Impala Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
Hi! Please help!! I have a problem with my 2008 Impala 3.5 flexfuel., 310 000km. If I slowly accelerate, everything is fine. But when I put the gas pedal more than halfway down, the engine stutters and hesitate. Also when I decelerate and I want to accelerate, the engine stutters at 1000-1200rpm, and I need to release the gas pedal and try to push it back very slowly to accelerate. The code P0300 (randomly misfire) is active and when the engine hesitates, the check engine light flashes during 30 seconds. The plugs are ok (40 000km but I took two out of the head and they are good) the wires are also ok (changed a couple of months ago) I also changed the coilpack, the throttle pedal and the throttle body....but didnt fixed the issue.. When I changed the throttle body, Ive seen that there is a lot of sludge stucked on the "walls" into the intake manifold. The car was a taxi before I bought it. It was 240 000km, but Im not really sure it was the real milleage, (and what about the idle hours!!) so I think it might be really dirty in the engine. I bought a seafom can to put in the fuel tank to clean the injectors, and to clean the interior of the engine. Does someone already had the same problem or know what I could try to fix it? I do not have a lot of money to bring the car to a mecanic and I really love this car. I drive a little more than 100 km a week. Thank you for your help guys, and girls !!
 

·
Registered
Joined
·
297 Posts
Hopefully you used ac delco for the plugs, wires and coil pack. Couldn't hurt to inspect and clean the maf sensor.
 

·
Registered
Joined
·
294 Posts
I would check your vacuum lines for a leak. Vacuum leaks can cause random misfires. Might check your intake too. Also make sure your battery is up to par.
 

·
Registered
Joined
·
1,090 Posts
Have you checked for fire at the plugs? There are cheap test lights that can be found at most parts stores that go between the plug and wire that lights up if there is fire on that cylinder. Not sure about the ignition setup on that model, with the single coil pack. Have seen an ignition module fail on one coil pack bank cause random misfire p0300, which caused 2 cylinders not to get fire on a 3800 where there are 3 coil packs mounted to the ignition module, your car does not have that type setup though.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #5 ·
Last evening, I looked around the intake manifold. I took off two hoses that goes from near the throttle body to the valve covers (one before the throttle body, on the intake rubber pipe, to the rear valve cover, and the other one after the throttle body, to the front cover). I cleaned them with some brake cleaner. They weren't clogged but really dirty from the inside.. I replaced the orings and put the hoses back. I also replaced the map sensor oring. This morning, the check engine flashed as usual, but the code has changed for P0303 (cylinder #3 misfire) instead of P0300 so I think I maybe solved one problem, but there is something else. My randomly misfire has changed for cylinder #3 misfire. I'll change the cyl#3 plug with the cyl#4, and the wire of the #3 with the #1 . So if I get a P0301 code (misfire cylinder 1) I'll know that the wire is faulty, or P0304 (cyl#4 misfire), I'll know that the plug is faulty. If cyl#3 still misfire, I'll know that the coil pack is faulty. I think it would be a good test. I also want to clean the interior of the engine with seafoam. I don't know how to check for vacuum leaks without any tool. Can anyone give me some information about how I can test for vacuum leak?? With 300 000km on the clock, the car needs a good tune up. I want to keep it for a while. I really love this car. Thank you again for your help !!
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #6 ·
Ok...... After work I switched cylinder 3 plug with cylinder 6, and wire 3 with wire 1. Start and drove, check engine flashed. Look for the code: now I have cylinder 1 misfire... (P0301 instead of P0303) so I took of the faulty wire and changed it for another one I picked at Kenny upull last week end. Restarted the car, drove a few minutes. Check engine flashed, looked for code: P0301...... Came back home, took off the SECOND faulty wire, changed for another one, still got P0301.. Changed the coilpack for a used one I also picked at Kenny. Still code P0301... So I think the injector could be faulty.. But I dont understand why I got cylinder 3 misfire this morning....
 

·
Registered
1007 Chevy Impala SS 5.3L
Joined
·
6 Posts
Ok...... After work I switched cylinder 3 plug with cylinder 6, and wire 3 with wire 1. Start and drove, check engine flashed. Look for the code: now I have cylinder 1 misfire... (P0301 instead of P0303) so I took of the faulty wire and changed it for another one I picked at Kenny upull last week end. Restarted the car, drove a few minutes. Check engine flashed, looked for code: P0301...... Came back home, took off the SECOND faulty wire, changed for another one, still got P0301.. Changed the coilpack for a used one I also picked at Kenny. Still code P0301... So I think the injector could be faulty.. But I dont understand why I got cylinder 3 misfire this morning....
Did u ever figure this out cause I’ve done everything you’ve done tit for tat. Po304 still. I’m starting to get mad.
 
1 - 7 of 7 Posts
Top