Won't Time:Starts cold, runs 45* BTDC, stalls when warm

[MorToy]

Issue:

I can easily start engine cold. It runs--fast. Timing light is showing at least 45* BTDC, probably more. I peg out the distributor adjustment bolt groove (all the way to the left as you look straight on) and can get it to maybe 40*. I take off, and plug, vac advance tube and it retards, but only to about 30*. Just about the time I get in the flow of making adjustments engine is warm and goes from fast idle to stalling dead--never kicks down to proper idle. Won't easily start again until cold.

What I've done:

Triple checked that I am starting with TDC. Confirmed this with not only the dust cover, but the crank shaft pulley mark to the oil pump mark (the TDC mark on the head is perfectly in the middle of the camshaft pulley peep hole). Distributor rotor is at #1 (10:30) and the contact is dead-on the pick up).

I remapped the vac lines and they seem to follow the multiple diagrams everyone has posted (I also have the '83 FSM). After rebuild couple years ago I replaced *all* vac lines with new OEM Toyota ones (dealer gave me a great price).

I did discover I am missing the check valve (the orange and black one) on the vac advance tube as well as the jet that goes to the carb choke valve. I have a three port vac advance--I plugged the second port on the upper section.

Recent lead up work done, performance history:

It had been running poorly for awhile. Mileage was around 16 MPG, pinging on hills, and oil fouling faster than it should. I knew timing was off and I've struggled to maintain proper timing since the rebuild.

Yesterday replaced the after market crankshaft pulley and key with an OEM Toyota set. I installed the new Toyota crank pulley (man, it and the key's tolerances were much, much tighter) and put it all back together. Fired right up, running fast. Dies once engine gets warm, about the time it would have normally kicked down to idle. Timing is off the chart BTDC.

[dlb]

if the RPM are up in the fast idle area, say 2500 rpm, that will have some effect on the timing since the mechanical advance is operated by small weights in the dizzy that increase timing advance with rpm. a true ignition timing reading can only be achieved with the rpm in the regular idle range, say 700-1000 rpm. so i wouldn't worry about the timing yet. even that far advanced, it should stay running once warm so let's focus on that first and come back to the timing later.

i'm a little unclear on the other symptoms. are you saying the car has been running poorly for a while, but this specific problem of stalling on idle once warm started suddenly yesterday?

did you change any of the carb settings recently? could be as simple as the idle speed screw is set incorrectly so that once warmed up and the fast idle system kicks over to the regular idle, there's not enough gas to keep it running. another likely cause could be a massive vacuum leak, possibly at the base of the carb or the intake manifold.

have you checked the carb float bowl level?

[Mark]

It sounds like you set up your timing manually for 0 degrees BTDC. I've found lately that the manual method usually gives me a slightly retarded timing (about 3-5 degrees compared to what a timing light shows). I'd guess that your timing is actually a few degrees AFTER TDC at a normal idle speed. The factory setting is 5 degrees BTDC. When checking with a light, I'd disconnect and plug all the distributor vacuum hoses (mine's the 3-hose as well). I don't bother plugging the ports on the distributor.
Anyways, I don't think the timing is the cause of dying at idle (it sounds like it's close enough to run). To me it sounds like a big vacuum leak. Even if all the hoses are connected correctly an internal diaphragm could be leaking (EGR, etc.).

[MorToy]

Thanks guys.

dlb: you answered one of the questions I thought about yesterday--should I try to get the fast idle down then try timing it. Makes sense if the fuel and air is dialed in even an out of timed engine could chug along.

Other sytmptoms: prior to this work it was running, but idling fast. I could also never get the tming into factory spec, but it was not this far off. Since the crank pulley replacement yesterday, I have not tried driving it.

I did try moving the idle down a bit awhile ago. I'll check it out. The float also seems OK--level pretty much in middle of window.

Mark: good idea about EGR. I'll check it. Sorry for the confusion on TDC/timing--wanted to establish that distributor went in set to TDC so you all know I did not randomly slap it in with the rotor way before #1, hence, causing the out of range timing.

