Hey guys I had my car tuned by steve this last July and it has been running ok but now that we are getting into the colder part of the year I am running into this problem. The car this summer was always around 35-45C Air intake temps when driving around and never had any issues but now when I say go get in my car at night to go home my temps are staying around 19c-25c and if I get on it I get hesitation.

Is this ignition breakup? Plugs were changed about two months ago.
thanks for any help.

-Chance

 

its common to get breakup when your running over 12psi on the stock ignition. but i always thought that breakup occured at high rmps. looks like you might have a different problem

 

yes I just noticed last night that I was getting more than 14psi not much but close to 1 bar instead of .90. I also notice that my car would hesitate full throttle but if I gave 90 percent throttle it would be fine and seemed to run really good(fast)

 

anyone?

 

You may need an ignition amplifier or:

Since it was tuned, it does not have a stock ecu. I assume a PFC. If not the following still basically applies.

There is a PFC table called "Air Temp vs. Injector". It varies fuel usage based on air temps. Same boost with hot air requires less fuel as the same boost with colder air.

Some tuners leave the table as stock (bad for a modded engine).
Why do they leave it alone? Maybe they have never normalized the table for proper tuning. For perfection, it would require you to AFR tune your engine as the temperature changes due to seasonal changes. I did mine over three seasons. The main points are at 50C, 30C, and 10C.

The stock Air Intake Sensor is located under the UIM where it reads hotter than it should
and can heat soak giving a high false temp. That is why the AIT sensor should be moved to the IC outlet or TB elbow.

The table was setup for the stock engine which ran rich when hot and then leaned out as the air temps got colder. This is backwards for a well tuned engine with proper IC and rad cooling which the stock engine did not have.

That is the basics.

If you AFRs are going rich with the cooler air temps and causing misfiring, then your table may need adjusting.

 

Thank you for your info cewrx7r1, very informative.

I know an ignition amp. Would someone like Steve Kan not adjust these Air temp vs. injector?

It is a pfc and I should note that my boost is going past its set .9 bar to 1. bar. I am guessing I blowing out the spark with the added boost?

 

In the earlier days of PFC research and knowledge expansion, some tuners were late getting the news, and some still haven't gotten all of it.

I have only seen about 4 of Steve's maps over the years, and the last one has it.

 

I started to change the AIT comp map 2.5 yrs ago with the PFC so you should already have it map out. If you are running closer to 1bar, you are boosting too much since the car was only tuned to .9bar so everything past that boost pressure will run alot richer to prevent you from blowing the engine. Additionally, cooler air=denser air so even if you run the same boost the amount of air is also denser which could cause break up w/o an ignition amp.

 

Ok great thanks for your guys help!