I was all about to replace my injectors due to a cold running problem, but then I realized that it runs just fine when it's warmd up, so this gets me to ask you guys a question. On cold days, even without plugging it in, it used to start and run great with no issues. NOW, it runs fine, but only when I plug it in. When I don't plug it in, it acts as though there is air in the fuel system. Kinda like when you run it out of fuel. Normally with that issue, I'd let it run for a few minutes, rev it up a few times and it will clear itself out and run fine after that. That isn't working with my situation now. I can rev the hell out of it, and it won't balance itself out until it warms up and it smokes a lot. It runs so bad that the whole truck shudders when it hits 3rd gear while trying to even just keep speed. After 5 minutes or so, it clears out and runs fine for the rest of my trip. So, my question is, is it possible that after about 2 years on new O-rings that they could've gone bad and this is causing my problem? or is it possible that an injector or two are going bad and whatever is wrong with them seals itself up as the engine warms up? I having trouble convincing myself to spend $1500 on injectors for a truck with 420K and starting to rust out

 

Don't pull the pin on inj just yet.

Many threads here on glow plug health.

Is your degas bottle foaming with oil on top?

Do your research. Sounds like a bad GPR or UVCH and/or glow plugs.


Any and all of the things I mentioned are easily done and comparitively dirt cheap compared to inj.

Denny

 

I'm thinking possibly glow plugs as well, and maybe a shimming of the injector poppets. I'd check glow plugs first.

 

I did injector cups a couple of years ago. I did the glow plugs and o-rings then too. It starts up just fine, with the GP's, even when it was -20. it just runs like crap for the first 7 or 8 miles. Did the .25 mod a looong time ago,

 

I would look into worn poppets and shimming them. A few guys here have done it, the kits are available on fleabay for cheap and it's not too hard to do.

 

Just wondering if the EBPV is sticking until it warms up enough.

 

450k Mi. is a fair amount of Mileage. However, do you know if the Injectors have been replaced in the past. With the exception of a few, I never saw Injector Issues on the 7.3L until about 250k Mi. And those were primarily Work Trucks like Electrical Service Truck that run constantly (Idle).

Running badly when its "Cold" can be many things. ie: A Sensor providing incorrect data to the PCM.

My suggestion is you get a Scantool and Monitor Sensor I/O and compare them to DELTA first. This will provide a look at the overall performance during this period.

Perform a "Buzz Test" and Cylinder Contribution Test - This will at least narrow it down to a Bank and perhaps the offending cylinders.

"Cold Problem" can often be resolved by changing Oil and/or using a lower viscosity Oil: ie: 5w40 or similar.

Get the data first and save some Big Bucks! You may end up spending Big Bucks in the Long Run but, at least you know it will be the problem.

 

Did you use Motorcraft Glow Plugs? Glow plugs are also my first guess. If you're due an oil change, that could cause your problem. Fresh oil makes a difference in these trucks.

 

After a little more research, I think I'm gonna try to shim the poppets. $75 and a couple of hours is well worth the gamble. A few weeks ago, I did run the AE to get readings from the injectors. BUT, it looks like the bad reading I got on 2 of them may have been caused by the CPS. I'm out of town this weekend, but I'll probably work on the shime one night after work next week. I never hears of this until this thread. I'm actually pretty excited to see how it works. Even if it only gets me another 80k or so. Just get me to 500k and I'll be happy!

 

What you are describing, sounds exactly like worn poppets. Either shim them, or invest in new injectors.