HOW DO YOU DIAGNOSE AN ENGINE MISS

[sam peterson]

I have a 1996 4x4 3500 dually with 62000 miles. Ever since it was new it had a slight shudder when the trans shifted into lockup. The problem was blamed on the trans. The engine has been upgraded to a Dr Perf Phase III setup. Performs great with lots of power. I desided to rebuild the trans to handle the extra power of the engine. Install a Suncoast conv & transgo shift kit etc. Thought this would kill 2 birds with 1 check. Cure the shudder and fix the trans. Trany works great but still have the shudder. The trans shop says the problem is a miss in the engine. How do you diagnose this type of problem? Has anyone else had this type of problem. Any help would be appreciated. Sam

 

[zzman]

Sam I had a problem like you are describing with my little p/u. Ford ranger. When the tran locked up, you could feel a vibration like the engine was missing. It would go away then. Ford did many things trying to find it. New drive shaft, checked the engine through-out. They asked me what I thought it was. It sounds like the bands/belts were slipping in the tran. You could feel the vibration at lock up only.
The problem was bent fins in the torque convertor. Was that way since new. They replaced it and that was it.
Maybe your miss may not be your engine. .
Just a thought, good luck and let us know.

------------------
97 3500 SLT REDext cab duelly p/u 5sp 3:54 2wd 245/75R16
3" straight exhaust stock torque plate slid full foward star wheel tweeked
105,000 miles still with plenty of ZOOM... ZOOM... ZOOM

RON Z

 

[radixr]

If you have a way to measure temperature, check the temperature of the exhaust manifold at each cylinder. If one is lower than all the rest, that cylinder is not firing all the time.

 

[sam peterson]

Thanks for the response guys. First let me say that my knowledge of the diesel motor is ZIP. I have not had any dyno test done on the engine upgrade either before or after. A stop watch was done before with 0 to 60 being 15 sec. after it was 10 sec. After the trany work & upgrade it was 8. 5 sec. The nice part about this Dr Perf Pkg is that it only takes about 4 hours and it was done in my shop with no messing around after the install. The gear ratio is 3. 54 and it has real good pulling power at 55 to 75 mph. The shudder problem started when new at low rpm, approx 1250 to 1500. and progressively got worse as miles were put on. The dealer said it was normal and don't wory about it. After the trany had been rebuilt by the dealer on warrenty. I paid for the converter & the shift kit, they did the install. No difference in the shudder prob. The rpm range is between 1200 & 1750 after lockup. I installed a lockup switch to see if it made any difference but it stayed the same. The shudder only occurs on light throttle & goes away if you put your foot down and comes back if you reduce speed from 65 down thru 50. Sorry to draw this out, but it is a nerve racking situation. Thanks Sam

 

[HEMI®Dart]

EMD Diesel Power

Is it true that if an injector has a leak at the end injection line, and its small enough , the fuel escaping is under enough pressure to "cut" your finger or hand like a razor blade?

[This message has been edited by HEMI®Dart (edited 01-27-2001). ]

 

[illflem]

Bill,it's worse than just a cut. Any high pressure injector leak or hydraulic leak that hits you from very close range can inject the fluid/diesel into your blood stream without even cutting you. You will need to get to a hospital ASAP,it can kill you. In all the years I've worked with high pressure systems I've known only two guys who have had it happen,both were from sliding their bare hands along a hydraulic hose looking for a pin hole leak. Both said they could tell that something was wrong right away, oil taste in their mouth and headache. They had to be hooked up to a blood filtering machine in the hospital for two days. If you ever see a mist type spray of diesel under your hood put on gloves and use cardboard to find the leak. The same caution goes for fuel injected gassers.



[This message has been edited by illflem (edited 01-27-2001). ]

 

[Archive]

Originally posted by HEMI®Dart:
Is it true that if an injector has a leak at the end injection line, and its small enough , the fuel escaping is under enough pressure to "cut" your finger or hand like a razor blade?

<font color=blue>I'll second what illflem said. Anytime your searching for leaks on a fuel system or a hydralic system, use a piece of cardboard to investigate the area. The mist might be too fine for you to see but it will either cut you or get into your bloodstream. So use caution when working around high pressure fuel lines or hydralic lines. If your working on hydralics make sure you bleed off the pressure in the cylinder. Hydralics was my favorrite class back at Denver Automotive and Diesel, I took it twice #ad
The teacher had spent 25 years with Grove (cranes and manlifts) and was teaching because he got hurt on th job, so he had lots of real world experiences to share. Anyhow back to the point of the post... ... use cardboard #ad

 

[EMD Diesel Power]

#ad
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Looks like illflem and KatDiesel beat me to answering HEMI@darts question. #ad


They are both very right... if u suspect a HP (high pressure) fluid leak of any kind... go after it with cardboard... If u dont... u better hope there is a hospital within 10 mins of the place. . If u get enough diesel fuel in the blood... u can actually see the poisoning moving thru the bloodstream... (shows up dark red... like tracing lines... ) when it hits the heart... you're literally done...

Ive never seen this happen... just heard of the stories... not a good thing to just *shrug off... *

Thanks for *beating me to the punch*, illflem and KatDiesel... #ad
#ad

 

[HEMI®Dart]

WOW!!

Thanks for the education you guys. I didn't realize how dangerous a small fuel injection line leak could be.

Everybody should read this thread! Especially us guys that do our own fuel system work.

