Making 325i run Smoother and Better check-list ?

[Z2TT]

Hi Guys.

Well first time owning a E30 325i, and with no info on what previous owner has replaced or not replaced not sure where to start, not wanting to spend hundreds replacing every single bit. The engine has apparently been rebuilt 100,000km's ago but it doesn't run Lexus smooth so to say, but its not bad either.

I'm trying to make it run as smooth and powerful as possible, without knowing how these should run in good nick it's a bit hard to know where I'm at.

The engine rubbers seem in good condition from visually having a look. Sometimes when I give it a quick rev it wants to be a bit lazy to rev initially like a stutter that is felt.

I'm thinking to inspect the condition of the distributor cap and rotor and replace.

Do the Ignition coils ever go faulty or bad over time on these cars commonly?

The other thing I wanted to do is change the fuel filter, allthough this should have been done during the factory services throughout it's life. It seems as if it has never been touched.

The Fuel pressure regulator looks New.

I will remove a spark plug to check for wear and gap.

Is there anything else I should look at?

I just feel for a BMW it could run more smoother, It doesn't idler perfectly and can be felt on the steering wheel somewhat, allthough I can't say for sure how it should run.

When turning the engine off, it makes a "jung jung" sound allthough there is no sign of it or knocking when running

I'd appreciate any tips and suggestions.

Cheers.

[Brianmoooore]

Get the injectors professionally rebuilt, deal with a myriad of small air leaks on the inlet side and return all adjustments that may have been messed with to their factory settings.

[Motorhole]

To add to your list; don”˜t forget to change the cambelt if there”˜s no certain evidence of it having been done recently, a snapped cambelt will kill an M20 engine.

Idle control valve can be removed and cleaned with brake cleaner. Make sure there are no bodges in the throttle body area in an attempt to cure a poor idle that is actually the result of a bad vacuum like or ICV.

[Z2TT]

Thanks Guys.

The Service records say the Cambelt was replaced about 30 to 50000 km's ago

I'm out now to check for leaks around any vac hoses and more likely the inlet manifold gasket. I will take the intake hose off and inspect throttle body and give it a clean if needed and the same goes with IACV.

I have heard the AFM can cause issues and people reporting remarkable improvements by simply spraying a cleaner through it, yet I was a bit skeptical since these are flap type AFM's I think and not Hot-wire, perhaps the wiki links may have more info and I will read up.

Next issue is gearbox is hard to shift into 1st and 3rd and I think 2nd too only when in Motion, sounds like Synchros have never been changed.

[Z2TT]

I have checked all the hoses and what not, using carby cleaner to spray around hose joints and gaskets to check for any vac leaks at idle.

The Wiki Page of common problems mentioned a rubber plug at the bottom of the inlet manifold that seems to be common for rotting and sucking in air, could somebody guide me on exactly where this is, I would like to try spray some carb cleaner at it to see if the idle changes.

IACV is out and while looked pretty good I cleaned it out for good measures and all hoses including the main big one between AFM and TB is in very good condition.

Breather hose appears to be in good condition with no cracks

I have checked the TPS switch and at idle it joins the circuit without any problem and at 75-80% Throttle it engages the full throttle circuit.

[Grrrmachine]

The Wiki Page of common problems mentioned a rubber plug at the bottom of the inlet manifold that seems to be common for rotting and sucking in air, could somebody guide me on exactly where this is

From the Wiki:

"The next item is a small rubber plug on the underside of the throttle body, which can only be accessed with the throttle body removed."

http://www.e30zone.net/e30zonewiki/inde ... n_Problems

[Brianmoooore]

I have heard the AFM can cause issues and people reporting remarkable improvements by simply spraying a cleaner through it, yet I was a bit skeptical since these are flap type AFM's I think and not Hot-wire, perhaps the wiki links may have more info and I will read up.

AFM issues are relatively rare, and I wouldn't recommend touching it unless it is suspect for a good reason, and then only after thoroughly testing it with a battery and meter and proving it faulty.

Next issue is gearbox is hard to shift into 1st and 3rd and I think 2nd too only when in Motion, sounds like Synchros have never been changed.

I would be very surprised if the gearbox has ever been opened up, let alone synchros replaced. I've never come across any E30, or BMW in general, with even slightly dodgy synchros. The gearboxes develop a rattle with the layshaft bearings at idle, but this is just a noise and causes no other problems. The only other gearbox affliction is a tendency for them to develop difficultly in engaging first gear when cold in winter. This can be cured by using ATF as the lubricant rather than 80 oil.
The gear lever linkage does suffer severe wear, however (easily cured), which can result in the lever fouling the bodywork before the gears are fully engaged.

[Brianmoooore]

The Wiki Page of common problems mentioned a rubber plug at the bottom of the inlet manifold that seems to be common for rotting and sucking in air, could somebody guide me on exactly where this is, I would like to try spray some carb cleaner at it to see if the idle changes.

You refer to distance in kms instead of miles, which suggests that you might not be in the UK. If you are in a country where emissions equipment was fitted, you will not have this rubber plug, but instead will have a rubber hose connecting to a small solenoid valve, with another hose going from there to a carbon cannister.

I have checked the TPS switch and at idle it joins the circuit without any problem and at 75-80% Throttle it engages the full throttle circuit.

There's more to checking the TPS than this. It's important not only that it works, but it works exactly when it should. The idle section should switch immediately after the throttle butterfly leaves its stop - any delay here will result in a flat spot when accelerating from idle. Unfortunately, adjustment of the TPS interacts with the setting of the throttle stop, which should never be moved from its factory setting. If there's any evidence that the stop has been meddled with, then this needs to be addressed before attempting to adjust the TPS.

[Z2TT]

Yes I am in Australia. I have checked the underside of the Throttle body and yes there is a hose that leeds to a solenoid that connects to the carbon canister, which I believe the ECU triggers at certain times. All these hoses are good. There is another device under the manifold which was interesting, it looked like a mini hand grenade and had a wire or hose going upto the middle of the fuel rail.

Re : TPS - The idle switch goes open pretty much as soon as the throttle is moved, there is no noticable delay or movement amount until it goes open, it's very precise. I can see factory paint blob where the throttle stop is so it doesn't seem to have been adjusted at any time.

Re : Gearbox - Perhaps it may just be me used to smoother boxes or perhaps I'm downshifting to 1st and 2nd at too high speeds, it just doesn't seem as easy as other boxes I have driven.

After putting everything together and starting it up, it seemed to want to stick to idle at 1500rpm when driving, perhaps the ISCV got stuck after I cleaned it. At times if I rev the car a bit, it would stabilize at 1300rpm, then slowly crawl to 800rpm - Is this a factory strategy that the ECU uses at times ?

Perhaps if there was some sort of issues, I took the battery clamp off just now and left it for a bit then put it back on to reset the ECU.

I have also now checked the plugs, they are the factory type Bosch ones and the gap is at 0.8mm instead of 0.7mm, perhaps I might replace them.

[Grrrmachine]

What was the state of the plugs? If they're blacker than usual then the car might be overfuelling, which can also cause a higher rev (especially from cold).

[Z2TT]

It's been quite fun getting to know this car and engine and this Website seems to have a lot of good information. Just found a sticker on the Fusebox that the cambelt has been replaced 33,000km ago, good sign.

The plugs were not black or fouled at all, they were white.

Next up on the list after replacing plugs may be to remove the distributor cap and have a look at the contacts as well as the rotor.

[Brianmoooore]

Get the injectors professionally rebuilt, .