93 5S-FE issue

[liampire]

Hi i'm having some issues with my celica and need some help.

1. My first o2 sensor in the engine bay, when the car was purchased, the plug has melted on the exhaust and I am unsure where it goes to. I want to just solder the wires together. My o2 sensor only has one wire comijng from it. Where would this originally go?

2. Ran a dignostic, got code 25 "Air-fuel ratio lean malfunction". I'm assuming this is due to the O2 sensor not being plugged in. When driving the car shudders sometimes, not always.

3. Refer to picture . What is this? This is an image I took from another post. The one on my car has been effected by heat and the little outlets are broken. There are no vacuum lines hanging loose but I have noticed on the plenum there are two sections that have been blanked off. Where are the vacuum lines meant to come from?

4. Car has a high/irregular idle. I've looked on the net and i'm thinking cleaning out the throttle body/IAC will sort this out? Any ideas?

If someone could post up some useful engine bay pics to help me out here it would be much appreciated.

Thanks in advance.

Liampire.

[Keisari]

2. A bad O2 sensor circuit will throw a code 25, yes.

3. That would be the bimetallic vacuum switching valve (BVSV). It's part of the fuel evaporation anti-pollution system, though I don't fully understand its function. One end goes into the charcoal canister, the other *I think* goes into one of the three vacuum ports on the top of the throttle body near the EGR valve - probably the one missing a vacuum hose.

4. Many things can cause high and irregular idling. Cleaning the TB is a good place to start (I'd do this after sorting out the vacuum hose issues though). Also check the ignition timing. If it is significantly out the engine can idle high and, if too far out, can make it run poorly. The next thing to check is the ignition components. Take the plugs out and make sure the tips are in good order, look for white corrosion on the spark plug lead ends on the distributor cap side (also take the cap off and look for corrosion, cracking and oil leaks there and on the rotor button. When you put it back together, spray the outside of the cap with WD40 to exclude water and inhibit further corrsion). Make sure the battery terminals are happy.

Failing this and the dozen other things it could be, there's always the idle adjustment screw on the top of the throttle body. It can only adjust the idle so far, of course.

Good luck, hope some of that was useful.

[liampire]

*UPDATE*

The car doesn't have a bad idle, it idles fine but when driving the car up a hill the car rev fine but then when the revs get to like 5000rpm it will just temporarily shut out for a second. Pretty sure you can hear like a click noise... This also happens when going over speed bumps quickly or really rough roads. Best way I can describe this is when I owned a toyota soarer and hit my 180km speed limit the car would just buck a little, it is also the same feeling like when you put a boost controller on a turbo motor and the ECU cuts the fuel when the boost runs too high. Sometimes the car will also just turn off when driving normally. Anyone follow me??

So here is what I have done so far, but has not made any difference:

I went to the wreckers and have now swapped out the following parts to see if there are any changes:

- O2 Sensor

- MAP Sensor

- Replaced my damaged BVSV (green thing pictured in my first post) and yeah it is part of the EGR system, it starts operating the EGR when the engine has reacher operating temp. Also found some vacuum lines that had been disconnected from the charcoal canister and EGR system, they were blocked off with small bolts so no vacuum leak. I connected these but I don't think I have done it correctly. If someone could post a good picture of their engine bay with close ups of the EGR, BVSV and charcoal canister that shows vacuum routing that would be great!

I checked all the other vacuum lines for leaks, no problems.

I checked the ignition timing, this read as 20 degrees, isn't standard 15?

I haven't dismantled the throttle body and IACV yet as the idle is fine, the problem is when the car is running.

I have noticed that the front engine mount is worn out. Could this throw a sensor out? As my problems happens at high revs or going over bumpy roads could the motor be vibrating too much to cause a high knock sensor reading and the ECU shuts the motor off?

Another thought was the catalytic convertor could be clogged?

Any other ideas or ppl have that experienced similar issues with their 5S-FE motors???

[Keisari]

I haven't experienced that 5000rpm wall, but I do experience one between 2500 to 3000 that I have yet to sort out. You say the timing is at 20 degrees - the stock timing is 10. I wonder whether that ticking at 5000rpm you described is engine knock and timing retardation.

I will try to take the photos you asked for tomorrow morning.

[Keisari]

Hey mate, sorry for the lateness, work has been a real killer this week.

Anyway, I have taken the photos. They show the routing of most of the vacuum lines, however some run behind the engine. To make it a little easier, I've also uploaded a some vacuum routing schematics from the BGB.

Good luck!

Engine shot

EGR hoses

EGR hoses 2

EGR hoses 3

B-VSV

B-VSV (aka. TVV) schematic

EGR, VSV, B-VSV, charcoal canister schematic