Hesitation after engine Warms up

[shields]

My car runs really well when cold. But as the car start to warm up, slight and progressively worse hesitation begins to happen.

The hesitation is upon acceleration and mainly noticed in the first three gears.

All my electrical components are brand new, fuel filter and O2 sensor are new as well.

What could it be?

[DaN]

Every electrical component on the car was replaced?
That must have cost alot, do you have a list handy?

[shields]

Okay, I keep a log, and here are the things I've replaced within the last few months:

1987 BMW 325e Service HISTORY

ENGINE Electrical and FUEL:

Spark Plugs.

Spark Plug Wires.

Distributor Cap and Rotor.

Ignition Coil.

Fuel Filter.

O2 Sensor with New Bosch.

Throttle Body/Plate and PCV hose cleaned.

Engine oil replaced with
Castrol Syntec Fully synthetic 5W-50.

STEERING and SUSPENSION:

New Front Struts. Front Strut Mounts.

New Rear Shocks.

New Entire Rack and Pinion Assembly.

New performance Tires.

Transmission Fluid replaced with Fully Synthetic Castrol Gear oil.

Differential Fluid replaced with Fully Synthetic Castrol Gear oil.

Wheels balanced.

Steering professionally Aligned.


COOLING SYSTEM:

New Thermostat.

New Temperature sending unit (gauge assembly).

New Coolant Temperature sensor.

[jtuner]

hey does your car hesitate and sometimes make a loud POP like it's backfiring through the intake??
I'm havin the same problem with my sisters 4 door... my next thing to replace was going to be the distrib. cap,, I already replaced the afm and the TPS.... can anyone help!!??

[Brew]

Test your O2 sensor with a multimeter while the engine is running.
Just because its new doesn't necessarily rule it out.

How does your exhaust smell? Is the motor running rich? Could be the fuel pressure regulator.

[shields]

Test your O2 sensor with a multimeter while the engine is running.
Just because its new doesn't necessarily rule it out.

How does your exhaust smell? Is the motor running rich? Could be the fuel pressure regulator.

I noticed that my idle is also surging when I keep my foot on the gas steady in gear 4 on the freeway.

I notice the surging first thing in the morning right when I turn the car on, but it kinda goes away. But it looks like it surges throughout.

No smell, but my gas milage is now crap...

[KenC]

Fuel Pressure Regulator?

[shields]

Fuel Pressure Regulator?

That could be.

But it could also be the fuel pump. It has been making an annoying and noticable BUZZING sound while working. I have a feeling one of the pumps is shot...

Are they supposed to make this sound?

[jtuner]

DUDE!! Are you sure we're not workin on the same car?? LOL Yeah the FPR down by the fuel pump under the driver side door is makin this loud buzz/squeal!! I think we've found our problem.. I'm gonna change that out on my car, and if it fixes our problem i'll let you know! My sister thinks that shit is real annoying anywayz lol I'll let you know how it turns out

[shields]

cool.

Last night I read somewhere that when the FPR dies, the pump has to do all the work; therefore it makes that buzzing sound and the SURGING begins.

Well, I don't get paid until next week, so I can't do anything about it until then. But if you change it this week, let me know what the results are.

good luck!

[Brew]

DUDE!! Are you sure we're not workin on the same car?? LOL Yeah the FPR down by the fuel pump under the driver side door is makin this loud buzz/squeal!! I think we've found our problem.. I'm gonna change that out on my car, and if it fixes our problem i'll let you know! My sister thinks that shit is real annoying anywayz lol I'll let you know how it turns out

That thing underneath and behind the driver's door is a fuel filter on "i" cars, and I think a secondary fuel pump on "e" cars. The FPR is on the front of the fuel rail.

[jtuner]

Yes actually you're right, there is two fuel pumps on the 'e' cars.. one in the tank and one under the door,, but right after the one under the door, there is an FPR.. I have no idea what it does, but it's on all of them...
To be honest, mine doesn't have it, and it runs fine,, but the FPR by the second fuel pump is most definatly the thing making the noise... :)

[shields]

Just checked the compression.

Low, Not good,

didn't even reach 9.

[arnoldgtr]

It's not a FPR. It's called a pulse damper. Take it off and throw it away. The newer BMW's don't even have them.
I took three rusty ones off my 318i project when I changed all the fuel hoses.

[jtuner]

Is this is the little tiny black box with the copper wire spool that comes off the airbox? If not where is it, and how can I get it off.. This car is startin to get on my nerves.. i'm GOING to fix it tomorrow come hell or high water.. Thanks

Jordan