bcrunner86

after rebuilding my truck before summer i have had this problem since day 1.

symptoms -
-first start of every day it will not start first crank (tries but hesitates and just stops) second crank will start and run fine, i will let the engine warm up, drive for around 5-6 minutes and pull up to a stop sign and the idle is all messed up, sounds like a diesel, but still accelerates fine
-some days i never hear the diesel sound but other days its all i hear
-truck still drives fine when it sounds really bad.
- also when i maintain a constants speed sometimes the truck will jitter (almost like im hitting bumps but im on a flat surface, this doesnt always happen)
things i have done -
checked for vacuum leaks, adjusted TPS many many times (sometimes i bypass tps and the idle would not change) replaced air filter, oil filter, caps and wires, replaced spark plugs and injectors, pretty much a full tune up.

oil changed 3 times so far and rebuild has around 5000 miles on it.
theres a small hole in my exhaust just after the cat, covered up with carboard and a metal zap strap

Long story short me and my dad have tried many things but we are starting to think it might be an electrical problem, bad sensors or something. any suggestions??

osv

the cranking start problem could be different from the rough idle problem.

try unplugging the vacuum hose at the top of the egr, and put a screw or something in the end of the hose, so you don't have a vacuum leak.

there is a valve in the front of the motor that opens at ~122-130 degrees, and it sends vacuum to the vacuum modulator, which opens the egr... but only after the engine is warmed up to some degree... so that is a potential temp-related problem.

if the symptoms don't change, leave the hose plugged up, and plug another hose into the top of the open egr port... when you put vaccum to it, even by simply sucking on it, the engine should die immediately, which tells you that the egr itself is functional.

bcrunner86

Okay ill have to try that tomorrow, ill also try to post pictures of my engine bay and some videos of the diesel sound.

bcrunner86

hey i just checked my fuse box, and there was a 10 fuse where the 15 EFI fuse should have been! i have put in a efi fuse now, think this was the problem??

Stetson_md

My moms 4rnr 22re sounded like a diesel when she had a exhuast leak (blowed apart muffler) and a bent valve
And it could only be heard at less then about 35mph or under hard acceleration when you where in the truck. If you wernt in the truck you could hear it fine

bcrunner86

I wish my problem was that simple, my exhaust leak is only the size of a quarter so i dont think thats the problem, and wouldnt a bent valve be dealt with during the rebuild? I dont think its a problem with the engine itself because it only has around 5000 miles on it,

Btw I drove it to work today after putting the EFI fuse in and it ran fine until i got to work, turned off the engine and turned it back on and magically the diesel sound was there, what could make my truck sound so crappy just for turning it off and back on??

osv

since the 10 amp fuse didn't blow, it doesn't make any difference.

lets try another tack... where EXACTLY is the sound coming from? open up the hood when you hear it.

is it coming from under the truck(exhaust), or under the valve cover?

bcrunner86

under the valve cover, but the hole in my exhaust (about a quarter big) makes the sound a little more intolerable, but i actually think when i pulled that fuse it did something because the only time i hear the sound now is if i am constantly starting and turning the engine off, and a minute of driving and the sound is gone. my idle is also alot smoother