89 2.9l high hydrocarbons and rough high idle
 

1989 2.9l trying to get it to pass CA smog but hydrocarbons are high...idle is around 1000rpm (i have re timed it a bunch to 10btc) very rough but no hesitation while going up through the band and smoothes out about 1500. thought maybe missfire or a clogged injector but replaced fuel injectors, spark pugs, wires, cap rotors, EGR valve, MAP sensor. ran seafoam through it too and nothing. tired of throwing parts at it so any help would be awesome. oh and compression test passed and i do not think it could be o2 sensor because just hydrocarbons are high.

Re: 89 2.9l high hydrocarbons and rough high idle
 

Check for a leak around the intake. Spray carb cleaner around while the engine is running and listen for a change in how the engine runs. Also you could try clening your MAF (Mass Air Flow) Sensor.

Re: 89 2.9l high hydrocarbons and rough high idle
 

Does a 1989 have a MAF?

Re: 89 2.9l high hydrocarbons and rough high idle
 

2.9L are notorious for rough idles

Re: 89 2.9l high hydrocarbons and rough high idle
 

mine idles at 1k rpm and its kind of a shaky idle could just be the motor mounts are worn allowing for more movement

Re: 89 2.9l high hydrocarbons and rough high idle
 

Only the later california emission models had a MAF system.

Re: 89 2.9l high hydrocarbons and rough high idle
 

easy fix.....

get out of Kalifornistan

lol

Re: 89 2.9l high hydrocarbons and rough high idle
 

I'm having the same problem, with my 88 of the same size. Plus I live in Washington, the emissions laws are pretty damn close to Cali's. I read somewhere that the 88 2.9 is particularly finicky about grounds. The poor guy ended up replacing just about every sensor he had just to find out a ground hadn't been reattached to the back of the block after a professional rebuild.