------------------
Bill R
94 2500 SLT 4x4 5 Speed, 3. 54 LS, JRE 4" exhaust, Autometer Pyro, Boost & Water temp gauges, Bosch 215 HP injectors, Timing @ 14. 7º, JRE Stage III #4 plate 270/675, AFC spring kit, Scotty Air, Bully Dog Propane Injection, Roadmaster Active Suspension, Optima Red Tops, Geno's Exhaust Blanket, Espar Heater (won it!), Synthetic lubes throughout.

[This message has been edited by HEMI®Dart (edited 01-27-2001). ]

 

['956Wheel]

High pressure is NEVER to be underestimated! At the powerplants where I work you look for steam leaks with a stick with a rag on the end (high tech) the rag either cuts and goes bye-bye or catches on fire. Heres a kick, a Bosch pump very much like our 7100's just a bit bigger is used as a "jacking oil pump". It literally picks up the turbine and generator shaft (400 tons or so) onto an oil wedge before rotation... yes babbit bearings. Oil leaks are found by cardboard on a stick. The gauge on the pumps reads 4000 psi!

------------------
9535hundred

 

[illflem]

Bill,you're right it's something anybody even poking around under the hood should know,I'll move my post over to Gen Diesel,so more folks see it,it's sort of hidden in this thread. I would appreciate it if Kat and EMD could also add their 2¢

 

[EMD Diesel Power]

A quick way to qualify the injectors (and the engine) would be to crack open the fuel line at each injector one at a time, with the engine idling of course. #ad
Not sure on the wrench size... dont have the manual with me at the moment... .

Be sure to protect yourself from possible fuel spray... wrap the injector nut area with a rag... should only take about a quarter turn or so with the wrench before u get fuel leaking/spraying out...

If that injector is good... the engine will have a prouonced change in the labor--(like an increased hammering sound)... idle speed will drop a bit too...
if its bad... the engine labor wont change at all... idle speed stays the same... .

if they all come out good... then Id start looking into other areas... (like zzmans idea on the transmission)

hope this helps... . sorry for the long post. . #ad
just didnt know how indepth your diesel knowledge was... so I cover all bases. . *VBS*

Let us know what you find. .


------------------
"Shadows" 96' 2500 SLT, Reg Cab, 12V, 4x4, NV4500, 4. 10s, LB, LSD, Black Exterior w/chrome rockers, Camel/Tan Interior, Towing Pkg w/ Tekonsha electric brake controller, Walker Muffler, Kitty wandered off to the woods... K&N Filter--Silencer Ring gone,AFC opened up a bit, Optima Yellow-tops, 235/85/16 Michelin LTX A/Ts Other Upgrades pending $$$$ TO THE BOMB BAY!!!!!!!

 

[John_P]

Sam:

Last fall (Sept. 2000) I had "major"
modifications done to my P7100 pump.
This included the 370 injectors
along with the other items you see
in my signature. Prior to all this
work I had a new TC, valve body, etc
installed just like you. I was getting
the "shudder" you described with the
STOCK TC and valve body but AFTER the
new parts were installed it went away.

Anyway, after the 370's and the pump
mods I had a "slight shudder" AFTER
lockup at about 55 MPH. Dan Scheid
traced my problem to "not enough line
pressure" with all the increased H. P.
that had been added (i. e. 370's,pump
mods, timing change etc. ). He
recommended I install a "BD Pressure
Loc" (which I probably should have
done anyway). They went ahead and
installed the Pressure Loc and the
shudder stopped. I have had no problems
since then Sam.

By the way, how do like the "Dr.
Performance" pump? Have you had a
chance to dyno your truck since you
did the pump change?

I hope this has helped you some.
E-mail me if you need more info.
----------
John_P

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Red '96 4x4 2500 Auto 3. 54, TST #5, Major Pump Mods(By "Scheid Diesel") 370 Diamond B Injectors, Gov. Spring kit, AFC Spring kit, Banks Exhaust, Prime Loc, Cummins Chrome Kit, Pro-Torque Converter, BD Valve Body, BD Pressure Loc, Isspro Gauges, Sendel 16" Alum Wheels w/ 33" BFGs

 

[Skydiver]

I agree with Rad. A Temp guage will work. Might try this. Put a very small (10 drops)amount of motor oil on the rusty part of the (when cold)exhaust manifold then drive 25 miles you will see the oil on the cold or non-firing cylinder. The good cylinders should evaporate the oil. Remember be safe oil can burn(10 drops). Good luck.

 

[Extreme1]

Let me see if I have the symptoms:

Shudder (miss) after torque converter lock up at around 40-45 mph.

RPM is 1200-1400ish.

Happens under light throttle, goes away if floored.

Is this is right, it IS normal! The engine is "lugging". Annoying, isn't it? I can't drive mine at 43 (when it locks the t/c) to about 47-48. Bigger tires makes it worse. There was a TSB about throttle linkage which seems to help on rough roads.

Hope this helps!




------------------
'94 3500 4x4, 207,000 miles, Never had a cat, Auto w/shift kit (thanks Dave G), 3. 54 Gears, TST #5 plate, 235-85-16s, Rancho 9000s w/remote, Isspro gauges inplace of cupholder & Amsoil Air Filter & Lubes, AWOL intake boot (put the silencer ring after I pulled the boot-too loud!?!). NRA member. Blue Ribbon Coalition member.
"Warrantee? We don't need no stinking warrantee!"

 

[My 6 Eats V8's Old File]

this sounds to me like the governor could be to tight like mine, 1300rpm with very light load, and very high governor kits. It helps to turn the governor springs down 2 clicks but it also makes less power. #ad