Howdy there. I am experiencing a rather annoying popping around 1800-2000 RPM while in drive in my 66 Gmc with an 89 TPI motor (and 700r4 trans). In park, it revs fine. Its a bit wierd actually. It will only do that if I have the throttle at a certain amount. I have tried replacing the TPS and its still present. I've had this problem before and thought it was a shorted power wire grounding out. I replaced the wire and things seemed okay until about a month ago when I started having the problem again. I again went through the wiring a dozen or more times and made to sure to cover anything that looked suspect. The problem has come and gone in that time. Its back, and I cant seem to find any wiring that is suspect. Furthermore, I have watched the volts with a volt meter during the poping and they dont change a bit. I have tried measureing at a number of sources. The only thing that does change is my tachometer bounces around quite a bit when the popping starts. As soon as I let off the throttle, the popping stops. Also, if I hold a lower gear, the RPM will reach 3000 RPM without popping, but if I give it throttle while maintaining that lower gear, the same popping happens. I still cant tell if the tachometer change is relitive to the actual RPM changes, or if its getting an invalid signal from the Ignition control module. I am replacing the coil and ICM and going to see if that helps, but I thought I'd post and see if anyone has experienced this before. Its incredibly annoying especailly since it will go away making me thing the problem is gone, and then at random times come back.

Any help is appreciated.

Dylan.

 

my car makes a popping noise while driving. but its more like an air popping noise. from what ive been told about air popping noises in an engine that the lifters are going bad. doubt this will helo you but if it does than hey.

 

If it were a mechanical issue with the rotating assembly, Id guess that I would experience the problem in park as well as drive. I get a strong feeling it has to do with something electrical.

 

i experience this only in drive (when a load is placed on the engine)and not in park.