So I have a 1999 Pontiac Sunfire GT 2.4. I am gettign the misfire got P0304 Spark plug is fire, replaced the whole IDI with everything on it from my currently disabled cavalier. Still runs @!#$ty, youc an feel the engine shake in neutral and in drive and on the brake you can hear it running rough, giving gas little or alot sounds perfect. Compression on all cylinders is around 175ish nothing lower than 150. spark plugs are good. THe only thing I can think of is vaccum leak at the itake manifold area, or I did find a wire spliced into the injector part of the wiring harness. A White wire with a green line. I dont know if it was done by GM but it didn't look like it. Any clues people?
The idi system kinda sucks in my opinion. I was having issues with mine, I put new boots and all in mine. I finally got tired of putting money in the idi system and just did the neon coil swap. It was instantly %100 better. Seems to start faster as well.
I also have a mysterious P0304. Same symptoms. Plugs always look fine too. I'm using MSD coils though.
Fairly certain no vacuum leaks after my latest gasket replacement.. but it probably is. Ideally you need to pressurize the intake while the car is off so you can spray soapy water etc. and see the leak. That's what I should do too. Would be funny if that's what it was again.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Does yours run rough, but he'll my whole dash shakes when I have my foot on brake at the stop light in drive neutral you can feel engine shake
Yup, everything is very vibrate-y. All signs point to vacuum leak for me though. I'm eager to confirm this week.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
I don't know what mine can be, the intake gasket looked fine to me nothing broken bent or bad looking unless the smallest thing can make it misfire this bad, injector wires are fine, will injectors pulse fine. This is just confusing me, ugh. Changed all the IDI cover...no change...Also love your alero, how much all in all to turbo it with rebuild? I'm planning to do it to my cav.
~ $3,000
It is my experience that the smallest leak can make it misfire like this.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Well couldnt find a leaking intake, as for that random wire that was spliced into the injectors a white wire with a green stripe...what is it for?
Does the car have a remote start?That could be what that wire is for. They prob tapped into the fuel injector to get a tachometer reading for the remote start to work.
Peter
'06 Cobalt ss/sc W/G85 Package
Gm Stage II W/2.79" Pulley
K&N Drop In Filter
Custom Magnaflow Dual Exhaust
No remote start but it does have an aftermarket alarm, as far as i know...
I can't stand the boots either mine was misfiring same way so I did a coil swap from a eclipse. No problems since
Well finally broke down and took the known good injectors from the cavalier (used engine should come with them when I get it). Put them in the sunfire. As i was doing it i stripped the fuel inlet bolts ugh. got it on, it leaked everywhere from that spot found out I lost a ORing in there. Put one on and runs like a champ now..No more shaking =DDDD
