New user w/ perplexing problems

Hey everyone! New to Tacoma World and I've got some really strange issues I'm hoping someone might be able to help with. Well technically I've been searching for months here about idling issues or hesitation problems and nothing seems to work. So here goes....*deep breaths*

I have a decent little 97' Taco, nothing special, just a base model 2rz engine 2.4L 2wd 5 speed. It ran great up until recently and has absolutely no frame rust underneath or anything so I don't really want to give up on her just yet, but I'm about at my wits end.

It all started one day when I was headed to the store and I took the driveway ramp up into the parking lot a little hot, and it kinda jarred the truck a little. I think the shocks are toast on the poor girl cause she wobbles for a week after hitting a bump. Anyway as soon as I got up over this driveway entrance, the truck immediately stumbles and dies. I take evasive action and get it pulled safely into a parking spot. I attempt to restart it a few times and it fires up ok but immediately stalls and dies, the check engine light is on and it will not stay running unless I keep my foot on the gas. So I fiddle around under the hood a little and figure I just need to get it home. I some how manage it get it home by slightly keeping my foot on the gas so that it doesn't stall and die. Pull it in the driveway at home and it sits for a few months because I don't really use it that much, it's kind of a side vehicle I use to haul debris and stuff.

I start searching around here and come across some info about the TPS so I order one and replace it. I get the new TPS in and start it up and everything seems fine so I take it for a little spin around the block and before I can even get around the block it was almost as if that new TPS failed instantly and it started dying again. So...I get back home thinking WTF! While troubleshooting again I realized that if I disconnected the TPS wiring harness the truck would idle but really rough. So I order a couple more cheap TPS from rockauto thinking ok these things are junk and I better get a few to have on hand! Put another TPS in and the same thing.

A few more months go by and now I am at it again, do some more searching around here and find info about the IAC valve so I replace that. Now this is where things get really weird. I replace the IAC and start the truck with the TPS connected. The truck starts up fine and idles perfectly fine but the moment I try to give it gas, it starts to stumble and die, if I let off quickly it will go back to idle but if I continue to try and give it gas it will stall. If I ever so slightly give it the lightest little touch on the gas it will accelerate ok, but the moment I try to blip the throttle or give it too much gas it starts to stumble and stall again. If I disconnect the TPS wiring harness it idles really rough stumbling bad, it doesn't stall but it acts like it wants too, but when I blip the throttle while the TPS is unplugged it revs or accelerates just fine, almost like nothing is wrong. While the TPS is unplugged and I'm revving it I'm noticing black smoke coming from the exhaust that smells really bad and it shoots black soot and stuff on my garage floor. If I plut the TPS back in, the bad smell and black smoke goes away and it idles just fine, but the moment I give it any gas, it wants to stall...I just do not get it!

Oh I also forgot, I did buy a cheap little ODB scanner to check the codes and it said no codes were found! But the damn check engine light is on!?

Also I decided to replace a few other things in the process of all this and searching around here for possible problems. So far I've done the TPS and IAC as I've already stated and cleaned the throttle body real good and all the little ports. Went ahead and did new plugs and wires. New Gas cap. New PCV valve and both O2 sensors. Replaced a few vacuum lines that appeared to be cracking some. I have a new Wix fuel filter but I haven't installed it yet, debating doing the relocation I saw here for it. Oh yea and I also just cleaned the MAF and it has a few air filter. I think that's about it for now.

Could it just be the fuel filter? I don't understand why it would rev just fine when I unplug the TPS. Oh I also noticed while I was in there digging around that my exhaust manifold is extremely rusty, and has what looks like a 3 or 4 inch hairline crack in it. Could that cause all this? Anyway sorry for the extremely long post, I really hope a few of you read all this and might be able to help shed some light on this for me! THank you in advance and have a blessed day!

 

The fact your light stays on with the Engine Running Does not bode well for the code reader you bought.

 

Great, I thought the code reader I bought might be junk...thanks rockauto! I'm afraid to try and drive it to autozone and get it scanned cause I dont want to get stuck and have it towed. Maybe I need to just load it up on my flat bed and get this damn thing scanned again with a good scanner =(

 

If the battery has been disconnected it will delete all the codes.

Was the code reader able to read all the tests even if they were incomplete ??

You have no friends that can lend you a Code reader?

I carry a Code reader in all the OBDII vehicles

Now the Check Engine Light should Come on with the Ignition Switch on engine not running .

 

Yea I disconnected the battery and it did clear the check engine light but it came right back on. Nah I live out in the middle of no where, I've decided I'm just going to load it up on my trailer and take it to autozone so I can get more info for you all. I also took a 2min video just a minute ago that I'm going to upload when I get back to show you guys exactly what its doing. If I can figure it out lol

 

Just get you one of these little Autel's - Walmart usually has them in stock as well. Then you won't need to put the truck on a flatbed for the next code you get. ;-)

$36 Autel Professional OBD2 Scanner AL319 Code Reader, Enhanced Check and Reset Engine Fault Code, Live Data, Freeze Frame, CAN Car Diagnostic Scan Tools for All OBDII Vehicles After 1996, 2025 Upgraded

https://www.amazon.com/Autel-AutoLi...,B06XQF6RBZ,B07H3M98FL&srpt=VEHICLE_SCAN_TOOL

 

Just got back from Autozone and their scanner didn't work either, theirs failed to even get a connection. Mine did connect and scanned, it just said there were no codes while I'm staring at a check engine light. Also hooked the cheap scanner I got from rockauto to my GTI and it worked fine on there, showed a code I've been having on the GTI for a while now just like my vagcom scanner. I'm going to try and load a video I took here in a bit, just spend the last few hours at Autozone and all the guys there are completely stumped as to what it could be. Some say fuel pump but others say Nah, its getting fuel just fine when you disconnet the TPS, almost smells flooded or super rich. Others said maybe fuel pressure regulator or maybe the MAF.

