Constant engine miss - ideas???

[BCook1]

Greetings,

Well I am trying to do things right with this truck but I am getting my #$% handed to me every time I turn around. I have picked up a constant miss through all rpms. I just had the injector pump set by a professional shop. The timing was at about . 5mm and they moved it to about 1. 5mm I think. The diesel noise was noticably louder. The max mph in each gear went up about 2 mph. It seems to have slightly more power although it still won't hold 5th towing. The mileage has dropped from about 10 towing to about 8 mpg. The fuel smell is much stronger - bad at idle. Now it has a miss after about 500 miles. I have run Stanodyne fuel treatment for the last 6000 miles. It sounds like a gasser with a fading plug or wire. Any ideas??

Thanks in advance

Also - any reputable shops in the Black Hills of SD or near Denver? I don't mind paying for expertise if they get it right the first time.

 

[Dman]

After timing blues

First guess would be a loose injector line fitting at pump. Would be drippimg fuel on ground. Also check bolt in center of pump head (where the lines attach to pump) that is removed to set timing. Again, would be dripping fuel

 

[BCook1]

Couldn't find any obvious fuel leaks. What I meant to say was that the diesel noise is now louder after the pump was adjusted. Does anyone know what the cylinder pressure should be with a wet and dry compression test? At least that would rule out the mechanical hopefully. If I have a bad injector (150,000 miles) which injectors should a person replace the stock ones with - I have seen quite a few options on the site. Someone mentioned the lift pump - but I don't understand how this could be the problem - If I replace the lift pump do I have to have the injector pump checked again?

Thanks

 

[JLEONARD]

You can find the faulty cylinder/injector, by loosening the injector nuts on the fuel line one at a time... . the faulty one won't change the idle/miss as much as the good ones... . like pulling spark plug wires to find a miss.



If you have an ir temp gun you should be able to locate the faulty cylinder by it's cool temp compared to the rest.



I agree that it doesn't sound like the lift pump... . but the lift pump is totally seperate from the injection pump... no need to check the inj pump after changing it.



Injector choice depends on what you want out of your truck... any of the upgrades are good, they are "tunable" to a certain degree and should improve both you power and mileage.



Hope this helps. Good luck.

Jay

 

[cerberusiam]

Sounds like you have an injector that is either hanging open or popping too soon. It could be just dirty injectors or the pump starting self-destruct. Either way at 150k they are probably due for some tuning.



I have used Rapid Diesel Service in Rapid City SD in the past with good results. I think they are still in business. I have some contacts there I can ping to see who would be available. Let me know and I can find out.

 

[BCook1]

More info.

OK, I have an appointment with a dealer and hope to hear back from Rapid Diesel soon. They came recommened by others as well. More info - It looks like I lost about 1 psi - am down to 14 at the max where I would sometimes get more than 15 and the egts seem lower. I never got close to the red and barely got into the yellow towing - granted it is winter up here. A call to Midland in Fargo (they set the pump) confirmed the injector idea - apparently once the pump was brought up to where it should have been, the injectors may not have been able to handle the pressure increase. That would explain the excess fuel smell and bad mileage - maybe even the guage reading changes. Know more tomorrow.

Thanks for input,

Brennan R. Cook

 

[phillips5]

I don't believe that bumping the timing ahead could increase line pressure on the injectors. I do believe that there is a falty injector. At 150k it is time. Also if you only get 15psi boost tops that pump must be under stock. To my experence most stockers are 18-19psi tops.

 

[BCook1]

Injectors good...now what?!?!?

OK, I just had Rapid diesel service check as much as they could. the lift pump pressure is good, the pump pressure is good. So I had them pull and test the injectors - all came in within 150 psi of stock. They all cycled good and were clean enough so that they did not require cleaning. And the spray pattern showed good. They said a rebuild on the injectors would not even be noticed so I left them. The miss is still there. It is very subtle, has not changed since I first noticed it. The mileage is horrible. The tank was filled 275 miles ago and the low fuel light just came on. Only 160 miles of this were towing. I don't get it. Is there any way a faulty pump could result in bad mileage? I don't know enough about these systems to venture a guess. I am headed to Denver - that will be a good test for mileage in a slightly warmer environment and I will put a double dose of stanodyne in each tank. I have been running number 2 and will continue to do so. I am going to look for a leak in the tank next - where can all this fuel be going?

 

[cerberusiam]

Definitely a gremlin there somewhere.



Have you checked and set the valve lash lately?



Are you seeing any extra smoke at an idle with engine warm/cold?



Injector line tips straight with injector tops?



Have you changed fuel filter and air filter lately?



My lift pump is leaking and I can smell a strong fuel odor all the time. It is showing on the block below pump but does not leave a puddle. Are there any leaks that are obvious?



My mileage dropped when the pump went south so its possible there is a developing problem. After I changed pump the injectors are now overdue for refit but mileage towing has never dropped under 10 mpg.

 

[BCook1]

I think I covered all the obvious...

The valves are set, the air filter is good, the fuel filter is new, I assume that Rapid diesel service knows what they are doing and checked everything possible with the injectors. About all that is left is the pump and I would change that if I could justify gambling a thousand dollars on a possible fix. I am going to run a few tanks through it over the next several days and if it is still as bad on fuel as it is now I may just have a pump put in. There are no obvious leaks and the fuel smell is definitely at the tailpipe. I can't think of any other options. One weird thing is that the only time I got low teens towing was going over high passes in Colorado. I would have thought altitude would have made things worse. Maybe it was just a fluke.

Thanks

 

[dpuckett]

While you're headed to Denver...

Take a detour to Greeley, and stop by Rocky Mountain Fuel Injection. I talked to them a few years ago, and they seemed to know what they were talking about. THat was long before I started following the Pastor and reading from The Book. I'll look up their address and phone number and post here.



Rocky Mountain Fuel Injection

150 E 18th St

Greeley CO

970/256-2672

Take 34 eat to 8th Ave; turn left at the light & go north to 1st Ave; go east about 1/4 mi; best I recall, they are on the right as you go east. Be careful of the Avenues and Streets- AVE runs N-S; ST runs E-W.

Daniel

 

[cerberusiam]

Looks like you covered all the obvious things I guess its on to the not so obvious.



Possibly a kinked injector line slowing down the fuel pulse?



A plugged return fitting allowing the injector to hang a bit too long?



A cyclinder starting to go?



The injectors within 150 psi sounds a little suspicious. That would be 10 bar and thats a pretty big gap. If they were all off that much it probably wouldn't be that bad but a couple out that far could roughen things up.



You PDR guys that have worked these injectors considerably, what problems have you seen with the balance and advanced timing?

 

[BCook1]

Back to 10mpg

Well at least the mileage improved as the temp went up. 400 miles and 40 gallons of fuel later I made it to Greeley. Unfortunatly it was late and even if I could have found Injector service it would have been closed. The miss is very small but it is still there. The only reason I notice it is because it wasn't there before. I am going to drive this thing until the problem is so obvious that it can not be missed. If you see a white/silver 92 next to the road you will know who it is.

Thanks to everyone for all the input,

Brennan R. Cook