4AFE - Frankenmotor up and running STRONG

[oldeskewltoy]

Ok... I have a 1st generation 4AFE from a 1989 All-Trac. The engine was beginning its death rattle so I put together a replacement engine.

Here is what I assembled: 20V shortblock, replacing the 20V pistons with slugs from the "high compression" 4AGZE (8.9 to 1). This combination gave me a very stout bottom end, and a slight bump in the engines compression (9.5 to 1 to about 10 to 1)

To complement the bottom end, I also did a bit of work on the head - http://www.toymods.org.au/forums/tec...p-porting.html

AND I decided to use the 2nd generation(1990-1992) intake manifold to hopefully lower the peak torque rpm



The car is up and running, it idles like a dream(nice and quietly @ about 700rpm), but there is a slight bog/lag I'm experiencing. At any throttle position I get a bit of a lag that goes away once the engine climbs to about 4k rpm. Once she hits 4k she screams up to 6300 very quickly.

I did some prelimenary diag and found a code 51 - A/C or no "IDL" signal from the TPS. I swapped in a good - before use - spare with no change in the engine bog/lag, and the code is no longer there.

Part of the mod to fit the newer type manifold required adapting the EGR from the newer engine to work with the older wiring and plumbing. This was necessary because the older system has a bolt on egr tube, while the newer engine has an integrated EGR tube. The newer system shows 1 extra ECU switch to atmosphere - when the switch is engaged it closes a bypass engaging the EGR. What we did is to use a plug over the bypass port so the newer manifold would mimic the older system.

That pretty much covers the details... anyone's questions I'll be happy to answer.

Can a faluty EGR system, or one that may have been incorrectly connected cause a low speed (under 4k) throttle lag? Would pinching vacuum lines closed be effective in seeing if the system is a problem? Could the EGR system cause a lag/bog, or should I begin looking elsewhere??

Elsewhere - ignition timing is set @ 10 BTDC with the T-E connector in place, where it should be

[MWP]

You did all that work to the engine but are still using the factory ECU?
And why are you running EGR at all?

[oldeskewltoy]

You did all that work to the engine but are still using the factory ECU?
And why are you running EGR at all?

yes.... and in my area there still is emissions testing, so I kept the EGR

[shadowR]

Issue is the tune, not the mechanicals IMHO.

[thechuckster]

temporarily disable the EGR and check the VSVs are not allowing air to the manifold when off. See if bog/lag disappears when EGR disabled.

cam(s) in the right spot?

fwiw: I would have expected the earlier manifold with longer runners to have better torque down low?

[oldeskewltoy]

temporarily disable the EGR and check the VSVs are not allowing air to the manifold when off. See if bog/lag disappears when EGR disabled.

cam(s) in the right spot?

fwiw: I would have expected the earlier manifold with longer runners to have better torque down low?

disabling the EGR is my next step....

There are 4 alingment dots on the 4AF cams(intermesh type) each dot on each cam was correctly aligned. I'm also pretty sure the timing from cams to crank is also correct because the car runs so smoooooothly @ idle

concerning the manifold differences... here is the dyno chart from the same publication

[oldeskewltoy]

Everything is fine... it turned out to be two different things. the first was ignition timing - although I had thought it was set, it must not have been - it was out by over ten degrees. The 2nd item was the EGR modulator had a vacuum leak

[Sam_Q]

so hows the final result? how does it run?

[oldeskewltoy]

so hows the final result? how does it run?

it runs quite well... there is this long hill near me... with the old engine I could pull fairly well up it with 2 people in the car(3rd gear), now she screams up the same hill with 3 people in her. No dyno pulls yet, but there is most definately more power there now.

[PrettyCoolWagon]

Well done OST - been a long time coming...

[oldeskewltoy]

I got the 1st oil change done today. Rechecked the timing and adjusted it a bit more as well. Grunt pulls HARD... very HARD. She pulls so hard that I've hit the rev cut a few times by accident. In fact I'd be willing to bet she'd dust a stock, and maybe even a few modded AE86s...... (I'll let that sink in a bit)

Yes, she is that good right now. The only changes so far are the intake, the 1/2 point bump in compression, and the ported head, the cams are stock, the exhaust is stock still too. The header I bought from Ireland** can't be used until I re-make the downpipe. The All-Trac uses a curved downpipe to avoid interference with the E55(all-trac) gearbox, the downpipe that came with the header is straight - for fwd applications, NOT 4wd.




Comparing the old engine(bottom of pic) to the new engine (top of pic) a few things besides a cleaned up cam cover can be seen.....
1) note the EGR modulator, and the EGR valve are no longer in the valley between cam cover and intake plenum.
2) if your eyes are really good, you'll see the absense of the 5th injector, and if they are superb you'll see the blocked 5th injector line
3) again if your eyes are good you'll see the wiring splice required to fit the IAC - Toyota also changed its location - originally it too was in the intake valley, but they changed it to be on the end of the intake manifold
4) yep... same wires, same cap and rotor, SAME spark plugs too



** - header from Ireland -