911sc runs bad, professional help wanted!
07-24-2013, 08:59 PM
#16
Addict
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It's probably worth pulling the fuel injectors out of the intake manifolds, putting them into glass bottles and watching the fuel flow patterns. Poor of blocked injectors will cause all sorts of cross cylinder running faults that would result in a poor burn pattern and require an overly rich mixture to compensate for the poor fuel stratification.
To flow the injector without running the engine, remove the air filter and lid, pull the crash plug connection off the back of the air flow meter with the ignition on, then lift up the paddle to adjust the fuel flow.
If one injection is flowing poorly, check that it is not the metering head by changing its position on the fuel pipes. You can sometimes clean the injectors with an ultrasonic cleaning bath, however in most cases buying a new one would be the best solution as cleaning rarely gives 100% performance.
To flow the injector without running the engine, remove the air filter and lid, pull the crash plug connection off the back of the air flow meter with the ignition on, then lift up the paddle to adjust the fuel flow.
If one injection is flowing poorly, check that it is not the metering head by changing its position on the fuel pipes. You can sometimes clean the injectors with an ultrasonic cleaning bath, however in most cases buying a new one would be the best solution as cleaning rarely gives 100% performance.
07-25-2013, 03:22 PM
#19
Team Owner
Measuring CO% AFTER the cat tells you nothing. To set CO on a USA '83 SC:
1. Open the test port at the front of the cat
2. Disconnect the OXS wire in the engine compartment
3. Hook up & zero tester
4. Start engine and bring up to temp until the front oil cooler is hot to the touch; idle speed = 900 rpm
5. Check CO - use test port and be sure that the hose on machine cannot suck in outside air (hose should fit snug at test port and machine)
6. Spec = 0.4 - 0.8%
7. Adjust as necessary - always turn the wrench toward rich (clockwise) before moving toward lean. Never leave the wrench in the adjustment hole, or lean against the airbox, while checking/adjusting.
Connect the OXS wire, close the test port, and go for a drive. Now, if you don't have a good running car, you can begin to diagnose the problem.
1. Open the test port at the front of the cat
2. Disconnect the OXS wire in the engine compartment
3. Hook up & zero tester
4. Start engine and bring up to temp until the front oil cooler is hot to the touch; idle speed = 900 rpm
5. Check CO - use test port and be sure that the hose on machine cannot suck in outside air (hose should fit snug at test port and machine)
6. Spec = 0.4 - 0.8%
7. Adjust as necessary - always turn the wrench toward rich (clockwise) before moving toward lean. Never leave the wrench in the adjustment hole, or lean against the airbox, while checking/adjusting.
Connect the OXS wire, close the test port, and go for a drive. Now, if you don't have a good running car, you can begin to diagnose the problem.
On my 78 I have a cat but dont have a O2 sensor obviously .. i also dont have a test Port so how would I check my CO ? I did it after the CAT, did i do it wrong ?
oh wait , now i remember the cAT is gone ..
must have fallen off and a chunck of exhaust pipe was welded by accident.. But hypothetically if I had a cat how would I do it ? did it have a test port before that cat on my car that was cut out with the cat ?
...oops .. i mean fell out ..
07-25-2013, 06:17 PM
#20
Rennlist Member
Yep, your test pipe...er, cat, had a test port with a cap nut. It, before falling off, faced the inner sidewall of the left rear tire, and was welded to the pipe between the forward mounting flange and the cat's body. After your cat fell off, measuring the CO% out the tailpipe is correct. Do I see a smog pump in your picture?
07-25-2013, 09:19 PM
#22
I haddah Google dat
Rennlist Member
Rennlist Member
Some people, I don't know who.....weld a second bung into their repaired test cat so they can run a wideband O2 sensor for their Innovate AFR gauge. In your case, you would have only one O2 bung ahead of the repaired sport ...uh, cat.
07-26-2013, 12:15 AM
#25
Team Owner
08-01-2013, 12:51 PM
#28
Hi,
I got the fuelpressure tester! I connected the meter between the fuel pressure regulator and the fuel distributor. I let the air out.
The pressure went up until 1,4
I started the engine, pressure down to 0,5 while starting
Engine running (cold) 1,0
Engine off 1,8
So according to the manual the pressure is to low. It should be 3,5??
I meassured the voltage at the WUR, its 11,5 volts so that's okay
Do I have to replace or rebuild my control presuure regulator? Or is there something else?
I got the fuelpressure tester! I connected the meter between the fuel pressure regulator and the fuel distributor. I let the air out.
The pressure went up until 1,4
I started the engine, pressure down to 0,5 while starting
Engine running (cold) 1,0
Engine off 1,8
So according to the manual the pressure is to low. It should be 3,5??
I meassured the voltage at the WUR, its 11,5 volts so that's okay
Do I have to replace or rebuild my control presuure regulator? Or is there something else?
08-01-2013, 05:21 PM
#29
Team Owner
so ..er ... dude .... did you do what was asked of you several times ? measure the CO BEFORE the cat ? results ? . Is English your second language maybe and you didnt get that ?
08-01-2013, 09:53 PM
#30
I haddah Google dat
Rennlist Member
Rennlist Member
If accurate, then the fuel pressre is too low to set idle and would result in very lean running, which would result in low power and backfires.
Most people would do the easy stuff first, which is to change the fuel filter, and check the sump screen at the bottom of the fuel tank. A 7/8 inch bolt makes a nice tool to remove the drain. Just tighten two nuts together, and you can use a wrench to remove the tank sump screen, which can be clogged with rust or dirt. It can be a faulty fuel pump, check valve, etc. too so I would remove the check valve, which is on the output side of the fuel pump (the line with the banjo fitting). You have to drain the tank to do either operation, but hopefully you find the cause of low fuel flow. Fuel pumps are expensive. It could be the WUR too, but I'm not that familiar with CIS fuel systems.
Most people would do the easy stuff first, which is to change the fuel filter, and check the sump screen at the bottom of the fuel tank. A 7/8 inch bolt makes a nice tool to remove the drain. Just tighten two nuts together, and you can use a wrench to remove the tank sump screen, which can be clogged with rust or dirt. It can be a faulty fuel pump, check valve, etc. too so I would remove the check valve, which is on the output side of the fuel pump (the line with the banjo fitting). You have to drain the tank to do either operation, but hopefully you find the cause of low fuel flow. Fuel pumps are expensive. It could be the WUR too, but I'm not that familiar with CIS fuel systems.