Celica Forums General Discussion Engine and Performance Throttle Lag 2000 GTS

Before everyone goes yelling at me to search the forums, I have absolutely scoured every forum possible for the last 3 days in regards to this issue.

I have a 2000 Celica GTS with the 6 speed tranny. It has 240k km. The only aftermarket thing on it is a short ram intake. I have all the vacuum lines done correctly thanks to this forum. I'm trying to track down a stock airbox so I can switch everything back to stock as I've heard that helps, but so far that isn't an option for less than $300. So in the meantime I'm open to options.

When I bought the car it seemed all good cause I wasn't pushing the car and being careful with my new car ya know ... But now that I've started pushing the gas abit I've realized that from idle, if I push the gas hard the engine bogs before the rpms go up. It seems worst when the engine is cold. If it's cold and I punch it, it sounds like it's gonna stall. When it's all warmed up it still bogs but not as bad and the rpms shoot up a second after. Once I'm rolling it's fine. Never had any bogging between gears. Even while revving the engine it only seems to happen when i rev it from idle. Idle is steady at 1400rpm when warming up and 800rpm when warm.

So what's my issue? I've cleaned my MAF sensor and re did all my vacuum lines. Didnt help. Cleaned my throttle body. Made the car run smoother and helped abit but still there. Ive heard fuel filter but I really don't wanna go there... Anything else I can do before I bring it to a shop?

Bogging has to do with air/fuel mixture.

Does the car show any CEL codes?

Check the plugs to see how well they burn.

1. make sure all vacuum lines between the airbox and throttle body are hooked up correctly and no leaks.

2. The MAF may be clean and tested good but may still be bad and gives wrong dats. Swap in a known good DENSO MAF. Other Toyota and Lexus car use the same MAF.

3. The O2 S1 is mixture sensor. If bad it will cause problems.

There is no CEL.

The spark plugs were done fairly recently with iridium plugs so I don't think it's that.

I think the vacuum lines are correct. I know there is a diagram under the hood for them but it's kinda hard to follow. Any chance you have a picture of how they should be? Does plugging that one vacuum line because of the short ram have an effect on this?

What model/year of Toyota or Lexus vehicles have this same MAF sensor? I'd be willing to try that.

I don't think it's my O2 sensor because I don't have a CEL.

Thanks for the reply!

The 1/4 inch black rubber vacuum hoses go from nipples on the air box to those on the throttle body. If one is unplugged or leaky, the engine would bog down or hesitate. Happened to me once; mechanic removed the hoses and forgot to plug one back in. Took me months to figure that one out. Damn.

Whoever installed the short ram should know how a plugged vacuum hose act in the system.

Just remove the airbox and check all nipples. Make sure the they are all connected with hoses.

AFAIK most Toyota and Lexus sedans use the same DENSO MAF. My Celica GTS, with 300K miles, was having a P0171 system too lean. I checked everything, MAF was cleaned and electrically tested good. Tore my hair out but could not find the fault. I swapped in a DENSO MAF from a Lexus GS300. That fixed the code. So MAF may test good but may still malfunction. Sure way to test is to swap in a known-good MAF in another car.

If not the MAF then dirty fuel injectors may not spray enough fuel in quick rev up. You need to use a good scanner to map and monitor fuel trims to see if the fuel injectors are working properly. You may want to spend $100 diagnostics at a Toyota dealer. They can pin point the cause with their fancy scanner, then you can fix whatever issues.