E34 535is problems...

[Jake Casson]

I have a 92 535is manual and would grateful for any help on the below topics.

Firstly I have bought a pre cat exhaust as I want to do away with the cats, what happens with the lamda sensor when I fit this? Can I disconnect it?

Then I want to richen the fueling up, I have a power boost valve so should I play with that or is ok to adjust the air flow meter? I know it would be best to have the ECU all remapped on a rolling road but does anyone know anything about these cheap chips that are being sold on ebay, people rate them in the feed back?

And one last question (for now), my fan (blower) has started making a noise (where it ticks away as though there's a leaf stuck in there) is there an easy fix?

Many thanks in advance

[mholbrook]

First of all, a 535 with a manual trans is probably more car than you think. Unless you are gutting this thing for a track car, I recommend you lose the idea of dumping the cats. Do you imagine you will get more power without the cats? I doubt you can and for sure I doubt you will be able to manage the engine without the 02 sensor and the cats etc.

The clone/generic chips on ebay are just what you think. Junk. Spend the $200 and get an EAT chip.

The fact that your fan blower is making noise makes me suspect that there may be other issues with the car. I highly recommend you take a systems approach to this car. First, is the braking system completely up to snuff. Can't go fast if you can't stop. What about the suspension system? Are the shocks, sway bar links, upper and lower control arms, etc, etc, etc up to snuff? Cooling system. Radiator, fan clutch, hoses, belts etc?

Step back from the go fast and make what you have perfect. You can improve the handling and be able to better use the horsepower you have. Think of about 4 or 5 modifications that you want to do. After you are sure the systems of the car are in good shape. 1) EAT Chip, $200; 2) Sway Bars M5 front and rear for about $300 shipped from BMA; 3) Suspension springs and shocks, $700 - $1000 4) 16", 17" tires and wheels, $1000 up.....you get my meaning?

By the time you have your car sorted out, have learned to do some maintenance and get it right, you will be less tempted to take a sawsall to it in an effort to get more horsepower.

Finally, the nut behind the wheel. Ever been to a BMW driving school? Driven enough autocrosses to shed the "Novice" moniker? You don't learn to drive fast on the street. You learn it at the track and from those who have gone before you. And your car has to pass inspection before it ever turns a tire.

Just my .02 worth.

[Alexlind123]

If you really want to, you can probably remove the cats without any difficulty as you only have one o2 sensor which is befor the cats. I dont see why you would want to do this though.

[Jake Casson]

Thanks, but what are you saying mholebrook?

Ive had this car since I was 18 (now 22) and have restored it, spending around 15000 pounds on it. This includes rebuilding the top end (didnt really need it) porting the head and fitting a performance cam, power boost valve, eco tec valves, K n N panal filter (induction kit actually reduces the power on these as cold air feed is poor). It runs on 18s and looks perfect so I really dont see what your going on about "mholebrook"......?

I want to take the cats off as they've rusted away quite abit anyway, plus I dont need them for the MOTs. Surely they restrict the flow? How come the pre 1990 cars dont have cats nor a lamda? What will happen if I didconnect it? Thats the whole point as I then can turn the fueling up?

[mholbrook]

Sorry about that, your original post sounded like the typical kid that wants to chop up the car in the mistaken thought that he can make it go faster before making sure it is even safe to drive.

I recommend you find another (1) used cat in good condition, or see if they sell a generic cat (in the US that is usually Magnaflow) and replace it with that. I'm sure you could figure out how to fool the Motronic system somehow to think there was an O2 sensor there but ultimately, the car will run correctly and better and cleaner with the cat. And we are all for clean air and preserving the earth are we not?

[Erwin8r]

Thanks, but what are you saying mholebrook?

Ive had this car since I was 18 (now 22) and have restored it, spending around 15000 pounds on it. This includes rebuilding the top end (didnt really need it) porting the head and fitting a performance cam, power boost valve, eco tec valves, K n N panal filter (induction kit actually reduces the power on these as cold air feed is poor). It runs on 18s and looks perfect so I really dont see what your going on about "mholebrook"......?

