Texas_Ace

iTrader: (18)

Ok, as those that have been reading my “blog” thread know lol. I have a few problem that have come to surface with my RX7 since I got it running and inspected last week.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
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First off I got the AC working by retrofitting it to r134a, blows nice and cold now. BUT whenever I turn it on the car dies if I don’t hold the gas in some. This makes it impossible to use the AC except when on the highway as it dies whenever I come to a stop. Very dangerous as well. Any idea what the problem with this is?<o:p></o:p>
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Also, I have noticed what is either me getting used to the power of the car or some power loss since I have actually started driving it. It also just doesn’t seem to be running quite as good.<o:p></o:p>
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The idle is also a little rough, and it constantly fluctuates about 100rpm when idling. No idea why. And when driving it it is either the tranny/drivtrain or the engine, I can feel some “knocking” in the floorboards when driving slowly. At speed it smoothes out some, though the tranny does make some rather loud whining overall. Part of that could be that I removed the shift boot when fixing the shifter.<o:p></o:p>
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After looking at everything, the ONLY thing I noticed that looked different then when it seemed to run better is that the voltage seems a little lower then before. It is now sitting at about 13.8volts when the car is running, it seems like it used to be closer to the 14.4 it should be. Are the electrical systems in the RX7 that sensitive that the little bit of voltage drop could effect something? I had the battery and alternator tested and the battery is fine, the alternator also worked, just at about 13.8 volts instead of 14.4 but was working.<o:p></o:p>
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One thing that also make me think something electrical is that I have not had any 3800rpm lag when I first was driving it but now I will get just a little from time to time, I regrounded everything, so I am lost here.<o:p></o:p>
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I have been driving it fairly easy overall, shifting at 4k most of the time, a handful of redlines when I was testing how fast it was. Then 1 burnout just because I have other tires from the 5 lug swap that will go on it and I wanted to see if it could. lol Otherwise it has been driven pretty easy.<o:p></o:p>
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I am pretty sure the OMP is working, but I premixed this last tank of gas just for good measure, but is was run for a about 50 miles without premixing.<o:p></o:p>
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So any idea what/if there is a problem with the engine? Something just doesn’t seem right.<o:p></o:p>
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But besides that I have got to figure out why the engine dies when the AC is turned on, I MUST HAVE the AC to drive the car in the summer (I carry people and they need it, I want it). and right now I can’t.<o:p></o:p>
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Any tips would be great. Want to get this car finished and drivable.

jackhild59

iTrader: (7)

When you turn on that A/C, the inside fan and the fan clutch use quite a bit of amperage, causing the alternator to add load to the idling car. Put this with the load of the A/C compressor itself, and the car will stumble and die with the sudden load.

The BAC valve is supposed to bump up the idle to balance out the added load of the A/C and the alternator. Trouble shoot this system, get it functioning right and you should be golden. Procedure is in the FSM.

Regarding the voltage fluctuation, there is a temperature compensation circuit in the voltage regulator. What you are experiencing is pretty normal.

Power? Well here is part of the problem: 134a conversions are not a really good idea on the 7. The condenser area is not large enough. This leads to higher pressures. 134a has higher pressures in normal operation, so when you have the normally higher pressures of 134a and the insufficient condenser area contributing to even higher pressures, you can get significant power drain due to the higher pumping losses in the A/C system. The solution to the problem is to slightly reduce the charge. Then the capacity is reduced and well, that just really sucks on a summer day in Texas, doesn't it?

This is why I don't recommend using 134a in 7's. I use only Genuine R12 in my old cars. I know that Freeze12 is also fine-I have tested it and many 7 owners in Arizona use it with great results.

Texas_Ace

iTrader: (18)

Thanks for the info, so the BAC valve is what controls the idle with the AC on, i will look at that, i have woundered if it it working anyways.

So the voltage being at 13.8 is normal? Strange but what do i know about these cars.

with the AC pressure i hooked up a agauge and the pressures were right in the green range on it. About 15 - 20psi on the low side if i remember right. that is too high? i could try letting a little r134 and see if that does anything.

