csb41502 Posted January 27, 2015 Report Posted January 27, 2015 I just picked up a cutlass supreme with a 3.1the other day . First question is when I was changing the o2 sensor there was a 2 wire connector with a green and a black wire just about melted to the manifold. Second I did a full tuneup (spark plugs,wires,fuel filter,pcv valve,o2 sensor,air filter) and it still throws a code for cylinder 2 misfire. It only idles a little weird at idle and sitting at lights.Once u give it ggas or driving along its completely smooth. Can it be a fuel injector? Quote
Nas Escobar Posted January 27, 2015 Report Posted January 27, 2015 Fuel injector or coil. I'd check the coil first, much easier to replace, not to mention the coils do fail after time. Quote
csb41502 Posted January 27, 2015 Author Report Posted January 27, 2015 Fuel injector or coil. I'd check the coil first, much easier to replace, not to mention the coils do fail after time. I swapped the coils around already and it still stays with cylinder 2. They said the car was sitting almost a year but started it up frequently. Quote
Schurkey Posted January 27, 2015 Report Posted January 27, 2015 Second I did a full tuneup (spark plugs,wires,fuel filter,pcv valve,o2 sensor,air filter) Compression test results? Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 Compression test results? I didn't even think of that. It could be a bad cylinder? Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 Could it be a knock sensor or cps? Quote
Schurkey Posted January 28, 2015 Report Posted January 28, 2015 Could it be a knock sensor or cps? I don't know what a cps is. Unlikely to be a knock sensor. I'd expect either ignition (ignition coil, spark plug wire, spark plug) or fuel (leaking or plugged injector, defective injector coil.) Â Having said that, sure, low compression could be a factor--leaking valves, poor ring seal, etc. Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 A crank position sensor. I swapped coils around and it always stays with cylinder 2. It's got brand new plugs and wires and fuel filter and o2 sensor. I'm gonna hope it's a clogged or burnt out injector. They did say it was sitting for almost a year Quote
Nas Escobar Posted January 28, 2015 Report Posted January 28, 2015 Check compression before swapping out sensors and other pieces. Â Verify a good cylinder then work from there. Also, check the ohms of the fuel injectors. Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 Is there any way to test the injectors with the plenum on or does it have to get removed? If so is it difficult to remove? Quote
Nas Escobar Posted January 28, 2015 Report Posted January 28, 2015 Well, I was going to suggest checking the ohm reading on the fuel injectors. You do have to remove the plenum to access the fuel rail and I think the throttle body has to come off to clear the plenum. Â The plenum is held on by a 12 or so 10mm bolts. Fairly easy to remove. You also need an ohm reader as you want to check that the fuel injectors have a reading past 12 ohm. Â I would start with the compression test first, as that might be easier for you to do. It would require removal of all spark plugs and the fuse for the fuel pump and coils. You don't want the coils to fire iirc. Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 Is that a sign of weak lcompression? It only happens at idle. When your driving along its smooth as can be. I just don't have the money to do large engine repairs Quote
Nas Escobar Posted January 28, 2015 Report Posted January 28, 2015 Diagnostics basically means hunting down the problem. A rental tool is all you need, the major parts stores should rent you a compression tester. Â If you swapped out your coils and it still has a misfire and the spark plugs and wires are new... then it becomes a matter of figuring out what it is. The compression test eliminates the possibility of compression/cylinder failures. Then you eliminated a major potential issue. Quote
csb41502 Posted January 28, 2015 Author Report Posted January 28, 2015 Is that a sign of weak lcompression? It only happens at idle. When your driving along its smooth as can be. I just don't have the money to do large engine repairs Quote
Galaxie500XL Posted January 28, 2015 Report Posted January 28, 2015 A compression check can definitely help...miss at idle is a classic symptom of a burnt valve. A vacuum gauge can be a help as well--typically a burnt valve will manifest itself with erratic vacuum readings, particularly at idle. Is that a sign of weak lcompression? It only happens at idle. When your driving along its smooth as can be. I just don't have the money to do large engine repairs Quote
csb41502 Posted January 29, 2015 Author Report Posted January 29, 2015 I did a compression test and everything was good. All I have left is injectors and fuel pressure regulator. The icm is good. If I unplug 1 plug wire at a time it misses worse. I don't know if it has anything to do with it but a lot of times the low oil level light stays on. I just did an oil change. Could that green and black harness be off something important? Quote
csb41502 Posted January 29, 2015 Author Report Posted January 29, 2015 I just checked the regulator. I pulled off the vacuum hose and it's totally dry Quote
rich_e777 Posted January 29, 2015 Report Posted January 29, 2015 What were the compression psi numbers? Also sounds as if that injector on the misfiring cylinder isn't atomizing fuel, compare spark plugs from that cylinder to the rest. Or swap injectors, just make sure you replace the o-ring on the injectors when you pull them out. The don't work so well being re-used, I learned the hard way once. Quote
DiscoStudd Posted February 1, 2015 Report Posted February 1, 2015 I would pull the valve cover and check to see if either of cylinder 2's rocker arm bolts are stripped or popped out. Quote
csb41502 Posted February 1, 2015 Author Report Posted February 1, 2015 The compression numbers were #1-180 #2-170 #3-170 #4-160 #5-160 #6-180. I was told those numbers are good for all cylinders. I never thought of pulling the valve cover to see what's going on Quote
csb41502 Posted February 3, 2015 Author Report Posted February 3, 2015 It's been running a lot worse over the last 2 days. Now I get a p0300 for multiple misfire and it runs so rough at stoplights in drive with my foot on the brake it stalled a few times. Is it a vacuum problem? Quote
Schurkey Posted February 3, 2015 Report Posted February 3, 2015 It's been running a lot worse over the last 2 days. Now I get a p0300 for multiple misfire and it runs so rough at stoplights in drive with my foot on the brake it stalled a few times. Is it a vacuum problem? Put a scan tool on that vehicle and find out. Quote
rich_e777 Posted February 3, 2015 Report Posted February 3, 2015 I don't know how this happened but I had a frayed fuel injector wire on cylinder #2 or #3, the manifold design messes me up but it was the middle injector in the back, and this caused a misfire until I used some liquid electric tape to fix it while I wait for a 1st gen to pop up at the yard so I can get the fuel rail harness. It worked good enough I don't stress it as much anymore. That liquid tape is some good stuff for things like that. Quote
csb41502 Posted February 4, 2015 Author Report Posted February 4, 2015 I've been trying to do searches but am not understanding. How do I test the injectors and the harness? I can't afford to get injectors or get it scanned with a good scanner until this weekend. Quote
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