Need Happy Honda Guy
We have this vehicle that has a condition where the idle speed drops pretty dramatically when sitting at idle in gear and the AC clutch cycles on.
I thought we fixed this with all the mounts.
Car is 4CYL with 163,275 miles on it. (I mistakenly called out a V-6 earlier)
Car back in: Started with and alternator replacement and battery disconnect.
We have performed all over due maintenance: valve adjustment, plugs, T-body and intake clean, LOF
Relearned crank pattern, reset idle as best we know how.
Note: this car has no idle motor.
We have to be missing something, so I am tossing it to you guys for suggestions.
*Scott is helping me edit this post, I apologize for the lack of info on my initial post.
Hi Daniel, I'm working with Gene and have updated the post with more info.
I missed the symptom here also. What is the complaint?
Hi Gary, I'm working with Gene and have updated the post with more info.
Hi Justin, I'm working with Gene and have updated the post with more info.
YMM, auto vs manual, etc??? Symptom and or DTCs???
Hi Randy, I'm working with Gene and have updated the post with more info.
There is a TPS memory clear and idle relearn done with Honda HDS scan tool, I have also done this with Autel Maxisys. Without a factory level scan tool, try this: Clean throttle plate, disconnect battery again and touch cable together for few seconds. Then start engine and let it get fully hot without touching throttle, after fully hot rev it up and then recheck hot and cold idle.
Gene, What are the A/C Head pressures when issue happens and is the field coil circuit clean when engaged ? I assume from your post the Issue only happens when the A/C is turned on?
Hello Craig, the head pressure is about 180 psi. we have checked the charge on the a/c everything is dialed in. we notice if the fans are disconnected or if the unplug the alternator and turn on the a/c everything is nice and smooth. It seems to me the more lots on the engine the worst its felt. We checked the engine vacuum hot at idle is 21 in. in gear is about 18 in. and when the a/c is commanded on it will drop to about 9 or 10 in. and slowly recover to 15 in.
One key thing here I notice is that you stated if you disconnected or if the alternator is unpluged everything is smooth. You also mentioned that you replaced the alternator. Why was the alternator replaced originally, was this issue present the vehicle came in the first time?
Is the alternator a decoupler style?
Fuel trims? How are they looking?MAF at idle?
the alternator was not charging when the vehicle came in. mass airflow is reading 2.5 grams at idle no loads. the fuel trims are about 3%.
What is the reading with ac on? Read Rudy’s reply, I have seen the same thing he is describing on another vehicle. It was failing IM240 and a shop was struggling with it. They brought it to me and first thing we noticed was it had a power issue. Long story but what happened on that one was the compressor got so hot it welded the clutch to the compressor bearing and then locked the engine up in my bay.
Sounds like something is lugging the compressor down when it engages. Maybe over oiled system? Maybe the customer has been adding refrigerant to it? You said this started when the alternator was replaced? Does this car have a one way clutch type alternator pulley? If it goes away with the alternator unplugged, that's where I'd start looking. Hope this helps.
Hi Gene have you try to do TP relearn under special functions most oe level scan tools have that option snap on, Autel, after you do the tp relearn you need to go into PGM live data and look for pid that says idle learn it should say completed or not if not completed you need to let it idle for at least 20 min until that live data status shows the idle learn completed
If the charge is correct and the pressures are correct,Id call it a bad compressor.
I have replaced quite a few for that problem on Honda K series equipped vehicles. Including on my own vehicle.
Thank you for all the input. I'm not great at posting, my technicians usually do this as they are working on the car.
we are at wits end, spent allot of time and parts chasing this, still no luck. to date we have replaced compressor, made sure oil level is correct, I'm sure it's not AC.
To recap, at idle, in gear, when AC turns on there is a noticeable 200 to 500 RPM dip, engine vacuum dips to 10 inches. When AC engages, the radiator fans also engage, this is when the incident happens. If we disconnect the alternator, the symptom stops, if we disconnect both radiator fans, the symptom quits. The alternator out put is 15 amps at idle, jumps to 40 to 50 amps when AC engages. Again, disconnect alternator, gone.
Battery has been replace, several alternators of different brands, the fuse box, the throttle body, we checked for rouge AC current, voltage dropped all powers and grounds.
Tuesday, looking to re-flash computer??? We seem not to have a good enough understanding of the charge system, any super star Honda help would be really appreciated.
Gene, Seems like low Alternator output. I am sure your guys checked the voltage drop from alternator to battery. What about running a fused wire from alternator to battery? Be interesting to see what changes when Alternator/fans are unplugged(fuel and/or spark readings).
It's been a few days since the customer has picked up the car and I am still some what not exactly sure on the cure. We ended up replacing the alternator with a different brand and the concern was gone immediately. The only difference that we could see was the voltage out put on 1st and 2nd alternator was 14.6 volts, the 3rd replacement voltage out put was 13.8. we did test for AC voltage at the battery, none detected. I'm sorry we did not get the why for this one, but after a week of frustration, having it fixed and gone sometimes outweighs the why. Thank you for all the feed back.