Q: 1995 BMW M3 won't pass smog at idle, random misfire, new coils, plugs, injectors, knock sensors, tested sensors with scan tool

asked by on July 01, 2017

I have a random sputter at idle, won't pass smog at idle 200/100HC, passes at 2500rpm. tested sensors with scan tool and all are working new gaskets and hoses new bosch ignition coils new injectors new knock sensors new o2 sensor(only 1 on car, pre cat) fuel pressure regulator fuel filter tested computer and dinan and Turner chip re timed engine 3 times along with smoke test 3 times swapped MAF and no change( 2 good ones off friends car) only things I haven't replaced are fuel pump(tested with fuel pressure gauge at 51 psi) before fuel pressure regulator throttle position sensor and vanos solenoid/vanos ICV(cleaned a couple months ago, I live on west coast and had another e36 have a very rough idle from ICV getting salt buildup) the problem is it is so slight and random most shops don't even know it's misfiring but it just won't pass smog Thanks for reading and if you have multiple options I will perform all today that are possible thank you!!

My car has 200000 miles.
My car has a manual transmission.

Since you have replaced so many parts , it would be very difficult to determine what exactly is causing this without performing a physical inspection. I wouild stronly recommend having your vehicle inspected by a qualified professional to trace down what is causing this issue. Consider YourMechanic as vehicle inspections can be performed at your home or office.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Hi! Thanks for wanting to help!! 2003 bmw 325i. (M54 - Automatic) Car ran really rough before I started work on it. Shaked/ran ve

Check for vacuum leaks, including that through a malfunctioning EGR system. When you first start the car, on cold start the mixture may be rich enough to overcome such leaks, but almost immediately the ECM can't keep up with the...

2008 BMW Z4 alarm won't beep when locking but lights flash and red light blinks under rearview mirror

Hello. If the horn is working normally then you have a programming issue. In most cases the control module for the alarm will need to be reprogrammed by the dealer in order to make it operational again. If the horn...

Check Engine Light NOT coming on during start-up

When you turn on the key, the check engine light should be on, this is a bulb check function. As you know, the check engine light has to be working to pass inspection. The bulb may be out, or it...

Related articles

Ten Sports Cars That Double as Good Daily Drivers
The best daily driver is a car that's reliable, usable, and still fun to drive. Popular daily sports cars include the BMW M3, Subaru WRX, and VW GTI.
A Buyer’s Guide to the 2012 BMW 6-Series
With With an eye-catching restyled exterior that still boasts the basic signature grille shape, the 2012 6-Series is packed with modern features while maintaining its classic image and top-of-the-line performance. Key Features 4-way adjustable suspension BMW apps –...
How to Purchase a Pre-Owned BMW
BMW BMW offers a wide selection of luxury cars. In many circles, owning a BMW is a sign of success. While most balk at the price of a brand new BMC car, pre-owned models provide a viable alternative if you...