Electrical niggles. NZ AE82 GT Corolla

[Al]

Recently I have had a shit load of work done to the Corolla. Of that work was a new starter motor, battery, temp sender for the dash, all the maintenance pieces and so on.

A few niggles remain. It still doesn't like starting sometimes, the starter cranks along well but it won't fire easily unless I give it a bit of gas. I haven't had to start any other EFI car with my foot slightly on the gas. I have been told this could be a map sensor wiring issue? The wiring going into the map sensor looks intact. Idle is a little rough but doesn't hunt up and down or idle high. Sits at 1000rpm or so.

When giving it a few revs, like a quick second gear run up to redline, the temp needle jumps around sometimes, like straight up to hot then back to cold, then back to normal position.

Tonight it was wet out so I put on the wipers, which for some reason were incredibly slow, even on the fast setting, they were crawling up and down the windscreen. The stereo turned off. So I pull over, the stereo comes back on, and the wipers are back to normal.

What could my electrical gremlins be?

[jondee86]

For the starting and idle...
Clean the throttlebody to make sure there is no buildup of crud around the
butterfly, then check the TPS setting to make sure the IDL switch is changing
state on fully closed throttle.

For the voltage drop...
Check your grounds. Basically loosen off any ground connection you find, give
it a twist left and right to disturb any corrosion between the contact surfaces,
and tighten. Make sure your battery lugs are clean and tight.

Cheers... jondee86

[Stu-]

As above - good advice there.

I wonder if the fuel pump is a bit slow to build pressure for the initial start? I had this with a customers AE82 Liftback, it was the combo of a clogged filter and a very sad pump. Swapped them out and it was back to being a 1 turn and it starts deal.

Could also check the cold start injector is working (only works when its cranking and cold) but to be honest I usually rip that out for conversions and they still start perfectly

[UZZ30]

Could be your ECU capacitors. They typically control injectors so if they're stuffed (which 95% are after 15-20 years) its going to give you certain issues.

I've been repairing a lot of Soarer parts and other UZ / JZ engine ECUs lately with good results.

If you're electrical savy, open the ECU up and take a gander, if not I could look at this for ya.

[Al]

Great thanks for all the suggestions.

The throttle body, TPS, IACV etc should have been all cleaned and checked when I got the big service done as I requested them to be sorted as the idle was really low and choppy and it would cut out as you clutched in at intersections.

The car did have a leaking heater core for some time before I realised it was leaking, I wonder if some coolant found it's way into the ECU?

[sergei]

Those cars have the ECU with relatively manageable board, so it will easy to spot water damage.
When caps gave up in my AE101, one of the smaller electrolytic capacitors (~10uF?) leaked out and shorted VVT transistor base to some other signal trace, this caused all sort of weird issues, starting, lumpy idle, random stalling. The VVT was turning on intermittently.

What I did I replaced all the electrolytic capacitors (Aluminium cans in black plastic wrapper) in that ECU, with success.
Old cars are relatively easy to work with: through-hole components, and at most double sided PCB.

This capacitor problem is plague from early `90 to early `00, especially with Nichicon branded caps. It affects anything from TV to Network switches (I replaced caps in some old "dead" 2900 Ciscos with success).

BTW: Nichicon is a good brand for caps (unless they were made >10 years ago ).

[Al]

Ok ran the diagnostic tonight.

I have code 10 and 11.

10 Starter signal. No STA signal to ECU when engine is running over 800rpm.

Main relay circuit.
IG switch circuit (starter).
IG switch.
ECU.
The vehicle has been push-started.

11 Switch signal. Air conditioning switch on or IDL points in the throttle position sensor off. Not registered in memory.
Air conditioning switch circuit.
Air conditioning switch.
Throttle position sensor.
ECU.

Will investigate further.