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Followup To
Question -
Hi Josh, I have an E30 325i but does not perform like one. I have so far changed the air flow meter, throttle body and fuel pump. The air flow has been set on the machine and tappets were recently reset as they were noisy. With all of this it still lacks power. What else may be the problem?
Answer -
Shahed,
I'm taking it that you have driven another E30 325i before driving this one? How many miles are on your car. Some times these engines get "tired" and loose a little compression. Seems that you have done most of the homework, and replaced the usual suspects.
What are the exact symptoms? Does it sputter or hesitate? if so what RPM?
Does it drive smooth, but just doesn't seem to go like it used to?
How long has it been since you checked the catalytic convertor? They get clogged sometimes and its a restriction for the exhaust. If you have gutted the cat then this doesn't apply.
Have you checked the O2 sensor? Sometimes they get faulty and let the engine run rich/lean.
I've heard of this new internal cleaner that is supposed to work really good. It's called "seafoam" and can be purchased at the local parts store. Get the engine up to operating temp (drive it for 10-15 minutes) then with the engine idleing, remove the vacuum hose running off of the fuel pressure regulator and stick the vacuum line into the can of this cleaner. Let it suck up about half the can, and turn the engine off. Let it sit for 10 minutes, then start the engine. This will clean all the valves and the tops of the pistons. There are directions on the can. I've heard that this made other people's BMW's run like new again. Since I have not tried it, I can only say to use this as your discretion... although it sounds like it works great.
There are SEVERAL possibilites, but I need more information.
Thanks Shahed,
Josh
Hi Josh,
Thanks for the response. This vehicle was initially a 320i auto which has been converted to a 325i manual. It has a 320i manual gearbox and the original diff. I think the computer box is for a 320i as well. The reason for me saying it lacks power is because I could not pull away from a 1.6i Golf which the only mod done to it was an induction kit. There is a bit of splutter only when you decelerate (about 2500 rpm) but other than that she goes smoothly but just not fast enough. There is no catalytic converter. The model of this vehicle is 1984 and mileage is about 150 000 km's.
AnswerOk.. well that answers you problem. The 320i has a 2.0 liter M20 (M20B20), while the 325i has a 2.5 liter M20 (M20B25). The difference is the diameter of the piston and the stroke of the crankshaft. I dont know the exact numbers without looking them up. Since the 2.5L engine has larger pistons and a longer stroke on the crank, it pulls in more air than the 2.0L engine. Since it pulls in more air, it also needs more fuel to keep the ratio correct (14.7:1 = air:fuel). The 320i engine management (computer/ECU) will take the O2 sensors signal and make adjustments to fuel as needed. So if the O2 sensor tells the ECU that the engine is running lean, it will alter the fuel injector's duty cycle. That means that it will tell the injector to stay open longer and release more fuel into the combustion chamber.
The problem you have... is that you're fuel system cannot release ENOUGH fuel to feed the 2.5L engine. So your engine is most likely running lean (16:1, 17:1 Air/fuel ratio). This is BAD, as the lean engines burn HOT compaired to the 14.7:1 ratio.
So you should AT LEAST upgrade your fuel injectors to 325i fuel injectors, but I would get a 325i computer as well. It should just plug in and be fine. Ford Mustang 5.0L fuel injectors are a direct replacement for E30 fuel injectors. Although they make some that are too big. if you go that route, buy the 19 pound injectors.
You should also upgrade your fuel pressure regulator, as I think that the 320i's FPR is set at a lower rate than the 325i's. 2.5 bar, vs. 3.0 bar (I think).
This should have you set...
let me know if you have other questions.
Josh
