Exhaust Popping On Overrun.

[rebuilder86]

Hey altezza

Is 120 shit compression? this is not a race engine :P

Of course it doesnt diesel on, thats not why I installed the solenoid, I installed the solenoid and switch purely for the purpose of disabling the idle circuit on overrun. Not sure why our telling me to not run the solenoid circuit.

I just today drove across the island to the city, and sure as hell, when i get to a downhill , I press the idle fuel cut off switch that I created, the result is a nice quite smooth ride down the hill with nota single pop. altho its pretty annoying holding in a momentary button for a 3 minute downhill run haha.

SO in short, its definitely fuel coming through the idle circuit on overrun.

[altezzaclub]

Haha! 120 is certainly not good, a stock motor starts at about 170psi and wears away to maybe 110 before it get new rings/rebored. Why are the pistons dished??

 

The dieseling is why Toyota installed the solenoid on the KE70, but if you have an earlier model it wouldn't have one. The car doesn't need it for that problem, but its interesting that having it is solving a problem Toyota never thought about!

 

You need a tacho sensitive switch like fuel injection uses. That way you have a vac switch to kill the solenoid on over-run, then the solenoid comes back on when the revs drop to 1000rpm as the tacho switch activates the solenoid again. When you drive away again the tacho switch turns off and the vac switch turns on.

 

Here's a starting point-

 

http://www.autospeed.com/cms/article.html?&title=Simple-DIY-Rev-Switch&A=0798

[rebuilder86]

Nah that wont work, if it opens up just because its down at 1000 rpm it could be opening when i am flooring it from slow walking pace in 2nd.

 

This is not a KE anything, its a stainlesss steel flindstones mobile. I came to rollaclub because all these stainless steel jeepneys are fitted with surplus ex corolla engines (4k) that were shipped here after the war when the filipinos realised they wanted jeeps like the Amerikanos!

 

 

No idea why pistons are dished. Most likely because the engine was rebuilt by a stupid filipino who beleives it was better. These people really are the least inteligent race on earth. Intelect is missing from their culture. Probably the wrong head for the dished pistons too.

Edited February 26, 2016 by rebuilder86

[Banjo]

Toyoat Corolla 4KU engines have dished pistons. i know, I've got one in my car at present.

[rebuilder86]

Yeh i think ive come to the conclusion that this is a 4ku and not just a mix n match of parts. Just found some photos of the rebuild and noticed the head face comes to a point between the valves just as seen on google image search of dish piston heads

[rebuilder86]

so over the last few days ive learnt a few things:

1. A compression compression test doesn't indicate anywhere near the correct figures until after about 10 seconds of cranking over, it builds up a few PSI at a time.

so over the years I've probably rebuilt many motors that i haven't really needed to haha....

 

After doing the test properly, I can now say I have 150 PSI, see pic.

 

2. Unscrewing the idle pickup tube and slow jet assembly a little bit to compensate for an idle fuel supply problem is making the issue worse, as it is creating space for fuel to get through the thread when under high vacuum scenarios. With the jet assembly screwed in tight, the issue is still there but a little less prominent, but then there is no chance of a smooth idle.

So now I'm suspecting an internal carburettor vacuum leak which is forcing me to open the idle fuel circuit up beyond its designed capacity to get idle, and therefore is letting through so much fuel at high vacuum that the fuel is vaporizing at the outlet and then again at the exhaust valves to a nice combustible mixture.

 

 

Therefore, in an effort to go back and address the idle issue, I have checked and tested the hot idle compensator seal, which lets is supposed to let air in through the bottom of the secondary venturi when hot, that is sealed nice and tight so can't be the cause of the lack of idle at cold. Ill give that a tick.

The Idle air bleeds are all standard non-adjustable bleeds and I can't see them being incorrectly designed, so I'm goign to give that a tick.

I've also checked the sealing faces of the power piston in the fuel cover, it seems pretty damn good also, so I give that a tick.

Now, the secondary throttle plate, this seems like a pretty good place to let unwanted air into the plenum. So I thought why don't I block the secondary venturi off with some duct tape over the inlet. TADAAA, Engine wouldn't start, wouldn't idle, blew lots of smoke and wouldn't run. alarm bells ringing, it shoudl only be idling and running on the primary side so why did the duct tap affect it.

So I took the carby off, and had a look. Blew into it and couldn't blow any air, and it looks like the plate is original untouched and is sealing very well, but then i notice just how large a hole the hot air compensator outlet is.

So I drew my attention back to the hot air idle compensator. Took the damn thing out of the carb, jammed sum rubber into the outlet in place of the bimetallic spring valve assembly, opened the idle speed screw a fraction, put the idle mix screw back to stock, put it all back together, started it, and what do you know, an idle at a mixture setting of 2 turns. This is the first time I have successfully had an idle at factory settings.

Will be interesting to see if I need the hot idle compensator. I don't care if she runs a bit rich when hot, that is better than throwing air down the wrong venturi and having the idle fuel circuit just throwing in massive non-burnable droplets of fuel to get the right mixture!!!

 

STILL BANGS AND POPS ON DECELERATION THO!

Edited February 28, 2016 by rebuilder86

[rebuilder86]

And ill be damned!!