Speed Limiter on my e34 525i Touring

[Jon K]

Dude honestly if you bored your intake manifold you probably screwed up the flow - the OBD1 intake manifold is proven to outflow an OBD2, and is portmatched - it's dead on gasket match. Not sure why you'd port that.

Boring the throttle body has a questionable effect as well.

As for polishing piston tops and valves? Thats a new one to me. Do it yourself cold air intakes usually hurt performance - I know this for a fact and have gone from stock to bolt ons then to a custom CAI which hurt my performance, to supercharged, back to stock, then to CAI again, hurt my performance again, etc. Put the factory airbox in and replace the intake manifold and throttle body with a standard one and I bet you'll notice better performance.

[bad_manners_god]

Dude honestly if you bored your intake manifold you probably screwed up the flow - the OBD1 intake manifold is proven to outflow an OBD2, and is portmatched - it's dead on gasket match. Not sure why you'd port that.

Boring the throttle body has a questionable effect as well.

As for polishing piston tops and valves? Thats a new one to me. Do it yourself cold air intakes usually hurt performance - I know this for a fact and have gone from stock to bolt ons then to a custom CAI which hurt my performance, to supercharged, back to stock, then to CAI again, hurt my performance again, etc. Put the factory airbox in and replace the intake manifold and throttle body with a standard one and I bet you'll notice better performance.

Well, what I did was just stick a clean rag and clean out the grim and dirt that had built up.

The pistons heads/valves were done with a 3" steel brush on a drill, mostly to clean off all the caked on stuff.

[Brandon J]

I've had this problem for a really long time, almost as long as I can remember. I original bought the chip in hopes of removing the limiter but no avail. I have Regular fuel most of the time, every 2 weeks, I drive it till it's almost empty and fill up with supreme to clean out the lines, injectors, etc. Here is a list of maintence I've done: (Note: I had this problem before ANY of this maintence was performed)

-New Upper Control Arms
-New Lower Control Arms
-New Cross member
-New Stabilizer Bars
-New Tie Rod Assemblies
-Rear Self-Leveling Delete
-Bored Intake Manifold
-Bored Throttle Body
-Custom Cold Air Intake
-DINAN Performance Chip
-DINAN Transmission Chip
-Fan Shroud Delete
-New Head Gasket
-New NKG Spark Plugs
-New Oil Pan
-New Oil Pan Gasket
-New Radiator
-New Thermostat
-New Thermostat Housing + Gasket
-New Valve Cover Gasket
-Polished Piston Heads and Valves

I have done almost everything naturally aspirated (w/o stroking) to the M50tu when I had that engine. Your throttle body didn't need to be bigger. I did M3 cams, 3 custom chips, flywheel, diff, custom intake, 540 MAF, etc. You don't need the larger TB and why did you delete the fan shroud. The shroud helps the radiator cool. If you have had this car and there has been a problem for a while, perhaps you got some bad gas one time and sucked some dirt into the fuel filter. This could limit the fuel you need for the load at those higher speeds. The fuel filter is on the list of maintenance things. The next thing I would check is the intake and MAF. If you are using an oil based high flow air filter, over time the oil on the filter can go onto the MAF sensor affecting its reading. If these are not the problems, then you might want to keep an eye on the fuel pump as they can go slowly or completely at once.

Here is another thing I would check. You say you have polished pistons and valves, and you increased the throttle body bore, did you add the extra fuel. Your car could be running lean and the computer could be trying to compensate. It can only do so much so you would need a new custom chip with the appropriate fuel pulse, timing, and flow. You got the head work done, you should have done more homework and known to get a custom chip or increase the fuel too. The '92 m50 engines don't have knock sensors like the '93 and up M50tu engines. So, if you are running lean and there is pinging, the computer will not tell you. Make sure you don't have any pinging from a lean condition. Go through a tunnel to hear the engine while driving under load.

