what would you check next?

[LittleHorse]

Fixed the exhaust leak Friday, no change. Will be checking fuel pressure tomorrow.

There is no smoke in the exhaust and my oil consumption is about half a quart in 4,000 miles so i think a ring wear problem is unlikely.

 

[LittleHorse]

Lol. Key on engine off, fuel pressure jumps to about 12psi and then bottoms out at about 2 within a few seconds.

Start the engine and the pressure climbs to about 32 and jumps as it should when goosing the throttle. Turn the engine off and it falls to 2 psi again.

I take it this probably indicates leaking injectors? lol


By the way, I forgot to mention I've been getting about 17mpg in highway driving and barely 15 city, and the thing shakes like crazy at idle.

Looks like I'll be shopping for some injectors. I was really hoping they'd be fine since the only place I've looked so far is AutoZone and they're about $60 each.

My thought is that one or more injectors is stuck open and/or severely leaking, causing the O2 sensor to pick up a rich condition, which then signals the computer to try to lean out - so I could have 2 cylinders running rich and 4 running lean. Sound logic?

 

[LittleHorse]

anybody ever had any experience with remanufactured injectors? Says they're flow matched with a lifetime warranty and appear to be legitimate.

 

[LittleHorse]

ok, I thought injectors made perfect sense given the behavior and the results of the fuel pressure test.

But I installed reman injectors last week and it made no change whatsoever. I also fixed the exhaust leak (again, first fix failed) but it made no difference, other than eliminating that annoying click sound.

Tomorrow after I finish installing a power steering pump and new front shocks I'm going to test the TPS and MAP sensor. I tried to have it done today at AutoZone, but much to my surprise apparently they don't do that anymore. I guess the bean counters must have figured out that they would make more money if people just bought new sensors without testing the old ones. So i'm gonna have to buy a vacuum pump to test the MAP sensor.

If those are both fine, I'm kindof at a loss. With my vacuum steady and in spec and burning less than half a quart of oil between 5k oil changes it's hard to see it being a ring or other mechanical problem. The only electrical things left will be the coolant temp and oxygen sensors, which I don't think would be the issue since the behavior is present in both open and closed loop operation.

 

[BRUTUS_T_HOG]

have you checked the ignition timing?

remove the SPOUT shorting bar and use a timing light to adjust timing to 10degrees BTDC

 

[LittleHorse]

have you checked the ignition timing?

remove the SPOUT shorting bar and use a timing light to adjust timing to 10degrees BTDC

AH! That reminds me...I spent about half an hour last week looking for the SPOUT connector to do exactly this. The stupid Haynes manual doesn't give it's location worth a crap. It does pretty well for the 2.3L Ranger, even shows a pic, but nothing for the 2.9. Where the hell is that stupid thing???

Also, any tips/tricks to adjusting the distributor with it shoved back there between the intake and the firewall? I have my fingers crossed that I'll find out the timing is correct so I won't have to mess with it.

 

[LittleHorse]

my TPS tested out fine but my MAP sensor only has about 2.5V at zero vacuum...to the best of my knowledge it should have like 5V.

Can't test it with vacuum yet 'cause I don't have a vacuum pump...but if throttle is wide open but the MAP sensor is still reading a fair amount of vacuum I could see how that would not run very well.

 

[dernst]

To properly test a MAP sensor you will a vacuum pump with guage and a way to measure frequencies (Hz-- Hertz). I did it one time with a rpm meter but I wouldn't do it again.

The way I test it now is to just do a swap. I have an extra one from when I purchaced an extra motor to rebuild. Maybe you can borrow a known good one from a friend to do a test swap.

For MAP info look here

http://fordfuelinjection.com/?p=27

 

[robertc1024]

Somebody posted a picture of the SPOUT connecter in a different thread a couple of days ago. Let me see if I can find it for you.
http://www.therangerstation.com/forums/showthread.php?t=71433

 

[LittleHorse]

To properly test a MAP sensor you will a vacuum pump with guage and a way to measure frequencies (Hz-- Hertz). I did it one time with a rpm meter but I wouldn't do it again.

The way I test it now is to just do a swap. I have an extra one from when I purchaced an extra motor to rebuild. Maybe you can borrow a known good one from a friend to do a test swap.

For MAP info look here

http://fordfuelinjection.com/?p=27

I came across that link and then I found some other posts here on TRS that talked about checking voltage...so I was hoping that maybe the voltage varied along with the hertz in such a way that testing voltage would be a roundabout way of checking it.

I went ahead and just bought one over lunch, since it's about the only thing left to check anyway. I have another 90 Bronco II that I've swapped with but it doesn't run that great either so I've got no real certainty that the MAP sensor on it works any better.

I hate diagnosing by parts swapping but if AutoZone is gonna quit offering testing services and I have to buy a bunch of special tools then sometimes it economically makes sense to just buy the sensor.

 

[LittleHorse]

Somebody posted a picture of the SPOUT connecter in a different thread a couple of days ago. Let me see if I can find it for you.
http://www.therangerstation.com/forums/showthread.php?t=71433

Thanks, I'll look there for it after work.

 

[robertc1024]

Ok - keep posting up though. Sorry I can't be more help. I've only had to do routine maintenance on mine so I'm not too insightful on these weird problems.

 

[BRUTUS_T_HOG]

AH! That reminds me...I spent about half an hour last week looking for the SPOUT connector to do exactly this. The stupid Haynes manual doesn't give it's location worth a crap. It does pretty well for the 2.3L Ranger, even shows a pic, but nothing for the 2.9. Where the hell is that stupid thing???

Also, any tips/tricks to adjusting the distributor with it shoved back there between the intake and the firewall? I have my fingers crossed that I'll find out the timing is correct so I won't have to mess with it.

its near the distributor, looks just like the picture.. you'll just have to look.

the distributor is easy to adjust all you have to do is loosen the bolt enough to move the distributor but not loose enough that it won't stay. just move it slowly until you reach 10 degrees BTDC, then tighten the bolt and recheck

 

[LittleHorse]

just got back from a 9 day vacation and finished installing a new PS pump and replacing the front left shock (of course the stud broke off the radius arm). I am pleased to report it now starts up without an excessive amount of cranking, likely to to not having the injectors lose all the fuel pressure when turned off...but I still have the bucking and surging and general lack of power.

I did notice the bucking and surging seems like it may only be in closed loop...but it still is majorly lacking power in open loop.

I've got a huge PS fluid leak now so I'll have to take care of that before I can do much driving and checking timing and whatnot.

 

[techsvcs]

have the tfi module checked i have had to replace 2 of them because of the bucking/surging problem i changed everything just about before i went back to ignition module because i just had it replaced 3 months prior then i said what the heck and took it to autozone to have it checked and it failed all red lights on the test and one green. they gave me a new one and blamo problem gone! i understand that because the module is located on the distributor and towards the back of engine the heat kills these module. there is a mod where the module is re located to the front of the truck. hope this helps.