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Hello, Ive been having this problem with my celica that goes something like this:

Usually on colder starts, and also even when running for a while,

If I try to increase the throttle rapidly there is a big lag as if the gas is not combusting.

Usually when i first start the car it bogs, so i have to gradually ease fuel in until it kicks in and starts to run normally.

it seems like the fuel cannot respond as fast as the throttle, i assume it has something to do with fule delivery but it could also be some crap with air flow.

Ive never had a check engine light and i just changed the plugs, i had this problem for a while because it goes away after the car 'warms up'.


please help thanks please
 

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JUST RE ENGINEER IT
98 Prizum
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Get a fuel pressure gage on it, also, if it is a mass air system, look for a loose intake rubber hose, also check the hose for holes, there are lots of things that can cause this, the next 2 your not gonna like though, I have seen the TPS do this and never set a code, also the computer can get whacked out and do the same thing, it simply forgets where the TPS started from when you pushed the gas. What you have is a lean tip in bog, I see that it goes away after it warms up, this is because when cold, the intake needs a big shot of fuel when you hop on the gas real fast, and it sounds like it only happens when the computer is in open loop mode, this is when the computer doent monitor the o2 sensor and just kinda runs on a pre determined program until the engine temp comes up and the o2 warms up, then it goes into closed loop and watches whats going on much more closely and changes the fuel map to compensate for changes or problems the best it can. Change the fuel filter and get some brakeclean and an old toothbrush, leave the motor off for a while and pull the intake hose off the throttle body, where the butterfly valve is, hold it open and spray the crud around the valves edge and the edge of the valve plate itself, and SCRUB:hammer: , leave it set for a while with the valve open and the hose off to dry out good, then reassemble, and go get ya some seafoam at a parts store and put it in the gas tank:D
 

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If anyone is interested I would like to start this thread back up after so long. I have the same problem where my engine seems to have trouble burning fuel. The difference is that it does not go away when the engine warms up. It only really happens (as far as I can tell) under large load at low RPM. I have already gone through the air intake system. I have tested my MAF sensor and it returns proper values and I have cleaned it already so I am sure that my intake is not the problem.

I was considering checking the fuel lines now but I am not sure how to go about that. I want to check the fuel pressure but I don't know what I need to do that. Also, I think I should just change the filter out because I don't know when it was last changed. Any suggestions on things to check in the fuel system?

Also, I haven't checked anything like the injectors or fuel rail. Could these things cause a problem such as refusing the engine fuel?
 
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