Resetting ECU seems to negate the problem entirely, but it is temporary.

Hmm

Maybe I have a bad TPS / AFM...

 

Going through with the later model intake conversion.

I got an upper intake manifold, throttle body, and AFM for under 200 from two different boneyards after some haggling. Then came home and gave the intake parts a good cleaning. Just need to get a few water hoses from Toyota and I'll be ready to install.

The inside of the manifold was not bad at all (from a 94). But you shoulda seen these before I cleaned the outside! Yeehaw

 

Interesting ECU observation...... Have you checked for stored CEL codes after it runs wonky? It would seem if resetting the ECU helps, there should be a code stored.

The intake looks nice!

 

Thanks!

It looks even better in the car!


I get no codes to help me out, and the problem persisted after the swap. On to overhauling the fuel system. This is expensive, but somehow very fun. My brain is a sponge

New part lineup for next week:
• denso fuel pump from sparkplugs.com
• flamethrower fuel injectors
• possibly new FPR
• fuel filter (why not when I'm replacing everything else )

Concurrent research lineup:
• ignition heat soak? *unlikely, tried throwing cold water and ice on dist at no avail*
• coolant temp sender? *possible that the engine thinks it's always under temp, running rich*

Looking up the FSM for temp sender as we speak

Some new symptoms... The engine is backfiring out of the intake on the worst startups. The first time I heard it was about 2 or 3 weeks ago, and it is becoming more frequent.. Or maybe I am just starting up my car during heat soak more frequently.. Probably that.

Also I noticed the other day that I have a nasty rattle emanating from the center console. It is happening during accel AND decel, so I am praying to god that it's not pre-ignition. More on this tomorrow, need to confirm that ASAP. Scares the crap out of me.

On a good note, it appears the engine is now holding onto its coolant. I think it was the water hose on the bottom of the 87 TB.. Hose clamp was not tightened at all. *smacks face*

Did I mention the odometer reads 491,000 miles? There is a reason I am okay with replacing all this stuff... I have no idea how old it is. I can only assume that some of these parts have endured the wrath of every single one of those miles.

Also did I mention that I love this car?

 

I started with ECU signal first: attached the negative to body ground, jammed positive lead into THW in the ECU, key ON. Nothing. Looking back, I must not have had it in far enough.



Next on to check water temp sensor. I put my hand on the thermostat housing and it felt like it was around room temp- even though it's a tad nipply outside (it just RAINED in LA!). The resistance was 1.8ohms- in the range of 72deg F. Blowing on it made the resistance rise evenly and slowly. Check pass!



Looking at the connector (sorry didn't take a pic) it was FILLED with gunk. Looked like oil had gotten in it. Unfortunately I am out of electric cleaner at the moment, so I just put a few small dabs of dielectric grease in there and snapped it back on.

Back to the ECU side of things & back to THW. Reading 2.15V! Getting somewhere! I kept the lead in the ECU, then went over and blew on the water temp sensor housing again. Voltage at the ECU started climbing by a thousandth, slowly and steadily up to about 2.19 and climbing. To finish up, I grabbed a cup of hot water and poured it on top of the water temp sensor housing, and voltage at THW quickly dropped to 2.05V.

Lastly I unplugged the water temp sensor with the leads in the ECU getting voltage to simulate a bad connection. It jumped up to 5.1V. So that means if it doesn't see the sensor, it might think the engine is COLD- which would make it run super rich.

Maybe that is part of it, fingers crossed. It still doesn't explain the disappearing fuel pressure when off. But, I have a new fuel pump and injectors in the mail for that.

 

So the cold start condition seems to be entirely fixed. Now just trying to tackle this curious warm start issue.

I was setting timing a couple of nights ago, and when I went to restart it warm it started doing the same old low idle crap. Anyway when I triggered the timing gun, I noticed it was blinking extremely erratically... It was almost random. When I applied some throttle the randomness smoothed out.

Could it possibly be a bad ignition coil? It's weird because it only seems to happen on warm starts and goes away once I am moving down the road and put a few short loads on the engine.

I just got done with the fuel system overhaul.. Flamethrower injectors and a new denso fuel pump. A noticeable difference during normal operation, but the warm start issue persists.

 

Just curious...how did the old injectors look?

You'll get the warm start solved too. Could be the coil if it's throwing wonky signals when warm.

