• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

    So with that I ask that anyone with a question about one of our build ups or a general tech question to please use the forum as it was intended. I am absolutely available by telephone to answer your questions as well but at times may direct you back to our website to better field your question or questions. Most other private messages I will be glad to answer for you.

    Thank you for your understanding.

    Jeff Ismail

Fuel Injection High Idle in Hot Weather


What can cause high idle in hot weather?

I have Affordable Fuel Injection sold here before Hamilton FI; IH 345/auto and aluminum intake and stan's headers. Recommended Robert Shaw thermostat, can't remember the thermostat opening temp.

Just made my annual trip to Colorado for 4 wheeling:)

No problem on the whole trip UNTIL driving home across Nebraska and Iowa it was in the high 90s all the way. Highway cruising at 70 MPH and every time I stopped the idle was screaming at 1500 RPM. I had to stand on the brake just to hold the truck still!

Popped the hood to check throttle linkage; all good and tight to idle set screw, so definitely IAC/PCM kicking the idle.

No engine light unless I leave it idle high for several minutes, then I get a check engine light.

When I shut off the truck and restart, no high idle and no check engine light. Runs absolutely fine. Restart fixes the high idle without waiting for the truck to cool. High idle returns after every long highway drive in hot weather.

I have the stock dash temperature gauge; never gets above halfway whatever that means:unsure: Plenty of coolant, no indication engine is hot.

The fuel injection does have have a temperature sensor. Does the fuel injection think the engine is hot and kick the idle?

No AC; driving that heat was pretty miserable:(
Update: Forget all that nonsense about hot weather.

I checked codes and found 22: TPS Low Voltage. I cleared codes codes and drove on 2 local trips.

First trip was fine.

Second trip (I voted :) ) was a few miles each way. 70 degrees, short local drive, high idle issue returned with a check engine light. Code 22: Low TPS V. Intermittent fault that started when hot and led to wrong conclusion.

Do I now replace throttle position sensor?


i would look at the plug at the TPS and the wires going in and follow them up a little bit looking for anything torn or chafed before i replaced the TPS if all wires looked good, tight, connected, then replace TPS

that is just what i would do
Apologies for the junk post; my son's keyboard does funny things.....posted when hitting random keys on keyboard trying to find caps lock.

I had already checked wiring; replaced TPS sensor and all is good.

The TPS sensor that came with the FI had a part number, but I could not find any reference to that number. Used ACDelco sensor from 89 pick up and works fine.