Hey guys,

So i have an 06 TRX4 with the 5.7 with around 51k miles on it. I fist started to notice the rough idling and the stalling out while coming to a stop after driving, often at a stop sign or light, at around probably 40k miles. After doing a little poking around on the internet i discovered that the throttle bodies get gunked up and can cause this to happen. Needless to say i cleaned my throttle body and the problem went away up until today. I'm assuming that it's just due for another cleaning. Also probably in the past 6k miles or so ( i don't really remember when it started happening) my tach has been fluctuating back and forth between normal and being anywhere from 500-1000 rpms too low. Most of the time it would surge back and forth between low and correct but as of late it's pretty much off all the time. At idle it shows 0-100 rpms and cruising it's right around 1000. The only time it will correct itself is if you really mash the gas.

Has anyone else had this (these) problem(s) and if so whats causing the tach to be off and is it possible that these two issues are related?

Thanks in advanced.

 

What do you call normal idle speed? Mine is 500 unless it senses a load. Turning the steering wheel even slighly causes a load and bumps idle to 650 etc. Defrost on, ac on its 650. I checked my t/b at 30k. It was almost spotless. I changed plugs to Autolite Iridium XP 5325s at 30k and idle which was not bad before went super smooth. Thought my imagination but others have posted the same. I use no fuel additives but I also only use Top Tier fuel 95% of the time. Chevron/Shell and such. You have another issue effecting tach and possibly connected to a running issue. Do not use any PULSE DURATION spark plugs.(E3s) They will cause running and electrical issues. GM has tech bulletins out on the issues with them. Milli voltage bleed over. Any ADD ONs?

 

Throttle body shouldn't be bad enough already, but it never hurts to clean it. I do mine at about 15k intervals and at that rate it's never too bad. Did it the first time at 30k and it was a gummed up mess.

EGR and PCV will cause this as well. Also, grounding the throttle body often helps with idle fluctuation on any "fly-by-wire" TB and is a nice $5 or under mod. This easy mod will also give noticeably better throttle response...