Two dead cylinders... I need help....

[SWThomas]

On my way home today I pulled up to the stop light to turn into my apartment complex and I noticed that my truck was shaking and making a ticking sound on the drivers side. Hasn't done this before. I get home and call Bob to get his opinion and he said to look at the plugs and coils. So I start the truck and start unplugging coils. The two front coils on the drivers side made no difference in the way the engine ran when I unplugged them. All of the rest made a noticeable difference when I unplugged them. So I pull those two plugs and they are black and smell like fuel. So I think bad coils... I test both those coils for resistance with my multimeter and they both check out fine. So I throw two new plugs in and put the coils back on and start the engine. Same thing...:shrug: So I remove the two coils and put two of my stockers on there. Same thing...:shrug: So I disconnect my battery for 10 minutes, reconnect it and reload my tune with the XCal2. Same thing...:shrug: So I check to make sure the coils are getting power. Both are getting 12.5 volts. Then I crank the engine and watch the Wideband. I'm seeing 13.1-13.3:1 at idle. I go to the engine and unplug those two fuel injectors and the A/F comes back up to 14.7:1. Then I plug them back in and it drops back down to 13.X:1.:shrug: So I'm getting fuel, I'm getting voltage, the COP's aren't bad and there's two new plugs in there. What could this be???

My next step is to do a compression check on those two cylinders...

 

[ducman996]

Injectors stuck open?

 

[Fade 2 Black]

Do the comp check and lemme know.

 

[SWThomas]

I have to wait until my wife gets home before I can go to the auto parts store and get a compression tool.

 

[ecoastkid]

Injectors stuck open?

with that A/F ratio at idle...this is what I would be thinking as well.

It happened to my buddies cobra. The computer went bad and two injectors were stuck open because of it.

 

[Fade 2 Black]

I have to wait until my wife gets home before I can go to the auto parts store and get a compression tool.

In that case you can either check the signal coming to those inj. compared to a known good cylinder and/or swap one or both inj. with another to see if the problem follows or not.

 

[SWThomas]

with that A/F ratio at idle...this is what I would be thinking as well.

It happened to my buddies cobra. The computer went bad and two injectors were stuck open because of it.

So if the injectors are stuck open, would they pump enough fuel into the cylinders to prevent the plug from igniting it?

 

[SWThomas]

Is there a way I can check to see if those two injectors are operating correctly?

 

[Fade 2 Black]

So if the injectors are stuck open, would they pump enough fuel into the cylinders to prevent the plug from igniting it?

Yes.

IDK of any way short of a flow bench to test them. :shrug:

 

[my98stang46]

Is there a way I can check to see if those two injectors are operating correctly?

pull them out and put 12v on them and you will hear a click if theyre working

 

[Fade 2 Black]

Did you relaod the tune and or reset the PCM?

 

[chrisheltra]

If you cant isolate the problem how do you know you have 2 dead cylinders? Not trying to be a smart ass just wondering.

 

[SWThomas]

Did you relaod the tune and or reset the PCM?

Yes.

 

[SWThomas]

If you cant isolate the problem how do you know you have 2 dead cylinders? Not trying to be a smart ass just wondering.

Because there are two cylinders that aren't doing anything and the rest are. Okay, I'll call them "disabled cylinders".:lol:

 

[SWThomas]

I think I just jacked something up. I was testing the voltage on the injector harnesses and when I removed my multimeter pin, the fuel pumps kicked on to full and won't shut off now. What did I just do???

 

[bda1855]

sounds like a valve issue... but i dont know... do a compression test.. that will tell you whats up..

 

[FordFanStan]

Spencer,

Well there are several scenarios that come to mind.

Stuck injector like the other said.

Another we have been seeing lately is a bad coil. Let me explain... if this makes sense to you. There is voltage and information being sent to each coil, as well as out that coil and onto the next. It gives feedback. When one coils goes bad, it can give bad feedback. We have noticed ie. a misfire on #2 cylinder. We end up replacing all the coils, plugs, and injectors, on the passenger bank. It would not solve the problem, until we replaced the coils on the driver side. The bad coil did not affect the cylinder it was on, yet one on the completely opposite bank :shrug: .

We have software called IDS. It is Ford software. It can truely test compression, injectors, each coil, etc. all via the OBDII port and the battery. Some of the fuel tests also require the supplied fuel line and valves. Very helpful. Although you will probably only be able to go to the dealer there to have them use it and diagnose the problem.

Pull your hi-low relay and see what happens to the fuel pumps now... Stan

 

[SWThomas]

Spencer,

Well there are several scenarios that come to mind.

Stuck injector like the other said.

Another we have been seeing lately is a bad coil. Let me explain... if this makes sense to you. There is voltage and information being sent to each coil, as well as out that coil and onto the next. It gives feedback. When one coils goes bad, it can give bad feedback. We have noticed ie. a misfire on #2 cylinder. We end up replacing all the coils, plugs, and injectors, on the passenger bank. It would not solve the problem, until we replaced the coils on the driver side. The bad coil did not affect the cylinder it was on, yet one on the completely opposite bank :shrug: .

We have software called IDS. It is Ford software. It can truely test compression, injectors, each coil, etc. all via the OBDII port and the battery. Some of the fuel tests also require the supplied fuel line and valves. Very helpful. Although you will probably only be able to go to the dealer there to have them use it and diagnose the problem.

Pull your hi-low relay and see what happens to the fuel pumps now... Stan

I'll swap out all the GMS coils with the stockers as soon as I do the compression test and figure out why my fuel pumps keep running. I'll go pull the high/low relay right now and see what happens. They only run when the key is turned on. But they run at full power and won't shut off unless I turn the key off.

 

[FordFanStan]

When was the last time you filled up with gasoline? How much was in the tank/did you fill? Was it quality fuel? Those two injectors could also be clogged. How long did your truck sit after you used race gas the other week? Did you immediately run regular fuel through your system afterwards. I'm sure you did since you stated your drove to the track and back.

We have also noticed dried race fuel clogging injectors pretty bad if it sits for a while. But usually only over a period of a couple months or more, not a week or two :shrug: ... Stan

 

[FordFanStan]

It sounds more of an fuel issue, or electric issue with the fuel system, not the ignition to me, but these can be a serious pain to diagnose at times...