I want to take the cats off as they've rusted away quite abit anyway, plus I dont need them for the MOTs. Surely they restrict the flow? How come the pre 1990 cars dont have cats nor a lamda? What will happen if I didconnect it? Thats the whole point as I then can turn the fueling up?

Mike's suggestion is solid (There are "high flow" aftermarket alternatives), but if you were really determined to dump the cats, it would not really be an issue as your 02 sensor is before the cat... If you do remove the cats, make sure your entire exhaust system is set-up that way so that you make ponies in the right places instead of losing them... You can add and FPR, larger fuel injectors (the Ford Mustang injectors work great), and a higher-flow fuel pump--but these in and of themselves will not guarantee a lot more horsepower. Judging by the mods you have done (the ported head, etc.), it might just be worth it to try, however... Oh, and also as someone suggested, get a good chip--no sense going cheap at this point...

[Jake Casson]

Are the cars over there set up different?

So how do pre cat 535s run without a o2 sensor, and most 535s over here are pre cat as they stopped making them in 92 and mine was one of the last made....?

Any ideas on the fan, my other car has started to do it to, its a bit rubbish in the blower I reckon? Question is, is it easy to get to?

Cheers

[Kalevera]

This is an interesting thread, probably one of the most relevant on the forum at the moment.

You don't need to worry about the 02 sensor when replacing the cats. I, for one, think it's environmentally irresponsible to run a car without a cat, and installing something like a carsound magnaflow is the best of both worlds. Don't waste money on an aftermarket direct fit replacement, they don't last. Don't forget, you need some back pressure.

Now, the pertinent question regarding richening the fuel mixture is: why (and how)? The question of why: how lean is the car actually running? The most effective way to take advantage of a ported head or intake would be to control how the DME receives A/F mixture info (edit: versus just throwing fuel at it). Converting the car to a programmable MAF or the split second MAP setup would probably be the best way to extract gains out of those modifications. The design II/III injectors and the 3.5 FPR are also a nice upgrade, but I'm not sure that they're necessary. Changing the fuel pump is overkill.

On the blower motor: fairly typical occurrence. Remove it and you'll probably find a few mouse nests in there -- how long's it been since the microfilter was replaced? Once it's squeaking, it's trash. The squirrel cages and motor are balanced as a single unit at the factory and there are no serviceable bearings. Good used blower motors are inexpensive and readily available -- probably the best route to go -- and it takes less than an hour to change it out.

Edit: FWIW, a way to keep rodents out of the airbox when storing the car for any period of time is to turn on the recirc with the key in the accessory position before disconnecting the battery. The second the car is turned off/key to position 1, the flaps will open (regardless of IHKR/A settings) if there's juice to actuate the flapper motor.

best, whit

[Erwin8r]

Are the cars over there set up different?

So how do pre cat 535s run without a o2 sensor, and most 535s over here are pre cat as they stopped making them in 92 and mine was one of the last made....?

Any ideas on the fan, my other car has started to do it to, its a bit rubbish in the blower I reckon? Question is, is it easy to get to?

Cheers

The 02 sensor feeds information in an oscillating fashion to the ECU. Pre-02 sensor FI cars take their readings at other places (airbox, atmospheric temp, etc.) in order to decide the fueling rate. I don't know what the differences are between Euor and U.S. spec E34's and how the years correlate, but we had the E34 535 between 1989 and 1993. And while there were a number of changes during these years, they all, of course, were Catalytic-Converter equipped.

[Jake Casson]

Thanks everyone, interesting thoughts. Looks like I'll have the lambda welded into the new exhaust. Really thought I could do away with it then it would ran richer, cant remember how lean it was running but it was much less than it should.

Im sure there is alot of extra power to be had with the work ive done. Just need more air and fuel going into the engine. Will look at importing one of these EAT chips if there that good. Dont have them here in the UK.

Whats this about bigger injectors, is that gonna be worth while and costly?