vader1

My car was just tuned, and it is bahaving kind of goofy and the tuner is going to take another look. The car was really hot after a three hour tune, and going home everything was normal and I switched on the ac and it started to run in the 10:1 range. It is also running in that range at certain times and it is going back to get that sorted out. I just switched to a stand alone from a Emanage but I do remember that it had similar behavior once before on a scorching hot day, as soon as I turned on the AC it went pig rich and I could not run the AC.

So outside of running the compressor off of the engine (extra load) and drawing more current, does the AC do anything else that I need to consider? Does it do anything with vacuum?

I have a 6 lb boost SC setup on a mostly stock car. I am just trying to understand what happens when the AC is switched on that the ECU could be reading besides current draw and a little extra load. Is there any other interaction with some temp sensors or create any vacuum or something? Just want to make sure everything is mechanically the way it should be before sending it back to the tuner.

s2000Junky

Thats a good question, ive noticed similar situations in past and my thought on it whether accurate or not appears to be load related. You have a hot day which already increases the load on the motor, coupled with driving another accessory ( A/C ) I think some simple fuel cel recalibrations in the load range the car is experiencing during these instances should resolve the issue. I think it can be delt with by some simple tuning. The trick is to pinpoint that more finite load range, which may be difficult to simulate on a dyno, and more likely something you eventually find on the road. Being an emanage tuner, I have spent a fair bit of time just running the laptop in the car on my normal excursions, and if something comes up I will make adjustments until the issue gets rectified. Not always easy to do when you’re paying a tuner by the hour. One reason why I hate relying on tuners to make my car run right, because almost always it never runs as good as it could in normal DD situations.

jaundice

What tuning source are you using? I can answer questions about KPro but not AEM.

camuman

There is an offset percentage modifier when ac is kicked on. I run aem and I can't remember if it added fuel or added rpm by messing with the iac valve which typically put your idle in a slightly different spot which needs to be tuned for. And then you have to also adjust the offset tables for intake temps and I think water temps.

vader1

Ok cool. I am sure my tuner will know how to handle it. I was just curious about the behavior. I have had a huge bunch of mystery problems could not get the car to run right on a pretty much plug and play base map on a Haltech and the car won't even idle now without going past 9:1 afr ratio. I am convinced my total crap Deatschwerks injectors crapped out and are just leaking huge amounts of fuel. It is getting towed today to Full Blown for new injectors and a retune so I should get it back next week. The injectors were recommended with the kit because they were cheap but they did not flow the advertised rate and now I think they are toast.

Was in Full Blown on Monday and they had several GTRs in getting work done. They have moved to a pretty nice new space and have a fairly large inventory of parts in big warehouse racks. They seems to be doing pretty well for themselves.

CoolGuy094

Sorry to hear about your troubles man. I had fueling issues during my first tuning session as well. What fuel pump are you running again? And what new injectors are you getting?

I had a goofy idle with AC on after my first tune, but the tuner was able to clean it up on my second visit after my fueling issues were taken care of. There are definitely certain settings that have to be made to allow the car to run properly with the AC on. Your tuner should know what to do... its possible he just didn't even think about the AC during the tune.

vader1

Actually the problem is deeper than just idle. I am running a walbro 255 and I think my pressure is just fine. A long time ago, when I bought my kit I was recommended some Deatschwerks injectors that were supposedly 550cc. I got the injectors with a flow report and at whatever the given pressure they were measured at, the flow rate was tested at about 472cc for each injector. Why they would sell advertised 550's with a flow report of 472cc I don't know but this was years ago and I was not sophisticated enough about tuning to know what I was reading in the report anyway.

My base map was set to run to air fuel targets under boost and the computer would just run extra duty cycle to meet the target. Since the computer was just doing what it was told it was running 100% duty cycle and I was running out of fuel at 7000 rpm and making no more power. Two different "tuners" could not tell me why it was flat lining and I did not know enough to tell by looking at the map. LJ at Full Blown, knew exactly what the issue was and told me, even though the other two guys were clueless why it would run out of steam at 7000 rpm. Now that I understand what was happening, it boggles my mind the other two tuners could not explain the flatline. The duty cycle table would have told him in an instant.

I had it tuned and LJ did the best he could but it was pretty clear I would have to get new injectors and I was going to go easy on it for a couple weeks and come back. But I think the tuning session put the injectors on critical (at least this is my theory until I find out when it is all done) and one or more just failed and are stuck open or just leaking tons of fuel. Literally just spraying wildly into the cylinders. The car fire up but as fuel pressure builds it just heads south in a hurry beyond 9:1 at idle. Stepping on it and shoving in some boosted air will lean it out to 10:1 but that is all I can hope for right now. It used at least two gallons of fuel when it went haywire on the way home and that was only 20 miles. It is so rich I am worried about igniting the cat and melting it.

So it is going for some fancy looking 725's Full Blown sells and more tuning. I think that should cure my mystery issues, all of which can be explained by odd fueling.

But to be clear, I don't blame LJ for any of this, he seems to really know what he is doing and is very good with communication. The other two guys I went to were just stumped, and looking at the duty cycle tables they should have been able to point to the issue in a second. One was a kid who was recommended by the Civic crowd, the other is a guy with a good reputation on Mustangs and has been tuning for years. Each was employed by a decent shop. The first guy (the kid) when he could not get my fueling right just called "supercharging a four is stupid, you should just sell it and get a turbo." He did also made the car so rich I flashed it back to what I had when I came in a few miles from the shop and chalked it up to a $150 mistake.

All this has made me really appreciate a guy who knows what he is doing and understands tuning and engines. It is just too easy to get a basic understanding and sell your services as a tuner and not really know what you are doing or how to diagnose an issue. I really value what a good tuner can do and now I better understand the bad tne horror stories. I don't tune myself because I don't know enough about it, so I pay people to do it for me. Those who know what they are doing are worth their fee, but there are people out there who seem to know just a little more than me and claim to be experts. I don't want to give the names of the bad ones, I don't think that is fair, but if anyone in my neighborhood wanted a rec I would say "don't screw around, go straight to LJ."