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Cylinder No.5 not firing

Hi Steve,

I made the following post back on Oct. 4, 2004. Sounds like we are having the same trouble. I rarely drive the car but was looking at buying a fuel pressure tester from NAPA for about $45.00. Let me know what you find out on yours.

Thanks, Jeff

94 Pontiac SSEi.

The car is showing a miss on the #5 cylinder, occurs only when engine is under boost from the supercharger. Occasionally also shows miss on #4 and less frequently on #6. This was found by using a scan tool.

Have swapped plugs, wires, injectors, injector wires, and coils with those from either #3 or #1 cylinder, but problem stays on #5. Also tried a new ignition control module. Engine runs smooth in the driveway at all rpms. Only misses under load and only under boost conditions.

I'm thinking fuel pressure regulator?? fuel pump??

The fuel filter was recently replaced. I run 92/93 octane.

Problem occured after car was parked for several months with only being started every couple of weeks and idling to operating temp. The car has

177,000 miles. Ran great before parking it.

Any help would be greatly appreciated.

Thanks, Jeff

Reply to
Jeff & Carol
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Fixed it!! Temporaraliy...

Took the computer out and apart. Lots of corrosion. The transistor for injector number 5 was missing the base leg. It had corroded away leaving two points that looked like the current was arcing across for some time now and finally the gap got too big to jump.

So for now, I soldered in a patch to allow injector number 5 to fire until I get a new transistor. I wrote down the numbers, but before I head to the parts store, I'm going to try finding a "broken" computer that someone replaced so I can get the transistors and outer case. Then I'm going to coat the thing in something to keep this from happening again.

Steve

Reply to
Steve Mackie

Hi...

Good work, congratulations!

Persistence pays off :)

If you don't find a dud machine to pull spares off of, and can't find a source for another let me know... I'm an old retired electrical guy, so maybe I can help. No promises, but I'll try.

Ken

Reply to
Ken Weitzel

Thanks for the info. Good work! IIRC, your car is a GP around 1994? Is your ecu behind the right kick panel? Ecu's there seem to corrode a lot.

Reply to
« Paul »

'95 Monte, RF fender, behind headlight.

Reply to
Steve Mackie

Spray the circuit board with DeOxit, available at Radio Shack. Never used this on a car CPU but have used it on other circuit boards where corrosion is a problem and use it on PCs to clean memory cards and other connectors. Works great. Best contact cleaner I have ever used.

Reply to
Jimmie

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