4Crawler

iTrader: (3)

Might check the EGR valve. Try tapping on it and see if the idle smooths out (valve might be sticking open) or try disconnecting/plugging the vacuum hose to the EGR, the EGR modulator might be plumbed incorrectly causing the valve to open when it should be closed. Also, make sure there is vacuum to the fuel pressure regulator (in the fuel reail under the intake), if not present, that can raise the fuel pressure and load up the engine with too much fuel. And spray around the intake and vacuum lines w/ carb cleaner or propane and see if the idle smooths out. Might be a small vacuum leak someplace.

trythis

did you try replacing all your vacuum lines, your thermostat, and check the temp sender?

ANd how can you check timing of the engine speed is fluctuating that much?

toytruckbmerbike

try taking the intake line for the fuel off where it meets the intake and see if there may be foreign material restricting the flow of fuel ? happened to me in a past toy hope it helps

1989toy4wd

Might want to take a look at the Idle air control valve, my truck idles rough sometimes, and I know its because this is messed up. My AC wont run unless you give it a little gas while stopped, and if the lights are on and other stuff if drawing from the engine power, I have to give it more gas. You might also want to check the engine mounts, cause sometimes these go bad and make the whole truck shake!!

Itoyota

well, here's an update.
No vacuum leak : checked with latex hosing and a bottle of propane.
No EGR problem, the valve operates properly, closing after warm up.
Vacuum line to fuel pressure regulator, Looked for hanging hose lines didnt find any. (If i located the proper line, it goes into a small diaphram type saucer with a bent vacuum line)
Vacuum lines haven't been replaced, but i tested for leaks on most lines. (looking for colored vacuum lines)
Thermostat? It works fine, and wouldnt cause a rough idle in any case.
Temp sender as well, working fine, and shouldn't have any effect on idle.
?????Idle air control valve?????

My814x4

What kind of compression do you have?

trythis

I am just tossin out ideas here, as if it were my truck.

The vacuum hoses may not be leaking but they might collapse from age and the goo that gets in the lines. Carbon and oil I guess. I noticed a big change after switching them and had no leaks to begin with.

I suppose The temp sender could affect idle if it is reporting that the engine is cold and dumping extra fuel through the cold start injector, then stopping that when it suddenly thinks it is warm.

Is it a mechanical roughness like it is banging around? Random vibration that could be caused by a bad bearing, broken cam, loose piston?
Or does it seem to breath erratically causing a rapid air/fuel ratio fluctuation?

Maybe it is time for a compression or leak down check and have a looksie inside the valve cover?

Is there any chance the brake booster is just blown, and is hiding a massive vacuum leak?

Have you used a vacuum test to check for vacuum levels?

I would unhook the fog lights to eliminate anything extra.

Itoyota

well, the brake booster could be a possibility, considering i cant find a vacuum leak, but then again ... i disconnected the hose to the brake booster and held the line shut with my thumb = no change... the engine was just rebuilt so the likelyhood of it being a bearing piston. And it doesn't feel like a mechanical tap ... it feels like a vacuum or a electrical ignition/ fuel mixture problem.
Since the roughness dissapears after a 1000 RPM
The head has been milled a great deal, 4x by now ... So compression is gonna be higher and i now that'll give me a wee rough idle.. but it shouldnt be bad enough to shake the car or kill the engine when electrical load is applied.
I bulletproofed the electrical system with extra grounds to the battery and fog lights.
This is killing me ... and i am still getting sh$^Ty gas mileage. I think, cant really tell for sure since i have been idle-ing the engine a lot as well as 4 wheelin' through 2+ feet of snow up here in DULUTH MN!
maybe vacuum lines are up next down the line then...

Itoyota

well who would have thunk.
With a brand new full rebuild, done right, by quality professionals ... there are major compression leaks in cyllinders 1 and 2. and when i say major i mean major, talkin 50 psi in number 1, and 75 in number 2. here's the worst part.
It's not looking like it's the valves! Don't have a leakdown tester, but i did a ring test by squirting oil through the spark plug hole then testing compression again .. and number 1 shot up to 75 and number 2 went to 90.
I was also able to to visually see leakdown of the regular compression test needle within 1-3 secs of 3 psi incriments.
The rebuild's gone 25,000 miles AT THE MOST .. probably around 10,000 and the warranty is for 50,000 or a year. It's been 15 months!!!
Ill talk to the machine shop, and if they are aren't gonna help me .. well ill start a new thread called ( best rebuilt 22re money can buy ) and where can i get it.

any ideas on how to be 100% sure the problem is just rings. It may be valves and rings in combination... it may not be rings at all. What you guys think?