325e Full Throttle Problem - BMW Forum - BimmerWerkz.com
3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

 
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#1 (permalink) Old 03-16-2005, 04:48 PM
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Hello. This is my first post here.
My dad has an '87 325e automatic. About a month ago, the gearbox clutch pack died, so it was changed and now it runs fine,. But while at the shop, they seem to have disconnected or messed with some component of the EFI system. At the same time they changed all the vacuum hoses (to get rid of an intermitent idle problem), and the car now idles well, has no misfires/hesitations, etc. The problem appears only when you floor the accelerator (part-throttle is OK). It has no effect on the rate of acceleration. It's like the ECU is not receiving the signal from the throttle position sensor. The car accelerates and doesn't hesitate, but is like you were slowly moving the accelerator (or like the secondary jets or acceleration pump clogged in a carburettor equipped car), like the ECU never knows the car is on WOT and not part throttle. FYI, filters are new, no vacuum leaks, 2 year old distributor, old coil and cables.
I have yet to check it, since I don't get to see my dad very often, but I wanted to gather some info before messing with it (I adjusted the EFI of my much newer car, and from what I have seen it's a bit different from the Motronic 1.0 unit on the 325e). What do you think may be causing this effect?
Thanks already!
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#2 (permalink) Old 03-16-2005, 05:17 PM
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i dont really understand what its doin. is it boggin down when you floor it?
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#3 (permalink) Old 03-16-2005, 07:26 PM
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I think what he means is that when he floors it, noting seems to happen, like its not getting enough fuel for being at WOT. My 325e does the exact same thing, it gets on my nerves and i have no idea what the problem is.
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#4 (permalink) Old 03-16-2005, 08:54 PM
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Quote:
Originally posted by norcalE30@Mar 16 2005, 06:26 PM
I think what he means is that when he floors it, noting seems to happen, like its not getting enough fuel for being at WOT. My 325e does the exact same thing, it gets on my nerves and i have no idea what the problem is.
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there is a WOT switch, try cleaning the contacts.

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#5 (permalink) Old 03-16-2005, 09:19 PM
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Quote:
Originally posted by Kowalski@Mar 16 2005, 08:54 PM
there is a WOT switch, try cleaning the contacts.
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Could you elaborate on that a bit more?
I always assumed that the 121 horsepower issue sort of held the Etas back.


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#6 (permalink) Old 03-16-2005, 09:21 PM
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Must be because it is an "e" Just joking, may be a problem with the fuel pressure regulator, which has a vaccum hose that runs directly from intake manifold, if not hooked up will not function properly... Also check connections around Idle control valve and mass airflow sensor,... Good luck!
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#7 (permalink) Old 03-16-2005, 09:55 PM
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Hey, hey, hey lets not go taken any cheap shots at the e's. There just like an i just a little slow, no need to pick on um...lol.
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#8 (permalink) Old 03-17-2005, 12:23 PM
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Just a little slow he says...
It's cool, nothing wrong with getting good gas mileage and cheap insurance.
I can admit my car's slow, I'm secure.

But really, what's this WOT switch.


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#9 (permalink) Old 03-17-2005, 02:55 PM
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Quote:
Originally posted by Aether@Mar 17 2005, 11:23 AM
Just a little slow he says...
It's cool, nothing wrong with getting good gas mileage and cheap insurance.
I can admit my car's slow, I'm secure.

But really, what's this WOT switch.
[snapback]313499[/snapback]
i believe its on the throttle body and when you floor it it hits a connector the WOT switch, jordan had problems with this a while back and he bent to connector to fix it.

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#10 (permalink) Old 03-18-2005, 08:20 AM
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OK, thanks to everyone, I was suspecting the throttle position switch, but since I don't own the car I'll have to look at it later. I was also suspecting the fuel pressure regulator since it's the 1987 original.

