choppy acceleration
- Thread starter imtjm
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Mr.W said:
What model BMW do you have? How many miles/km?
We must know these things to be able to help you
We must know these things to be able to help you
the a/c works great (except when idling when it's hot out, which I've heard can be fixed by replacing the fan clutch), i've replaced fuel pump, fuel filter, fuel pressure regulator, AFM, ACV, ACU, recently cleaned out fuel injectors replacing wires and spark plugs, distr cap
like i said, it only happens when i have the a/c turned on. i know i probably need to replace the fan clutch, since at idle in hot temp, the temp guage is above normal and the cold air doesn't flow sometimes until i hit the accelerator, just wondering if the fan clutch has anything to do with the jerky and lagging acceleration. or something else. thanks
I don't think the fan clutch has anything to do with non linear acceleration. My fan clutch failed recently and it just stopped engaging fully which led to overheating but there was no difference in acceleration, at least none that I could feel. The only thing the fan clutch drives is the fan so I don't think a small fan would do that much harm, plus, the fan clutch operates independantly from the A/C, but it does help out. As wierd as it sounds, you might have a low level of freon in the system. Try turning the A/C on full blast, open the hood and look at the A/C compressor, if it engages and disengages often then add freon. Oh and also, try doing this, drive around with the A/C off, see if you get normal acceleration, then turn on the A/C and about 30 seconds after that see if you experience the chopiness in acceleration. If you do, it certainly can't be the fan clutch and my bet would be on either low freon level or the compressor. Hope I helped with at least something. Good luck and enjoy that lovely 3 series. ![[:)]](/images/smilies/smile.png "Smile [:)]")
i know it's not the freon b/c i don't have freon, it's been converted (that was a joke). actually, i had the system recharged when i replaced the compressor and had it rechecked and it's good to go. i replaced the ICV already, so i'm not sure why i'm getting lag. it only happens when the a/c is on. i have great acceleration when the a/c is not on.
when i accelerate, the air is noticably stronger, and then whn the acceleration kicks in it kicks in, it's just the stuttery and lagging start that is frustrating. any other thoughts? thx
when i accelerate, the air is noticably stronger, and then whn the acceleration kicks in it kicks in, it's just the stuttery and lagging start that is frustrating. any other thoughts? thx
Well, glad its not the freon or the compressor because those can be costly. Oh and eric said ICU -Idle Control Unit not ICV - Idle Control Valve. Just clearing it out.
If you want same acceleration as if the A/C is off and still want cold air, then drive in winter time, heh, just kidding. When you want that normal acceleration, make the whole A/C/Heater system cool down the air thats already in the car and not outside air and after that just shut the A/C off. The air will still be the same temperature but the A/C will be off and there you go. Mine goes for hours like that. When you forget your money at home and are running low on gas during a hot summer day you figure out a lot of different tricks, hehehe.
If you want same acceleration as if the A/C is off and still want cold air, then drive in winter time, heh, just kidding. When you want that normal acceleration, make the whole A/C/Heater system cool down the air thats already in the car and not outside air and after that just shut the A/C off. The air will still be the same temperature but the A/C will be off and there you go. Mine goes for hours like that. When you forget your money at home and are running low on gas during a hot summer day you figure out a lot of different tricks, hehehe.
i just replaced all the fuel lines and just about everything in the fuel line except he fuel line dampeners,so i don't believe it's the fuel line. it only happens when the a/c is on. i just don't know what it could be. i guess i'll replace the ECU since that is the only thing i haven't changed, unless someone can think of something else. thx
i never really read all the posts, cuz i didn't really feel like it but i do know that both the Idle Control module and Enging Control module have inputs into them that let them both know when the ai conditioning is on..... have no idea how to diagnose this or waht.. but it might help you.
also if your freon is low... and the pump has to work more often due to low freon.. then your pump is going ot start and disengage frequently casuing an intermittent loss of power once and a while.
also if your freon is low... and the pump has to work more often due to low freon.. then your pump is going ot start and disengage frequently casuing an intermittent loss of power once and a while.
my engine does the exact opposite when the a/c is turned on, it drops about 100rpms. thought that was normal since the a/c puts an extra strain on the engine. but maybe not. so if my engine is decreasing rpm rather than increasing rpm, then i guess i have another problem that i do not know how to fix. suggestions?
anyways, i'll diagnose the ICU and ECM
anyways, i'll diagnose the ICU and ECM
If it does the opposite and if you replaced all the components the only thing might be is the connection or the wires.
Eric, I know that's not his problem but since he is experiencing it with the A/C on, why not turn it off and not experience it until you get it fixed? Remember how your caliper failed and you had to engine brake and hand brake your way home? That wasn't a solution at all it was just a way to get buy for that period of time. See what I mean? Now bow and apologice.
Eric, I know that's not his problem but since he is experiencing it with the A/C on, why not turn it off and not experience it until you get it fixed? Remember how your caliper failed and you had to engine brake and hand brake your way home? That wasn't a solution at all it was just a way to get buy for that period of time. See what I mean? Now bow and apologice.
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