Have you pulled the engine coolant temp sensor that feeds the ECU and looked at the probe? We've seen some get pretty scaled over from water minerals and a wire brush will expose the nice metal probe so the ECU get a good signal.

 

We're you getting codes for the temp sensor. My 86 keeps throwing a code for the thermo switch on top of the thermostat housing I know there are 2 others, the green and brown one I replaced the sensor with a stock one from Toyota and a new wire spliced in I will have to open up my ecu and check to make sure it's getting voltage all the way through. Are there different codes for the different thermo sensors

 

This thing starts up great when cold. My my my Just drove home from a thxgiving party and it just growled to life. The days of sputtery cold start are over!

rw - I will post a pic of the old injectors tomorrow. There was certainly some buildup, they definitely needed to be cleaned/changed! Glad I did it.

I did the fuel pump today and it made no difference that I can notice. However I discovered I have a nasty pinch in the main fuel line as it exits the tank. Going to get this fixed at a shop sometime very soon, my buddy says it should only cost about 20 bucks! I wanted to cut it and MIG it back together but he said "no way I would ever recommend that unless TIG". I was optimistic, but decided to wait and do it right.. rather than be left with a stranded car



Also looks like the PO had some sort of aftermarket fuel pump. The denso unit on the left and who knows what on the right.



I haven't pulled the coolant temp sensor to look at the probe side, but that is a great idea. I saw some youtube videos of people cleaning them and how nasty they can get. I think that followed by a proper burping is a great idea chasing this warm start issue. If it's anything like my coolant overflow reservoir, it looks like the bottom of a boat that's been sitting in the pacific for two decades.

punks- as far as I know the coolant temp sensor is the green one in front, next to the brown which is the cold start injector time switch. The one on top is the temp sender for the dash gauge, I think.

But yeah, there are three water temp sensors for sure. One for CSI, one for ecu water temp, and one for dash gauge water temp. If you are throwing a code for one I bet it's the one for ECU.. which is the greeny.

In other news...

Getting some weird electrical things going on. Today I started it as I headed out for the thanksgiving party (warm start, low crappy idle), I paused on my way out of the driveway gate and flipped on the lights. The engine died! Something weird going on. Started it up and turned lights on, and everything seemed fine.

But then on my way home (now more in tune to what my lights are doing), I noticed my voltage surges during acceleration- causing my dash voltmeter to bounce/oscillate slightly and my lights dim in and out and the same time. Kind of like it does with the blinker on, except I was just accelerating. Very odd.

When I got home I popped the hood and checked the basic connections to battery, ignition and such. Everything was tight. The coil and ignitor were both incredibly hot to the touch.

 

Found this on another site:

I've also seen it mentioned several times on the web about heat soak and how it applies to the ignition systems as they age. Maybe my next step will be replacing these things one by one. What do you think I should start with, if any?

Thanks for the continued feedback, everyone I am so determined to figure this out. I am learning so much about this car it is kind of priceless.

 

Cleaned some crud off of the alternator positive lead, surging voltage under acceleration fixed

Starting up pretty well. The past 24 hours I have really noticed a difference in the way it is running. I'm trying to get the fuel and electrical on LOCK

EDIT: tootally forgot to mention, just replaced the 80a main engine fuse. I noticed it was starting to corrode. No change in random idle stumble. I got some grounding cable and connectors.. Imma try hooking that up directly from coil to battery and see if that helps. I am starting to wonder if this is just a grounding electrical issue. Might as well check

 

The random idle stumble improved a lot when I cleaned and corrected the grounds. I went into detail about the grounds in this thread:
https://www.yotatech.com/forums/f116...-wires-285006/

Basically I added a ground from battery to coil, and cleaned/greased all connections including the alternator connector. #3 and #4 engine grounds from this thread were not hooked up properly / at all. Still have yet to find #4, and #1 is hooked up to the front of the power steering pump instead of the bracket where it should be.

The truck now starts on the first crank of the starter every time- I get the feeling it's from the fuel system refreshments (flamethrowers + new denso FP).. I love it! Cold idle up works perfectly with the later upper intake / tb, idle is pretty buttery, and everything is feeling dang near rock solid except for the low idle after warm start issue.

