Metric Mechanic 2900 Sport

[jneumss]

Hey guys, I have an '89 325iX that has an MM 2900 Sport. It has headers, high flow cat / Magnaflow silencer, 286/276 cam, MM ST HiFlow Head, 10:1 CR, stock AFM with CAI, Bosch 344 DME.

Couple of questions with it:

1) It seems to run hot in traffic (between 1/4 line and center when moving; starts to get up to 3/4 line when sitting in traffic) - Head gasket replacement, water pump, thermostat, and coolant flush were done in March.

Is this normal? Should I do an electric fan conversion?

2) It idles really strange - I have read that a variable idle is pretty normal for the M20, but here is what is does:

• cold start - high idle (1500 - 2000 rpm);
• normal operating temp - variable idle (600 -1100 rpm) and sometimes slight vibration;
• with A/C on - high idle (2500 rpm +) whole car vibrates and water temp usually goes to 3/4 line or higher

Soooo, what should I expect it to idle like?

Thanks!

[jeffnhiscars]

Odds ar very high that rising temp in traffic is your fan clutch. confirm with the ole newspaper test

[berlow94]

It seems like a calibration issue.
That ecu is propably freaking out trying to run that modified of an engine.
With all of those hardware changes you could really take advantage of a proper calibration done with a standalone ecu.


Sent from my iPhone using Tapatalk

[TobyB]

Yeah, you need more fan, one way or another.

And the idle hunting would have me digging around for a vacuum leak-
I've always wanted to get a smoke test rig going, like Jim Levie describes.

You MAY have too much engine for the ECU, but it's worth the effort to make sure
the existing one's fully functional first (tps, o2 sensor, fuel pressure, spark plugs, etc etc)

t

[mr2peak]

That is WAY to much engine for the DME, unless it's a custom chip.

Electric fan won't cool as well as the mechanical fan. The mechanical fan moves a lot more air than a 16" fan will ever move. Definitely try the newspaper test.

And get a proper stand-alone! Go get a whodwho or blueapplesoda PnP unit. You spent a bunch of money to get the engine, skimping on a way to control it is a really bad idea. A stand-alone is easily worth another 10-20hp on a highly modified M20, not to mention increased drivability as well.

[digger]

there is something wrong with a sensor or a leak etc, it isnt a fault with the capability of the stock ecu as all MM m20 engine use stock ECU with nothing more than a chip, even though stock is far from the best solution, it can perform quite flawlessly.

[jneumss]

Ok, so I went for a drive today, got the engine up to temp and then did the newspaper test. Everything checks out with the fan clutch.

On the ECU, I know that it was changed at some point, but I do not know which chip is installed, if any. The engine was redone back in 2007 by the previous owner. I will pull the cover off and take a look tomorrow.

As of now, the plan is to get a MS2 setup configured over the winter and installed by the spring.

digger, do you have any suggestions on what sensors could I start with?

[digger]

for the idle, the TPS needs to be set and working correctly with no bad wiring, faulty ICV and vacuum leaks are another cause of fast idle. the bentley tells you how to test TPS and set throttle body clearance correctly.

[jlevie]

The hunting idle when the engine is at normal operating temperature could be a bad TPS, bad or sticky ICV, intake leaks, or a combination of those. The only reliable check for intake leaks isa properly executed smoke test.

[Kershaw]

Reading jlevie's posts ending in advice to do a smoke test just warms my cockles, i tell ya.

[ELVA164]

Those words will be inscribed on his headstone I think.

[CamE30]

Check the coolant temp sensors just to rule them out, could have gotten a bad one or may have just been over looked. If they are ok then I would make sure the electric fan on the outside is turning on itf it is still installed. It should come on when you turn the AC on as well.

[jneumss]

Well, I was on my home last Wednesday night and my oil pump decided to shut down on me. Unfortunately, I could not pull over or shut down the car as I was in the middle of a 4 lane highway and by the time I was able to stop, there was a bunch of racket coming from the head.

The intake rocker arms for 4, 5, and 6 were starved and ground down on the cam. I took a sample of the oil and the filter in to my local shop and we found that there was cam hard-surface particulate in the oil. No clogged supply ports in the head would lead me to believe the oil pump was beginning to fail, hence the intermittent/low pressure and lack of flow in the head.

So I'm going to do a full-rebuild myself. I'm going to replace the oil pump and overhaul the bottom end with fresh bearings and rings since I'll be in there. I'll reuse the MM 86mm pistons and the eta crank.

For the head, I think I am going to go with a different cam, I did not love the way the MM 286/276 needed to be revved above 5000 rpms to make any power. I may go back to a square cam (272), or else have my current cam ground down and re-hardened at (274). After all, this is my daily driver.

And this time, I am going to install a proper standalone to manage it. Leaning towards the MS3.

[digger]

In my experience MM cams needs a good set of decent length headers and exhaust setups they have little overlap, also get a adjustable cam gear to dial it in correctly. mine had no torque below 5000rpm also with their cam until i got an exhaust it improved dramtically. put a better cam and it was even better...

That was the MM rally cam though,it was all sorts of wrong with timing, i cant comment from personal experience about the MM sport cams though, however a forum member who measured his found it was more suitable. id be looking at a non back split cam my self or a much smaller split if you have their heads, they port intake side alot but minmal work on exhaust so the exh cam needs to be bigger than they use

the first part of the engine cycle is getting the old gases out and starting to get the fresh mixture in while the piston is going UP if you dont do that you wont make good VE ever

[berlow94]

Well, I was on my home last Wednesday night and my oil pump decided to shut down on me. Unfortunately, I could not pull over or shut down the car as I was in the middle of a 4 lane highway and by the time I was able to stop, there was a bunch of racket coming from the head.

The intake rocker arms for 4, 5, and 6 were starved and ground down on the cam. I took a sample of the oil and the filter in to my local shop and we found that there was cam hard-surface particulate in the oil. No clogged supply ports in the head would lead me to believe the oil pump was beginning to fail, hence the intermittent/low pressure and lack of flow in the head.

So I'm going to do a full-rebuild myself. I'm going to replace the oil pump and overhaul the bottom end with fresh bearings and rings since I'll be in there. I'll reuse the MM 86mm pistons and the eta crank.

For the head, I think I am going to go with a different cam, I did not love the way the MM 286/276 needed to be revved above 5000 rpms to make any power. I may go back to a square cam (272), or else have my current cam ground down and re-hardened at (274). After all, this is my daily driver.

And this time, I am going to install a proper standalone to manage it. Leaning towards the MS3.

MS3 is not a proper standalone. It's a fancy version of a DIY project. Motec, Vipec/Link, Emtron, Haltech are proper engine management solutions...

I've never heard of an oil pump just shitting the bed out of nowhere like that?! On a DD nonetheless. Not even like it was a race car that lived at high rpms... Curious what you find upon teardown.