 

When your scanner connects can you access live data?

 

Check the fuel trim with scanner while running. Cracked exhaust manifold will read as lean by O2 sensors and trick the ECM into adding fuel which will show as a negative number on the LTFT (LONG TERM FUEL TRIM)
The cast iron exhaust manifolds are notorious for cracking, usually at top middle. I bet the front bottomed out and when BANG on what bumpstops are left, if any.

 

Seeing the codes and being able to access the live data is invaluable. Otherwise you'll just be throwing more parts at it until something sticks - and there's no guarantee any parts will fix this if you have a communication error due to wire integrity or something else which is quite possible seeing how the scan tools you've tried don't connect or fail to show the codes present despite the check engine light being on. That's why I asked above if you can access the live data with the scanner that will connect. Then you could chalk all this up to scan tool issues and not a PCM communication issue and should be able to pull the codes with the right code reader and get pointed in the right direction. Accessing the live data you'll be able to see the airflow of the MAF, check the fuel trims, and TPS performance.

 

I'm not even sure the cheap litter scanner I got will run live codes but here is that video I made that might explain things better than what I'm trying to do.

 

Yep you are correct, that is exactly where it's cracked. Could a cracked exhaust manifold be causing this? I guess I need to go get one of these scanners from Walmart because I'm pretty sure my little cheapo scanner can't do the live data stuff.

 

The cracked manifold wouldn't produce the symptoms you're experiencing. The fact that you can unplug the TPS and it mostly clears up bear that out. It could possibly show elevated fuel trims at idle. W/o seeing live data it could be any number of things: MAF, TPS, exhaust blockage, fuel pressure...

BTW: Is that a Duke I saw in the garage?

 

Haha no, it's a 2010 Kawasaki Z1000. Thanks for everything so far guys, I am done for the night but I got that scanner and will post more info tomorrow

 

Well I left the taco on the flat bed last night and just stuck it in the barn because it was getting dark and I didn't want to mess with it. Went to get it off the trailer today and put it back in the garage and it wouldn't start at all. I'm not sure if the cold did something or because the guys at auto zone were jackin around in there and unplugging everything, swapping relays etc. It just cranked over and over, it almost tried to start once but died. I probably tried to start it 4 or 5 times and nothing. I remembered one guy had swapped the tail and efi relays or fuses not sure exactly what they are. So I swapped them back and it finally fired up so I could get it off the trailer. Also tried the new autel scanner with no luck, would not connect. So I tried my first cheapo rockauto scanner that did connect but found no codes and now that one will not connect

 

So at this point you need to re-establish communication before throwing any more parts at it. Since people were swapping things around you need to ensure everything is back in its original state. Use the fuse box covers and verify all the relays are where they're supposed to be, and check all your fuses. From there You will need to get the wiring diagrams and check the powers and grounds at the PCM. You also need to pull up a pin out of the OBD2 connector and troubleshoot there ensuring power and grounds on those lines at the connector. Once all these basics are done and if you still have a problem you will be at a junction point of how deep you want to get into this by yourself versus hiring a diagnostician to figure it out. It will likely consist of troubleshooting the networking communication lines and require you to have an oscilloscope and the proper knowledge to diagnose it. It can be done as a DIYer but you have to ask yourself how much time and energy are you willing put into advanced diagnostics.

 

Looking at the 2RZ-FE wiring diagrams:

Fuses to especially pay attention to:
7.5A OBD fuse
20A EFI fuse.

On your OBD connection check the following:
Pin 16 - Check for power (violet wire)
Pin 4 - Check for ground (white w/ black trace)
Pin 5 - Check for ground (brn wire)

Likewise there's some communication lines at the OBD port but you wouldn't be able to check those w/o a scope. (edit) I suppose you could check those for at least some kind of voltage but being communication wires you won't be able to see the signals w/o a scope.

Check ECM Powers and Ground:

Pin 6 / White-black trace - Ground
Pins 5,17 (brn wire),21,31 - all other wires white w/ black trace - Grounds
Pin 16 / white w/ red trace - Power
Pin 1 / blk w/ yellow trace - power

 

Thank you for all of this! I will check these things tomorrow and check back

 

So I got to checking some of things you mentioned here. All fuses are good. Went ahead and checked continuity on all fuses as well as the OBD you mentioned all checked out good. While I was under the dash checking the OBD port I noticed this bundle of wires wrapped in electrical tape, is this normal?

 

It's probably normal - I have something similar on mine (5VZ) but the heat shrinked bundle goes into various connectors. Is that one large open ended connector at the end?