Now I am confused 18hp less today after an upgrade/downgrade

[eta]

In May my car had the folloing engine spec.
525e 10.2:1 CR bottem end, 885 head, motronic 1.3, 083 AFM, eta throttle body, A-tech 2.7i chip. 325i intake manifold, stock airbox/filter, log manifold and eta exhuast.

Dyno plot from Surrey Rolling road in May (the date in the file name is wrong)


Peak power 159.6hp an 186 ft.lb torque.

With those results I fitted a big bore 325i throttle body. these are results from Surrey Rolling road today.



The result less torque throughout the rev range and peak down to 175 ft.lb and 18 hp less @ 141.8 hp. How is this possible. I did find when I got home the hose from the TB to the rocker cover had a crack at one the elbows. What does this even do and surely this would not cause a 18 hp loss. I taped up the crack until I order a new hose next week. I will do back to back runs of the eta TB and this BBTB as soon as I can at Surrey RR to rule in or out the TB being the problem.

Could I have a fueling issue? What is going on here? The car does not feel slower and sounds wonderful.

The only other change is the use of 20W50 API SE spec oil. Just what the manual calls for (well the API SE bit). The oil is only available in 20W50 form and I am seeing lower mpg but I have been hitting heavy traffic on my commute recently so it is difficult to tell.

I know I have asked similar questions before but now I am more confused. this mod is meant to work to de-tune the engine! something has to be wrong.

[gareth]

how's the air filter this time? not all clogged it it?
maybe a fueling issue, it seems to just stop at 4-5000RPM where it was still steadily climbing before.
do those graphs have AFR's on them?

oh, that hose is the crankcase breather

[blue30]

Torque curve looks very poorly on the second graph!

[AlpineAde]

how's the air filter this time? not all clogged it it?
maybe a fueling issue, it seems to just stop at 4-5000RPM where it was still steadily climbing before.
do those graphs have AFR's on them?

oh, that hose is the crankcase breather

Graphs 2 and 4, Gareth...right hand side.

[oakey]

I don't know much about this stuff but the AFR lines differ a fair amount between the two runs. The first run shows the afr at 4500 rpm as about 12.4 the second run shows a 13.2 afr at 4500rpm.

[carannc]

Its going very rich when you are looking for power, try a std chip in ecu, what cam are you using in the head ? assume its calculated engine power not wheel power?

[Ant]

hmmm

BBTB is 16% larger in area so how its made the mixture go 11.5:1 AFR on full load over 5K is beyond me ! @ WOT the AFM signal is ignored so the fuel calc is based on load/rpm only on the WOT lookup table, ie the engine/ECU has no way of "knowing" the BBTB is there.

the air leak will have leaned the mixture off a little , but its all gone the wrong way.

Less than the sum of its parts for sure, should be 185 bhp/190 lbs/ft given the CR and flow of the 885 head.

check the fuel reg maybe Malcolm ??????

[eta]

New air filter was fitted just before the run and yes the airbox was closed properly. A generic one but thats what I have always used.

The poorly torque curve is exactly the problem, I don't get why.

The crank case breather is a pipe that runs from the crank case to the inlet manifold, at least thats what I thought. This hose runs from the rocker cover to the TB. Does it suck oil vapours from the cylinder head into the intake air chrage due to the vacuum being created by the air rushing past the port in TB that this connects to? In which case a split in that hose would not cause a power loss.

Thankyou so far for the suggestions.

[carannc]

That tube you mention is very important for smooth running / idle. If there is a leak after the AFM like this it probably runs like a dog, that goes for splits in the boot before the tb as well.

However as ANT says the ecu picks up the closed contact on your tb on WOT and uses a different calculation so that air leak should matter less. IF that is engine power, i would do a compression check / ignition check to make sure all cylinders are firing properly, as that could also give a rich reading.

[phelix]

Did you change the throttle position sensor? Check that it's installed correctly and providing the WOT value at WOT. Is the TB opening all the way when the pedal is floored?

