Troubleshooting high speed hesitation in 2000 Corolla

[crypticlineage]

I posted a similar thread a few days ago but several things have popped up since then, hence this new thread...

2000 corolla manufactured 9/99
Engine replaced at miles 117500
Donor engine came from 2003 corolla manufactured in 2002

Problem: Hesitation above 65MPH, cannot accelerate past that point.

Checklist:

1. Spark plugs: Checked. OK
2. Coils: Visually inspected for any burnouts, discoloration, OK
3. Exclusively using 93 octane BP gas now
4. Added fuel injection cleaner at the last fill up.
5. Engine trouble codes: CEL is OFF, No codes set, not even pending.

Possibilities?..

1. ECM mismatch: The donor engine is a 2003 (02), but the ECM is still from 2000 (99). Could this be causing the hesitation? If I get the new ECM, will that cause problems with my 3 speed automatic tranny because if I am not wrong, 2003 onwards Corollas have upgraded to a minimum of 4 speed transmission.

2. Fuel System clogged: This is possible and may require fuel filter or pump replacement, but I would like to save that for later because of the difficulty of the job.

Any other thoughts?

I am considering getting a factory repair manual for my rolla and wondering if its would be more useful to subscribe to some sort of online manual system for cars rather than buying the printed manual. The manual is over a hundred bucks.

[Dr Tweak]

Likely it's the ECU mismatch. You should swap over the wiring harness from the '00 engine and you would probably be fine.

-Doc

[crypticlineage]

Dr. Tweak: Thanks for a quick reply. Do you mean I should replace the ECM to a 2003 and plug in the existing wiring harness into the new ECM?

Edit:

Okay, I think I misunderstood you. You meant keep the existing ECU, just use the harness from the old engine onto the new engine. Thats exactly how it is right now. The swap mechanic kept the wiring harness from the old engine and used it on the new one.

So then you think the ECU may not be a problem? Any ideas on what I could do to solve this problem?

Thanks.

[crypticlineage]

One more thought:

9th generation corollas have 4 speed automatic transmission by default
My car (8th generation) has 3 speed automatic transmission

In 9th gen, the engine engages 4th gear around 65MPH which is exactly where I am experiencing the hesitation. It seems likely that the engine is trying to find next gear to switch into, but there is none, hence the hesitation.

However, the ECM is still from 8th gen. Who dictates the gear shifting: ECM or the engine itself? My ECM is set up for 3 speed transmission, would it still want to switch to 4th gear if the engine is a 9th gen? You know what I mean?

Also, the hesitation can be experienced even when the car is parked and engine is revved using the throttle cable. Are the gears actually shifting when it is done, and they're just not driving the wheels?

I wish I could solve the mystery soon.

[DoubleEdgedWomb]

I'm guessing the engine is not getting enough fuel/air/spark (pick one) at high revs. When the car is not moving, these are the only things effecting it. The transmission does nothing (though I hope you're not revving the engine in park, that could be bad).

[crypticlineage]

DoubleEdgedWomb: Thanks for the input. You're right, I keep on forgetting about this important part. I need to troubleshoot air/fuel/spark problems if any first.

I think I will start with Plugs:

1. Install new plugs, see if that makes a difference
2. Clean Throttle body
3. Clean MAF sensor
4. Check Fuel injectors for deposits (anyone got pics of dirty injectors to compare to?)
5. Lastly, replace fuel filters

Please add to the list if I have missed something important.

[ghost_ryder35]

if its not the ECU then I'm willing to bet it has to do with air (damn MAF sensors). I come from Nissan Sentras (2002-2005) I went through 4 MAF's (and at $200 a throw thats not cheap) in 30,xxx miles

[REN69]

Could be the ECU, I believe the 99 models still had no VVTi and after 99 the 1ZZFE came out with the VVTi so the mechanism is probably not functioning properly due to the wrong ECU.