e38 750il 750il engine running rough sometimes.

[jenglemn]

My 1996 750il has an engine stutter sometimes. It happens at low revs with low load, and now at stop lights. The motor will drop off completely and save itself and come back to regular idle at stop lights. When running down the road at 40 or so in final gear it will do the same, creating a stutter that is felt. It has been doing this for a long time, but now has progressed. No codes are present. Many motor, air, and ignition parts have been replaced during the years for other circumstances unrelated to this issue.

Random low load, low rev failures usually indicate ignition issues. Any ideas?

[CPHES]

MAF sensors and intake manifold gasket leaks - there is a way to reuse the intake gaskets - I’ll look for that link.

[jenglemn]

MAF's and boots were replaced last year. 1 rear intake baffle was replaced last year. Plugs and wires, cap, were replaced last year. This car has always had this stutter when driving in final gear. I could eliminate is by shifting into 4th, thinking the overdrive was wearing out. Now the stuttering has gotten worse and is happening when driving down the highway, and at stop lights. I am happy it is not the transmission! The car does not get driven much, and is garage kept.

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MAF's and boots were replaced last year. 1 rear intake baffle was replaced last year. Plugs and wires, cap, were replaced last year. This car has always had this stutter when driving in final gear. I could eliminate is by shifting into 4th, thinking the overdrive was wearing out. Now the stuttering has gotten worse and is happening when driving down the highway, and at stop lights. I am happy it is not the transmission! The car does not get driven much, and is garage kept.

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The car will not setup for monitor inspection clearing this year, and kicks various misfire and air codes occasionally, so I know something is going on.

[CPHES]

Any error codes? A 96 should be obdii. I know that 95’s are an odd build.

[jenglemn]

Yes..I just looked to see if it setup for inspection and it was. It also just kicked 2 p1270 codes. (manufacturer fuel air metering)

And after driving a bit when start up got 12 codes..p0300 (random Multi misfire)
p0307 cylinder 7,
p0309 cylinder 9,
p0312 cylinder 12,
p0308 cylinder 8,
p0310 cylinder 10,
p0307 cylinder 7,
p0312 cylinder 12,
p0308 cylinder 8,
p0310 cylinder 10,
p0309 cylinder 9

All on the left hand side!

[jenglemn]

And after driving a bit when start up got 12 codes..p0300 (random Multi misfire)
p0307 cylinder 7,
p0309 cylinder 9,
p0312 cylinder 12,
p0308 cylinder 8,
p0310 cylinder 10,
p0307 cylinder 7,
p0312 cylinder 12,
p0308 cylinder 8,
p0310 cylinder 10,
p0309 cylinder 9

[Timm]

The stutter in 5th gear is most likely to be the torque converter lock-up clutch - often mistaken for a misfire! More info on this forum and below:

https://www.meeknet.co.uk/E38/BMW_E3...dy_Misfire.htm

...but it sounds as if you have new problems as well....

[jenglemn]

It is one of the MAF's. I diagnosed it by tapping on the left bank sensor at idle and the symptoms were reproduced. All the misfires on the left bank pointed to that MAF. I replaced the MAF, and all is well. Sometimes that stutter in overdrive is a tranny failure, and a bad MAF will give the same characteristics. Lesson learned on this one...don't buy cheap MAF's from Rock auto.

[CPHES]

Glad it is figured out