For those who wanted me to elaborate a bit more on the problem: if you drive the car leisurely it feels completely normal (good idle, accelerates well, no hiccups, etc). When you push the accel a little farther the car doesnt' accelerate as well as before (it's an auto, so the kickdown made it feel very fast at overtaking), and if you push it completely (full throttle) it's like you haven't. There are no hiccups, hesitations or whatever, just the feling that the engine slowly starts accelerating (in any case it's faster than some other cars, just not as fast as it was)

For those comparing the "regular" engine to the eta, I havenīt driven a non eta 325, but I really appreciate the extra torque at low end the eta is quoted for (especially since the car is an automatic). My dad's car has the fuel cut-off at 4750 rpm (in the tachometer, don't know the actual number), and when it nears the 4000 rpm mark it feels more and more powerful so it's really a dissapointment as I wonder what power the engine would develop at 5000 or 6000 rpm (I know the eta head is not designed for high rpm because the camshaft has less supports than the 325i)

Thanks
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#11 (permalink) Old 03-18-2005, 08:33 AM
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Quote:
Originally posted by Aether@Mar 17 2005, 12:23 PM
Just a little slow he says...
It's cool, nothing wrong with getting good gas mileage and cheap insurance.
I can admit my car's slow, I'm secure.

But really, what's this WOT switch.
[snapback]313499[/snapback]
The WOT (wide open throttle) switch is an electrical switch connected to the intake butterfly valve. It senses its position. That way the ECU knows if the driver is either idling the engine, giving it part throttle or full throttle. This is necessary because the ECU can determine the amount of fuel injected to the cylinders (controlling the injector aperture time I think).
For example, in a downhill the car could be doing 3000 rpm when you are using engine braking to keep the speed steady. The car is inhaling a certain amount of air that is metered by the airflow sensor. The ecu has no way of knowing if you are accelerating or just using engine brake. It does by checking the input from the throttle position sensor, if it's closed then the ecu knows you don't want to accelerate and shortens the injection pulses (or may cut them completely).
Usually there are three modes of operation, idle, part throttle and full throttle. If idling the ecu injects just the right amount of fuel to keep the engine running steady (if you are stopped), or shuts the injectors off (if you are using engine brake). If part throttle, the ecu uses the "closed loop" mode, in which all parameters are considered (throttle position, temperature, air intake, etc), but the deciding one is the oxygen sensor whose reading tells the ecu to inject more or less fuel to lower emissions. When going full throttle, the ecu simply injects fuel according to preset values stored in memory based almost directly in the readings of the airflow sensor, as you may be overtaking a truck in a two lane road and don't want the O2 sensor telling the ecu to cut your fuel supply because your emissions are higher.

Sorry for the long answer!!!
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#12 (permalink) Old 03-19-2005, 02:58 AM
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Just how much faster IS the 325i? Around town and inter-city highway driving, my ETA kicks most car's butts, even with the slushbox. I don't know any Civics that can pull 80km/h in first gear given five seconds from a dead stop. Maybe its because I'm new to the land of BMW, but she seems pretty fast to me.

Then again, if someone could give me a ride in a 325i.... ... maybe I'd be spoiled.

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Changed the car's name, now it's - Roxanne -1985 325e
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#13 (permalink) Old 03-19-2005, 09:09 AM
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Quote:
Originally posted by LGO@Mar 18 2005, 08:33 AM
The WOT (wide open throttle) switch is an electrical switch connected to the intake butterfly valve. It senses its position. That way the ECU knows if the driver is either idling the engine, giving it part throttle or full throttle. This is necessary because the ECU can determine the amount of fuel injected to the cylinders (controlling the injector aperture time I think).
For example, in a downhill the car could be doing 3000 rpm when you are using engine braking to keep the speed steady. The car is inhaling a certain amount of air that is metered by the airflow sensor. The ecu has no way of knowing if you are accelerating or just using engine brake. It does by checking the input from the throttle position sensor, if it's closed then the ecu knows you don't want to accelerate and shortens the injection pulses (or may cut them completely).
Usually there are three modes of operation, idle, part throttle and full throttle. If idling the ecu injects just the right amount of fuel to keep the engine running steady (if you are stopped), or shuts the injectors off (if you are using engine brake). If part throttle, the ecu uses the "closed loop" mode, in which all parameters are considered (throttle position, temperature, air intake, etc), but the deciding one is the oxygen sensor whose reading tells the ecu to inject more or less fuel to lower emissions. When going full throttle, the ecu simply injects fuel according to preset values stored in memory based almost directly in the readings of the airflow sensor, as you may be overtaking a truck in a two lane road and don't want the O2 sensor telling the ecu to cut your fuel supply because your emissions are higher.

