96 4Runner Hard start when engine warm/hot (long/detailed)

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Jukelemon said:
Really need to get an idea of what the specified ranges should be. But let's put that aside.

Here is what we know. When it is cold, and you pressure is 22psi, the engine will start, idle etc. When it has been run, and then rested, pressure is 28 psi and will not start. It seems illogical to think that fuel pressure is an issue.

I have thought, in relation to my issue, that it is an issue with my cold start injectors in that the relay does not recognize a certain temp range, and as such, does not utilize the cold start injectors-which in your case might explain why you must use starting fluid.

I go back to thinking it has to be relay related/signal quality related not pressure becasue of how well it starts cold-like mine.

Have you cleaned out your throttle body yet-I mean really clean with a toothbrush and carb cleaner? Have you checked your Coolant Temp sensor?
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I was thinking the exact same thing along the pressure idea...where one pressure it will start at but at that same pressure when the engine is hot it won't start...

On this engine there are no cold start injectors, my buddy did test the coolant sensor, but he is testing that again.

Since the fuel pressure didn't give us a clear reason why I was thinking about other stuff...what if the pressure has nothing to do with it and the spark is weak (for whatever reason, bad coil pack or whatever, although one coil pack is brand-new) so the plugs get fouled easily when they are hot (maybe easier to foul when hot, no idea)...and spraying in the starting fluid makes it start because starting fluid is easier to start than gas vapor is...what if the engine is badly carbon'd up and when hot it won't start because gas is preigniting and staring fluid helps maybe because it's just more vapor in there so has something to burn now...who knows...my mind was just wandering thinking about that...

Good ideas...thanks for the reply...
 
i will try to find some fuel pressure specs for you.
if you think the heat range is wrong on the plugs, make sure you have the right ones installed. they should be NGK stock # 6953. The side of the plugs will read:BKR5E-11
The '5' is the heat range. on the heat range scale, 2 is hottest and 12 is coldest.
 
WristPin said:
i will try to find some fuel pressure specs for you.
if you think the heat range is wrong on the plugs, make sure you have the right ones installed. they should be NGK stock # 6953. The side of the plugs will read:BKR5E-11
The '5' is the heat range. on the heat range scale, 2 is hottest and 12 is coldest.
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Cool, we have all the Toyota documents about pressure specs and all that, so the only thing I'd be curious about is what real-world numbers others are getting.

Good point on the plugs, I'll look at that tomorrow.

Thanks,
Mark
 
It could also be the case that an ignition component is not working properly under high heat conditions-as you have said low spark and the ignition fluid has a higher combustion rating and will lite as opposed to gas.
 
Jukelemon said:
It could also be the case that an ignition component is not working properly under high heat conditions-as you have said low spark and the ignition fluid has a higher combustion rating and will lite as opposed to gas.
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ive been thinking about this problem hes having at work for the last week. and this is one of the things i was going to look into, if there is a tsb on this. i couldnt remember the year, so i didnt look.
but this is a good place to investigate.
like i said a while ago you need an inline spark tester. a bright light indicates a good spark. and obviously a dim light is a weak spark. give it a try.
 
WristPin said:
ive been thinking about this problem hes having at work for the last week. and this is one of the things i was going to look into, if there is a tsb on this. i couldnt remember the year, so i didnt look.
but this is a good place to investigate.
like i said a while ago you need an inline spark tester. a bright light indicates a good spark. and obviously a dim light is a weak spark. give it a try.
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Will do...

Just as an update (Eric just got back into town tonight, so from now on the updates will probably be from him, since 'technically' it's HIS vehicle) :

After replacing the plugs today (old plugs were correct NGK ones and had been in about 5-10K miles, but looked really bad, dark, a bit oily, burned somewhat, just overall looked quite used, not consistent with the mileage at all, and after doing a fuel sytem with RedLine fuel cleaner, and 3 SeaFoam treatments, cleaning MAF 2-3 times, running premium fuel, putting in a fuel pressure guage...absolutely nothing has changed, tonight tested it again and same exact problem. I do agree that it seems to be a ignition related thing now.

The TSB is related to a engine wiring harness grounding issue I believe, and I believe (though would have to lookup) is related to hard starting...hmm...maybe we should look into that... :doh:
 
the plugs you describe would indicate improper ignition. that can be the secondary or primary iginiton circut, of course, but a bad ground will seriously affect your over all performance. i will see if i can sneakinto the office at werk tomorrow and look up more TSB's.
 
Jukelemon said:
Have the coils been tested?
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Tested as far as impedence testing yes, however, not sure if Eric did that testing with them hot or not...he's bringing the vehicle to my house today to test out a few more things, and test them all hot...
 
WristPin said:
on thos first page here, there is 2 threads that have different problems. all trace back to bad grounds.
toyotas get all pissy when ther ground strap is loose.
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Cool...thanks for pulling that up!

Do you know where the grounds are on the engine/wiring-harness? I'm sure we can just look for them, but if we knew what ones were typical problem ones it'd be nice to start there.

