134,000 miles has msd cap rotor wires and motorcraft platnium plugs. base time is set at 10 degrees. has good fuel pressure. i haven't really worked on the SD trucks much but know that tps and map are pretty important. far as i can tell no vac leaks that i have found and put voltmeter on tps and did a slow sweep, didn't appear to have any dead spots or shorts. at idle it reads .77 volts. is there a way i can test the map sensor with a dmm? or any other suggestions to look into? all insight is appreciated

 

MAP sensors are frequency based and it will probably fluctuate since the motor isn't idling smoothly. One thing you can do is take your coil and ignition control module out and have them tested. Most auto parts stores will test the for free.

 

Is the truck rocking at all? Check the spacing on your plugs, and make sure they are seated correctly. I had a rough idle issue when i did my plugs, the spacing was off and causing minor miss fires. Are you sure the timing gears are set correctly? If motor was rebuilt it might be off timing even tho it says its right.

Other than that idk. Could also check motor mounts, could be going bad and causing unwanted vibration making it seem like it is idling rough.

 

I would pull the spark plugs and do a compression test. You can't know what is wrong until you check the compression. I would first test with the engine cold after sitting all night, and then give each cyl 1 squirt of oil with an oil can, crank it over a few times and test the compression again. Compare your tests, low cyls are a problem.

 

Any codes? Have you cleaned the throttle body? Is the EGR functioning properly?

 

Idle TPS should be about .99 at idle if I remember right.
If you relace it go with the better TPS and not the el cheapo. You'll be buyinh another one real quick. the El cheapo lasted me about 2 weeks...

 

Most liked to use the copper plugs with the modified electrode with the lightening. Works the best.

 

well did compression test all were pretty good and only about 15 pound difference between them all. i haven't cleaned throttle body or anything with it. prolly couldn't hurt and will when i have time. as far as egr goes i dont really know how to test if it is working properly. pulled the vac line of it when idling and there was no vacuum in that line which i believe is normal and i applied vacuum to the valve and it tried to kill the motor which again i believe is normal, please correct me if im wrong. it does need motorand trans mounts which i have been neglecting to do, but along with the rough idle it has a slight rpm surge while cruising that i have been starting to notice. nothing extreme at all just barely noticable.

 

well kinda getting a new issue now that every once in a while when mainting 45 it acts as if it shifts itself into neutral then will hit 2nd or 3rd... with the tps i read through an old chilton i have and said the range for it was something like .6 to 1 volt. it was at about .9something and i figured the closer to the middle of that range would be better and just loosened the screws and adjusted it down a bit. that was the same time i put the msd cap rotor coil on it and set base time to about 13. that was when this issue first arose and i thought it was sensing a spark knock or something from the added timing and it was the computer taking the load off the motor. it went away after going back to 10 degrees. today i had the ign mod tested and passed same with coil. and got a map sensor and went for a drive and it didnt really seem to help with the rpm surge but it did "shift" into neutral again once while cruising... it seems to shift and drive fine so i dont think there is any issue with the trans itself other than that. and it sometimes has a hard shift when just barley on throttle on occassion.. sorry for the long and most likely confusing post. again all insight is greatly appreciated

 

oh and i have no codes. sorry i forgot to put that in the other post

 

I would double check the fuse box for damage/growing green stuff. Also the power diode. Closely check out electrical connections 1st. You can always plan a trans Reb as it continues to worsen. When your reving and not going too good you know. Pulling the drain pan, removing the trany valve and looking for broken metal will help locate that type of error to the hyd system of the trany. Also allows for metal chips inspection/filter changes/ general trany maintenance. If it isn't electrical, eratic hyd pressure will cause havoc to the control functions, creating wear/damage/clutch/piston distruction.

 

it only has the hard shift once in a while which would lead me to believe its an electrical issue. if the computer dose sense a spark knock dose/can it shift the tranny in neutral like that to take the load off the motor? 95% of the time it drives and shifts perfectly fine. just has this slight rpm surge. i dont think that the surge has anything to do with the tranny as it will do it in all gears and when the OD button is off so it shouldnt even be trying to lock the converter. i still have yet to take the TB off and clean it up. hoping i will just find something simple like EGR valve with buildup and leaking slightly or IAC gummed up or something. when i bought the truck i was told the previous owner had taking it in every 2 months since it was new for oil change, tire rotate and checkup. has had at least 2 tranny fluid and filter changes. the fluid thats in it looks to be fairly new, still nice pink color and no smell of burnt clutches or anything. when ever i get time i plan to check wire harness/connections for motor and trans.

and thanks all for all advice so far

 

No, the GEN 1's were not equipped with knock sensors from the factory.

Throttle tip-in will cause ECU to delay converter lock-up which will initially raise the RPM's and then lower once the converter is locked. The ECU can/will also flash(unlock and then re-lock) the converter during shift transitions.

Turning the OD off will not keep the ECU from locking the converter after tip-in.