As for the power loss, the power loss also seems to be when the AC is off (as that is still how i am driving the car most of the time). It just doesn't seem to have as much power as when i first drove it.

I will checkt he BAC valve though and see what happens.

JM1FD

iTrader: (1)

That cheapo low side death kit gauge is a good way to wreck your system. You need high and low side readings using decent gauges to even try to figure out what might be going on with your system. Besides, the high side pressure is the reading that is indicative of the load on the compressor. I suggest you take the system back to R-12 before your compressor is ruined by an improper conversion. Taking the system back to R-12 will require you to disassemble the system, flush all the components with an appropriate solvent to remove the R-134a oil and putting a new dryer on. If you insist on using R-134a you should still tear the system down, flush it, add the appropriate oil back in, and replace the dryer.

Texas_Ace

iTrader: (18)

well the problem with going back to R12 is that you can't buy r12 and i asked a shop how much they would charge to put R12 in it and it was a few hundred bucks! I only spent $500 on the car, no way was i spending that much just to get the AC fixed.

Otherwise i would have gone with R12 in the first place. I think i will let a little r134 out though and see what happens. I might pick up some proper gauges as well if harbor freight puts the back on sale pretty soon. until i can get the car to idle with the AC on though i won't be using it anyways.

JM1FD

iTrader: (1)

Can't buy R-12? You mean the 200 some odd auctions on eBay for R-12 are all hoaxes?

As I said...if you don't want to go back to R-12 at least tear the system down, flush all the components, replace the dryer and put R-134a and the proper oil back into it. Otherwise your compressor will more than likely be dead within a season or two.

Texas_Ace

iTrader: (18)

Never thought to check ebay for r12, just knew you could not buy it new anymore. Even per-owned though it is pricy. i did put oil in the system, so that should be fine.

Really all i care is for it to work till the end of summer, by next year chances are i will have moved on to something else.

I am just broke and can't afford any more $$$ ont his car, it is really at the point of "Work right, or be sold" If i have anymore problems or big expensies with this car i am going to just sell it while i can still get what i have put into it out of it.

It is just that point, we have all been there with one car or another. One way or the other i don't regret getting this car, it was a great learning car if nothing else.

jackhild59

iTrader: (7)

Ok, this is why I recommended Freeze 12- an R12 substitute that works quite well.

http://cgi.ebay.com/ebaymotors/FREEZ...spagenameZWDVW

And yes, you can buy R12. That is all I use in my old cars. Napa/Orielly's charge $25 per can for R12, so you can even buy it reasonably cheap locally. Gotta have a license to buy, not so with Freeze 12.

Here is a reasonable high quality gauge set:
https://www.ackits.com/pc/35772/Refr...22+%26+R502%29

jackhild59

iTrader: (7)

Low side pressure is not the issue. And the low cutout switch will cut the compressor at about 22psi. The issue is highside pressure. And you DO NOT want to charge R134 or Freeze12 until the sight glass is clear. If you do, you will have busted hoses at least, and maybe ruined compressor.

Yes, what you have is a 'Death Kit'.

Texas_Ace

iTrader: (18)

I asked at pepboys just the other day and they said they have not carried R12 in years. Didn't try napa though.

Might get one of those freeze 12 kits though.

Not arguing, just know that i needed the AC to work for as cheap as possible. got kit, used kit.

The Freeze 12 kit above is about the most i would spend on the AC at this point. I really am that broke and that close to selling the car altogether. lol

jackhild59

iTrader: (7)

Where are you located in Texas? If you are in the DFW area, I would be glad to help you charge the car correctly with Freeze12 using my equipment.

If you have a friend with all the equipment, you don't need any equipment, just the cans of Freeze12.

Cheap is good, I can relate, but if the 20 year old compressor vomits the Black Death due to overpressure, then the car is probably totaled. And you still won't have A/C. If I can help, let me know.

Texas_Ace

iTrader: (18)

Some help would be great, but looking at your profile Double Oak is a LONG way from me, darn the luck!