iamsuperbleeder

bare with me, this is a LONG post



alright, here's the story...



You guys may know that not long ago I put on my header and full exhaust; replaced EVERY part of the exhaust

For the first day after the exhaust install the truck was running normal and great.

I don't know if any of this is related to the exhaust install, but a day and a half later, the idle went all to hell... it lopes at idle like it's got a really tall cam in it.

At first it wasn't all too terribly bad, I just turned the idle up a little and lived with it. And with the idle turned up to almost 1000 RPMs, it wasn't even noticable.

Well just in the recent week, it has gotten a LOT worse...

When I start the truck in the mornings, or after sitting for long enough to cool down, it idles high as it should while cold, and there's no really stutter noticable.

Once it runs for about 1-2 minutes and the cold-start idle goes away and the ECM goes into open loop, that's when the idle issue comes back, and it lopes BAD now... like, 3X's worse than it use to...

One thing that's strange is that it hasn't effected anything else It accelerates just fine and smooth (and as quickly as any other 22re on 31's and stock gears, which is not very quick at all ), and the gas milage has stayed level too...

If I kick the AC on, the idle comes up cause I have the idle-up valve adjusted a little higher than normal (cause I often sit at idle with the AC on for 15-20 minutes periods), and the lope isn't noticable, but it does still seem to have a random miss

Same as if I just step on the pedal a little while in nuetral and standing still, just to bring the RPMs up some. Say I bring it to 2500 RPMs; well it will not hold steady... I get it to 2500 RPMs and keep my foot steady, and I can watch my tach, and the RPMs drop about 50, then come back up 50, then drop, then come up, then drop, then come up... about a second for it to drop 50 RPMS, and another second for it to come back up the 50 RPMs... and I can feel and hear it too, so I know it's not my tach screwed up... At the same time, it randomly misses, and you can feel the motor miss a beat, and hear it "putt" in the exhaust...



My theory is that it's sencor related, and some sencor is causing the motor to starve itself of some fuel... and the only reason I think that is because if I introduce more fuel manually with the help of starter fluid while the motor's running, it smooths out and runs GREAT!!!... all for about 2 seconds till all the starter fluid gets sucked down, then it goes back to idling like crap... BUT, I don't know where to start looking...


My question to you guys, is what sencors are important to fuel delivery while the ECU's in open loop?


The O2 sencor has maybe 7k on it... the TPS has less than that... and the AFM is a used replacement I got after I f-ed up my original The plugs are brand new (literally, I just replaced them less than a week ago, and no change), the wires are in brand new condition, with less than 5k on them, and the cap and rotor are the same story; but I don't think it's ignition related any how.

The one thing I would like to change out, but I don't know if it's related, is my temp sencor for the ECU. I have all the reason to suspect it has a say-so in the fuel mixture, but I'm not certain.


anywho, thanks fer read'n my long thread if ya got any suggestion, don't hesitate to post it!

redvette

Funny thing. my 3.0 does the same thing... Maybe they are long lost siblings. Sorry cant help any.

DIRTYBOYZRACIN

Try unplugging the tps and running it i just fixed mine last night sorta similiar problem i changed every sensor on the motor turned out to be wiring harness problem with it unplugged itll idle higher than normal but mine runs great

Skoalbandit

How is the fuel pressure regulator?

iamsuperbleeder

try'd that

it idled hight at first, but still missed

then within 2 minutes of having it unplugged, the idle came right back down and did the same thing it was doing with it plugged in...

well, I fooled with that too, as far as unplugging the vaccum line to it. while idling when I unplugged it, the RPMs came up a hair, but still missed; I don't know if that means anything

YoYoMa

Have you cleaned/tested your IACV? The IAC went out on my 87 and started giving me the same issues. After cleaning the TB and MAF, The problem was still there. When I took my truck to the shop to have the cracked downpipe welded the guys told my the IAC was going bad. I swapped it out with a new one (not cheap) and now my truck is idling as even as can be.

wheatus

vacuum leak?

