Today I went over a friends house to check out her car. When I tried to start the car it only continued to crank but no start. Sounds like a normal crank. I checked and verified there is good spark. Fuel pump is running. This leads to my first question. Is there and where is the test port to check fuel pressure? I didn't see anything under hood. I finally got the car started after cranking it four times for about 30 seconds each time. It ran rough and died out. It did this two times then I gave it gas to keep it running. When you press the gas above 3,000 RPM the engine runs smoothly and when you stop pressing the gas it runs rough for about 7 seconds then dies out. Checked for codes with aftermarket scanner and had P0301 Cylinder 1 Misfire stored. Removed intake to access #1 cyl. then swaped coil from #1 cyl. to #6 cyl. and spark plug from #1 cyl. to #5 cyl. Put everything back together and erased codes. Vehicle started and ran rough. Scanned for codes and retrieved a P0306 Cylinder 6 Misfire. Simple enough I need a coil so I thought. Replaced coil in cyl. #6 which was originally in cyl. #1. Ran vehicle and it still runs rough as it did when I first got it started. Scanned for codes again: P0302, P0304, and P0301. Cylinder #1, #2, and #4 misfire. I disconnected cyl. #2 coil wiring and engine idle did not change. I disconnected cyl. #6 coil and engine ran rougher. There is a large hose that goes from the upper intake on right bank side to the lower intake at the rear of engine. Where it attaches to the upper intake it is a rubber elbow which collapses when the engine is running in open loop and closed loop. Checked the hose for blockage and found nothing. Reattached hose at lower intake and sucked on hose (yumm) and noticed no restriction. I was able to get it to not collapse by putting pliers around it and ran engine. Still runs rough but did not collapse. I think it collapses because the rubber is weak. I looked over repair pal's advice colomn and saw a couple places where people mention intake gaskets failing. I sparyed brake cleaner around intake and noticed no change in engine RPM then sparayed carb cleaner around intake and still notice no change in engine RPM. Do you think it's the intake gaskets? Any help would be appreciated and Thank You.
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2001 Mazda Tribute
Question: Engine runs rough.
Answer #1prodrag January 13, 2013, 07:47Rookie
You seem to have a misfire in all the cylinders intermittently. I do not think is your intake manifold gasket
as there was no change in the engine RPM with the carb cleaner. Sounds electrical, however i would check further before tearing into the manifold gasket.