Engine sputters between 3500-4000 RPM

[delfin]

I have a 1987 325i with about 217k miles on her.

I just recently changed the oil and seafoamed the engine trying to see if I could fix the problem.

Every time I put the pedal down between 3500-4000 RPM the engine starts shaking (almost feels/sounds like backfiring) and then lets off once it's out of that range.

The problem is worse the colder the engine is.

Any idea what this might be? Thanks.

Could it be the spark plugs or injectors?

[Reap3r]

Fuel filter, spark plugs possibly

[AndrewBird]

Since it does it when colder, could be the cold start valve or a faulty coolant temperature sensor.

[Julien]

i'm gonna go with faulty (or badly adjusted) throttle position sensor, vacuum leak, and air flow meter as possible culprites

[baaaaaaa]

I had a similar problem to this except the engine would kinda cut out around 5000k. After alot of work it turned out to be the mass airflow sensor. Then it ran fine. You should clean yours and check ot to see if it is faulty like muine was.

[Adrian_Visser]

nitro rustler that your answer to everything lol

Cold start valve or possibly coolant temperature sensor. If it doesn't do it when warm, you can pretty much rule out the ICV, MAF and throttle body.

it's not the tps and vac leaks wouldn't have an effect (for one thing when the throttle is open most of the way or is at WOT vac is almost nil)

not to dis everybody.

the afm is possible, break down of the plug wires can cause similar symptoms ( missing at higher rpms) a shop might have a tester for plug wires which can put the high voltages seen in the system through them and readout on an oscilloscope the losses, or you could just try a new set (oem are best). Maybe check the Cps too?

[delfin]

So funny, I was changing the fuel filter and one of the hose clamps put a hole in the hose on the gas tank side of the line. Needless to say it's everywhere. Anyone know how to change that hose out? Let alone where to get one?

[Julien]

hose: get fuel line from local parts store... normally you can replace all the fuel lines without dropping the tank, so look and you'll see where it goes.

[delfin]

replaced the line. nice and easy.