compression test...

[junkfixr]

reveals... 180 + p.s.i. on all cylinders except back passengers side which is 175 / more or less.

Does this sound normal ? No leak downs detected and I'm wondering if the guage is correct. Sounds like alot to me ?

 

[Spitfire1975]

2.9? Mine is 160 on all six. Tested with engine warm? Coil unplugged and WOT? Roughly 7-8 engine rotations? Cylinder readings should be within 10% of each other. I had a Volvo with 180 psi, so it is not unheard of. Don't know about the Colognes though......No leak down is good........perform a vacuum test as well. Will give you the other half of the story.

 

[junkfixr]

sorry.. meant to post on 2.9 fourm...but

thanx for the help. Didn't test it warm, has been sitting a couple of days.

All plugs were out & upper manifold was off. Just wanted a baseline before I went any further or dumped any more cash into the truck. It seems that all cylinders were even across the board so I'm grateful to know I don't have a cracked head or gasket problem.

As far as the vacuum test.. what am I looking for here & what's it gonna tell me ? My truck is running very good , but extremely rich & the mileage is down from 18 to about 8mpg.

Would one (or more) sensor(s) possibly be responsible for this problem ? I've done EVERYTHING except replace the computer.. so now that is my gut feeling.

Do they stay in open loop and run rich if a sensor (or more than one) is not responding...? EEC IV module About to cut the top off the upper intake & heli-arc flanges on each manifold riser so I can mount 3 two bbl carbs if it keeps this up ... LOL A 2.9 with a six pack & Accel distributor

 

[Spitfire1975]

They can. What have you changed? Have you pulled codes yet? Checked for vacuum leaks? Vacuum test will let you know if valve seals are bad, etc...(other guys here will know more). It can also give you an indication of plugged cats. Vacuum should be around 20 in. and not fluttering around too much.

Coolant Temperature Sensor, Air Temperature Sensor and O2 Sensor control your open/closed loop positions. (I don't think others do?).

 

[98 ranger xlt]

Thats still normal. your compression test numbers can have a 10% varience