98 Mark Viii Running Lean

[jtmforever]

I got a obd code p0174 and p0171 for a while now. My fel pressure was 25 psi so I changed the fuel pump and its back up to normal specs. I've blocked the pcv hose, intake breather, and sprayed around looking for leaks. I can not find any. I changed the fuel filter too. After resetting the pcm, my long term fuel trim is slowly creeping back up to 25%. If I rev the engine higher, the ltft goes back to 0%. Are there any other vacuum lines to look for or anything else. Please help

 

[mikemark8]

don't know how much is different a second generation is, my first gen (96) has a bunch of vacuum lines, and they dry out and crack sometimes making it hard to find leaks-i had a similar issue a few years ago and sprayed like crazy, found nothing, then just started removing lines and going over them with a magnifying glass-i found one plastic hose with small cracks, about 2 inches long and very fine. replaced and problem solved. Also, check IMRC shaft ends, they are known locations for vacuum leaks.

 

[slowmkviii]

Could need o2 sensors

 

[BILLBOATS]

Defective IMRC can set a lean code

 

[jtmforever]

Ok how do I check the imrc. And if it is leaking, How can I repair it?

 

[BILLBOATS]

Make a hole(take things off the back of the motor. I took off my hood making much more room to get at IMRC. I also took off the wipers and black windshield lower molding strip. Have a friend start up the car and with a flashlight look at the controll to see if its moving the metal arm connected to the shafts protruding out the back of the motor. It should move up and down like a old choke pull off. The other way is to remove the imrc, suck on the vacume till the metal rod contracts. If it stays contracted, the imrc is good,. If it returns to its non contracted position after you suck on the vac line without letting go, its got a tear in to diaphram . I have heard one guy from new jersey say a shop vulcanized his. This would mean cutting the imrc's shell open some how or bending the lip that goes around it. I have never taken one appart. The best thing after you make sure its imrc is to find another one and replace it. They are right and left handed so be sure you know if its the drivers or passengers side yours is on. They are hard to find. Buy the way the Jersey guy said his repaired one lasted just 3 mths.

 

[BILLBOATS]

hey, do you look or just write