A few years ago I took my truck in to have a crankshaft position sensor changed and the truck has never run right since.

The symptoms are that it will idle rough not like a miss but like the timing is wrong. It will be louder than normal and rougher. Then while just sitting there idling it will sometimes smooth out and be totally normal and stay that way until you drive the truck then it will usually go back to the rough idle until you let it sit for a while without touching the throttle. When the idle smooths out it is instant like someone flipping a switch. Also when you are accelerating and ease off the throttle you will hear an abrupt change in what sounds like engine timing and the engine will get louder abruptly which I never had noticed before.

Since all this started I have done the following things most but not all of which were to try and fix this problem.

1. Rebuilt Engine Head after Turbo Failure
2. Replaced VP-44
3. Replaced ECM
4. Replaced IAT sensor
5. Replaced ECT sensor
6. Replaced Boost sensor
7. Soldered all the TST boxes connections
8. Replaced crankshaft position sensor again
9. Replaced camshaft position sensor

Any idea what could be causing something like this? I almost think the truck is simply cursed.

Thanks,
Keith

 

disconnect the TST and see what happens and report back--chris

 

Are you saying to completely remove all the wiring or just remove the box? I have removed the box and tried that and I have also changed boxes during that time from a PMax 2 to a PMax competition.

 

yes and no--I'd just unplug all the wiring at the engine and plug the stock connectors back in and see if that helps--if it does not help then you just plug everything back in like before--does this make sense???....chris

 

Yes it does. Unfortunately I cut the factory wires at the MAP sensory plug and soldered them directly to the PMax MAP plug while troubleshooting in order to eliminate a connector being at fault. I had been thinking it was some type of connections problem and went around soldering everything and checking wires a while back to no avail.

I did just try unhooking the pump connection as well as the actual box but that made no difference.

Keith

 

can you get your hand on some injectors to swap in---it's either electric or fuel related and with everything you've changed it may be time to think fuel issues---chris

 

To tell you the truth I had wondered about injectors but wasn't sure it could cause such a sudden change. I have had the same DD III injectors for the past 80,000 miles or so. I had thought about changing over so some of the newer extrude honed injectors.

Who makes a good set? I haven't kept up with injectors the past few years. Are the Jammers the best type to get?

Keith

 

the more I'm thinking of this it sounds like maybe an injector isn't popping off--injectors these days are like trying to ask someone which color haired women are the best--no right answer no wrong answer--so it may be best to contact Floor It Diesel www.flooritdiesel.com and get some injectors from them---John is a top notch guy--the only problem with flopping out injectors is if it's not the problem you've thrown money away--best if you have the time and can wrench yourself is to borrow some---if you have no one who can help you out then talk to John and see what they can do for you---or if you can wait 2-3 weeks I'll send you my stock injectors and you can borrow them to see if that's the problem---you pay the shipping and I'll send 'em your way when I get them out---let me know----chris

 

One more question for you. Looking at the Mach injectors that the website you provided I noticed they cost about 3 times what the Jammer injectors cost. Can you tell me what the difference is? I am more concerned about good spray patterns and thorough combustion than big injector holes since my PMax can deliver more fuel than I can burn even on moderate settings.

I appreciate the offer but I was hoping that if I went to the trouble change them I would get some that I could leave in there. My understanding was that these DD III injectors I put in 7 years ago didn't atomize the fuel nearly as well as the newer ones do.

Thanks again,
Keith

 

did you check and make sure the tone ring was not damaged or loose when you changed out the sensor?

 

I have never heard of the tone ring. Which sensor are you referring to? The crankshaft position sensor?

I am going to take a leap since I don't know any better and tell you that the dealer replaced my first crankshaft position sensor because my tach kept not working and thats when all this started. Then about 5 years later the same thing happened and I put in another one myself.

Thanks,
Keith

 

I should've checked to see what injectors Floor It sold--the Mach series are well liked by a lot of guys but you can get some Jammers they are DD's newest series---call Winspeed here in CA they can get them shipped to you---925-370-7245--tell Brett I gave you the #---again on injectors it's real hard as everyone thinks their's are the newest greatest---I don't think the smaller ones are all that much different from each other----chris

 

Tone ring is what the sensor reads, its a notched ring that's mounted on the crankshaft.

My check engine light came on last week for the cps, and the tach is intermittent and truck stumbles from time to time. I'll be replacing the sensor this week and checking to make sure the ring is tight on the crank. I read somewhere on one of the forums where someone had to pull his pan and replace the ring. I don't remember exactly where and I could be wrong on the specifics.

 

That is kind of scary. Is the ring steel?

 

Update. As mentioned before all my problems started after a crankshaft position sensor was replaced at the dealer a few years back and then I had another one that seemed to fail last fall. So that puts me on my third CPS. Well, last week I was accelerating onto the interstate and my truck hesitated for a moment and then had the check engine light come on. My tachometer also started working jumping between about 2500 RPM, where it should have been, and zero. Funny thing is that after cycling the ignition I haven't had the problem since. Do you think there could be something else at fault rather than the CPS?

Keith