Engine/Transmission (1994 - 1998) Engine Studder

[DRiecke]

My truck has a studder. I was told that is was caused because of the larger injectors that was put in. When it is under boost it dosent but when Idling it sounds like Duh Duh Duh. Do I need to match the pump with the injectors?

I have changed the fuel filter(it studdered pryor to this,,no air in the system) It doesnt use oil, or water and gets 20 miles to the gal. It seems to be a good running truck. I would like to get this studder to go away.

Any inputs would be much appreaciated

Thanks

 

[JFaughn]

Welcome to the site .
For detailed answers , we need details [ when you read threads , you'll see at the bottom of post , truck info & mods , fill this in in the user control panel ] .
Who's injectors and which ones , with out info I could assume quality issues either way , could cause your problem , if they are good , then bigger injectors can require more timing .
A shot in the dark without more info .

 

[JacobsD]

I've heard stories of many of the 160 and 175 pumped trucks doing this when you do fueling modifications. Causes I have heard are anything from the cam in the injection pump to delivery valves to timing. Nobody seems to have a real answer of what fixes it.

 

[DRiecke]

Gentlemen, sorry for the limited info. The previous owner installed 215 injectors and adjusted the boost up to 29 psi. the stock fuel plate has been adjusted up to 90% of it's adjustment and the AFC has a couple of turns.

I does smoke a bit, the owners manual says 175hp/450 BHP. I'll work on my profile.

Thanks

Dana

 

[Missouri Mule]

I have heard of 370's causing studder but not the 215's. Usually a plate will get rid most of the studder on 370's. May be it will get rid of all the studder with 215's.

 

[Driftwood Ram]

What is your idle RPM?? Stick or Auto??

 

[DRiecke]

I have a 5 speed my idle is around 700. The tach is siting just above the middle marker.

Thanks

 

[Vaughn MacKenzie]

Let me guess, does it also do it at light throttle when driving between 1000-1300 RPM? Sort of a shudder in higher gears under light acceleration? Very common issue with 12-valves unfortunately, both of my trucks have it to a degree.

 

[DRiecke]

Thanks,

I really appreciate all your inputs. I'll keep them all in mind. I hate being ignorant when I talk to the mech.

Thanks

Dana

 

[Vaughn MacKenzie]

Dana, did you get the truck before or after the injectors were put in? If it was smooth before it could just be an issue with the injectors. . . maybe the popoff pressure is way off on one. If you had another set you could try them or take what you have to a diesel injection shop to be checked.



Do you know if anyone installed a governor spring kit? If these aren't balanced right it could cause the slight miss you're having.

 

[JFaughn]

Vaughn , you did not mention a fix for your symptom , does that mean you have not /can not get rid of the shimmy ?
I've kinda just live with it , but have been on the lookout for getting rid of this , maybe when I can afford more mods , Goerand trans 1st , then ???
Would like to solve 1st if possible then mod .

 

[Vaughn MacKenzie]

In my case I tried injection pump tuneup, injection pump replacement, valve job twice, compression check, tweaked GSK, 3 different sets of injectors all to no avail. Putting in a set of DDP Stage 2 injectors helped the most. I finally gave up and learned to live with it. For a long time I thought it was a weak hole which is understandable with 408,000 on the clock, but when I lug it down to 400 RPM then roll onto the throttle all cylinders fire very even and smooth. It starts the miss around 800 RPM and clears around 1300-1400.

My '98 does it a bit but I know it's the junky Bosch 300 injectors I have in it.

Vaughn

 

[JFaughn]

I glad that we have sites like this , so we can let those that can , put all those tries at a fix , it could be a dangerous idea if there were a fund generated by members , for subsidizing all the experimenting that is done ,
I have to feel lucky then , my shudder is between about 1150 -1300 at extream but common 1250-1275 .

 

[Tom C]

Let me guess, does it also do it at light throttle when driving between 1000-1300 RPM? Sort of a shudder in higher gears under light acceleration?

I've had five of these trucks and all ran smooth when stock. All also got a shudder when modified... . :{ Although it seems more noticeable with an automatic.

I just live with it...

 

[DRiecke]

Vaughn,

I know this is a little late. I bought this truck off the TDR sight, Risky but checked the history and it was clean. The mods were done prior to the purchase. I like the idea of increasing the power. But I also want it to run the way it is supposed to. The truck is a great truck I love driving it and has a lot more torque than I am used to.

Thanks for the reply. I will keep all these in mind.

 

[Tom C]

when Idling it sounds like Duh Duh Duh

DRiecke,



I just re-read your original post. Sorry, I misunderstood. I though you had a studder while driving. The engine shouldn't studder idling. Besides the simple things to check like filter, water in fuel etc. or a little more complicated task like checking timing, you can really dig into it and have the injectors pop tested and have the injector pump bench tested.

 

[highmilage94]

My truck has a studder. I was told that is was caused because of the larger injectors that was put in. When it is under boost it dosent but when Idling it sounds like Duh Duh Duh. Do I need to match the pump with the injectors?

I have changed the fuel filter(it studdered pryor to this,,no air in the system) It doesnt use oil, or water and gets 20 miles to the gal. It seems to be a good running truck. I would like to get this studder to go away.

Any inputs would be much appreaciated

Thanks

I have the exact same problem, i know what it is, but i just havn't got around to fixing it yet. There is a small relief valve in the very top of the delivery valve holder (directly below fuel line flare on the pump) that has a face seal. My face seal has chipped off#@$%!this was 10 fold more notaceable with bigger injectors. I realized the problem when i installed my delivery valves. The sdudder occurs due to the fact that the injectors require a certain amount of fuel to pop off with efficient atomization. So if there is any change in fuel flow/ pressure you willl acquire a small miss, or duh duh duh... :-laf