230KBenz

I did some testing with IAT sensor and put together a plug in harness with some resistors that has been working pretty good. I started running it this week and its running very well with about a loss of 1 mpg. Next time i get to the drag strip I will find out for sure but this is a good 5 to 10 hp for next to nothing. I just want to see if anything gets messed before I consider it a success.

2003 C230K magma C5, C7, 6 spd.

Nektopoli

Does it affect the fule/air mixture?

NP

230KBenz

yes, this is one of the sensors that lets Motor electronics determine fuel delivery. On a factory setup the motor will be trying to achive a 14.7 : 1 mixture that is ideal for emissions, however the ideal ratio for performance is somewhere from 12 to 12.8 : 1 I next i want to find out exactly how the car is running now all i know so far is that the injector pulse went up half a millisecond at idle. I have to bring it back in to see what may have adapted. I wasnt sure at first cause is was worried that the O2 sensor feedback would cancel out the extra fuel but so far its doing good, i noticed a great difference between the other cars i drive at work that are the same as mine. if it works out i think its much better deal than $100 per 1 HP from a ECU reprograming.

2003 230k magma C5, C7, 6 spd.

Buellwinkle

What's the IAT sensor reading? Do you have an OBD-2 scanner? I thought about doing this on my car. What size resistor did you try? Which color wire on the sensor did you put the resistor on? And did you put it in series or parallel? People do this all them time on the Ranger and S10 forums I participated in. Never seen a dyno though to prove it's effectiveness. What they like to do is put a 3 pole switch so in center postion it's stock (no resistance), to one side it's everyday driving (moderate resistance) and the other side it's high octane or special occasion driving (higher resistance). One person even uses a 5 position rotary switch to fine tune it as he drives. The key is to see if it causes any pinging. To do that you need the scanner so you can see if the engine is pulling back timing because if it is you can lose power.

230KBenz

The next thing i want to do is find the nearest dyno and find out the readings. The setup is very simple, I modified a test harness from the MB electrical test kit and soldered in a 30K resistor right now. My first testing i used a decade box inline with the sensor so I could change the resistance while i was driving. I also looked at the actual values of engine sensor inputs with and with out the mod. It took the Intake Air Temp down to 7c from 45c which is alot but thats what it took to get a change in injector on time. I would like to try some other combinations and see if I can make it any better without over working the cats but i dont think the o2 will let that happen. I used the factory benz diagnosis system and there are only two wires going to the sensor so you can put the the resistor on either side.I can give you the number for that test harness if you want to try it.

2003 C230k magma C5, C7, 6 spd.

Buellwinkle

I'm wondering if you'll see anything on the dyno, mainly because on the dyno at full throttle you are running in open loop mode and I don't know if the IAT sensor even looked at. If you have the wire harness part numbers I need I can get started on my antique 2.3L.

230KBenz

I have to look into it some more to find out exactly , and try to get access to a dyno. Let me check first to see if the 111 has the same connector for that sensor. Im going to read threw some information here to find out exactly how this car reacts to certin inputs and see if its possible to do anything else with it.

230KBenz

I went with a different resistor tonight and it seems to work better that the last one. I also found out that by keeping the IAT under 35c the computer will not retard timing as it dose in most situations. The logic table will retard timing 3 degrees for every 30 degree increase in temp. Tomorrow i will do some track testing if it dosnt rain so hopefully i can get some answers.

2003 c230k magma, c5, c7, 6 spd.

Buellwinkle

That's great, timing is what the IAT controls usually. I was surprised it also had an affect on injector pulse width. I've been using a bigger IC and IC mister to achieve just a slightly higher IAT, maybe 40-45C.

pugguy2001

So has anyone else try this mod? I heard about this mod being done on plenty of cars. How about our cars?

pugguy2001

Bump
I still think this will solve some problems. Maybe an adjustable IAT module makes better sensor.
I just read this on another forum:
The PCM uses inputs rom the IAT sensor to
calculate
-injector pulse width
-adjustment of spark timing ( help prevent
spark knock with high intake manifold air
charged temperatures

So your fooling the engine to run richer...
Is this worth anything? Well youll probably just
burn alot more gas. And long term effects? I
doubt there is any power to be gained there
unless your running a SC.