice the amount of air as needed for a stock 840rpm idle speed.
Then the fuel is just injected to match that air-flow. Running twice as much air through the engine at idle than stock will most likely open up the AFM a little more and more fuel will be injected. I suspect that originally, the mixture was lean, too lean due to the vacuum leaks. Then someone tried to be tricky and adjusted the AFM to make a richer mixture to compensate for the vacuum leak... two wrongs that coincidentally cancels each other out does not make things right and we have the situation you're in now... So... let's gather some data first:
1. THROTTLE-PLATE position: take off the upper intercooler hose and eyeball the throttle-plate. Notice the tiny hole at the bottom of the throttle-body that sucks vacuum to activate the evaporative canister. The throttle-plate should be about 1mm behind that hole, about 1/2 way between fully closed and directly over that hole. Adjust the throttle-plate closed position with the stop-screw on the right side. While you're here, inspect the inside of the intercooler hose for oil. On my car when I first got it, I cracked open the throttle, and oil dripped out of the intake-manifold for about 3 minutes (also had about 2-3cc of oil sitting on the back of the intake-valves), still passed smog though...
2. TPS-ALIGNMENT: this is critical in getting the DME to switch between the idle and partial-throttle maps. Just the >CLICK< when you open the throttle ]s NOT a valid test, you MUST check the TPS electronically. So pull off the TPS connector and measure resistance (ohms) between pins #4 and #6. With the throttle closed, these pins should have less than 0.25 ohms resistance, anything above 0.5 ohms and you've got a bad TPS (or dirty). It'll mechanically click, but is functionally dead because it doesn't tell the DME to switch to the idle-map when you close the throttle.
3. IDLE-SCREW: should be set to about 1-2mm below the top-surface of the hole on top of the throttle-body for standard idle of 840rpm. If it's in further than this, it's compensating for vacuum-leaks somewhere.
4. VACUUM-LEAKS: measure idle-vacuum using a rubber T hooked into the following points, KLR-pressure line, FPR, fuel-dampener, compressor-bypass valve. You MUST use a T at the nipples on the FPR, fuel-dampener, CBV so that those devices can operate properly and you can monitor the vacuum going into them. Here's a list of vacuum readings you want to get at idle, they should all be identical around 18-22 in.Hg:
- KLR-line (inside cabin): cold = ??? in.Hg, warm = ???
- FPR nipple : cold = ??? in.Hg, warm = ???
- fuel-dampener nipple: cold = ??? in.Hg, warm = ???
- CBV nipple: : cold = ??? in.Hg, warm = ???
You also want to hook up a vacuum tester to the nipples on those devices and check to make sure they hold vacuum indefinitely, leaks will cause anything else hooked up to the vacuum system to malfunction as well
5. AFM-ADJUSTMENT: There's actually TWO adjustments on the AFM. One is a barn-door bypass similar to the throttle-plate bypass. This vents air around the barn-door without being measured. More air around the door results in leaner mixtures, less air around the door gives richer mixtures at idle. Due to the small volume vented, it doesn't affect air-fuel ratios at anything other than idle. This is adjusted by popping off the dime-sized cover on the outside of the AFM and using a long allen-key to reach in.
The other AFM-adjustment is the spring tension. You need to carefully pry off the plastic cover on the AFM and find the wound-up spring. In the middle is a big ratching adjustment screw. Tighten the screw to lean out the mixture, loosen it to richen the mixture. Re-seal the plastic cover with silicone so you don't get leaks past the barn-door.
You find the proper spring-tension by monitoring the AFM's voltage output at idle and some other operating point. Hook up a voltmeter's +positive probe to the AFM's input line near the DME inside the cabin, pin#7 green/red-stripe wire. Use the big brown/yellow-stripe for ground. Measure the AFM's output voltage under the following conditions:
- idle at x-RPM, voltage = ??? (should be 0.79-0.89v)
- 45mph/3rd-gear steady-speed, voltage = ??? (should be 1.9-2.1v)
Set the 45mph calibration first, then use the external barn-door bypass screw to set the idle-voltage and mixtures.
Do the above tests and adjustments in that order or else you'll have to go back and re-do the adjusments back & forth later in an endless loop as one change messes up something else down the line. If all the above checks and adjustments are OK, then your chips are mapped for way too much fuel, your FPR is stuck at too-high a pressure, or your cat is bad.
