throttle body cleaner islike 5 bucks so it cant hurt. but i dont think thats it. bad 02 sensor prolly isnt causing the issue and it should throw a code anyhow. but like lugnuts says sometimes OBD I fails, soive posted on an earlier thread how to check it manually.

check everything that lugnuts said, and lug, do you remeber when flathead31coupe was having this same problem? howd he solve it?

Id PM himand see if/how he fixed it, power ram.or backtrack through his posts, where youll find how to check o2 sensor if you like.

 

Not sure what F -31 found,he had multiple issues with his truck. Bad connections mostly I believe. On the MAP, if the port is restricted,it will pull a vac on the sensor,but not bleed the vac off fast enough for the sensor to react in time to fatten the mix. However,doesn't seem like the problem would be intermittent,unless throttle opening rate has an effect. The PVC ties in the back of the throttle body,can *** up the ports over time. Pulling the TB and taking a look won't cost anything.

An intermittent will drive you nuts. The best way I've found is to run test circuits with a bulb taped to the windsheild tied into whatever 12v + you suspect. Fuel pump,coil+ etc. if you suspect a loss of juice. Same for fuel pump/press,a gauge is the only way to catch it.

On the computer,a scanner that logs data,and gives a real time read of what's happening is a big help,and almost impossible to do without to eliminate possible problems.However,even a scanner isn't foolproof. On numerous occasions I've had all parameters to spec,and the damn thing run like crap. Even had a few that GM techline couldn't diagnose.[Chevies]

My best advice is to check all the simple stuff first,includingALL grounds. A bad ground forces devices to hunt an alternate route,usually through another
circuit,and also changes the resistance of an affected sensor. Seen it more than once,and chased my own *** trying to figure it out.

I'm old enough to remember points and carb tune ups,at times a twist of the idle screws,and filing the points doesn't seem so bad

[hr]

What's with the friggin lines!?! Posted,had lines in the text,gone now. Maybe I'm older than I think!

 

Do like lugnuts says check the fuel pressure you may have a fuel pump going bad I have seen many cases like that in my year in the automotive field. Cars or trucks will idle fine but given gas the fall flat on there faces. So check the pressure and if it is not to specs replace fuel pump.

 

i have an 87 d 150 and i was having a similar problem with my truck and it was a Black wire on the driver side fender that runs to a splice which turns into four splices which power the important parts of starting and running your engine.here is a pic of the splice i replaced that gave me fits.it will cause you too spend a fortune replacing parts and also cause severe hair loss.....good luck hope this helps.

 

well looks like im going to have some "fun" next weekend...
I talked to flathead31coupe he replaced the semc and everything works great he says.


I am going to buy a scanner with real time reading and start with the cheapest stuff first.

Side note: this truck was a texas parks and wildlife truck that wasnt used very much on pavement
has only 70,500 miles on the 318. I payed 1,200 for it

 

Im looking at the throttle body and I have some questions.

on the front of the throttle body theres a small piece of hose connected to the canister purge nipple but it has a bolt plugging up the end of the small line, is that suppose to be plugged up?? Also, on the back theres a short piece of line cut and plugged up with a bolt. Ill provide pictures.

 

hey i think there are3 hoses coming out of the TBI which could be the ones in question.
one to air cleaner
one that is plugged by factorywith a rubber stopper(not sure what its for - maybe to check TBI for vacuum?)
and one going to theAIR pump. Coincidentally, ive got that one blocked up witha bolt.
hopefully that saves you from having to get pictures.

heres a picture to maybe try adn makes some sence of my babble. http://i244.photobucket.com/albums/g...rfectcrime.jpg
you can see the one running from the back along the valve cover on the left, then going over to the right to the air pump. now if the line "sticking out the canister purgue nipple" is what i think it is you cant really see in this picture but it runs into the same hose bundle and also gets plugged (factory).

 

yes thats what i have. On the back of the throttle body where the main wireharness connects there is a nipple right by the connection. Is that suppose to be blocked?

http://i62.photobucket.com/albums/h1...3/DSC01419.jpg




[IMG]local://upfiles/68974/C0E11720A02A4D8CA7CD28718FCB7333.jpg[/IMG]

 

I think i might have found the problem...

After reading the chrysler service manual and tracing vacuum lines some of them arent hooked up right from what ive read and pictures

The way it is on mine is the speed control vacuum hose/power brake and the line from the fuel pressure regulator connect into the manifold vacuum source, and a another line that runs back to the tank (im guessing??)then a line from that source hooks into the three solenoids(egr,air switching, canister purge.) In the book it says the vacuum line from the fuel pressure regulator connects to the fuel pressure regulator vacuum nipple with a short piece of vacuum hose, which in the picture I have provided is right by the fuel injectors wiring connector, and on mine its plugged with a bolt!

http://i62.photobucket.com/albums/h1...rottlebody.jpg

 

NO vac. to the regulator should make it run fat. Was the reg. hooked to anything? Amazin' the way things get 'rearranged' ain't it?
Didn't get your pm till now, my apologies. Fix the problem?