Cut off at 5k RPM?

[Alpine30 Wolf]

I have an 87' 325is 5speed and when it hits up to 5k RPM the car seems to cut the gas off and throws me forward. It doesn't kill the engine, just goes back to normal after the cut off point. Anybody know what this could be or the cause? Thanks

[ck_taft325is]

Sure you have an '87 325"is" and not a '87 325"es" ?

[Alpine30 Wolf]

Sure you have an '87 325"is" and not a '87 325"es" ?

yeah, i checked the VIN and its an IS

[bmwsun]

Does it cut under full throttle?

[Alpine30 Wolf]

Does it cut under full throttle?

It does, but does when I'm not as well. I was told I have the wrong chip in it so I'm wondering if that could be the problem, but not sure if it's that or something else.

[QUKBMER]

If not the chip being wrong maybe the TPS ?

[rickycricketts]

if you have a chip for an eta then the rev limiter would be set at around 5200 rpm. but i'm not sure if it would even run with an eta chip.

[gotblah]

My car also seems to hit the rev limit around 5000. I have a 89ix. What should the stock rev limit be? Also when the engine is cold it seems to semi-rev limit around 4000, but once warm goes up to 5000

[ck_taft325is]

7,000 rpm on any "i" engine including iX cars. Are either of you chipped?

[Rennsport]

John just ordered a chip, so we will see if that works.

[Alpine30 Wolf]

ordered and put the chip in and still cuts off when i really press down on it, but if im easy on it it will pass the 5k mark. Whatever ill figure the thing out later

[EN318isPDX]

Fuel pressure?

[ck_taft325is]

Fuel pressure?

I would say a faulty FPR. Even a fuel filter issue possibly.

[e30austin]

Random old thread bump. When searching for "M20 cut off at high RPM", I found this thread. Looks like the OP was having an issue with the car long ago, but long story short, my brother now owns this car. Still having the same issue, six years later.

This car has some sort of chip with a 173 DME that someone swapped in along the way. This is a hard cut off. It will not rev past 4500 RPM at full throttle under any type of load. Under partial throttle, you can get it to redline, but that's it. It's not a fuel related cut off, it's electrical...the car bucks and stalls and the instrument cluster gets super fucky until you clutch in and let the revs fall back down under 3000.

I swapped in a 380 DME from a known good running 325i, still the same issue. I connected my Snap On Modis and got the following codes:

Idle Actuator ZWD Winding 2 (code 22)
Fuel Pump Relay (code 3)
Injector Valves - cyl 1, 3, 5 (code 16)
Injector Valves - cyl 2, 4, 6 (code 17)
Vehicle Speed Sensor signal (code 29)

I cleared the codes and went and drove the car hard. All the codes came back, except for the speed sensor code.

Any thoughts as to what's going on here? We were hoping to have the car ready to take to some track days next month. Thanks.

[Mueller168]

This is the exact problem I have! I was too afraid to make a post because I'm new and don't know whats allowed. I have a 90' 325i. Below I'll post all the research I've done from reading forum posts; and from what I can tell is the Wiring Harness is where the problem is coming from. I still don't know how to proceed personally to know if it's the DME, Wiring Harness, or the chip the car came with. My car 2/3 times will go to redline, but that 1/3 will just cut power. (If posting links isn't allowed I'm sorry, I'll change the post)

http://www.r3vlimited.com/board/showthread.php?t=287495&page=3

http://spece30.com/forum/41-electrical-gauges-and-sensors/63238-a-tale-of-three-harnesses

http://spece30.com/forum/41-electrical-gauges-and-sensors/57326-tip-be-wary-of-trusting-old-wiring-harnesses

http://www.r3vlimited.com/board/showpost.php?p=4472783&postcount=27

http://spece30.com/forum/42-engine/57800-spece30-and-megasquirt?limit=10&start=90

http://spece30.com/forum/41-electrical-gauges-and-sensors/34704-help-i-might-just-burn-it-to-the-ground

https://www.bmwcca.org/forum/index.php?threads/e30-throttle-randomly-cuts-off.651/

Steve