DupermanDave

I just got done with a clutch replacement (detailed here: https://www.yotatech.com/forums/f116...cement-193138/ )

Now that everything has been put back together, the truck won't idle properly. Even adjusting the idle screw has absolutely no affect on the engine. It has been burped, and I can get heat inside and the lower radiator hose gets hot...I'm sort of dazed and confused right now from the fumes from the low RPMs when at a stop light.

The only thing I can think of that I've changed that would affect this would be the alternator. I did replace the fan clutch while the radiator was out. I didn't need to loosen the alternator/fan belt, as it was loose enough for me to tilt/angle the puller for the fan clutch and get it installed. It seems to me that it may be loose enough to cause it to be slipping and not let the alternator do its job.

I also partially removed the PAIR valve and some EGR components. But I didn't think those would be affecting the idle.

I can hear a hissing/whirling noise coming from either the intake box or the area on the driver wheel well. It's hard to pinpoint it since it sounds like it's around the exhaust area. I tried spraying and pouring water on all of the belts to see of the noise would stop or lessen, but they didn't.

After the clutch replacement, the first few startups were fine. It's when I adjusted the clutch pedal and took it for a gentle test drive that it decided it didn't want to idle properly. So the first few startups were great, but after an actual drive it started acting up.

I'm needing some help on figuring this out. I'm tired and exhausted from the clutch replacement.

myyota

If you removed part of the emissions, i would look for a vacuum leak some were.

BajaRunner

If your idle adjustment screw isn't doing anything I'd look into making sure the thing is really burped... A pocket of air will sit in the IACV.

I personally can't get my truck to burp easily. I end up just cleaning up a ton of coolant.

DupermanDave

Just the opposite for me. Usually I don't have any problems burping it.

I started the truck up this morning and it idled fine...until I revved it a bit and gave it some gas. It immediatelt dropped to about 200-350 RPMs. I adjusted the throttle pulley so I can squirt some water on the engine to check for any air leaks in the intake or vacuum system. I couldn't pinpoint any.

The only EGR parts we removed were the EGR thingy on the back of the intake manifold and the EGR valve on the head. If it was a leak with one of these two components, wouldn't it have only affected the truck at highway speeds?

Also, I should mention that I have absolutely no power at all in first or second gear. It appears to not have any power until I hit about 30 miles per hour, which takes about 6 to 8 seconds to get to.

Here's a detailed list of what was changed on the engine during the clutch installation: coolant and oil drained, radiator removed and cleaned, exhaust PAIR pipe was removed from the exhaust manifold, exhaust manifold was removed from the engine, and the #4 spark plug wire was removed.

For everything that had a gasket I made a replacement.

I'm going to try burping the system after work. Going to park it on a curb or an incline and try burping it. Even though I get heat and it seems to be circulating, it still wouldn't surprise me if that was the cause. All of the searches I have found for idle issues and air in the collant indicate that air in the system would cause a high idle, not a low idle like mine.

BajaRunner

You're right. Low coolant usually makes it idle extra high.

I'd check your TPS adjustment. Try pulling the plug off and see what happens. (Im experiencing the same issues right now).

DupermanDave

Dangit. Burping the system is easy. I did consider the TPS adjustment, but I didn't see how that would get thrown off all of a sudden. Definitely worth a try.

Even with the TPS not adjusted properly, why would the idle air screw not affect it? I had an improperly adjusted TPS a while back and the idle screw still affected the idle.

DupermanDave

MORE INFORMATION!!!

So I went out on my lunch break and unplugged the TPS and the EGR. I figured the EGR may be stuck open and that may be causing it to stall. (by the way, it stalled every stop light on the way to work) Also, I let the engine warm up again and tried adjusting the idle air screw. This time it slightly affected the idle. So the idle screw does change the behavior.

The hissing noise I'm hearing is definitely coming from the air box. I've narrowed it down that much. I turned off the engine so I could unplug the VAFM/AFM and see if maybe a paper towel got sucked up or something. When I turned off the engine and went to mess with the AFM, I heard it click like it snapped shut. I turned the engine on again and revved the engine up a few times, turned it off, and went to the AFM. I waited a few seconds and then I tapped it with my fingers and heard it snap shut again.

Could the AFM be getting stuck open (or stuck shut?) What's the best way to clean it/lubricate it? (been searching all afternoon and cant find any info on a sticking VAFM vane.)

-edit-
The ride home was awful. I'd estimate I'm probably getting 5 mpg. I filled up the tank last night, and typically on a full tank I can go to and from denver (about 50 miles away) and it would only use half of the tank. After filling it up last night, I'm already half done with the tank and I've only gone about 35-40 miles total.

SoCal4Running

Wow that is bad mileage! Try unplugging the CS injector after warm up and see if its better. Maybe the computer thinks its still cold.