[eta]

Well the TB is opening fully I had to adjust the throttle cable to do this (replacing the eta manifold with the 325i one changed the position of the TB and hense the the throttle cable length so some modding was needed).

The throttle position sensor however is an open question. Is it running properly? Is it set in the right postion? How would I know.

The compression test is a idea I have had too. Also how do check the ignition system?

[GeoffBob]

Could be wrong, but from the AFR graphs it looks to me as if the Motronic is ignoring the AFM (at WOT) only at 4500 RPM and above!

Now, I'll probably get slaughtered for saying this, but I don't think this chip was created for this particular engine/setup - the primary difference being the exhaust back-pressure from the very different exhaust on the E28.

Now, at WOT and at rpm > 4500, your Motronic looks to me to determine the injector duration based purely upon RPM since its little brain says that at such-and such rpm the engine must be inducting such-and-such amount of air (instead of measuring it via the AFM). But since this isn't the engine the chip was dynoed for, its actually inducting less air than it thinks it is, and so the mixture goes rich. It basically boils down to the fact that your engine has a different volumetric efficiency (VE) to the engine that Ant’s chip was created for.

Malcom, my suggestion to you is that you get your engine as similar as possible to the engine for which Ant's chip was created ”“ in all respects, exhaust included. Otherwise, the instant the Motronic ignores the AFM in favour of how much air it ”athinks”a your engine is inducting, it will get your AFR wrong.

[carannc]

There are three positions for the TPS, idle, in the middle and WOT. From memory you should have a closed connection for both idle and WOT and no connection for middle position. So of the three wires coming from the TPS you should be able using a continuity tester to establish that you get connections on idle on WOT. You can also hear the clicks from the microswitches which helps adjust them, there is a small allowance for adjustment to facilitate this.
As for ignition a new rotor arm and cap / spark plugs is usually enough but check the leads for damage or visible sparking you are best doing this in the dark. What injectors were you using before ? the eta ones ? not sure if they are the same as 325i ones ?

[StuBeeDoo]

Might be a daft question, but is the "083" the 325i AFM?

When I had my 2.7 fitted, I initially left the 2.0 AFM fitted and it ran like a bag of s417. Once I fitted a 2.5 one, it was fine.

[eta]

Sorry its a 082 AFM I have fitted. It is a 325i AFM but from an earlier model I think. However it runs and idles well.

So in short a to do list;
Check TPS (although I assume it is working given the rich AFR above 4500 rpm).
Replace AFM with the 325i 027 kind (I have an 027 M30 AFM). I'll try a 325i 027 one first though as its simpler.
Replace ignition leads and rotor cap.
Compression test.
Check valve clearences.
Dual pipe exhaust. Given the eta exhaust manifold is the same as the 325i ones I have looked at, with the same inside diameter down pipe holes as the eta manifolds do. So What exhaust pipe diameter would be best?
Check FPR?

Anything else. All this will keep me busy over christmas.

Geoff What you said mkes perfect sense hense I though I would try the new throttle body to improve air flow (replacing the smaller eta one I had fitted). But I presume fitting that is not going to cause my power decrease.

Also as the AFR plots show nearly constant AFR until 4400 rpm with the BBTB I assume it is inducting more air but I have less torque so it must be something in the list above.

By the way thankyou all for the helpful suggstions.

[StuBeeDoo]

Dual pipe exhaust. Given the eta exhaust manifold is the same as the 325i ones I have looked at with the same inside diameter to the eta manifolds. So What exhaust pipe diameter would be best?

I don't know an awful lot about E28s, but I know the 525i had the M30b25 engine. Could the exhaust from one of those be made to fit relatively easily?? (obviously the manifold is different so the downpipes would have to be fabricated)

[eta]

Unfortunatley no point. The 525i uses the same centre and rear sections as an eta.

[phelix]

The throttle position sensor however is an open question. Is it running properly? Is it set in the right postion? How would I know.

