roy Arrington

OK, the service engine soon light led me to change the Bosch MAF sensor and the power and burn down relays. the new MAF was not Bosch but comes with a lifetime warranty. So after about a month it starts bucking every so often at highway speeds. runs smooth and thump a momentary problem that may or may not illuminate the light. so I changed the "new" MAF and got the same result. I just picked up replacement relays because the documentation recommends doing that if the sensor doesn't fix it.

Has anyone run into this recurring problem. I have the Bosch in the bottom of the tool box and may revert to putting it back in because I got good gas mileage...and just a nagging light. The new ones have taken 10 mpg off the average.

cv67

What brand was the new one?

Check the pins in the end of the connector, make sure they arent corroded or out of shape. Apparentyl if they are it can cause all type of gremlins.

GREGGPENN

Don't remember where I read this, but I believe the test for a bad MAF is rapping (smacking) it with the handle of a screwdriver. If the car idle changes, it has a loose connection and is bad.

5speedC4

I have to remember that one. Just remember not to use a hammer!

Sam Lam

Roy: How does the engine idle on the 89? Smooth or rough?
SAM

GlennS87

I had a Wells thin film MAF I tried a couple of years ago. The chip in my car is a modified ARAP (6E which is an 89 chip). I would periodically get the same symptons you mentioned. When I ran my scanner, I believe it was setting the code for MAF voltage high (either 33 or 34). I swapped back to my gutted Bosch and the problems went away.

I gave the sensor to a fellow forum member who did me a favor. He said it worked fine in his unmodded 85. I believe they use a different type of MAF but I don't know the sensor.

rick lambert

I've posted this before, but if you read your Helms, there is a section that talks about the voltage to the MAF being controlled through the
Fuel pump relay-might be worth checking.While your at it check the wires going into the relay-the insulation on mine was shrunk and bare wires were touching each other-common problem on earlier C4s.

roy Arrington

Great stuff. My Bosch was bad BUT did not seem to cause problems except for the service enging soon light. I will check out the fuel relay and the wires.


The car idles good and runs good with the exception of the recurring "bump or chug" and 16 MGP.

I'll run all these suggestions and see what happens. if it is still a problem I will check out the old Bosch with the new relays

thanks for the info

roy Arrington

OK, check this out. A new non-bosch MAF,2 new relays and the same problem. Changed the fuel pump relay (thanks for the info gang) still had the problem.

OK WHAT NOW! Well, what did I have to lose? I put the bosch back in and with the new relays the problem went away. I went for 30 mile cruse tonight and no chugging and no service engine soon light....gas mileage went back to the mid 20s.



this is a great place to get info for our cars