[MorToy]

Update:

I was able to set the fast idle per FSM. Sounded great. Shut it down. Reconnected the two hoses it instructs you to disconnect and plug (HIC and TVSV M port) and reinstalled air cleaner.

Started back up and stalls out.

Took off cleaner and disconnect hoses per fast idle set instructions again, runs like top.

I will check the slow idle screw next (have to head to Easter brunch).

[dlb]

hmmm. that seems to indicate something wrong with the HIC, EGR, and/or choke opener. my money is on the HIC being the culprit. reconnect the M port but keep the HIC hose plugged and see if the car runs normal at all temps then.

it seems unlikely but i wonder if the PCV and HIC hoses are mixed up. i know that either one is a large enough vacuum leak to stop the car from running so maybe double check they're correctly routed.

[MorToy]

I'll run the diagnosis you suggest when I get home from work today. I think we are getting close to trouble shooting it.

Stay tuned.

[irowiki]

Another thing to consider, if the timing is way too high, someone may have put the distributor in wrong and it is off some.

[MorToy]

Hi irowiki, nope, the distributor is installed correct.

More I troubleshoot it more I think dlb and Mark are correct: my post title should take out the timing reference and make it about a vac system issue.

dlb had great point that shifted my focus: absolutely no point in timing at fast idle because the weights are going to be spinning like made and advance the timing.

I'll stick with the HIC test, then move from there.

[c_j]

Hi irowiki, nope, the distributor is installed correct.

More I troubleshoot it more I think dlb and Mark are correct: my post title should take out the timing reference and make it about a vac system issue.

dlb had great point that shifted my focus: absolutely no point in timing at fast idle because the weights are going to be spinning like made and advance the timing.

I'll stick with the HIC test, then move from there.

On my last engine swap, I put the distributor in as per FSM, but I could not get the timing within spec. My distributor is currently 1 tooth off according to FSM, but my timing is in spec now. I had the dizzy in and out like 5 times trying to figure out what I was doing wrong, so I finally gave up and just made it work.

[Petros]

I too would suspect the distributor off a tooth, but until you can get it to idle down there is no way to verify it. I would look for a vac leak or misrouted vac lines, that is what it sounds like, run okay when chock is in use, but when choke opens the vac leak makes for too lean a mixture to keep it running. cold be HAC or that other thing on the fender that bleeds air under the carb to allow mixture control (EBVT or something or other). check the manifold bolts for vac leak too, they aways work loose after a rebuild with new gaskets. fixing that should improve your fuel economy too, too lean a mixture actually uses more fuel.


good luck.

[MorToy]

Thanks guys: good news, update! Think dlb made a wise bet.

I took dlb's advice and tried plugging the HIC line (the one that goes from air cleaner to throttle plate) and left everything else hooked up. Fired right up, drove it to get up to operating temp and I pulled over. Got out, expecting it to stall as it had been, and as I was about to pop hood, the engine kicked down to idle! Like a normal, functioning, engine!

Threw tach and timing light on and set the slow idle per near FSM spec and the timing was much, much closer in the ball park (5* w/ distributor advance plugged, 30* w/ advance back on).

As soon as I unplugged the HIC tube the engine began to race (even at idle). Put pencil back in to plug, engine happily purred again at proper slow idle RPM.

So, bad HIC valve? According to the FSM the HIC valve controls air to enter the intake manifold "to maintain proper air-fuel mixture during high temperatures at idle." It dies at idle at high temp. On the next exciting episode: I'll remove and test the HIC valve per FSM.

c_j and Petros: funny you said that about cheating the distributor a tooth or two--before I had this last round of issues I gave up with TDC tooth meshing and cheated it a tooth to get me closer to the spec timing. Drove me nuts, but figured ultimately it's all about the end result (timing).

[irowiki]

You might also ensure the hose is actually staying attached securely to the HIC valve. On one of my fleet, I had to hose clamp it onto the hic valve or air would just escape around it.

If it ends up being bad, I might have a spare one somewhere...

[MorToy]

irowiki: good call, I'll double check the connection. Thanks for offer. I will see if it fails test.

[MorToy]

Might have the culprit: the HIC valve failed two of the tests indicated in the FSM. Didn't bother heating it up to 85 degrees to do the last test.