running rich

[cutlassranger]

hey i seen on the spark plugs it running rich, how can i adjust this....what abotu the screw right in front of the engine new the throttle

 

[Psychopete]

hey i seen on the spark plugs it running rich, how can i adjust this....what abotu the screw right in front of the engine new the throttle

That screw is the base voltage adjustment for the TPS sensor. Do not touch it . The computer controls the idle. There are no other air fuel adjustments.

Are you plugs black from before? I noticed in your other thread that you replaced the fuel pressure regulator and it resolved some of your problems. Most fuel pressure regulator problems cause rich condition. You might just need to replace the plugs if you haven't done so already.

Pete

 

[AllanD]

As I always say when dealing with 86-87 2.9's

Check to make sure there are no vacuum leaks in the EGR system.

check the "christmas lines" (the red and green plastic lines)

After that REPLACE the Engine Coolant Temp sensor

checking for codes isn't always reveraling because the computer doesn't recognize an "almost right" sensor reading as wrong.

EEC4 is also specifically designed to NOT throw codes for the HEGO
(or it's be throwing codes constantly because the HEGO is an active sensor)

Or if you want to short circuit about half this diagnostics stuff simply swap
in an '88 Computer

'88's don't have EGR and thus don't go ape shit when it believes the EGR is malfunctioning.

AD

 

[RustedRanger]

My 87 is running rich once it warms up,I can smell it. When I first got it the exhaust past the converters was gone and it was annoyingly loud and the idle was high so I turned the idle down using the adjustment screw. Since then I have changed the plugs and filters and put on exhaust. I got the O2 sensor yesterday and want to change it today and I was hoping that is why mine is running rich. It has 147K on it and appears original (O2 sensor). My idle is wacky also,sometimes it idles at 1100 and then slowly drops down and sometimes it idles at 850 like its supposed to and other times it bounces up and down. I haven't learned enough yet to read the codes but I have done it on GM's and I don't have a voltmeter,but I can probably borrow one if need be. I read through the Haynes manual but sometimes it good and sometimes vague. So a coolant temp sensor is a good idea if the O2 sensor doesn't help the running rich? Thanks AD

 

[fastpakr]

First fix your 'idle adjustment'. Go get the voltmeter you need anyway and adjust the TPS so that the output voltage is around .8, then reset the computer.

 

[pun]

how do you check the egr system, when ni checked the codes it gave me 84- EGR vent fault, and 31-EGR valve control sensos fault. i know i dont have the red and green lines connected, thats the way i got the truck. can anyone explain how they go connected to the vacume system, i know the truck is running rich. i have a 86 2.9 also.

 

[fastpakr]

You should have a vacuum diagram on the core support. If not, you can go to your local library and find the Mitchell manual for Domestic Light Truck and Van (1986). It will have vacuum and wiring diagrams as well as troubleshooting sequences for each code that will allow you to nail down the exact cause of the problem.