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Discussion Starter · #1 ·
Sorry in advance, this is going to be long.

My recently completed 91 intercooled 12 valve engine seems like it's down on power. There is also a lot of white smoke out the exhaust both at idle and on the throttle.

A little background on the engine:
Originally out of a 98 2nd gen, this motor received one replacement piston on cylinder 5, all cylinders were honed and re-ringed, cylinder head was resurfaced and got a valve job, new head gasket and all new injectors from DAP.

I've driven the truck about a dozen times since installing the engine, not very far but each trip between 1 & 3 miles. Seems to be lacking a lot of power.

The engine starts extremely easily whether it's ice cold or fully warmed up. I would venture to say it does not even crank over a full revolution before it fires up and idles quite smoothly. When applying throttle however it feels like there is a stumble or a misfire.

Assuming a misfire was the cause of the sluggishness, I proceeded to try to pinpoint which cylinder or cylinders was not contributing by using a laser thermometer on the exhaust manifold ports after the engine had been running for about 5 minutes.

I will try to attach a video of that experiment in response to this post, but for now the temperature readings I got on the cylinders are as follows:
#1 127 deg
#2. 140 deg
#3. 128 deg
#4. 136 deg
#5. 163 deg
#6. 151 deg

It seems as though number one and number three cylinders are running the coldest.

Just for my own curiosity, and not that I don't trust the quality of diesel auto power injectors, but I swapped injectors number one and number five and then repeated the test. The temperatures stayed the same indicating that the injectors are not the issue.

Do you guys think the temperature variances are enough to indicate the issue or am I jumping the gun here?

The only other thing that has me concerned, is that my original 91 engine was also misfiring on cylinders one and three when I bought the truck. Granted when I tore that engine down cylinder number one was completely wiped out and cylinder 3 was scored.

But I can't help but Wonder if the ve injection pump which was transferred over from my original engine to this 98 engine, could be causing my issue. I've researched how the pump comes apart and it seems that there are six "cam lobes" for lack of a better term that fire the corresponding six cylinders. Could one or more of those lobes be worn down in my pump?

Is there a way to see those cam lobes without completely removing the injection pump? In other words could I take the top metering half of the pump off and be able to view that cam plate?

Thanks in advance for any help.
 

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Are you certain that the injector lines are routed correctly? Maybe 1 and 3 are crossed?

My understanding is that white smoke is raw fuel in the exhaust.
 

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Discussion Starter · #3 ·
 

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Discussion Starter · #4 ·
Are you certain that the injector lines are routed correctly? Maybe 1 and 3 are crossed?
I'm fairly certain that I don't have them crossed, but I can definitely recheck that.
The reason I don't think I have it wrong is because I never removed the injection line brackets, I remove them in two groups of three and reinstalled them on the injection pump in the same orientation they were removed.

If I remember correctly when you remove them in groups of threes they attached to the injection pump on two triangular patterns if that makes sense.
 

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Discussion Starter · #5 ·
I double checked the injector line routing today and it is correct.

When grouped together by their brackets, the front group(cyls 1,2,3) and the rear group(4,5,6) form inverted triangles where they attach to the back of the pump. See diagram below.

Triangle Creative arts Art Font Symbol
 

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Back to the beginning, just what damage did the pistons have in the original engine?
Has the IP been played with?
Do you have a fuel pressure gauge?
Not sure you will have an accurate temperature reading at idle.
 

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Discussion Starter · #7 ·
Back to the beginning, just what damage did the pistons have in the original engine?
Has the IP been played with?
Do you have a fuel pressure gauge?
Not sure you will have an accurate temperature reading at idle.
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The original engine had a dead misfire at all rpms, I originally thought it was a blown head gasket, but it turned out to be cylinder number one was destroyed. Cylinder number three was also scored but not as bad as cylinder one.

No the injection pump has not been messed with in any way other than me making a knurled thumb screw for the idle adjustment, it still has the tamper proof plug on the top of the air fuel control cover.

I have a fuel pressure gauge kit, but I have not put it on the truck or taken a reading yet.

The laser temp method of reading exhaust Port temperature was how I determined cylinder one was misfiring on the original engine, so that's what I did on this engine.

Yesterday, I had a buddy of mine who drives a 95 second gen 12 valve listen to the engine. He seemed to feel like it wasn't revving up high enough with throttle. He stated that it sounds like the governor is kicking in and shutting off the fuel way too early like around 2,000 RPM.
 

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Discussion Starter · #8 · (Edited)
Today I was preparing to remove the AFC cover on my injection pump and have a look at the diaphragm, the AFC pin and the horizontal pin that slides in and out as it rides off the pin cone.

Fortunately before I did all that I decided to install the extra boost gauge that I have laying around in the garage. Tapping in to the plenum just below the heater grid I discovered that I have zero boost building in the engine. I disconnected the piping coming out of the intercooler and started the engine to check for restrictions or clogs in the intercooler.



While there is a sufficient volume of air coming out of the intercooler pipe, I can stop it by putting my palm over the pipe. When I stopped it I heard a loud whistling noise coming from the area around the turbo.

That's when I realized there's a lot of slop in my waist gate actuator rod. I'm running a holset hx35w turbo. I'm beginning to think my wastegate is stuck open dumping all my boost.

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Discussion Starter · #9 ·
Well I found one problem:

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This is the hose that goes from the turbo outlet to the wastegate actuator. It's got a big hole rubbed through it.
 

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Discussion Starter · #10 ·
What are the chances of finding one of these on a Sunday?

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It must be my lucky day!
 

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Discussion Starter · #11 · (Edited)
Okay maybe it's not my lucky day. I installed the new hose and drove it around the block, but it's only making 3 PSI of boost.

Yes three is better than zero, but my expectations were a little higher. :sneaky:

Anyhow it seems like my wastegate actuator is toast. I'm assuming that the wastegate on the turbo must be spring loaded in the closed position. Mine is just flopping around in the breeze, it's got about 3/4 of an inch of slop in it.

I removed the little clip that holds the actuator rod to the clevis pin and the actual flap or gate in the turbo has no resistance it's just swings open and close freely. So I assume that the actuator assembly is supposed to have some kind of spring resistance in it to pull the gate closed and then that spring pressure gets overcome by boost pressure. Am I correct in this assumption?

I'm shopping for actuators online right now, hopefully I can get one here in a couple days.
 
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