Shamelessly plagiarised from the E30 idle FAQ:
Now before we begin to re-install the boot and other items, we will need to check the throttle switch on the bottom of the throttle body. This switch is used to control the idle control valve. If this switch has a fault, it will cause the idle control valve to operate incorrectly. In order to test the switch, first remove the electrical connector from the switch. Just push down on the metal wire, and pull it off. Inside you will see three terminals. From the left, they are numbered 2 then 18 then 3. First, connect a digital multimeter between terminals 2 and 18. Now open the throttle halfway and slowly let it close. When it is between 0.20 and 0.60mm from it’s stop, check for continuity between the terminals. Now, connect the multimeter between terminals 3 and 18. Now open the throttle slowly. Check for continuity when the throttle switch is within 10 degrees of being fully open. If you don’t see continuity while testing the terminals, loosen the screws on the bottom of the switch, and adjust the switch until it comes within these values. If you still do not have continuity, this means that the switch is bad and must be replaced.

[GeoffBob]

Geoff What you said mkes perfect sense hense I though I would try the new throttle body to improve air flow (replacing the smaller eta one I had fitted). But I presume fitting that is not going to cause my power decrease.

Also as the AFR plots show nearly constant AFR until 4400 rpm with the BBTB I assume it is inducting more air but I have less torque so it must be something in the list above.

Not necessarily. Your engine cannot inhale more air than it can exhale. Your engines VE is defined by both the exhaust and intake. It's for no small reason that a performance upgrade usually begins with an improved exhaust system. Without the engine being able to properly exhale, any modifications made on the intake side seldom realise much of an improvement. In your case, in fact, we see the opposite.

I'm no expert on your particular modded/converted 325 ETA engine, but if you want to see your engine deliver performance as quoted for other similarly modded engines with Ant's chip, you need to get your engine as close in all respects to the original engine that the chip was created for. It's great, for example that you have the same exhaust and intake manifolds. Now you need to run the twin pipes to the back and then I believe that all the pieces of the jigsaw will fall into place for you. Ask Ant what exhaust he recommends you run with his chip.

[eta]

Ant has a good memory. He has programmed that chip with the stock eta exhaust in mind. So that eliminates the exhaust assuming it has been programmed correctly which it probably has.

I will get a compreesion done this week and while I am at it I might as well check the fuel pressure regulator to see if it is over pressurising the fuel rail. New rotor cap and leads will be next.

[GeoffBob]

Ant has a good memory. He has programmed that chip with the stock eta exhaust in mind. So that eliminates the exhaust assuming it has been programmed correctly which it probably has

My apologies then. I thought there had been some discussion in your earlier thread with regard to you not having the correct exhaust?

Maybe I should ask this, in what way does your engine differ (everything from intake to exhaust) from the engine for which that chip was created? Only if your engine is a virtual copy of the one for which the chip was created (same intake components, same cubic capcity, same manifolds, same cylinder head (731 is what I think you should have), same CR, same valves, same stroke, and same exhaust) can you make the statement that you expect to see the same horsepower, especially at WOT when the ECU is ignoring your AFM's output and making an "assumption" with regard to the amount of air inducted into the engine as a function of engine RPM!

TBH, you could change a half-dozen different things on your engines intake and they would offer no performance increase at WOT (most likely degrade your performance - exactly as you have seen).

from this thread here

Just whacking a huge throttle body or carb on a normally aspirated engine won't necessarily improve the performance, in fact, quite often the opposite, as torque is usually adversely affected due to the lower air speed through a large bore inlet (venturi effect). This tends to give poor low-speed running characteristics, meaning you have all or nothing power delivery, and flat as a fart low-down throttle response!

[GeoffBob]

I just found this in your earlier thread. Why do I get the feeling that someone has already told you the same as I have?

As the ecu doesn´t measure air flow during WOT , then your air flow is way less then what ever the airflow is supposed to be according to Ant´s chip. meaning you are loosing alot of air flow above your peak torque.

