1997 GMC Jimmy V6 Vortec Engine Bogging..?

[Jim A]

I'm having an issue with my vehicle that I was hoping that someone might be able to guide me on how and what to start looking for. If I accelerate hard from a dead stand still, the truck still has a great deal of pick up and go, but not as much punch as it did a few years back. Around 90 - 100kph the truck feels like it's stuttering on the highway... Example, (Accelerate) (Decelerate) all rather quickly. I can end up traveling a distance and not have it happen, and sometimes it happens frequently. It seems totally random, but mostly happens after it’s warmed up. I’m suspecting it’s not burning the fuel properly due to high hydrocarbon reading from my emissions test. I’ve replaced, the PCV Valve, Air filter, and EGR Valve. I have no engine warning lights coming on and I know they do work. Could some one please help me determine what may be causing this? PVC filter and Air Filter done less than a month ago, and the EGR Valve has been done 3 Years ago.

Your help would be greatly appreciated.

Jim..

PS.. .Also, how can I check to see if an Electronic EGR Valve is actually working.

 

[Molson02536]

Start with the simple and replace your fuel filter and clean your Throttle body with throttle body cleaner and your MAF sensor with MAF sensor cleaner. You can get both cleaner at most auto parts store like Auto Zone. As for your question about your EGR, if there is a fault, the service engine light (MIL) would be on and the issue would be indicated in your DTC codes. The other reason your engine is bogging down at higher speeds is you may need to replace the distributor cap and rotor but that usually sets off the MIL, the only other thing that comes to mind is that your fuel injector system is leaking gas into your intake manifold. The fuel pressure regulator has a leak or one of the poppet nozzle has gone bad and leaking. You can replace the fuel pressure regulator and replace the poppet nozzle separately which would save you some money or you can replace the whole SCPI unit with the upgraded MFI system. Start with the simple and replace the fuel filter and clean the throttle body and MAF sensor, You can also clean out the EGR if you like. Good luck and keep us all posted on how you did.