Sorry for the long answer!!!
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Always ready to learn about these cars, thanks for answering!


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#14 (permalink) Old 03-20-2005, 09:32 PM
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Quote:
Originally posted by offabroadway@Mar 19 2005, 02:58 AM
Just how much faster IS the 325i? Around town and inter-city highway driving, my ETA kicks most car's butts, even with the slushbox. I don't know any Civics that can pull 80km/h in first gear given five seconds from a dead stop. Maybe its because I'm new to the land of BMW, but she seems pretty fast to me.

Then again, if someone could give me a ride in a 325i.... ... maybe I'd be spoiled.
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Well, from what I have seen/read the eta feels stronger in everyday use (especially if the car is an auto) because of the higher torque value from idle to 3000 rpm.
I remember having seen a dyno curve in an old spanish magazine from a 325i and the max torque was lower than the eta and the curve, while relatively flat, was higher from 3000 to 6000 rpm. At around 4000 rpm the eta and the i produced almost the same power (about 120 hp). As you may know, the eta "dies" at 4500 or 4750 rpm (depending on the year of production), but the i keeps going strong right to the redline. That's why it developed 170 hp (european version) from 2.5 litres back in the 80's-
I also recall that the eta does 0-100 km/h in a little less than 10 seconds and that the manual i can do it in 8 seconds approx, the difference being that the eta never goes past 4500 rpm and the i can rev all the way to 6500. So even if you drive it to the limit the eta never feels stressed, whereas an i will, at least, sound stressed. And in the everyday traffic (where you are not supposed to be racing), maybe an automatic eta will be faster.
I remark that point because I remember an E36 325i coupé that we encountered in city traffic around 1996. My brother was more nimble maneuvering his hyundai through the dense traffic so he kept on pulling ahead the 325. This annoyed the guy driving it, so he had to rev the engine to the max to leap past us in a tight spot. The street was a narrow one and everyone turned to see who was making such (to our ears beautiful) noise. Though both cars were going fast on a speed limited zone, everyone in the scene though only the 325 was racing.
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#15 (permalink) Old 04-03-2005, 02:19 PM
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Hello. Today my father came to my house and I managed to get my tester on the TPS sensor. The readings are OK, continuity at throttle closed and then before full opening (as stated in the haynes manual).
Later took it for a spin (to ensure I didn't messed anything under the hood-it's an old car ) and found that the problem is still there.
I did two test.
Put the car in first (auto) and gave it a partial launch, then full throttle and the car just rocketed forward to redline. This made me think that the TPS was fine now (maybe just needed to be reconnected-again the old connectors don't look taht good to me)
Then stopped again and put it in second gear. Launched again, this time flooring the accelerator and the car started moving slowly and the engine remained steady at 1500 rpm (no acceleration but no misses, burps, etc., it just kind of refused to accelerate), then slowly it started to climb to 2000 and then whoosh to almost redline, and then in second with so much force that the tires chirped when going into second (probably a bad set of valves in the auto box).
Of course this left me wondering. The TPS is OK. I can't blame the fuel pumps and the fuel pressure regulator since the car had fuel all the way to the redline. Ditto for the alternator, since it would have given me troubles at high rpm.

Any ideas? Thanks!
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