1991 m42 318i check engine light!

[E30ruben]

I've never ever had a check engine light turn on in any e30 that ive owned! So , i got a motor swapped, same motor same everything just another one because old one had low compression...Everything was fine up until today i started it and check engine light turned on and stayed on. When i first turned it on today i couldnt rev it, it would bog and die, as it warmed up it seemed to have gotten better. At normal running temperature the care runs eh ok, but seems a bit slower. I used my friends OB1 scanner and i got a code 43, i've tried looking it up online, any help guys please! Thank you all so much!

[Balleristic31]

Do stomp test and report back with the code

[E30ruben]

Stomp test...?

[CrusherCurtis]

http://www.e30performance.info/viewtopic.php?f=35&t=1528

BMW E30 Motronic Fault Codes

Procedure for acquiring error codes from Bosch Motronic DME - aka "Stomp Test"

BMW e30 s, which are 1988 and newer, have Bosch Motronic versions M1.1, M1.3 and M1.7 and can display fault diagnostic codes. Procedure for obtaining codes is:

For safety reasons, put the transmission in neutral, and turn the ignition key to "On" position but do not start the car
In quick succession fully depress and release accelerator pedal 5 (five) times
After couple of seconds Check Engine light will blink once, and start to flash code(s)
All codes are composed of 4 digits (see table below). For example, code 1211 is represented as Blink, pause, Blink Blink, pause, Blink, pause, Blink
When code(s) start to repeat, all of them have been displayed

code definitions here: http://e30world.com/fuel/BMW-E30-DME...ic-fault-codes

[E30ruben]

Thanks! Will try it tomorrow

[E30ruben]

Came up as 1223. Coolant temp sensor. Before I picked up my car from the shop my temp gauge didn't work and I asked him to fix it since it worked before the motor swap,. Car ran perfect. When I go pick it up check engine light is on and the symptoms above occur but now temp guage works

[oldmann]

2 Temp. sensors on M42, 1 for guage 1 feeds DME. The 1 towards front of engine is for the DME.

[E30ruben]

But what could those bogging symptoms be when the motor is cold...?

[oldmann]

Coolant temp. sensor not getting correct info. to DME when cold. Your Intake Air temp. sensor may also be an issue.

Air temp. sensor is part of the AFM, can't be replaced by itself. Bentley and Chilton both have directions for testing. May be dirty.

Either one of these could cause a cold engine issue.

You just swapped engines, Issue may be related to wiring, with everything being moved around for the first time in 20 yrs. oil and heat soaked
wiring gets brittle.

[E30ruben]

Coolant temp. sensor not getting correct info. to DME when cold. Your Intake Air temp. sensor may also be an issue.

Air temp. sensor is part of the AFM, can't be replaced by itself. Bentley and Chilton both have directions for testing. May be dirty.

Either one of these could cause a cold engine issue.

You just swapped engines, Issue may be related to wiring, with everything being moved around for the first time in 20 yrs. oil and heat soaked
wiring gets brittle.

But right after the swap, when my temp gauge didn't work the motor tab perfect, then he fixed my temp gauge and check engine light comes on and symptoms as stated above occur.

[oldmann]

Did your mechanic fix the temp. guage by swapping plugs and sensors?

How many mechanics fix one thing and screw up another, You won't know why one thing is wrong without cking out the sensors and plugs. They may only be loose.

Something changed after engine swap, dig in and find out what.

[E30ruben]

OK sooo.... ive still been trying to figure out the problem. I have purchased a new coolant temp sensor, the ones that feeds the dme, AND i swapped MAF sensors with a friend of mine off his 91 318is. On a cold motor, bogging still occurs! ive ran out of options.

I noticed that on an early morning start 7-8AM the bog doesnt occur. This is beyond weird