I hope you do find the culprit as it looks like you are trying to make a very nice touring there. Good Luck and I hope the information here helps you out.

[bad_manners_god]

I have done almost everything naturally aspirated (w/o stroking) to the M50tu when I had that engine. Your throttle body didn't need to be bigger. I did M3 cams, 3 custom chips, flywheel, diff, custom intake, 540 MAF, etc. You don't need the larger TB and why did you delete the fan shroud. The shroud helps the radiator cool. If you have had this car and there has been a problem for a while, perhaps you got some bad gas one time and sucked some dirt into the fuel filter. This could limit the fuel you need for the load at those higher speeds. The fuel filter is on the list of maintenance things. The next thing I would check is the intake and MAF. If you are using an oil based high flow air filter, over time the oil on the filter can go onto the MAF sensor affecting its reading. If these are not the problems, then you might want to keep an eye on the fuel pump as they can go slowly or completely at once.

Here is another thing I would check. You say you have polished pistons and valves, and you increased the throttle body bore, did you add the extra fuel. Your car could be running lean and the computer could be trying to compensate. It can only do so much so you would need a new custom chip with the appropriate fuel pulse, timing, and flow. You got the head work done, you should have done more homework and known to get a custom chip or increase the fuel too. The '92 m50 engines don't have knock sensors like the '93 and up M50tu engines. So, if you are running lean and there is pinging, the computer will not tell you. Make sure you don't have any pinging from a lean condition. Go through a tunnel to hear the engine while driving under load.

I hope you do find the culprit as it looks like you are trying to make a very nice touring there. Good Luck and I hope the information here helps you out.

I should clear up the fact, that I didn't bore anything, I cleaned it out with a clean rag. The Pistons and Valves we're just cleaned with a heavy duty steel brush.

[Jon K]

Brandon he def does not need new management for those little cleaning actions he's done. M50 doesn't have the knock sensors but its also 10.0:1 CR vs 10.5:1 CR, so its more conservative anyway.


But your post above says ported manifold and bored throttle body...

[bad_manners_god]

Brandon he def does not need new management for those little cleaning actions he's done. M50 doesn't have the knock sensors but its also 10.0:1 CR vs 10.5:1 CR, so its more conservative anyway.


But your post above says ported manifold and bored throttle body...

Yea, thats was from my word file as I kept track of things I've done, before I actually knew what polish, stroke and bore meant.

I'm going to buy a new obc and hopefully that will cure the problem

[Dave M]

Yea, thats was from my word file as I kept track of things I've done, before I actually knew what polish, stroke and bore meant.

I'm going to buy a new obc and hopefully that will cure the problem

Unless you're buying one to cure your buggered display, don't waste your money.

Does anyone here believe the OBC could responsible?????????

Dave M

[dacoyote]

Unless you're buying one to cure your buggered display, don't waste your money.

Does anyone here believe the OBC could responsible?????????

Dave M

I believe in unicorns... and that Harry Potter is real... but I don't think the OBC could cause the primary issue here...

[repenttokyo]

Scram?

I was doing 250 with 7 on board actually racing a supra non-turbo on the highway out-pulling him.

When the messege comes on, I hear the ding and then it starts accelerating slowly but I was able to get it up to 220, took almost 2 minutes from 175

a supra non turbo is pretty damn slow, and my 91 M50 is also pretty damn slow, there's really not much that it will outpull on the highway even with a 5 speed, if you want a rocketship, without significant mods i think you are in the wrong car.

Of course, if you are the kind of guy who does 250 with 7 people in the car, I doubt anything anyone says will get through to you in any case.

BTW, my car is chipped too, and yeah, it's still not fast.

[repenttokyo]

Well, what I did was just stick a clean rag and clean out the grim and dirt that had built up.

The pistons heads/valves were done with a 3" steel brush on a drill, mostly to clean off all the caked on stuff.

....that's not what polishing means. how much of your valves were ground off doing this?