In order to get an engine to run at any particular RPM, you HAVE to flow a minimum CFM through it, there's no way around this. If you open the throttle, you let more CFM through and the engine-revs pick up. You let off the throttle and you limit the air-flow and the engine slows down. There's absolutely ZERO way to have an engine idle at 1400-1600rpm without flowing close to twice the amount of air as needed for a stock 840rpm idle speed.
Then the fuel is just injected to match that air-flow. Running twice as much air through the engine at idle than stock will most likely open up the AFM a little more and more fuel will be injected. I suspect that originally, the mixture was lean, too lean due to the vacuum leaks. Then someone tried to be tricky and adjusted the AFM to make a richer mixture to compensate for the vacuum leak... two wrongs that coincidentally cancels each other out does not make things right and we have the situation you're in now... So... let's gather some data first:
1. THROTTLE-PLATE position: take off the upper intercooler hose and eyeball the throttle-plate. Notice the tiny hole at the bottom of the throttle-body that sucks vacuum to activate the evaporative canister. The throttle-plate should be about 1mm behind that hole, about 1/2 way between fully closed and directly over that hole. Adjust the throttle-plate closed position with the stop-screw on the right side. While you're here, inspect the inside of the intercooler hose for oil. On my car when I first got it, I cracked open the throttle, and oil dripped out of the intake-manifold for about 3 minutes (also had about 2-3cc of oil sitting on the back of the intake-valves), still passed smog though...
2. TPS-ALIGNMENT: this is critical in getting the DME to switch between the idle and partial-throttle maps. Just the >CLICK< when you open the throttle ]s NOT a valid test, you MUST check the TPS electronically. So pull off the TPS connector and measure resistance (ohms) between pins #4 and #6. With the throttle closed, these pins should have less than 0.25 ohms resistance, anything above 0.5 ohms and you've got a bad TPS (or dirty). It'll mechanically click, but is functionally dead because it doesn't tell the DME to switch to the idle-map when you close the throttle.
3. IDLE-SCREW: should be set to about 1-2mm below the top-surface of the hole on top of the throttle-body for standard idle of 840rpm. If it's in further than this, it's compensating for vacuum-leaks somewhere.
4. VACUUM-LEAKS: measure idle-vacuum using a rubber T hooked into the following points, KLR-pressure line, FPR, fuel-dampener, compressor-bypass valve. You MUST use a T at the nipples on the FPR, fuel-dampener, CBV so that those devices can operate properly and you can monitor the vacuum going into them. Here's a list of vacuum readings you want to get at idle, they should all be identical around 18-22 in.Hg:
- KLR-line (inside cabin): cold = ??? in.Hg, warm = ???
- FPR nipple : cold = ??? in.Hg, warm = ???
- fuel-dampener nipple: cold = ??? in.Hg, warm = ???
- CBV nipple: : cold = ??? in.Hg, warm = ???
You also want to hook up a vacuum tester to the nipples on those devices and check to make sure they hold vacuum indefinitely, leaks will cause anything else hooked up to the vacuum system to malfunction as well
5. AFM-ADJUSTMENT: There's actually TWO adjustments on the AFM. One is a barn-door bypass similar to the throttle-plate bypass. This vents air around the barn-door without being measured. More air around the door results in leaner mixtures, less air around the door gives richer mixtures at idle. Due to the small volume vented, it doesn't affect air-fuel ratios at anything other than idle. This is adjusted by popping off the dime-sized cover on the outside of the AFM and using a long allen-key to reach in.
The other AFM-adjustment is the spring tension. You need to carefully pry off the plastic cover on the AFM and find the wound-up spring. In the middle is a big ratching adjustment screw. Tighten the screw to lean out the mixture, loosen it to richen the mixture. Re-seal the plastic cover with silicone so you don't get leaks past the barn-door.
You find the proper spring-tension by monitoring the AFM's voltage output at idle and some other operating point. Hook up a voltmeter's +positive probe to the AFM's input line near the DME inside the cabin, pin#7 green/red-stripe wire. Use the big brown/yellow-stripe for ground. Measure the AFM's output voltage under the following conditions:
- idle at x-RPM, voltage = ??? (should be 0.79-0.89v)
- 45mph/3rd-gear steady-speed, voltage = ??? (should be 1.9-2.1v)
Set the 45mph calibration first, then use the external barn-door bypass screw to set the idle-voltage and mixtures.
Do the above tests and adjustments in that order or else you'll have to go back and re-do the adjusments back & forth later in an endless loop as one change messes up something else down the line. If all the above checks and adjustments are OK, then your chips are mapped for way too much fuel, your FPR is stuck at too-high a pressure, or your cat is bad.
