After 4age Conversion It's Playing Games

[TRD4age]

Ever since I changed my engine I've had nothing but little troubbles, to make things easy before I finished I

(From a 4ac to a 4age)

-Changed the fuel filter
-Replaced all fuses and relays
-Irridium plugs and custom 8.8mm top gun leads
-Air intake
-All the vacume lines
-Checked the map and the ecu

But still at the end of the day it likes to chew through $50 of fuel for only 200kms ($300 a fortnight). Search/hunt at idle, and now with the newer air intake since the other one it starts to break down when you want to go for some big speed with the hammer down, but also the two wires off the sensor at the air box (that conect to the throttle body and after the air filter) have broken

Can any one help with me sort this expensive problem
MATE WITH STANDARD TWIN CAM 500kms per tank

[takai]

Check the O2 sensor, they can cause excessive fuel consumption.

[TRD4age]

Silly question but where is it. Is that the one on the air box

[NeoNasty]

In the exhaust manifold. Dont check that its there.. Check that it works.

Buy the twincam16 manual. Read the section on engines.

Edit: I think I have the AE92 workshop manual if you want that. $30 plus postage.

[TRD4age]

To scared to cut the casing back tofind out how many wires and what colours to replace.
My book covers 1985 thru to 1992 and nearly every factory motor
car is ae82 (86 model) motor now in it is from 87 model

[WHITCHY]

Have you checked your fuel pressure? When I converted my AE86 from 4ac to 4age somehow the return line to the fuel tank got blocked or clamped, fuel pressure was like 75psi at idle! when it should be like 25 or 40 psi i cant exactly remember. so find a fuel pressure tester or send it in to your local mechanic and ask them to test fuel pressure for ya! That should help with the fuel consumption issues if it is blocked, i had the exact same problem with mine 200kms to a full tank.
And as for the hunting at idle, jump on the old toymods site and download the 4age service manual or buy one from someone and check that adjustment of your TPS, my engine used to hunt at idle too then I had a mate adjust the TPS to the factory specs and it was all good!
Keep the thread updated and let us know how the tests go.
Good Luck!
Cheers.
-Whitchy-

[roadsailing]

i found that fixing the air temp sensor gave me better fuel consumption, i have never run an O2 sensor and generally 1verage no worse than 10 litres per hundred, city and highway driving.

fix your hunting idle, i'd say it means you have vacuum leaks, disconnect your cold start injector (just the electrical plug) too

[c2888]

water temp sensor also has a massive effect on fuel usage.
If the ecu senses that it's cold, either it is actually cold, or it's just broken sensor, it will run in the cold part of the mapping, which is richrich
Check your waterworks to see the engine is actually getting to full temp.
Then check your sensor to see if its giving the right value

Dan

[TRD4age]

Thanks WHITCHY I'll get that checked on the weekend(also need check the tank lines cos changed those too)
c2888 which temp sender I have two one near the dipstick(guage) and one beside pot 4 on the headwith green plug