Flash319

Sounds like an injector. I would test all your injectors and wiring to them. I have said this before but 22re's run good (compaired to other motors) missing a cylinder. Idle will lope though.

iamsuperbleeder

hmmmm, that seems feasible...

but it has to be firing at least, cause I know how this motor runs on 3 cylinders; when I removed my intake manifold a long time ago to cleen it and put it back together, for some reason I forgot to plug in the injector to #4, and it ran like $#!@, but it was also really noticeable under acceleration too... I chased that for 2 days before I found that

I've searched high and low for one, and as far as I can see and find, the only way air is getting into the intake is through the air filter but yeah, I was really thinking the same thing too; I tried to find a leak with the starter fluid, and that's how I found out that a little spray into the intake will make the motor smooth out...

I thought that if that went bad, the idle just wouldn't come up under a cold start? I tried to remove it from the TB a while back, also when I had the intake disassymbled, and I managed to strip one screw out (where you use a screwdirver on it, not the threads), and the others wouldn't budge either, so I left it on. But the whole reason I took the intake and TB off was to cleen it in the first place.

chris1rb

i had this very same problem 3 weeks ago ran decent tell it warmed up because the idle air control valve is not closing after it warms up. i took mine off and yea the screws r a pain if they have been on there forever, sure enough though when i too it off the spring was pretty much welding open if dry coolant (the truck sat for 2 years).

anyways, cleaned it up got it to work decent, put it on and now my truck runs pretty good. every once in awhile i get a low idle for some reason, but i bet if i bought and replaced it with a new one my troubles would go away.

iamsuperbleeder

hmm...

the IAC may be something I need to look into

too bad it's Sunday and I have to work tomorrow otherwise I might try to mess with it now

I think I can deal with it till next weekend


thanks for all the input guys!

Skoalbandit

Do you have a compression gauge you could hook up to the fuel pressure regulator? it could be off by just 1/2 a pound and they run like crap...

That's the only thing I can think of where it will smooth out with ether being sprayed into the T.B...

If and when you figure this out, I really want to know what it was... Subscribed

mattaway

my truck has a very similiar problem. starts up and runs perfect when cold, but after it warms up it'll spit and sputter at the end of first gear and through the middle of second, once in 3rd it's fine. i changed the fuel filter back in january the problem went away for 2 months. recently it started acting up again.

jimep

As per the 85 fsm for testing the air valve- at low temp, coolant temp below 140*f rpms should drop when hose is pinched from the throttle body to the air valve. when warmed up it should not drop more than 50 rpms when hose is pinched. resistance between the contacts in the air valve plug should be 39 to 59 ohms and its a pain getting to it to check the resistance.

iamsuperbleeder

I'm wandering... could it be a valve-train issue?

Either a leaky valve, a bad spring maybe, or just maybe they need adjusted?

I might try to do the poor-man's leak down test that I saw on the show "Trucks" today they performed it on a Jeep 4.0 and found bad rings and an exhaust valve, so the trick seems to work

For those who don't know what I'm talking about, they broke a spark plug apart (removed all of the porcelain and electrode) and welded a male air fitting to it. They brought the cylinder they were testing to TDC, screwed in the tool, and hooked air pressure to it. Then they listened for air escaping, at the exhaust manifold, the intake, and through the valve cover at the oil cap hole. Pretty neat little trick if you ask me

YoYoMa

Neat idea. I'm gonna have to try that. :twothumbs:

DupermanDave

Where is the IAC on the 22re? I just spent 20 minutes googling it on my cell phone and turned up no helpful hints on where it is.

My truck has been idling horribly lately and I'm beginning to replace the engine piece by piece. If the next part I buy doesn't fix it, I'm going to swap in chevy 305. Will be cheaper than slowly rebuilding the 22re.

iamsuperbleeder

it's bolted directly to the bottom of the throttle body; it has 2 cooland lines running off of it; one straight down, and the other off to the side towards the engine

881stGenRunner

these problems sound very familiar to my 3.0 however mine will die when it gets warm and will not idle without me holding my foot on the gas.

Is the IAC on the 3.0 in the same place too? that sounds like a good thing to check out

iamsuperbleeder

well mine hasn't died on me yet; the lowest it drops down to when the idle lopes it right at or just under 500 RPMs... sure feels like it's gunna die though...

not sure about the 3.0's though; I can only assume so, but they're probably a different design than the ones on the 22re's