bogs when cold

[430hpToy]

so lately my 91 SW20 has been fallin on it's face when i first start it when it's cold. can't figure out what it is.... it only happens when the car has been sitting for more than 8 hours or so. if i let the car warm up for a couple mins it's fine, but if i start it and try to drive away it bogs down then comes back to life.

any ideas?????

[Zz_005_zZ]

I am now having the exact problem... I posted about it in mr2oc and the reply was to check the coolant sensor on the coolant neck, or to check the IAT sensor... here are the exact posts...


my car does not like starting when the engine is cold...turns over alot longer than usual, starts and I give it a little gas, and kinda bogs down under any throttle until the engine is warm... and ideas... BTW I have new plugs wires cap and rotor, so I know this is not the issue... I am thinking fuel pump, or this so called cold start injector??

Check your coolant temp sensor, and the IAT sensor.

The ECU can't set the correct conditions for a cold engine if it doesn't know the engine is cold.

Its NOT your fuel pump.

bill

Quote:
Originally Posted by billwot
Check your coolant temp sensor, and the IAT sensor.

The ECU can't set the correct conditions for a cold engine if it doesn't know the engine is cold.

Its NOT your fuel pump.

bill




OK..... unfortunately, I don't know what, where or how to check these sensors.... help please... I am mechanically inclined, but am not as literate on the issues on mr2's... only had this one for 4 months

You need a multimeter. It's the green sensor on the coolant neck. Depending on the temp, there is a specific resistance range you're shooting for, if outside, replace the sensor.
__________________
aka Boz


hmm
ok 2 things here..... what are the numbers I am shooting for>?? and where is the IAT (guessing intercooler air temperature sensor) located, and what are the numbers I look forward to seeing on the multimeter??

Quote:
Originally Posted by Zz_005_zZ
OK..... unfortunately, I don't know what, where or how to check these sensors.... help please... I am mechanically inclined, but am not as literate on the issues on mr2's... only had this one for 4 months



Fortuntely, all your answers are here:

http://www.mr2-tech.com/bgb.htm

(IAT is intake air temp sensor-measures ambient air temp)

bill

[430hpToy]

hmmm.... mine starts fine and idles fine. i can even give it gas in neutral with no problems right after initial start up. as long as i let the car warm up for at least 30 seconds before putting it in gear and driving away it's fine. it's not a huge worry of mine, but just being curious as to what it might be.

[tHa kNiGHt FaLL]

sounds like a bad sensor slowing your ECU from going into closed loop.

usually a coolant temp sensor...

a scanner would be nice. cause almost all ECUs are required to go into closed loop anywhere form 7-10 seconds. its an emission deal for the requirement. the temp sensor may not even be bad. just slow due to more resistance due to cold temps

[climax_mr2]

I thought it's normal for the motor to bog when you try to drive it away when its still cold. And that's why people almost always warms up their car a minute or two before driving away.. =\

[tHa kNiGHt FaLL]

Originally Posted by climax_mr2

I thought it's normal for the motor to bog when you try to drive it away when its still cold. And that's why people almost always warms up their car a minute or two before driving away.. =\

yea mine does it... my rx7 used to do it.

its just cause they are old cars. i consider it a good thing. it keeps me from trying to doing anything dangerous to the motor when its cold.