Oppo, help me figure out what's wrong with my Skyline.

"Kanaric" (Kanaric1) 09/10/2014 at 18:41 • Filed to: None

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I've had a few issues that I think are connected so i'm going to go into detail explaning them. I've been trying to figure this out myself for weeks now.

Car is R32 GTS-T

MAF Issue?

One of the things I had to replace when I got the car was the air filter, put a K&N in. Car would go into a limp mode occasionally, I put this in a "the K&N filter oil is polluting the MAF" category, would use MAF cleaner and this would be fixed. Or is it? Later, after I went back to a paper style filter, I had this issue once again. It would happen during a drive then go away. It even happened on the way to an autocross and was fine the entire night.

I think this is a separate issue than the main issue that's been killing my drivability.

Alternator?

A while back to improve cooling I had a dual electric fan setup installed. I did not install this myself, paid a local shop to do it. He said I needed a new alternator and I was going to take care of that myself. I turned on AC and drove off the lot and immediately had issues. Car was dying, like the key was turned off. I checked this off on the "yup alternator" box and eventually got it home after an annoying drive. If I turned on all accessories I would get a significant drop in voltage, however the AC absolutely killed it. The AC was set up, when it was turned on, to turn on one of the fans. The other fan was set up to turn on by water temp. If both fans were on the car would die when driving. On the way home it also seemed to not want to rev above 3000rpm. However where the MAF issue above it would feet like it would just hit a rev limiter just at 3000rpm this would basically completely cut off all ability to use the throttle only occasionally accepting my input again or just outright dying. At first i was confused and thought issue above was related to this.

Ordered a RB25 alternator online, RB25 alternators are interchangeable with RB20.

After Alternator Install

Today I installed it and haven't had much of a chance to thoroughly test it out since I had to go to work not long after I finished. Turned on the AC and the idle RPM was so low the car sounded like grim death. Worse than before. I was able to rev it however it felt a bit sluggish. All other non-ac accessories turned on and the car felt fine.

So I guess I have some theories. Keep in mind these are theories from a person with limited car knowledge when it comes to anything aside replacing worn things:

1. The AC's bearings are shot and it's bringing down the engine? The AC has kind of clicking sounds coming from it. It functions however i've been told that the "ac clutch sounds like it's going out" by someone and that it's bearings might be going out by another person. Weird that it's worse AFTER alternator install which is also obviously driven by engine speed. RB25 alternator might require a bit more from the engine and it's bringing idle rpm the extra 100 or so down. Before the replacement it would do this but it wasn't as bad.

2. There is some other kind of a power issue. The battery is smaller than i'm used to seeing in a US car. However it cranks the car fine and I haven't had to charge it. Grounding issue? Short? I was able to drive it today after this install. Had the issue from the MAF? section once but it went away. Did not test AC while driving for fear of becoming stranded when I had work in 45 minutes.

This is as far as i've got so far. I've been working on this issue when i've had time/money for a while now and am not sure where to go next.

Don't let my comments lead you somewhere it shouldn't. I have little to no experience diagnosing issues like this.

Nibbles > Kanaric 09/10/2014 at 18:51

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Sounds like AC compressor bearing failure. Looks like a factory RB25 alternator puts out 90A, that may not be enough to run A/C and all accessories. I (just) read about people upgrading to the 125A unit out of a Nissan Quest, may be something to look in to.

Pearson Hurst > Kanaric 09/10/2014 at 18:55

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No idea about the specifics on a Skyline, but most cars have a mechanical/electrical method for bumping up the idle when the AC compressor is engaged. If it fails, you will get exactly what you're seeing. Again, having never touched a Skyline, I can't even tell you if their solution is mechanical or electrical, but I'd find out, and make sure that it's working properly.

Sportwägen, Driver Of The Red Sportwagen > Kanaric 09/10/2014 at 18:55

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Do you have pics (of the car)?

Kanaric > Nibbles 09/10/2014 at 18:56

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Well the stock alternator in the RB20 that I had puts out 70 or 80 depending on which one I had. When I first got this car I was able to drive at night with AC on and brights fine without issue. In fact I put the car through a test of that at a night time autocross, complete with occasional AC use sinec it's Nevada and at night it was still almost 100 degrees.

It seems unlikely to me now that a new alternator with 20 or 10 more amps would be killed by a couple of fans only as an addition. Especially since people put serious aftermarket audio in these cars that I would think would big a bigger draw on power.

Kanaric > Sportwägen, Driver Of The Red Sportwagen 09/10/2014 at 18:58

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http://oppositelock.jalopnik.com/canyon-carving…

Kanaric > Pearson Hurst 09/10/2014 at 18:58

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Tomorrow i'm going to do a more thorough electrical test to see if it still has power issues with the AC off so I can hopefully narrow it down to something like this.

Kanaric > Nibbles 09/10/2014 at 19:05

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BTW could the bearings being bad cause issues with the car's idling?

Sportwägen, Driver Of The Red Sportwagen > Kanaric 09/10/2014 at 19:08

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NICE but YNOGT-R?

Kanaric > Sportwägen, Driver Of The Red Sportwagen 09/10/2014 at 19:13

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$4000 vs $12-$15000 buy in before import fees, far cheaper parts, easier to maintain.

Sportwägen, Driver Of The Red Sportwagen > Kanaric 09/10/2014 at 19:19

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Okay, that sounds very tempting!

RallyWrench > Kanaric 09/10/2014 at 20:25

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MAF cleaners are mostly spiffy rubbing alcohol, and don't always work, because once filter oil bakes on to the hot wire it's very unlikely to come off.

If memory serves, and if it's anything like an SR20DET/S13 chassis there's a separate relay for the compressor clutch that acts as a load reducer and signals the ECM to raise the idle. Is that working?

The AC clutch pretty much either works or it doesn't. If it's shorted, it could cause a big amperage draw on the alternator that could draw engine speed down, but if that's happening I'd expect a blown fuse. The only other alternative is mechanical drag in the compressor, which of course would only apply if the clutch is engaged. If you can verify the clutch is working, get a long screwdriver on the compressor with the handle to your ear & listen to the compressor. It shouldn't sound like a bucket of rocks.

Kickass car, BTW. I owned 50% of a GTS-T for a couple of years. Literally, half of a car. It was a front cut that I bought for the engine & trans for a 240Z project. Always wished I had the whole thing.

Kanaric > RallyWrench 09/10/2014 at 20:41

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I'll try these, suggestions. Thanks.

Nibbles > Kanaric 09/10/2014 at 23:52

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If the idle is rough when the ac is in, yes. A stalling compressor puts a lot of undue stress on the system, bogging the engine (lack of low RPM torque to keep it spinning) and draining the electrical system (again, too much work)