My guess is the problem is something like this, a grounding problem, totally unrelated to fuel at all...but after all we've done, atleast it has a clean fuel system... :D
 
mabrodis said:
Cool...thanks for pulling that up!

Do you know where the grounds are on the engine/wiring-harness? I'm sure we can just look for them, but if we knew what ones were typical problem ones it'd be nice to start there.

My guess is the problem is something like this, a grounding problem, totally unrelated to fuel at all...but after all we've done, atleast it has a clean fuel system... :D
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Think I found the TIS doc with all the ground points so we will check that tonight in addition to everything else.
 
and sorry i didnt get a chance to look at tsbs. the floating mgr was there, and he was riding my ass, and plus we were busy.
i usta have an account with alldatata.com they have TONS of repair info.
 
Update...

Tonight we pulled all the ground connections from around the engine, there are only 3 (passenger-side top of fender, driver's side of intake manifold and driver's side inner fender next to battery)...cleaned those off (didn't look too bad), used a dremel with a wire brush to get any oxidation off them, put them all back on...then pulled the coolant sensor (to test it in a pot of boiling water), and it more or less fell apart in our hands (which was interesting because it was working, we measured normal coolant temperatures previously with the ODBII reader, 199 degrees, etc), it apparently was broken at some previous time, we put it in water but even with it sitting on the counter couldn't get anything but a open on it, so apparently a wire or so was broken inside...so that will get replaced. However, interesting enough we put the broken one back in, just as a plug, and went to start it and it wouldn't start at all, we remembered we had opened the fuel rails, so it'd take a bit to fill all up again, but it took a long time, fuel pressure was sitting at 20psi it was sputtering and coughing, backfiring horribly, finally it crept up rpm-wise (fuel pressure went with it, or the fuel pressure crept up and the rpms went with it, couldn't tell), and then it idled perfectly, fuel pressure sitting at 34psi...

Connected a computer and the ODBII thingy said coolant was at -40F, must be some default value when it has no sensor to read...however (this was odd), the coolant guage on the dash still worked, it was at the bottom (cold) when the engine was cold, we let it run and it creeped up into normal range...this is all with the temp sensor on the top of the engine disconnected. So apparently that interior sensor reads something else? Anybody know what it reads? (we were not expected that guage to work at all)

So the fact that it had an awful time starting is suspect, but the computer also though the engine was at -40F, so maybe dumping in alot more gas or something, not sure what would happen with that, but that sensor is getting replaced obviously asap.

Even though the fuel seemed not-so-suspect before, I'm still not sold on that, when we were cranking away it was sitting right at 20psi, then as it was starting to start (coughing, backfiring, etc, for 5-10 seconds) the pressure was slowly creeping up and then at about 26-28psi it started running just fine. To me that was suspicous because if the pump/regulator/whatever could produce 34psi (like it was doing as soon as it got running, or started running as soon as it got there, however you look at it), then why wasn't it at that pressure while we were cranking it? I can not think of a rational reason why the pressure would be less while cranking than it would be while idling (are the injectors putting in more fuel while cranking than idling? Since it is trying to start a stopped engine, which usually takes a hefty boost of fuel I believe...but just guessing)

So all in all we did nothing useful to solve this problem...sigh..
 
Found that there is actually another coolant temp sensor that is separate from the EFI sensor that runs the gauge in the dash. The ECT sensor makes a difference in starting the vehicle since it was a pain in the ass this morning to get started. Should have that replaced tonight. Also contemplating the EFI relay and the Circuit opening relay which are both in front of the fuel pump. Not sure how I'm going to test those, but guess it is something else to look at. Still need to pick up one of those noids to check the fuel injectors.
 
Couple of things:

1- I have a coolant sensor that works. I replaced mine thinking it was the casue BUT it was not. So, do a part number comparison and see if the 22re's are the same. Mine is from a 92.

2- I do not think the gauge in the vehicle is connected to the coolant sensor-pretty sure it is not so that really tells us nothing other than the engine temp is going up and the T stat is working.

3- I still not think it is pressure related because it was fine at cranking last go around. As well, I ran my truck without a sensor i.e. sensor unhooked for a good 100 miles. No change and no issues. I am told that when a sensor dies, the ECU will default to a std map that insures driveability NOT starting i.e. it is made as a safety map to get home/shop/whatever. Now this is for a 22re, who knows what effect it will have on a v6 when removed in terms of starting. Also, the fuel pressure might be controlled by the ECU depending upon the ECU's coolant reading. Not sure though.

The temp sensor is not that expensive in the event that mine does not match up to the v6.
 
Just saw your posting. What sensors are now in question. The coolant temp sensor should be right under/near the throttle body. Where is this other sensor you are talking about?
 
Jukelemon said:
Just saw your posting. What sensors are now in question. The coolant temp sensor should be right under/near the throttle body. Where is this other sensor you are talking about?
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The ECT (for EFI) sensor is 100% broke so no question about replacing that. Picking that up at the stealership this afternoon and will probably put it in shortly afterword. The other sensor was just for the gauge in the dash which is working fine and I actually don't care much about.
 
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