BizarroStormy

I disconnected the IAC while it was cold and started the truck and it shot up to 2k rpm immediately. Shut down the truck, plugged the IAC back in and it went to 900 rpm. Unplugged the IAC while the truck was running and it slowly went up to 2k rpm after warming up. So it does seem to be IAC related. I replaced this IAC a few months ago to resolve another idle issue I was having so I assumed it would still be working. Should have a replacement in tomorrow.

Quick sanity check before I pull my manifold apart. My truck recently developed the wonderful habit of increasing its idle speed as it comes up to temperature. Starting at around 900 RPM and ending up at around 3400 RPM when it gets up to operating temperature. After cooling off the cycle starts over again. I checked all the vacuum hoses and discovered my EGR was not properly hooked up and found that the green vacuum line to my transfer case was broken (fixed my always on part time light problem). I pulled my throttle body and cleaned it out, especially around the idle servo but it was not that bad to begin with. Re-installed with a gasket and then with RTV after it didn't do anything. I purchased a REM from Nick (Thanks nick this thing is awesome) and it looks like all my sensors are working and it runs in closed loop even when going crazy with the high idle. So.... This is a manifold leak right?

Hey that was it, thank you so much! I would have never thought to look at that knob. Now I have fancy light that turn themselves off :).

So I replaced my missing pillar lights a few months ago and discovered that they always stayed on as if a door was ajar. So I figured the door switches were broken and left the black and white wire disconnected and just had manual pillar lights. I replaced the door switches today and they are still stuck on after reconnecting the black and white wire. Any advice on where to start looking for the loose ground? Thanks in advance

The TCU has been resurrected! I figured I couldn't break it more than it already was so I pulled the casing off it. The board looked great except for one small burn mark under the 100uF capacitor. Looks like it burst downwards and maybe took the resistor next to it out with it. I dug through my electronics bins and found a close-ish resistor and a 400v 100uF capacitor. I "desoldered" the broken components and added my junk bin finds and my truck shifts again! Thank you so much omega_rugal for helping me diagnose the issue!

I was able to get a 4 ohm ground from the plug and confirmed that it was getting 12v on one of the pins.

Just took it out for a ride around the neighborhood, and that is it exactly! I was even able to get it up into 4th gear manually. Very strange experience shifting an automatic like a manual. I checked the transmission fuse and it is fine, so I guess my TCU is fried?

So I just completely lost power with my overdrive gear selected today, the engine will only go up to 2000 rpm and barely creep along. If I switch it to the third gear position it drives almost normally but still sluggish and if I switch it to the 2-1 position it drives normally. I checked the transmission fluid level and it is high, but has always been high since I got the truck about a year ago. The color of the ATF was still pink/red, with no smell of any kind. This truck has about 220k miles on it, don't think the transmission has ever been worked on. Any idea what could be going on? Thanks in advance

So I did most of the tips and it didn't change my idle issue, that C101 connector was disgusting though. I replaced my air control valve, throttle position sensor, MAP sensor, and oxygen sensor (all at once) and it solved the issue. My truck Idles around 800-900 rpms now and doesn't go crazy while in park. Hopefully this will help my gas millage, I was getting around 13 mpg before swapping the parts. Thanks for all the advice .

Looks like I have some projects for the weekend. Thanks, I will report my results.

Thanks for the heads up, couldn't find the signature area under profile.

My truck seems to randomly pick what speed it wants to idle at. Sometimes as low as 300 rpm, once as high as 2000 rpm. This can change while I am driving it, and usually jumps up to around 1300 rpm when I throw it into park after driving it for a while. Also my part time light stays on most of the time even though I am in 2H, but turns off when I accelerate quickly. Any ideas on what is going on?

I got this one off amazon that worked. https://smile.amazon.com/gp/product/B0006302JU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 Might not be stock, but looks better than the screwdriver handle that came with my truck.

I am running 31x10.50R15LT WILDPEAK A/T3W. I don't plan on lifting the truck or putting any larger tires on it. I will work on my signature, I was planning on creating a project post after I got the front back together.

Thanks for the advice, I guess upgrading is never a bad idea. How much of a liability is the old smaller U-joint? I don't plan on doing anything too crazy in it and I managed to replace the driver side U-joint successfully.

So while I was working on all the other stuff that is wrong with my front end (steering everything), I decided to replace the universal joints in the front axle while they are out. I have never replace U-joints before and I bodged the job pretty badly on my passenger side. One of the needle bearings popped out while I was pressing it back in and it jammed the whole thing up. Then when I was pressing it out the cap cracked and I ended up pounding it out in pieces. This left a nice ridge in the end where the bearing cap sits, it also looks like the metal is cracked from my overzealous use of the press. Is this a total loss or can I just sand out the ridge? If so, where can I find a replacement? The casting is Spicer 41933 which I cannot find online.

Thanks for the tip on the black glue stick yxmj, how well do they hold up to the hot engine bay? It looks like my evap canister has been removed by the previous owner and the tube just vents into the engine bay, looks like they jammed the small orifice into the tube. I have noticed that the gas tank either has vacuum or pressure after a short drive to the gas station down the road. So maybe that tube is blocked. I just replaced the gas tank (full of rust) and cleared the vents. Anyone know if there is some aftermarket evap that will work? Or is it not a big deal to not have one and I should just epoxy over that broken port on the air box?

Looks like that is routed to the connection on the back, what normally goes on that large connector on the back?

So it looks like my airbox has a broken hose connector, can anyone tell me what normally connects here? I can't find any loose hoses, but it seems like the previous owner just did whatever it took to make things work. Also if anyone has any leads on an airbox, I have been having trouble finding a replacement.

So I got it worked out today. I got this Dorman HELP! 42344 PCV Valve Grommet, Dorman 47079 HELP! PCV Elbow, and DORMAN 47128 PCV Hose from Amazon. I then took the the white tip off the stock PCV hose and inserted it into the necked down portion of the Dorman PCV hose and used a clamp to keep it in as there is no barb. I then ran 3/16" SAE J30R7 hose from the white barb to the intake side. Drove it around town for about 30 minutes and it appears to be working and staying in place.

Thanks for the information everyone. Strokermjcomanche what did you end up using on the rear vent to get it to fit?

Can anyone tell me what vehicle this valve cover came from? I recently purchased this 88 Pioneer with a 4.0 and I was replacing the rear vent grommet and breather tube because the old one was held in place with a chain of zip ties. The vent holes are much larger than the stock ones as the (supposedly stock) valve cover grommet I got is much smaller and does not fit. You can see the stock one sitting on top of the current grommet in one of the pictures. Also if anyone can suggest a grommet that will take the stock breather hose that would be appreciated.