Archived Low power saga on 12 valve in BC canada

[96ram]

Ok this is a bit of a long story so bear with me(it has been a year in the making... ). I feel I need to explain everything in order to get to the root of this problem. With the mods I have on my truck I feel I have fairly low power and this was verifyed with a dyno run.

At W0T I have at 10ish psi at around 1500rpm(lots of black smoke), 15 psi boost @ 1800rpm(black smoke! engine still sounding like it's straining/lugging egts creep to near 900 post turbo(so 1200 right!?) if I let them), 17 psi at 2000rpm(engine note beginning to sound good egt's start to drop and smoke beginning to clear), 19psi at 2100 rpm

(engine sounds smooth no smoke)... ... ... ..... From here on up the boost climbs gradually to 30 psi at around 3000 rpm and smoke can rear its ugly head again a few more rpm higher(airflow limitations of the stock hx35 maybe?). The dyno concurrs with these figures with not about half available horsepower generated below 2000rpm and rising in a pretty flat line to max hp at around 3200rpm(ie 150 hp rising to 300 or so... . ) ...

Boost leaks have been checked twice in the last 12months, afc and starwheel were tweaked and all mods were done at BD power up here in Canada, fuel pressure was 22psi at idle(from bd's notes... . they said they checked it but didn't mention pressure at 2500rpm... . ??), bd pulled the injectors on my request and tested them and they came back good, the truck starts great always and runs fine though it hazes at startup/warmup a lot more than my buddies 98...

I have pulled and pushed as hard as I could on the waste gate actuator shaft with no movement(IS THE WASTE GATE STUCK?! or how else do I test as it was pretty awkward getting in there... ???) and tomorrow I will take off the fuel shutoff solenoid to inspect it. My haynes says to test using the ignition with the negative terminals unhooked on the batteries???

I believe this issue has been there since I bought it though I didn't realize until I had all the mods done.

This is all I can think of right now. I'm a newbie with these trucks so be nice please

 

[Alan Reagan]

If the wastegate is stuck (and it sounds like it might be) it sounds like it is stuck closed if you are getting 30 lbs of boost.



It sounds like you are getting plenty of fuel, but have you checked the filter?



Finally, could it be possible that the pump to engine timing could be off? Did BD check the engine timing?

 

[96ram]

Darn I knew I forgot to mention something. I changed my fuel filter a year ago with no appreciable effect and bd did the timing with the fuel mods(I have had bad luck with them so maybe the timing slipped straight away??? ... ) and I am going to change the fuel filter anyway this week... .

Thanks for the suggestions

I will be able to check the actuator and wastegate today aswell as the fuel shutoff. Could it be stuck partially open?? or have some nasty piece of something wedged in it(ie carbon... . )???

What is the quickest way to get a peak at the wastegate??

 

[Joe G.]

Throw the Haynes manual away. It's almost worthless. The fuel solenoid is working or you would not be getting enough fuel to make any smoke. There is no ignition on a diesel. The ignition switch will cause the fuel solenoid to pull up in the start position and hold it up in the run position. Other than that it has nothing to do with how the engine runs. Get a Dodge service manual. It would be cheap at twice the price.



The purpose of the waste gate is to restrict boost pressure. So if it is stuck closed then you would get as much pressure as the turbo was capable of producing with your fueling. If it is stuck open you might see the symptoms you have. Also check to see if you have any leaks in the intercooler system. A boot could have a hole rubbed in it or have split. You also may have loose clamps. If there are no obvious leaks pressureise the system with air and spray it with soapy water.

 

[96ram]

Ok I just managed to make an insert to check the pressure using a special shock pump... . got to 40 psi with no sound from the actuator at all(actually 70 psi first time because I was reading the metric part of the dial and thought I was at 5 psi but I think the diaphragm is ok on the actuator as no loss of pressure thereafter... ).



Pressure test has been done twice this year with same good result and no change in performance at all(apart from when I when full 4 inch instead of catback :-laf )



What is the easiest way to take a peak at the wastegate??



The saga continues... ...

 

[Joe G.]

I'm not sure from what you say what you are testing. If you are just testing the waste gate and it is stuck closed that is not your problem. The function of the waste gate is to limit boost. In order to do that it opens at a set pressure. If it was blowing open at something less than 18 PSI then it might be your problem. In any case, testing it with some other gadget than the engine running is not that relevant.



Have you tested boost pressure in the intake manifold? You need to do that with the engine running instead of some other pressure gadget. The test is to see if the turbo and intercooler system is providing the proper pressure at the intake manifold. If it is not, then you need to find what is causeing the low pressure.

 

[96ram]

Ok my actuator rod is moving about 1/6" at 40 psi towards the turbo and at 20 psi it doesn't move. If that is the correct amount of travel then I guess it is fine.

If my fuel pressure was fine at idle(22psi) then there shouldn't be a restriction?? So the overflow should be ok??

I am beginning to lean toward a worn out lift pump maybe as it may supply the right pressure at idle but not enough volume at higher loads..... am I right in thinking that?

 

[96ram]

Sorry Joe G. I was a bit vague there... I was merely testing to see if the wastegate was opening or closing properly and the other tests mentioned were pressure tests done at Bd

power twice this year to check for boost leaks.



Oh and I have a boost guage which is how I got those readings at the start of this thread can't keep my eyes off the road too long

 

[Joe G.]

The overflow valve provides a controlled restriction at the fuel return line to keep the fuel pressure up to a minimum pressure. If it goes bad the result is low fuel pressure.



The waste gate may be stuck open or nearly so. You seem to have eliminated everything else. I have not had any problems with mine so I don't know how much the rod should move. 1/16" does seem like it's not enough.



If the lift pump was the problem you would not be getting enough fuel to make all that smoke.



Lugging it (WOT below at least 1600) will make smoke even with the waste gate stuck open.

 

[96ram]

Sorry that was 1/6th of an inch maybe a little more... . was hard to see out in the cold! Well I still have solenoid adjustment to check, afc, prefilter in transfer, gsk adj, fuel lines and maybe the tank. Then I guess it's on to the holy grail for diesel shops -> the IP.

 

[96ram]

Fixed Finally!!!

So after talking to a fueling tech at valley fuel injection and a mechanic friend of mine I finally worked things out. From 1600 rpm I was making 12psi which meant enough fuel was getting there in the bottom end so I adjusted the plate full forward yesterday and now she flies :-laf but now I just need to fine tune the starwheel and maybe the plate to minimise the smoke and I'll be sorted !!

Hopefully this helps someone out there!



What I've learned is that you're way better tuning up the truck yourself then you know what you did and have only yourself to blame for the consequences otherwise be very careful who you use