car hitting on three cylinders

[gotbl4d3]

Okay here is the story i was driving home one night awhile back and my car started to idle real rough so i get it home and check my spark plugs and i could tell that number three cylinder plug was not getting any fuel so i did a compression test 141 on cylinder one 147 on cylinder two 120 and cylinder three and 150 on four so i got compression but im not getting fuel so i bought some used injectors from the classifieds and he sea foamed them and claims that he cleaned them all up so i got the injectors and put them in and i am still hitting three cylinders and my spark plug is still not showing that i am burning any fuel does any one have any idea on what this could be oh and my fiav is making a weird static\grinding noise would that cause that and i got a new rebuilt throttle body on it if that does anything and my emmissions are gone please get back to me and let me know what any of you guys would think it could be thanks

 

[SrKegler]

Since you only have one bad cylinder, check that plug wire first. Then check the wiring to #3 injector.

 

[chanley talon]

You might wanna pull the plug and leave it attach to the plug wire and see if its getting spark. If it is than that rulls out your coil miss firing. This would point to bad wiring or a possible injector. However you do have a resistor box on the firewall for the injectors. I would swap this if you can't find your problem. It is a silver box on the passenger side firewall.

 

[g4ebguy90]

For one thing, The coil on those is a waste spark system. So if the coil was bad, it would be missing on more than 1 cyl.

 

[95boostedGSX]

I was having that problem in cyclinder 2 tried a new injector that was not it i did compression test that wasnt it either i tried a new sparkplug wire and it running better.

 

[gotbl4d3]

Yeah I already checked and I do have saprk so how would I test the wiring to my injector and my fiav is making a weird grinding noise is that normal

Okay so I went back over everything checked on got compression I went through and have spark on all four cylinders they and I am still not getting any fuel to my thrid cylinder could somone help me on where I should go from here

 

[gotbl4d3]

Okay so I have done everything I could to find my promlem why my car is only running on three cylinders could it be my ecu that's causing the problem but if it was my ecu wouldn't it only be running on two cylinders instead of three

 

[SrKegler]

First pull the injector on the bad cylinder and swap it with one of the other injectors. Now start the engine. If the same cylinder is messing up, you know the injector is good. If the problem moved to another cylinder, you know that injector is bad.

If the injector is good, check the wiring going into the injector. These have a tendency to crack and break. If thats the problem, repair the wire.

 

[gotbl4d3]

okay i already have swapped it out with another injector and it is still messing up on the same cylinder. I also checked all my wiring and it was good. Could it be like my resistor pack or my FIAV. My FIAV makes a grinding and cracking noise when the engine is warm or could it also be a possible chance that my CAS is shot

 

[SrKegler]

FIAV wouldn't have anything to do with the car missing on one cylinder. Since you've ruled out injector and wiring problems that eliminates fuel problems. You said compression is good. Only thing left is spark. You said it's running better now that you swapped out the plug wire. Try putting a new plug in. The one in there now must be fouled out.

 

[gotbl4d3]

No I have spark on all my cylinders that was 95boosted who said had the same problem and switched out plugs and wires all my plugs and wires are brand new so i am getting spark i got compression but not getting any fuel to that cylinder what would i use to check if that injector is pulsing.

 

[jdub1992]

Check you CAS? Maybe that is going bad idk trial and error I'm gonna say.

 

[gotbl4d3]

Yeah I am also looking towards my cas also because I hooked a noid light up to the third cylinder that has been giving me problems and I am still getting a pulse on that injector plug and I also pulled my ecu to take a look and the power caps were leaking also. But if my ecu was causing it wouldn't give a pulse at would or what. No matter if its the ecu or not im gonna send it in for repair. Does anybody know who does a good repair job on our ecus

 

[SrKegler]

ECM tuning. Might even have them throw an EPROM chip on while they've got it.

 

[gotbl4d3]

Okay well I did another compression test just be safe and my third cylinder dropped to 90 now the first time I tested it was at 120 and so I went and did a leak down test and it showed decent percentage but when I did it I could feel air coming out of my number one cylinder what does this mean

 

[n3xu5l3ak]

If air was coming out of the number one cylinder while you were putting air into a different cylinder it would mean valves were open or if its an ajacent cylinder you may be looking at a blown headgasket. A blown headgasket could be a reason why the compression reading was varied as well if air was able to pass between cylinders.

 

[90YellowTSI]

maybe blown headgasket, maybe you have a valve slightly bent or burnt

 

[rlacasse1]

My guess is you jacked up your headgasket.

Take off your radiator cap and crank your car. Make sure your plugs are in that way your cylinders will build compression. If it shoots coolant out the when you crank it then you need a new headgasket.

 

[Mackadoches]

My guess is you jacked up your headgasket.

Take off your radiator cap and crank your car. Make sure your plugs are in that way your cylinders will build compression. If it shoots coolant out the when you crank it then you need a new headgasket.

I agree with this ^^

 

[SrKegler]

Depends on where the gasket is blown. If it's just between cylinders the pressure may not get into the water jacket.

From his description however, I doubt if that is the case. He only claims low compression in one cylinder.

 

[gotbl4d3]

See I am pretty sure its not a head gasket because I just did a cylinder head rebuild only about 1200 miles ago so I really do not think its that does anybody of any of ideas on what would cause that

 

[SrKegler]

When you pressurized the cylinder the valves, Intake and exhaust were closed. Now if air is leaking into an adjacent cylinder, how do you think it got in there. The only way I can think of is a blown section of the head gasket between the two cylinders.

One thing that is still confusing though is you say this in the only cylinder with low compression. The adjacent cylinder should also be showing low compression. When you do a leak down test it should be leaking into #3 cylinder.