I have a 97 and had my PCM reflashed by DP Tuners. It runs good and the fuel mileage has improved, (if I keep my foot out of it) and the power is terrific.
I am noticing a breif stumble in it at about 12-15 hundred RPM when I step into it. It seems like it is not getting enough fuel for a second or two or the HPP is not strong enough to fire the injectors.
I dont know too much about this engine but I know there is a sensor on the front of the engine on the fuel rail, maybe that could cause it.
I think it may have had this issue before the re-flash but it is more noticable after.
Has anyone else run into this?

Thanks
Tracy

 

Have you every changed injector o-rings?

 

No, truck has about 130K on it and I didnt think it would need it. I have heard of smoking and fuel leakage with the O rings but would they cause this stumble?

Thanks for the input,
Merry Christmas

 

One way to check is pull the fuel filter and see if the fuel has a blueish color to it if it does then you have a couple bad injecto orings

 

Merry Christmas to you and yours.

 

Thanks, Just changed fuel filter and the fuel was nice and clear. Changed oil and oil filter too, no difference in HPP that I can tell.
It seems almost electrical but goes away quickly like a fuel issue.
I think it runs too damn good to be anything serious but I would like to put my finger on it.
I just bought a new set of glow plugs and was going to put them in so I could change the O rings while I am in there but i am not sure they are the problem.

merrry christmas

 

Got a new set of S/S nerf bars from Santa today too. Wife forbid me from going to the garage today!

 

Call DP and see what they say, it may be something in their tune. They will take care of you if it is their issue.

 

I emailed DP and they didnt get back to me. I do think I felt it before the re-flash but it is more noticable now. Does anyone know what the sensor is in the front of the engine at the corner of teh valve cover on the drivers side is? A friend of mine thinks that may be the problem. Something about the fuel pressure?

Thanks

 

That sensor is called the ICP (injection control pressure sensor). It senses the pressure being produced bu the HOOP and sends its signal back to the PCM. The PCM then sends a signal back to the IPR (on the back of the HPOP) which then ramps the pressure up or down. There is a chance that your ICP may be bad. Unplug the wiring connector on the back of the device and if it is oily inside the sensor is likely bad. The other thing that you may need is to replace the o-rings on the IPR. Leaky IPR o-rings generally produce a hard start when warm but not always.