Another interesting thing I noticed today: my mpg has climbed a lot. Today I saw 20-21mpg city on the mpguino without paying attention to it that much, it actually surprised me because I was driving with a little more oomph off the line. Tonight, in the traffic loop at LAX, I averaged 20.5 circling about 3 times. The last time I went through there that many times, I got about 18.5mpg trying hard. As for instantaneous mpg, I can even get into the 20's in third gear, whereas I could not break 17 before. In 4th gear, I can now get an instantaneous mpg of 30 maintaining 35-37mph.. still haven't tested hwy yet. But, I am excited for the next trip to see how the highway mpg has changed. Recently I made a trip down to SD with 24mpg average, and that was before any of the fuel system and electrical refreshers... also with the top off. I guess I could hope for 25/26mpg hwy now with the right conditions

I still have yet to check the coolant temp sensor, and I just got called in for a weekend gig- so I won't have another chance to wrench again til Tuesday. I am already looking forward to it- can't wait to see if CTE cleaning fixes it! Part of me also thinks there could be some air trapped in there... needs a good burping

Thanks for reading my novel

 

I have some things in the mail to install this coming week

• OE fuel pressure regulator (been reading all over the web that it commonly causes hot start issues - and I still have the symptom of disappearing fuel pressure when sitting for a while. Other note, when I pulled the plenum to do the injector install, still had some gas in it towards the back even with CSI disabled and tested not leaking. My FP vac line is hooked directly up to plenum, it could totally be this!)
• LCE header w/ heated o2 relocation (treating myself AND trying to fix my cruise CEL)
• New coolant temp sensor (cheap, easy, why not at this point)

Merry early xmas to my runner

And hope you all had a great thanksgiving with your families!

 

Can you Silver Solder ??

That is how I would fix that twisted fuel line Have done so in my mis guided youth.

Like sweating a copper fitting but stronger.

You sure clean things nice

 

Aw thanks!! It's only going to get cleaner from here. Still nowhere what I've seen in scope's bay.

I've done a fair amount of copper sweating- where do I get the parts for silver soldering? And is MAP gas bueno?

Anyway cool. I was hoping I could fix that myself!

Thanks Craig

 

OK so! News!

In my suspicion for fuel pressure regulator being the issue, I plugged the vac line to the FPR as well as the vac line to the intake to prevent a vacuum leak.

Car has started up perfectly every time!

I was able to replicate it a few times as well- switching back and forth. With the vac line connected to the FPR, low idle at the warm start. Capped, perfect start. I really think I have found my culprit!

I have a new OEM FPR in the mail, but for now I'm going to run it with the vac line capped and see how it does. I'm hoping for the best.

I also wonder of this has something to do with removing the FPU VSV.

And a new pic

 

After doing a tiny bit of research about the FPR VSV, I am pretty certain mine went bad (probably stuck open or not getting voltage) and caused the hot start issue- the SOLE reason it is on there. Yeah.... Then I took the thing off completely.

So it turns out it does serve a purpose... To prevent hot start issues!

EDIT: forgot to mention. I did a really good coolant burp today. Lots of air bubbles came out. I think that has helped immensely as well. I also seafoamed and the idle stumble has improved even further.

I am getting super super close.

Next step is getting the LCE headers on in hopes that my lean o2 at cruise disappears. If that works then I'm DONE!

 

Is the new FPR on now?

 

You have a future detailing vehicles.

I have to laugh some spend so much time making the body and wheels look pretty but the engine compartment never sees any attention.

 

I have been following your thread. My wife runner has a little gremlin. I can let it idle all day in the yard and it will hold steady and never rev up or down. Sometimes it will idle like it should when in town and hold steady. Other days only when in town driving at a light or stopped, it will rev up and down by a couple hundred rpms. Never at home. Been looking for ideas to see what it could be. Chefyota had a similar incident and his was a computer. I haven't tried that yet.

I did notice on another thread where your coil was weak. Did it pass on a Primary and fail on a Secondary or vise versa?

Another component I have seen have issue and not throw codes is the AFM. Haynes Manual has a quick resistance check for it. The flapper will move easily but the electrics in it will fail. That has helped some of my issues.

My 86 Runner starts quick and no problems, my wife's truck just every once in a while.
Check all your sensors and give a good cleaning.>>> https://www.yotatech.com/forums/f198...l#post52044719

Your being a California truck and not having to deal with humidity may not have fuel issues, but I see a lot of Return Lines clogged>>> https://www.yotatech.com/forums/f198...l#post52064973 but I think it is chemical build up in the fuel system and not necessarily moisture.