You guys have helped me in the past so Im going to see what you got this time.
Ive had the TPI 350 in my jeep wrangler for 2 years now and its behaved fairly well for the most part. Now I want to sell it and its starting to give me a problem (seperation anxiety?)LOL
It will run drive and idle fine most of the time but now and again as I come to a stop the idle will start to drop. My normal idle is 750 and when this happens itll go down to around 400 (its only stalled a couple times). I can tell when its going to do this even while the R's are still as high as 1100, cause the engine just sounds quieter and smoother.
Its not like a vac leak because the engine never stumbles or misses.
Ive tried putting it in neutral,and sometimes it helps and today it made no difference. I was starting to think the 350 trany wasnt down shifting all the way to first and bogging the engine down, But now I dont know.
The couple times it did stall, as soon as I restarted it, it was right back to normal.
I drove around w/ the laptop a little today and didnt notice anything really wreird (altough I must admit I pry dont know what Im looking at). The IAC did get down to around 20-30-40 steps during the problem and at normal idle it is around 80 steps (but then again I dont know what any of that really means).
If anyone has Any ideas of what I should look into, please let me know.

Thanks Jeff

 

When was the last time you cleaned out the htrottle body? My guess is that the IAC and it's passage are gunked up with black stuff (oil residue from the PCV and breather systems). I'd pull the TB and clean it out thoroughly. Check the IAC and if it's gunked up too I'd replace it as well (my attempts to clean them have never born fruit). The ECM might not see this as a problem, since it has a physical cause and not an electrical one. The IAC may be telling the ECM that it's doing its job, but in reality it can't because of the contamination. I'd start there.

 

thanks,
Im planning on pulling the Iac tomorrow after work and ill see what it looks like in there.

jeff

 

well, everything looked clean in there. One thing that seemed odd was the idle never changed when I was plugging and unplugging the IAC's wiring.
Shouldnt it have done something?

Jeff

 

I replaced the IAC tonight w/ a new one and it made no difference :-(
Could the torque converter cause these symtoms? It almost seems as though its not downshifting. When everything works right, I can hear and feel the engine down shift and the idle will stay right were I want it. But, when this problem happens, Im watching the tach and listening for the down shifts, but I cant sense them and the idle just gets dgragged down.
the odd part to thought of it being a downshift issue is that slipping it in neutral dosent really help. Or would a converter do that if its sticking? and is that even possible?

please help.

BTW, this is just a 350 trany, not a lock up converter

 

Have I been black listed here? Doesnt anyone have advice?

I stopped at a tranny shop and they said its not the torque converter or tranny and they even let me use a known good MAP sensor to test w/.
Well, that wasnt it either:-(
So I hooked up the lap top again and went for a ride. A 1/8 mile from the house I pulled over and the idle dropped to 425 and just stayed there. So I just sat there and checked out all the sensor outputs and every thing was looking good. Then I noticed the INT. was up to 140, That I thought was different untill I noticed the IAC steps were at ZERO! Now I sat there for a good 5 mins letting it idle like this, Then I gave it just a touch of gas and brought the steps up to 9 but they fell right back to zero as soon as I let off the gas.
I shut it off and started it right back up and then all was fine! AARRGHH!
This situation happend 3 out of the 8 times I stopped.

SO please tell me does this sound like I got 2 bad IAC's, or what Is giving it the bad info to tell it to go to zero steps (Im guessing zero steps means its closed up and not letting in additional Air).

Please help me,
Jeff

 

thanks for all the help guys.

It was a loose connection at the speed sensor.