b16a misfiring

[rage_against]

so, ive got a da9 with a b16a, been reliable but its developed a problem i cannot fix.

its misfiring under load at mainly lower rpm mainly because it doesnt want to go over 3k it will misfire and shudder and get to the point of almost stalling.
now this only happens when the car is warm or at operating temperature when its cold the car is fine and will rev to whatever.

whats been done.

been to 2 mechanics. (that i have used before)
new plugs/leads
cleaned throttle body
new fuel filter
new o2 sensor
checked fuel pump and regulator both fine
changed distributer
checked ecu (by mechanic)

any ideas? anything else i should change/check?

thanks a lot.

[curtis265]

Got a CEL? Sounds a bit like the ECU's gone limp

[rage_against]

thats what i thought but when the ecu got checked we got told it was ok. and no CEL.

[stndrd]

Have you checked your coolant temp sensor to make sure it is going from 5V - 0.5V as the engine temperature increases?

[rage_against]

Have you checked your coolant temp sensor to make sure it is going from 5V - 0.5V as the engine temperature increases?

have not checked this. will check this.

[chongy]

Check your injectors
They could be dirty and probably require cleaning
When the engine is cold the ecu pulses the injectors more for the cold start enrichment.
Once warmed up this enrichment stops. This is probably why it only happens when the engine is warmed up.

[rage_against]

thanks for that! something else to tick off

[cbauto]

Any update

[rage_against]

was not injectors, but have not tried the coolant, will be doing that hopefully this weekend.

stndrd with the coolant temp sensor, should it read 5v when the engine is cold then slowly move up to 0.5v once the engine is warm?

thanks guys

[stndrd]

Yes that is correct

[rage_against]

ok so in regards to the coolant sensor the car was in the sun and went from 2.5v to 6v. thats close enough to right considering its in the sun?

[rage_against]

sorry update, it dropped back to 0.6 after being in the shade for some time.

new theory, could it be that theres a bad connection with the coolant temp sensor, so the ecu isnt registering that the car is warm?