Car Pulls Hard sometimes, other times not

[bmw5002]

My 91 rolla has about 190,000 miles on it but everything is still in very good shape. It is a 5 speed. THing is, when I first start the car cold (its wintertime) and drive, in first and second gear, the car drives normally until i get about half throttle. Then it hesitates for about 2-3 seconds and then it PULLS LIKE A BITCH. lol im sure theres no turbo or anything, its a stock 4a-fe. Its really fun. But then once the motor is warmed up, it no longer pulls like it has a turbo. Its just like a linear torque curve. What can i do to make my rolla pull like a beotch all the time?

[fredk]

coil sounds like its getting ready to pack it in

[bmw5002]

Explain? Ignition coil? Does the spark quality really matter to make so much of a power difference? And would that just be the hotness of the spark or does it have to do with timing? And why would it only pull hard when cold?

[fredk]

the f heads need a killer spark to stay running, the coil is very common problem

[toyotaspeed90]

^^^ not quite..... but the coil is internal... it's epoxy filled.... and if you live in an area that gets a lot of moisture (or in an area that usually doesn't and lately you have been getting a lot... ie, rain) then you can get moisture in the epoxy coil and it will cause a misfire... if this is the case, i have 2 spare (one with less than 2,000 miles on it) early 4afe coils

however, your problem doesn't sound like a coil issue..... your explanation leads me to think that your injectors are clogged or getting clogged...... when the car is cold it has the "cold start injector" which sprays excess amounts of fuel until the car warms up (why the idle stays higher until it warms up... kind of)... so when the engine warms up your CSI is turning off and your clogged injectors aren't doing the trick.

i would first just try some cleaner in the tank.... i *doubt* it will help much.... if it does, great, if it doesn't, oh well it was a $3 attempt, no harm no foul.... after that i would suggest removing the injectors and take them somewhere to be cleaned (many diesel shops can do this) and blueprinted. If you don't want downtime on your car email me as i have a spare set of 4afe injectors as well (toyotaspeed90@hotmail.com)

[bmw5002]

Do you think if i was to test the a/f ratio coming out the pipe i would see a lean condition when the car was warm with the clogged injectors? how much would you sell me those injectors for?

[fredk]

seafoam?

[toyotaspeed90]

well i'm sure mine would need cleaning as well.... they too have like 130,000 on them.....

[bmw5002]

are they expensive to buy new?

[toyotaspeed90]

generally rebuilt ones cost around $50+ for most cars (seen some upwards of $400 a piece rebuilt)

[tireboy]

hhhmmm seems kinda strange but my 86 nova does the same thing when cold .. it has a 4a motor n carb 5- speed and it is violent when cold like a super charger .. but when warms up it dissapears ???? coil???? give me a shout let me know ... its been puzzling me for a while now...trhanks ppl !!!!

[89rolla]

lol...mine is sweet when its cold..and i have a 4AF...once it gets its juice pumped into it and stops jerking like its gonna stall...its awsome..i usually HOOLLDDER down the street to get er going then when its warmed up..it sucks like its suppose to..lol

[neophile_17]

I'm gonna take a guess and say that when everything is cold you're taking advantage of denser air (Approximately every 5 degrees C drop in intake air temperature will increase power about 1 percent (http://www.canadiandriver.com/articles/jk/030827.htm))
As your engine (and associated intake pieces warm up) then your performance returns to "normal". I've even heard of some GM cars that warmed the intake air in cold weather in order to keep the throttle from freezing open. Anyways just an idea.

~neophile_17