DupermanDave

I just unplugged it when I parked it, but since traffic is so bad I'm going to wait until later to test it. I'll post back the results.

I did think of the cold start injector. On the drive home, if I was sitting at a stop light, it would almost want to stall and it would stumble and wouldn't want to give it any more gas. I figured maybe the engine was being flooded. The fumes are also pretty terrible and it backfired quite a bit once I was able to get moving forward.

1990yota-pickup

dave we will get this truck up to par, one step at a time...

DupermanDave

Unplugging the cold start injector does nothing for it. I unplugged it, started it and let it warm up for about 60 seconds and went for a test drive. Almost immediately after pulling out of my space and driving down the street I gave it a bit of gas and it sputtered out and almost stalled.

I parked it and started it and stopped it again. I can definitely hear the air flow box snapping shut if I tap it after shutting off the engine.

LifterCatcher

A vacuum leak is going to throw all of the above off, the IACV only works when the ECM is seeing the corrected amount of metered air via the MAF.

Its def a Vac leak.

The EGR valve uses vacuum to operate. When you removed the EGR valve and other EGR components what did you do with the vacuum lines that connect to the EGR? Did you plug them off?

The reason your idel is all messed and you are getting really bad fuel milage is because the truck is pulling in un metered air via a vacuum leak and the MAF is not seeing this air. Your ECM does not know how to compensate for this un metered air, so it goes into closed loop mode and injects extra fuel as a safety mechanism (more fuel is always better than not enough)

The vacuum leak can also domino effect other system sensors. So before trying anything else track down the vacuum lines that you removed from the EGR and plug them. Also I am not 100% sure if the 1st gen ECM is will notice that you removed the EGR. I have had several vehicles that needed a ECM retune to compensate for removing the EGR.

Let us know

Chris

DupermanDave

When I pulled off the vacuum lines, I labeled each one. I only pulled them off of 4 places: one from the EGR valve itself, and the other three were grouped together at the very back of the vacuum rail. I labeled the 3 that were grouped together so I knew exactly where they should have gone. I'll double check those again, though.

In the meantime, I pulled out the AFM and here's what I found:

http://www.youtube.com/watch?v=WUoLEAU4BB0

http://www.youtube.com/watch?v=ZkFKYi7Adk0

(yes, that's Top Gear in the background)

Isn't that vane/door in the AFM supposed to snap shut? If you can't see the video, it basically grinds closed. A few times when I was opening and closing it it got stuck and then snapped closed. The audio wasn't good enough to pick up the grinding noise it was making as it closed. The inside of the AFM has a thin layer of dirt that I'm going to clean away, but the door is definitely grinding on the dirt.

-edit-
I just went out and checked the vacuum lines, and they're all in place where I *THINK* they should be. The only one I have a questions about is a small 3 inch line that loops from one point on the vacuum rail to an other point. Other than that, everything is where it was before.

I tried snapping some pictures, but there's almost no room to get a good view in the back.

DupermanDave

I think I may have found the problem. I'll know today after work when I can put that sensor back in. I opened the black top that used to be sealed up by silicone and found there was a chunk of silicone in there that was keeping the vane from moving as it should have. After I pulled it out carefully, the vane is now free to move.

I'm hoping it didn't damage anything. If it did, oh well. At lease I know what part failed and now I can look into doing the supra AFM swap. But I'll have to wait and see if this corrects or at least changes the behavior of the problem.

dsleggett

Sounds like your vacuum leak is near the air box. The PAIR draws filtered un-metered air in there. Make sure your vacuum lines are connected. Let the truck idle and get your ear down close, you'll hear it. Also check all of your spark plugs to see how rich/lean things are running. This might tip you off to the problem too.

DupermanDave

I think I fixed the problem. I put the AFM back in and it seems to work fine now. It accelerates like it did before (still sluggish), but it's definitely an improvement over what it was doing yesterday.

1990yota-pickup

looking good dave...

DupermanDave

Yup. Got it fixed. Only problem now is it's blowing smoke because I think I overfilled the oil. Though I don't know how I did that. I checked the manual and it said 4.7 quarts, so I only put about 4.5 in knowing I wouldn't get all of the old stuff out once I drained it.

But, I'll just let it burn off. If it doesn't stop by the time I replace the gear oil, I'll just drain a bit off.

1990yota-pickup

when your rings are getting really bad just add a qt of 80/90wt during your oil changes...

DupermanDave

I've considered that. Right now the compression test I did incorrectly says I have about 150lbs in almost all cylinders with one or two in the 155 to 160 range. So I wasn't too worried. The engine wasn't warmed up when I did the test, which is why I say it was incorrectly done. For all I know, the compression numbers could be higher.