Cylinders 1 & 2 not firing when cold

[Sinsectan]

I've been chasing down a misfiring, knocking, and smoking cold start issue on my 88 F250 7.3 ZF5, and could really use some input. I bought the truck that way, after the previous owner had replaced the IP, injectors, had a valve job and head resurfacing done, along with many other miscellaneous parts. The truck was cheap so I've been taking my best crack at it.

The white smoke smelled like raw diesel, so the first thing I did was go over every possible entry point for air intrusion. There's air right after the IP return fitting, which is odd, but I've confirmed that it's air tight everywhere else.

Looking through the receipts he gave me, the injectors and IP were from from Pensacola diesel, and knowing their bad reputation, I pulled the injectors and shimmed them all up to 1900psi. They were all over the place before.

The truck now runs butter smooth at idle when warm, but the bad cold start still persists. Also, now when I rev past 1000rpm, it blows white smoke, which it didn't before.

I noticed that the #1 and #2 cylinder exhaust manifolds are cold when it's warming up, telling me that they're not firing. They get warm once the engine warms up, but still cooler than the others.

I'm going to do a compression test next, and I'm just hoping it's not a head gasket or stuck ring.

Could it be a bent/loose rocker? Worn out cam? A clogged lifter? Bad IP timing?

Any input is greatly appreciated. Thanks in advance.

 

[Rdnck84_03]

I'm not sure exactly what kind of cold you're dealing with for a cold start, my first check would be the glow plugs on the problem cylinders.

If they check out, compression test would be next. If that looks good I would swap injectors from working cylinders to the dead ones to see if it's the injectors.

If none of that changes anything then I would really start think that the IP has an internal problem.

James

 

[KansasIDI]

If it’s minus 5 or lower out, they are gonna be pissed off when they start, until they start to warm up. It’s about minus 15 here in northeast Kansas. My service truck with stock 7.3 started, misfired a bit, and was idling fine after a little bit. Part of the colder weather. My F250 with lowered compression, turbo, high psi injectors, and much more, did start yesterday in zero degrees, but was misfiring on a few holes for a couple minutes. I should have been plugging them in, but had other stuff to get in order, as I am going to Georgia for work this week.

 

[Nero]

Definitely check out the glow plugs on the problem cylinders. When you had the injectors out did you check them for leakage? Could be all the fuel is pouring out when it's not running and it has to de aerate too.

 

[Sinsectan]

I'm not sure exactly what kind of cold you're dealing with for a cold start, my first check would be the glow plugs on the problem cylinders.

If they check out, compression test would be next. If that looks good I would swap injectors from working cylinders to the dead ones to see if it's the injectors.

If none of that changes anything then I would really start think that the IP has an internal problem.

James

It was 22F out, nothing crazy. I'm going to change out my glow plugs with motocrafts next, and do a compression check, but I honestly don't think it's the glow plugs. The truck misfires for at least 10mins after start up, which is long after the glow plugs matter.

It is incredibly unlikely that it's the injectors, since hours before starting I had them on a pop tester and they worked great. I also know that it's cylinder 1 that's dead because when I crack it's feed line, the smoking stops, but cracking the other lines makes the engine run worse.

That's two things pointing to one, which that it's not firing. I'm getting an occasional popping sound too, so I'm hoping it's just a bad lifter

 

[Sinsectan]

Definitely check out the glow plugs on the problem cylinders. When you had the injectors out did you check them for leakage? Could be all the fuel is pouring out when it's not running and it has to de aerate too.

Glow plugs are on my list, but I still find it strange that they could matter 10-20mins after cold start, which is how long the truck misfires for roughly

Yes, I tediously shimmed and cleaned every injector to ensure they ran properly

 

[Sinsectan]

If it’s minus 5 or lower out, they are gonna be pissed off when they start, until they start to warm up. It’s about minus 15 here in northeast Kansas. My service truck with stock 7.3 started, misfired a bit, and was idling fine after a little bit. Part of the colder weather. My F250 with lowered compression, turbo, high psi injectors, and much more, did start yesterday in zero degrees, but was misfiring on a few holes for a couple minutes. I should have been plugging them in, but had other stuff to get in order, as I am going to Georgia for work this week.

It was about 19 where I'm at, and I expect a grumpy start up when it's freezing. It's just been an issue for months, where it's persisted no matter the temperature of cold start

 

[Nero]

Do a compression test and leak down then, that will tell you a lot about the power cylinders.

 

[KansasIDI]

It was about 19 where I'm at, and I expect a grumpy start up when it's freezing. It's just been an issue for months, where it's persisted no matter the temperature of cold start

Yeah, if it misfires at above 40 degrees when you start it, I would guess something is off…

Lowered compression, then maybe if it still misfires right after starting at 45, not sure that be a problem. Stock is a different animal though

 

[Sinsectan]

Do a compression test and leak down then, that will tell you a lot about the power cylinders.

Will do, I'm guessing it could be a valve issue, and those cylinders will read near zero. It has a bit of a popping sound when running, telling me that something's up in the valve train. Maybe a lazy lifter.

I'm going to keep digging away. Thanks!

 

[Sinsectan]

Yeah, if it misfires at above 40 degrees when you start it, I would guess something is off…

Lowered compression, then maybe if it still misfires right after starting at 45, not sure that be a problem. Stock is a different animal though

Yeah, something definitely is off. All of the other cylinders are fine except the one.

I'm almost wondering it's a sticky lifter or two, causing the intake valve to open at times giving me a popping sound in the intake.

I'm not one for "miracle in a bottle" additives, but I'd like to try a detergent in the oil next, maybe clear up some gunk in the lifters

 

[Sinsectan]

Kansas, I was searching for "popping sound" on the forums and found your post from last summer. Just wondering, what did this end up being? I have the same thing but also with occasional popping

Well today my truck developed a miss. Cracked injector lines one at a time, no change on #5 cylinder. It is a chuff with a click kind of miss, but is not a popping noise. I have been around an 83 with a bad lifter, it sounded like a Model B John Deere it popped so bad… so would my noise be injectors?

 

[KansasIDI]

Kansas, I was searching for "popping sound" on the forums and found your post from last summer. Just wondering, what did this end up being? I have the same thing but also with occasional popping

It ended up being a bad headgasket between cylinders 3 and 5… and the heads were warped out of spec entirely… so I then went the turbo 7.3 route. That 7.3 in Duchess (my 86 F250) makes a ticking sound, which I am fairly certain is an exhaust leak at the uppipe collector.

 

[Sinsectan]

It ended up being a bad headgasket between cylinders 3 and 5… and the heads were warped out of spec entirely… so I then went the turbo 7.3 route. That 7.3 in Duchess (my 86 F250) makes a ticking sound, which I am fairly certain is an exhaust leak at the uppipe collector.

Shoot, that's a bummer of a job

I'm thinking since my head gaskets were just done by the previous, and the problem persisted before and after the job (assuming he didn't mess that up somehow), and I have a popping sound, I'm looking at a stuck lifter being the culprit.

Changing those out isn't a small job, so I'm planning on changing the oil with Motorcraft oil and giving it some wide open throttle before I dig into. It sat for a while, so I'm guessing a lifter or two might just be stuck

 

[IDIBRONCO]

Shoot, that's a bummer of a job

I'm thinking since my head gaskets were just done by the previous,

Changing those out isn't a small job,

Well the good news is that I can say for a fact that a head gasket isn't your problem. #1 is the front cylinder on the passenger's side while #2 is the front one on the driver's side.