Smallport 4AGE problems

[REN69]

I'm having problems trying to get my smallport to pass emissions, it passed everything with flying colors except that at load (40km/h) the HC (Hydro Carbons??) reading shoots up to 113 (pass is 60 ) Cat was replaced, but O2 sensor and EGR valve are still intact.

We pulled 3 codes from the computer that have nothing to do with emissions (12, 43 and 44 I believe) the only thing these codes could have in common is a bad ground. So we reset the computer and I drove the car around for a day to see if it would pull more codes, yesterday we pulled code 41 from the computer (TPS sensor) the tech still thinks that it could have something to do with bad grounds so he cleaned the grounds located on the manifold (only ones we could find) to see if it will pull more codes. We reset the computer again and I gotta go back tonight to see if more codes are pulled.

My question for the wiring gurus (Dr Tweak, kpsxtyone, etc) where do all grounds for the ECU contact the body of the car or where do they ground at? The tech is trying to find where E1 and E2 from the ECU meet and ground to the body, he also mentioned E8. Like I said, we cleaned the connector to a nice wad of brown (ground wires according to his Toyota book) that meet on the throttle body/intake manifold as we could not find anymore.

Help, pics, donations are appreciated.

[kpsxtyone]

Dude,

give this a try.. get all the jumper cable you can get and start grounding the motor directly to the battery.. use the red leads to get as much ground as you can.. now for the ECU you will have to remove the centre console for this.. check out club4ag for the pin out for E1 and E2. its usuall the brown wire with black dots ( not stripe ) there should be like 2 of them at one side of the 3 connectors... splice it and put a ground directly to the metal part.. give that a try

oh yeah the ground for this should be close to the waterline its like 4 brown wired connecting grounded to one bold..

see if that helps

thanks,
Ryan

[REN69]

Nice, I'll give this a try. I think we did find the 4 brown wires connected to the intake manifold area, just behind the fuel rail. I wish I had a camera with me so I could take a pic, but I'm sure that was the right ground wires on the bolt.

[toyotaspeed90]

the grounds for the ecu is where you found them..... on the manifold....

however, that isn't the only ground..... just because the ecu wires are grounded well doesn't mean the engine is.....

there should also be a ground leading from the battery to the engine somewhere (and also to the body).... in most 4a fwd/mr2 cars the ground from the battery goes to the bolt that holds down the thermostat housing on the transmission.

there is also a ground on the passenger side that leads from the strut tower to the head (where the back engine hook is)... it should have a black connector where the ground pulls apart there..... those grounds are easily corroded and can cause problems.....

i would recommend replacing the passenger ground with a similarly sized wire, and replacing the ground terminal and sending extra grounds to the chasis and engine.... having extra grounds won't hurt and they aren't very expensive


***edit***
you should probably also look into the TPS code..... figure out exactly what is wrong with the tps..... the TPS on toyota's is a little different than other cars... most cars are a 3 wire tps that just has a variable reading (this is for 4 wire toyota tps's... 3 wires are different beasts all together)..... the 4th wire is actually to tell the engine when the throttle is at idle (it's an idle switch).... if the tps is failing and either reading correctly when open or not turning off the idle switch... then that will definately affect your emissions!

[REN69]

Car passed yesterday guys, after cleaning the grounds on the manifold the ECU stopped getting codes, the tech did a couple of test runs and it turned out to be EGR valve problems, the EGR valve seems to be getting too much air recirculation in, most likely due to a fouled EGR amplifier.

I will look into the TPS switch also as it seems even after hot, the car will raise the idle up to 1100rpm after driving, then it keeps it at 800 when sitting still.

So basically now I have 2 more years to drive this car too bad I'll have to etest one more time before it turns 20yrs old.