1992 5.0L mustang MS2 PnP, heads, cam, intake. Idle with AC on?

AUBURN1111 · May 4, 2018

Im trying to get this thing to idle with the increased load of the air-conditioning compressor on. Ive tried idle targets of 800, 850 and 900, when AC is turned on rpm drops then surges then shuts the motor off. If you hold the throttle at 1500rpm turn AC on then let off same result, doesnt seem to catch the idle rpm with the increased load. @a91what Any "Air-conditioning Idle up" settings that may help resolve this?

a91what · May 4, 2018

ouch that's not good let's take a look at the tune again. Did you happen to be datalogging when this occurred?

AUBURN1111 · May 4, 2018

I should've renamed it, sorry.

a91what · May 4, 2018

some big changes, i setup a initial value table for the idle lookup should help the stalling.

AUBURN1111 · May 4, 2018

installed latest tune, some oscillations and a little more with the AC on but it didn't die!

AUBURN1111 · May 4, 2018

Datalog with latest tune installed

AUBURN1111 · May 11, 2018

So I tried turning the throttle stop in 1.5 turns, recalibrated TPS, burned changes seemed to idle fine with load as well as recover after acceleration. I have a new issue after idling for a minute or so RPMs jump to 3000 and stay there? I had to shut the car off, suspecting IAC valve is going crazy on me.

AUBURN1111 · May 11, 2018

datalog showing RPMs swings from 900-2600

a91what · May 11, 2018

idle changes made.

AUBURN1111 · May 11, 2018

Data log with changes, seems like the recovery after letting off the throttle is oscillating back and forth a bit now

a91what · May 11, 2018

the valve is still acting wierd....
look at the rpm vs idle speed. first 14% got you a 900 rpm idle then 40% did.. with a higher map signal.

either there is a valve issue or you need to be sure that there is no loose connections anywhere also the MAT sensor is not reading at all. this could be a bad electrical connection.

AUBURN1111 · May 11, 2018

Looks like the IAT had failed, will continue working out the bugs in the morning.

a91what · May 12, 2018

Datalogs are a wonderful tool for diagnostics once you learn how to use them

AUBURN1111 · May 12, 2018

Installed new IAT sensor drove the car some, it seemed lean at idle and driving 14.6-15.9 so I enriched it a bit to get idle closer to 13.2-13.4. I notice a lot of bucking and stumbling at partial throttle 1/8th throttle range smooths out at 1/3 to 1/2 throttle. I also seem to have to use a lot of throttle and feather the clutch to get it rolling or its easy to stall. Not sure if IAT sensor affects AFRs that much hopefully I didn't get a bad one from the store? On the plus side.....it drives!!!!!!

a91what · May 12, 2018

The mat sensor plays a large role in fuel delivery. If it is reading correctly now then it is not unreasonable for the fuel to lean out. I will look into it later bbq time right now

a91what · May 13, 2018

After reviewing the datalog i can say you did a fine job getting the fuel adjusted and blended into the rest of the table.
do you have a datalog of you driving the car??? If you do I want to see if i can identify the source of the part throttle bucking [I am willing to put money on the fact it is fuel related (lean)]

AUBURN1111 · May 13, 2018

I do not have a data log driving, I will try to get something to you, currently cutting out my old cat back.

5.0Thunder · May 15, 2018

Good work guys. First thing I noticed when looking at that datalog image was the unchanged MAT. lol

AUBURN1111 · May 15, 2018

same tune Ver as above 5.1.1, still have some drivability issues, hesitation, bucking at part throttle. I believe it is what you suspected and that it needs more fuel. I haven't messed with any of the tune, wanted you to look at the data logs first.

a91what · May 15, 2018

Verified too little fuel. I adjusted mildly and blended. I will need another log from this new tune to verify fuel.

1992 5.0L mustang MS2 PnP, heads, cam, intake. Idle with AC on?

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