DF70 idle and IAC valve issue

[criosmunnings]

Hey All. I'm really stumped on this issue and would appreciate any help/advice.
I recently got a DF70 that would die near idle and was throwing 31 code. I Replaced the IAC valve with a used one from a damaged engine, and took it on a good run. Performed great, and code was gone.
At destination, the engine died while docking, and cranking was weak. I re-tightened the loose battery poles and restarted, but then the 31 code came back. I ordered a new IAC valve and installed - still got the 31 code. Mechanic came and tested all resistances, etc, ran Diagnostics and recommended replacing the ECM, which I later got from a damaged engine and installed. Unfortunately the results were the same - 31 code and engine dies near idle.
I then tinkered with the by-bass air screw, opening it up enough to keep the engine idling near 800rpm, but I can loudly hear the air rushing into the intake thru the by-pass. Took it out on a short run with this, but engine lacked power and then came back with 32 code instead (MAP sensor hose). I checked the MAP hose, which seem fine and clear, however I did notice some motor oil in the intake manifold. The 32 code is still there and the engine goes max around 3200rpm. Help! Any ideas?

[aquamort]

How much oil in the intake manifold was there? Also dont forget to check the little hole in the intake manifold under the MAP sensor if you havent already.

Good luck.

[catacom225]

Iac

Check your workshop manual ,on the larger engines the Idle must be taken above 1000 rpm and then it will sound an alarm, reset your recommended RPM, throttle the engine back over 1000 and alarm will cancel and reset

[criosmunnings]

Thanks for you input, aquamort, it's not much oil that is inside the intake manifold. A little, actually, in the plastic airbox that connects to the entrance of the intake manifold and trace amounts that I can rub with my finger around the intake mesh. I did pull the hose from the MAP sensor and blew on one end to make sure it's clear.
Catacom225, I tried your suggestion, according to the manual, opening up the air bypass screw to get the engine above 1000 rpm, but it never goes there. The most it would stay is right under 1000rpm, even with the bypass screw all the way open. It's strange that no matter how much I open the bypass screw, the Engine rpm does not raise much.

[criosmunnings]

Hey Everyone. Would really appreciate some ideas. Been working on this every day, re-reading the manual, checking all resistances, etc. I am now also getting a 2-2 error code - CTP Switch, along with the 3-2 MAP sensor hose switch.
According to the manual, the CTP switch should be getting 5V when you advance the throttle, but I'm getting 12V. Is that normal?

[criosmunnings]

Error Codes problem solved

Hi Everyone. I wanted to update everyone on how my problems were solved to benefit those that have the same problems I did. Unfortunately no results came from this forum, which was disappointing. A regular auto mechanic looked at the engine, ignored all the codes and did a compression test. One of the cylinders had little no no compression so he took it apart and found a burnt exhaust valve. Did a valve job, replace gaskets, etc, and all the IAC, MAP Sensor, CTP Sensor codes all disappeared and Motor works like a charm. I struggled with this for 6 months. Hope this helps somebody else!!!!!

[Moonlighter]

Thanks for the update and for sharing.

Nasty problem, but good you got it fixed. The old story - there isn't anything special about most engines, they need fuel, spark and compression! So if you go back to basics that is often they way to find the problem and thus the solution.

I see there were quite a few views of your posts, so it was noticed. My experience is that people will offer help if they can, but if they cant offer anything, not much point posting.