P0302 - Cylinder 2 Two Misfire Detected

[Tripp]

I have another thread but I figured I'd start this one seeing as I'm getting it narrowed down. Quick info: 1998 SL2, 162,000 miles. New starter, alternator, battery, fuel filter, and ECTS. Cleaned the spark plugs and took the ignition coils off and cleaned them thoroughly. Also cleaned the EGR valve.

I cannot figure out what exactly the problem is. When you first turn the car on, it idles at 2,000 RPM then after a few seconds drops down. Doesn't seem to skip or run particularly rough. Once driving though, the car starts skipping, sometimes worse then others. Seems to only happen when the gas is pressed intermediately or on a hill. While it's jerking, you can feel it suddenly pick up power, then lose it again.

I read to check the fuel injectors and some other stuff but I'm trying to avoid taking the entire intake manifold off if possible. Any ideas or clues because this is driving me crazy.

[1sksc2]

im having a similar problem. my 96 sl2 suddnely looses power and pick it right back up when the ac is running. i was told my iac isnt happy. and i have a rough idea. ive done everything i can think of.

have u replaced the plugs and wires

[ssewall]

1. Replace plugs and wires if they haven't been replaced recently. Make sure plugs are copper.
2. Swap the #2 injector with a different one and see if the misfire changes cylinders.
3. Swap the Coil packs, see if it changes cylinders.

[OldNuc]

While the plugs are out, do a compression test.

FSM states that a Fully charged battery is required to obtain the full 250RPM cranking speed for accurate results. So put the battery on a slow charger for 3 or 4 hours before performing the test.

To prevent washing the cylinders down with fuel remove the PCM B fuse to shut off the fuel pump, injectors, and ignition before starting the test. Remove all spark plugs and block the throttle open. Use a low charge rate battery charger to fully charge the battery before conducting the test.

To obtain any compression test numbers that have any validity when relaying information in a forum environment crank the engine until the gauge quits increasing and compare both the final pressure and number of compression strokes to reach the max pressure, cylinder to cylinder. You can do this test either cold or hot or warm just mention it when stating results.

[Tripp]

Thanks for the advice, I'm trying to hold off until next Friday to buy anything because I get paid then.

Friend is going to help me compression test it tomorrow and I'm also going to test the MAP and TPS sensor. Also going to take a look at the injectors.

Is it safe to take off the throttle body? Friend said there's a gasket that I'll have to replace if I do so. Same with the intake manifold.

[ssewall]

I've re-used the TB gasket twice, vacuum leak free.

[OldNuc]

No need to pull the intake. Neither the TPS or MAP will cause a single cylinder misfire. Plugs, wires, coils, ICM, intake vacuum leak, low compression, failed injector. If the engine pulls well at 2000+ RPM it is not likely to be an injector problem unless all the other possibilities have been checked.

If you do pull the intake you will need a new gasket. If you also have a high idle RPM then vacuum leak is the first thing to go looking for.

[Tripp]

So replaced the plugs and wires and that fixed the skipping and power loss for the most part. Cleaned the EGR valve as well and she's running pretty good. Friend helped me do a compression test. Car was hot/warm, was a hot day.

We got 205 PSI on the first cylinder, 220 on the second, 215 on the third, and 210 on the fourth. Not sure what the numbers are for this model but seems like I'm getting good compression but I'm still losing it somewhere. The transmission does slip, but I haven't had the money to buy a new valve body. Could this be where I'm still losing power?

Also, since I replaced the thermostat it has gone past half way, and on cool days it's not even getting half way up to a quarter so I'm going to replace it this weekend. What's the recommended brand?

Other then that, thanks for everyones help. I'm slowly restoring my car to it's former self

[3r!c84]

im having pretty much the same problem with my SOHC 1.9 changed spark plugs and wires. swaped coil packs still miss fire in cyl 1. pulled injecters cleaned them . didnt swap around but still miss fire. didnt compression test tho. out of ideas. it miss fires under 2500 then pulls pretty good the rest of the rpm range. i have swapped out the lifters because old ones making noise. these still make noise but not as much as other set. also replaced intakegasket that fixed the vacuum leak and high idle. i have done a induction clean service to it too. and cleaned the TB. besides that still miss fireing. car has 130k on it. 90% highway miles

[OldNuc]

2000 model year Sx-1 are afflicted with a folded intake manifold gasket at #1, this results in a misfire and eventually a high idle. Best approach is to just replace the intake gasket.
Intake Manifold Gasket Leak How-To
http://www.saturnfans.com/forums/sho...ntake+manifold

[3r!c84]

Originally Posted by OldNuc

2000 model year Sx-1 are afflicted with a folded intake manifold gasket at #1, this results in a misfire and eventually a high idle. Best approach is to just replace the intake gasket.
Intake Manifold Gasket Leak How-To
http://www.saturnfans.com/forums/sho...ntake+manifold

replaced that already

[OldNuc]

Have you run a compression test? Crank for peak pressure in each cylinder and count strokes to peak. Pull PCM B fuse to shut off fuel and spark for testing. If compression is good then go to J/Y and pick up a new to you ICM and swap it in.