Exhaust restriction can be a problem and is the most likely one. Do the exhaust first and do another dyno run.

[Gunni]

I think his exhaust was maxed on the previous run at high rpm´s,
then as it´s maxed and he´s made the intake bigger in hopes for more air flow , the opposite is happening where the bigger opening is causing a slow down of the air which then unfortunatelly
is causing an even less air flow then before.

From the AFR it´s visible it´s leaned nicely into 13:1 but then falls hard on it´s face, that´s a clear indication of a massive drop in VE in comparison to the previous VE setup.

Opening up the back end should sort this right away.

[eta]

O.K then, thats clear to me now. The local company that supplies stainless exhausts fits powerflow systems. Are the boxes they supply going to do what I need or I am better of going with someone else? In which case who? Also should I stick to twin pipes all the way through at the current ID diameter of the downpipes which is 1.5" or go wider? If I can stick with the current ID of 1.5 " then all I need to do is replace the rear single pipe section and back box which will be cheap. Also what kind of boxes do I need and I will get his job done ASAP.

If I need a larger ID for the pipes what should I go for?

[cliffybabe]

Here's what mine run at on Surrey Rolling last year after my eninge build, using a 885 head Ant's 2.7 Alpina chip, BBTB throttle, Alpina 6 Branch and Scorp exhaust system, i also had a K&N replacement panel in there





Seeing this thread has made me think i need to get mine back there now im running a BTB Manifold and cross pipe

[cliffybabe]

I've since also replaced my Fuel reg and currenlty looking into a trip to Sheps for UniQ

[eta]

Thank Cliffybabe now I can see the difference the exhaust makes. A big one.

[cliffybabe]

Thank Cliffybabe now I can see the difference the exhaust makes. A big one.

:lol:no problems, sounds amazing aswel, Im running the Scorpion Lemans twin tail and a scorpion centre section, at the time I had a alpina 6 branch but now i have the BTB manifold

[Gunni]

When I measured the standard 325i exhaust size I found it to be dual "1.75

anyway even with more air flow the mixture for cliffy looks rich.
I managed 178hp flywheel on a 100% standard 325i engine on a DD rolling road.

So I would say cliffy should have some left in there through a little leaning in the top end and possibly ignition advance tuning.

eta needs a better flowing exhaust and maybe some ignition tuning.

I really feel people should value the results they get from dyno tuned chips/piggybacks/standalones.
Off the shelve chips are for "off the shelve" engine setups.

[eta]

Your right of Gunni. A chip can never be optimal but I suppose no one ever claimed them to be. A plan is hatched in the correct order this time. The exhuast size you quote is ID or OD?

[Gunni]

ID , but I may well be mistaken as it´s probably been a decade since I measured one.

[Ant]

easy test for the exhaust as a restriction, split the system @ the centre and re-dyno

yes it will be loud, and yes less then the optimal length , but its a zero cost item that may show up something of use, waaaaaaaaaaaaaaaaaay cheaper than a powerflow experimental special.

[eta]

The idea I have had is to use second hand 325i exhaust manifold, 325i down pipes and a m535i exhaust. I would have prefered a 528i exhaust as the pipe diameter is closer but that is not available locally to me. With the 325i down pipes cut in the right place and M535i flanges welded on, it should then bolt up the 535i system. The parts will not cost me cash just some parts I have in the shed. For the cost of the petrol and dyno time to try Ant's decent idea I can get this fitted. I can then sell my 525e system once I have had it dynoed which will pay for that and some the petrol to get their and back.

I will be picking up the bits on Friday. A bit of jiggery pockery ahead but it might be a solution or just a waste of time. If it is the stock system will be back on and I will have to sell the bits I have bought. I hope this turns out to be a cunning solution instead of another folly.

[UweM3]

ID , but I may well be mistaken as it´s probably been a decade since I measured one.

45mm OD, same exhaust clamps as the M3.

[StuBeeDoo]

eta....
Did you ever get to the bottom of this?