Strange power problem 4AFE, help! Options

[onnaj]

Hi,

I've owned a 1999 Celica 6th gen (with a 20V Blacktop) before but unfortunately had to sell it for financial reasons :-(. Now i own a 1999 Corolla which has the 4AFE engine but basically is the same as the 7AFE engine, so hope you guys can help me out here cause i'm almost at the end of my ideas and it's getting really frustrating:-(

We noticed a lack of performance while driving in the Ardennes and later in Normandie. It didn't hesitate but was really really sluggigh (even though we know this isn't a fast car ;-)). After the ardennes holiday but before the Normandie holiday i've changed the spark plugs, rotor and cap and put the injectors in an ultrasonic bath with special additives in it. That didn't help :-( During our holiday in Normandie we noticed the fuel consumption was much too high.
When i got home, the first thing i've checked was the engine timing. I discovered it was set at 20 BTDC instead of 10 BTDC!! Now i've got it i though, but after setting it to the correct setting the car really ran like crap. Some little backfires in the intake, a bit fuel smell and soooo sluggish that 0-60 took 15 sec instead of 10!!

Then we checked base engine timing with the marks on the camshafts and the crankshaft pulley but it was spot on. Then we did the next things in random order:
1) Hooked up a vacuum gauge and it says about 18 Inhg at idle but the gauge goes up and down fast by about 1-1,5 Inhg (check the video: https://www.youtube.com/watch?v=v8w6S_IMrd4). So while the vacuum was high a vacuum leak wasn't suspected. When i read on internet it was more like a stuck valve. But that hardly ever happens on a 4AFE and especially not when having only 85000 on the tacho. Thas took us to the next point...
2) We've checked the compression numbers and they are 210 PSI (+- 2 PSI or so) on all cylinders. We also did the test before we hooked up the vacuum gauge and it was the same. So a stick valve isnt suspect to me.
3) but to be 100% sure i've checked valve clearances and they were also spot on!
4) I've changed the plug wires even though the resistance was perfect...but no changes
5) measured IAT and it was spot on with 3kOhm
6) checked O2 through connecting TE1 and E1 and measure how much the voltage changes in 10 second between VF1 en E1. That was more then 15 times, so also perfect!
7) injector resistance was 13.3 - 13.5 Ohm on all, so also okay. Even listened with a screwdriver and they all sound te same.
8) IIAL: 1) measured G= en G- resistance 226 Ohm 2) NE+ and NE1 resistance 452 Ohm 3) primaire coil resistance 1,5 ohm 4) secundairy coil resisantce 11.81 Kohm. So all spot on when comparing it with the manual. Only thing i don't know how to do is to measure the coil pick up. But regarding the resistance is all good i don't suspect it
9) Tested the TPS with a feeler gauge and it was also spot on
10) applied vacuum to the map sensor and measured the voltage output and it's 100% perfect
11) Coolant temp sensor resistance was 2.85 Kohm, so also exactly what the manual says
12) Tested fuel presssure with +b and FP connected, with running engine with FRP vacuum hose disconnected and with vacuum hose connected. Values are all within spec. When pinch the line the pressure goes up, so that's also perfect.
13) ....

Maybe we did even more but this is what we've done for sure. Only thing i could think of now is a defective ECU or Coil, but that last one i don't suspect as much. I thought about a clogged cat, but then vacuum should drop and with only 130k it's unlikely.

Hope someone has the golden tip for me, cause this is so frustrating. It's our daily driver. :-(
Tomorrow i'm going to unscrew the ECU to read the pinout, so i can measure the voltages directly at the ECU.

This post has been edited by onnaj: Sep 28, 2017 - 3:48 AM

[Bitter]

Have you checked mechanical timing? Often when it runs better with over advanced or over retarded ignition timing it's a clue that the mechanical timing is off and the ignition timing is used to mask the true cause and make it run 'good enough'. My bet is that the timing belt is off a tooth, if that's the case then replace it with all new components (idler, tensioner, pulleys, water pump, water pump hose, thermostat, hoses, etc) and you should have a well running reliable car with quick heat for the winter.