Excessive fuel consumption

MARK K PICTON

MEMBER
1996 JEEP GRAND CHEROKEE
4.0L
6 CYL
4WD
AUTOMATIC
250,000 MILES

The vehicle used to get twelve to thirteen liters per 100 km which was great. It is now using twenty one to twenty two liters per 100 km; very bad!
I had a reconditioned gear box installed and had a lot of problems with the car loosing power and stalling immediately after, it was if fuel was not getting to engine. Used injector cleaner in fuel, changed plugs and leads and eventually car settled down but is now running very rich. I have taken car for analysis and there are no codes revealing any issues. When I first start car a black charcoal burn comes out exhaust as if fuel not burning correctly. Can you suggest possible issue?

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,690 POSTS

Hello,

It sounds like you are having a problem with the MAP of MAF sensor which controls the amount of fuel that is used inside the engine. When these sensors go bad the computer sometime can not catch it.

Here is a guide that will help you replace the sensor

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Please let us know what you find ;)

Cheers, Ken

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Monday, May 22nd, 2017 AT 10:40 AM

MARK K PICTON

MEMBER
2 POSTS

Thanks Ken. Pulled the MAP out and did MAP Sensor Test using multimeter and my breath. Sensor appears to be working at 0 in. Hg. 4.67V and decreased as vacuum increased then increased to 4.67V as vacuum released.

2 Questions:
Is there anyway to clean MAP Sensor as appears to be sealed unit?
Even though appears to be working, considering its age and kms travelled, now that it is off would you recommend I replace it?
What else may be causing the excess fuel use?

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Monday, May 22nd, 2017 AT 7:57 PM

KEN L

MASTER CERTIFIED MECHANIC
47,690 POSTS

The map sensor does seem to be working and there is no need to clean it. A couple of things come to mind, first has the engine been tuned up lately? Next there can be a vacuum leak causing the problem here is a guide to help you find it.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

and third is a plugged exhaust system mainly the catalytic converter. Here is a guide so you can test that as well.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken

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Tuesday, May 23rd, 2017 AT 10:00 AM