livergang

Title sums it up in the best way possible, but I am working on an 89 4runner 3.0 automatic. Among the other neglect related Toyota issues, my main problem now is that I am having spark cut off once the engine reaches operating temperatures (Im assuming). This issue came on maybe a month or two into owning the thing. I drove it an hour or so after buying it earlier this year so it did not have this issue at that time. Can't exactly blame the last owners. Ultimately the best way I can describe the problem is that I can cold-start perfectly every single time. It's never had an issue with cold starting. Once it idles for about 10 to 20 mins, spark is cut before the coil/igniter. I have not traced leads down to the ECM or further yet but I'd like to assume things are working generally as they should because of how perfectly it cold starts and idles, throttle responses and all until its warm. After warming up, there is no more spark, timing light on the coil to distributor wire confirms this. I get maybe 1 singular flash on key turn but it will crank and crank and fill the cylinders with gas with no spark. After having the issue for a while I would just take my 20 minute drives assuming I would not be able to start the car for another hour after getting to where I wanted to be. I can let it cool down to practically cold-start temps again and it will usually start up for me after a little bit of a hiccup. I seem to get codes randomly depending on how much I am trying to start it after it cuts off on me but I consistently see 12 24 31 51.

As for potential complications that can be ruled out, I have done a lot of work recently as the timing belt and injector connectors needed to be replaced. Heres the list: new timing belt, replaced miscellaneous coolant with red, new vacuum lines, repaired broken solders inside AFM, all intake gaskets, cleaned and reinstalled knock sensor, new knock sensor pigtail, replaced bad ground wires on rear right side cylinder head, replaced any cracked wiring along engine harness, rewrapped and cleaned corrosion from all of engine harness after it leaves right side fender, new battery, replaced rubber fuel hoses, fuel line copper crush washers, set TPS in spec. On top of all of that, I went to oreillys assuming I had bad coil and or igniter and got replacements for both, any combination of all four (original denso's from factory and non denso replacements) with no change in my warm start conditions. I will most likely be returning the replacements from oreillys.

I have tested my distributor and AFM for resistances and both are within spec warm and cool. AFM test by removing the connector only works when cold-starting because it will still send spark to the coil for a short time before shutting off, this does not happen at all when warm.

I am going to say it would be safe to assume this is related to a coolant temp sensor of some kind, however, the block at the back of my intake doesn't have exactly the same connectors as others. I am going to throw up a picture of the block that I have and if anyone could provide with names of the sensors that I should be looking to replace or has an alternative answer for my issue that would be much appreciated. This was taken before cleaning off the entire bypass block, trust that they are cleaned up and the bad single wire to coolant sensor is making a proper connection again. Would replacing these sensors/switches be a good idea just in terms of reliability and longevity or should I be looking elsewhere? Electronically, these bypass block sensors and the red green and blue vacuum switching valves on the passenger fender have not been tested for correct operation.

I will be pulling off my intake to get a better look at and better access for potentially replacing them next week and I'll have a better picture then. Would love to get it back on the road and warmed up to properly time it as well. It looks sad sitting at the back of the driveway.