So I found out why my truck can't accelerate and sounds like it is backfiring around the AFM box... It turns out that the engine is only running on 2 cylinders BUT YOU CAN'T TELL BY LISTENING!

I have an 88 pickup 4X4 with MT and 22R-E. The motor is an 87 though... The truck is time 100% spot-on, has good spark with all four plugs, wires are good, spark plugs are gapped correctly, valves are adjusted correctly, fuel is good, TPS is new and correctly adjusted, there are no vacuum leaks or emissions leaks that I see, there are NO CODES, and yes, my ECU does work (as far as being able to throw codes).

I pulled the plugs on all cylinders and cylinders 1 and 4 looked normal but cylinders 2 and 3 looked wet. I cleaned them up and tried again (again there is spark from the distibutor through the wire to the plug... the plug just gets too wet to fire when in the block). Obviously the firing order is 1,3,4,2 which with what I see as far as my plugs go seems to indicate that I am missing actual combustion on every-other cylinder...

Could this mean my fuel injectors on those two cylinders (2 and 3) are stuck on? And then the plugs on those cylinders just end up floaded?

I apologize for the quality of the video and my father-in-law holding the camera... I forgot my phone at my house and had to borrow his camera to make the clip. As you can hear him in the background he is not overly up with modern technology...

[youtube]http://www.youtube.com/watch?v=w-ham4GG9Bs[/youtube]

 

Not sure what I did to get two videos showing (sorry)...

 

you sure each plug is actually firing? You sure the #2 and #3 plug wires are not crossed?

 

Absolutely! Tested every one individually...

 

I know you tested plugs, and so you are positive that 2 and 3 wires are going to the proper place not only on the spark plugs but also on the distributor cap?

Hmm.. weird that 2 injectors would go out at the same time, can't think of anything else at the moment.

 

Yes, I am sure all of the simple things have been checked. The wires work, the distributor works, the plugs work, everything is where it is supposed to be. Did you hear it run? Pretty amazing on 2 cylinders wouldn't you think??? There appears to be a possible exhaust leak (I am assuming) around the exhaust manifold/header area but I think that is from when the timing was being adjusted... Other than that noise it sounds fairly normal...

I even had my father-in-law come out and go over everything we are talking about here, so that I would have a witness. He used to be a bus mechanic so he is not as dumb as he sounds on the video... But he is useless when it comes to my Toyota!

Is it possible for a fuel injector to get stuck open? I would assume that fuel pressure is always present at the fuel rail and the electrical part of the EFI tells when to open each injector. But if those injectors were stuck those specific plugs would act flooded, right?

 

Fuel injectors can definitely stick open due to age, or if if the ecu demands too much fuel the injectors go "static" and stick open. But that second part is more for modified performance vehicles. Obviously a 22re isn't a performance vehicle, but if the ECU is malfunctioning you never know what it may be trying to do. But the fact that it's only 2 cylinders is still confusing me.

And I have no idea on an older vehicle like yours, but on newer ones you can measure the pulse width and duty cycle of an injector. Maybe someone else can chime in on how to do this on an older vehicle!

 

Head gasket being blown without any coolant in the oil??? Never heard of that?

 

head gasket can blow out several ways, cyl to coolant (steam in coolant and/or coolant in cyl), cyl to oil passage (high oil pressure and/oil severly burning oil: this one is less common) and oil to coolant passage (oil in coolant or coolant in oil). Coolant to outside of head (coolant leak onto the ground), Oil to outside of head (oil leak to the ground: uncommon as well if you don't count a botched timing chain cover install with the head on), cyl to outside (what sounds like a vac/exh leak: another one that is uncommon but in theory can happen as well) and what could be your case cyl to cyl which almost gives no indication and is one of the hardest to notice.

If it goes on long enough or is a bigger blowout then it will be cyl/oil/coolant passages mixed together.

cyl-coolant, cyl-oil, cyl-outside, cyl-cyl will all show a low compression test.

 

So as long as my compression is above 140ish this would be ruled out?

How exactly do you mean botched timing chain cover install??? Thanks

 

unless two of your cyls are at 160ish. I think the spec is 140-170 or something like that and no more than 10psi between any two readings.

I forget what the compression results are for cyl to cyl blowout, something is telling me there is a chance that the readings will be high. Just cannot remember what that symptom is when a compression result is high off hand.

 

Could you clarify what you mean regarding the timing chain cover install? Thanks

 

if you are like me and several others that have done a timing chain job with the head on and were not careful reinstalling it, you can pinch the head gasket that seals the timing cover to the head. It will leak oil like no tomorrow when the engine is off. But that part of the head gasket is not pressurized with cyl pressure. If large enough it can result in a vacuum leak though as well as a bad seal on the oil pan side of the cover all while still leaking oil when running.

There was a thread last week about this as well. Someone was asking how you can reseal this section without taking the head off.

 

My timing job was done leaving the head on. However, I was careful and putting it back in place and used a RTV on the corners as was reccomended to me... For arguments sake, if that was leaking (I don't think it is) that wouldn't cause the issue I am having in cylinders 2 and 3 right? But would it show up on a compression test?

 

The problem as described with the timing chain job would not show up in a compression test and would not affect just two cyls if it were a vacuum leak though there or the oil pan. Mine ran "fine" with a small vac leak through the oil pan and oil leaking from the timing cover-head area.

 

I am certain that my issue doesn't relate to a vacuum leak.

 

keep in mind a crack in the head between #2 and #3 intake and/or exhaust valve area would cause this is well in addition to a bad head gasket. But that would tend to burn some oil. A crack in the block between #2 and #3 would too but not common.

 

Keep in mind that it ran right a couple weeks back... So how likely is this scenario? It would seem more believable that the fuel injectors are stuck open (or would it)??? Thanks

 

I guess it can, not sure though. You can try putting #2 and #3 injectors in #1 & #4 cyls and vice versa to see if the problem shifts to #1 and #4.

 

How difficult is it to get to the fuel injectors? Does the air intake manifold have to be removed? (I haven't looked yet in the FSM, figured I'd ask first)???