Joe6pack

ugh! Well maybe that explains my idle drop. Although I don't know why any chip would touch the idle settings. But I have read here that idle can be affected. Why would a chip affect idle?

Anyway, other than the idle problem the car seems to run fine. It really seems to like warmer weather. The hotter it gets, the more the car seems to wake up. Also, there seems to be a step function on power above 4000 rpms. Once the car hits 4000 rpms it seems to jump in power.

I just can't get the idle to my liking. Turn on the A/C and the idle takes a hit. Turn on the lights with the A/C and there is a bigger hit. Up the idle to compensate and then turn everything off and the idle is clearly too high and "searches". When cold the car barely idles at 800 rpms with the A/C and lights off. As it gets warmer it seems to idle better and better. Right now, I have it set up to idle at 880 when sufficiently warmed - with the temp indicator half way between the lower mark and the upper mark. Maybe this is the best I can expect.

whalebird

Hello Joe. If I may add my experiance. It's been a few months but you did set your base idle and go through a partial test plan as per the bently. Getting back to basics, I would suggest you test your throttle position switch if you have not already. Just eliminate it from the possible failure sources - It's an easy test.
As for the chip, I have a bit of a controversial position. I have, on a number of occasions, run into drivability problems with chips. Usually a car with a chip installed by a previous owner that will hunt at idle or experiance cold start problems. I chased these problems much like you are and it became clear that I needed to eliminate the chip as a problem. I installed the stock chip and bingo - problem gone. On three occasions the car was turned over to the owner with the idea we would look at it after a trial period with the stock chip. All three times the customer returned and said the car ran better with the stock chip. I talked to autothority about this and was told that there base-map chip may need a reflash to compensate for regional differances in climate, fuel quality, and tuning etc. Furthermore, your '95 vintage chip may be out of date with todays fuel formulations and internal variations unique to your car.
I am luke-warm on chip tuning on an otherwise stock engine. There are people with the Steve Wong/Russel Berry chips that have reported stellar results, but I am a skeptic on a stock engine. You may have some research to do on this and, if your resolved to chip tuning, may want to look into a Wong/ Berry unit or have your chip reflashed by autothority. My experiance is somewhat limited and dated on this, so consider it only a single data point with the other guys who have had first hand relevant experiance. I'm sure they will share their views to help you through this.
Keep us posted and good luck.

Ed Hughes

I'd recommend Steve Wong....he's been doing this long enough and spend enough time on attention to detail depending on the car and setup, that cold start issues and idle should be a non-issue. My statement on my perception of Autothority being "garden variety" means more of an off-the-shelf, one-size-fits-all attitude.

I also think that one of the benefits of Steve's product is the drivability improvement, much smoother. Not all about HP...

But, then again, nothing wrong with stock.

ron mcatee

Joe6pack, I had an Autothority chip in my 88 Carrera. When I first put it in, it ran like a top. But over a few months it started having the problems you've mentioned. I went back to the stock performance chip that came with the car and it has continued to run very well for many years.

Joe6pack

Thanks for the great replies as usual. To make matters even trickier, my '87 has the 24-pin chip. So finding a stock 24-pin '87 chip is going to be tricky. I would love to have a Wong chip, but it's hard to justify $375 right now.

whalebird

Maybe you can find a stock chip (or borrow one) for diagnostic purposes. I think it's worth a look given your symptoms, especially if you are confident the usual suspects(vacuum leaks, grounds, etc) are all good.

rusnak

I keep a spare, complete dme with brain and all to troubleshoot with. I bet there are guys with stock 24-pin chips who keep theirs for troubleshooting reasons as well.

Joe6pack

Update and a question. I suspect my oxygen sensor is bad and I know that the car will run fine without it. Is there any downside to just unplugging it. I now believe it is the cause of my idle drop problem. Emissions aren't required in my area. The car has new plugs, cap, rotor, fuel filter and cylinder head temp sensor none of which fixed the idle drop. However, the significant improvement in performance allowed me to isolate the O2 sensor as the problem. I believe it was performing intermittently which is what made it so hard to isolate. Thanks in advance for the help.

John

Ed Hughes

I think your mileage will drop a few MPG.

rusnak

I know the tuner crowd likes to run with no O2 sensor but this makes absolutely no sense to me. Your afr will be all over the place with respect to rpm, and the default base map will be rich, as mentioned. Not good for the cat either.

If it was my car, I'd go back and check fuel pressure and the fuel air ratio with either a fuel air meter, or a CO% meter. Then you will know if it's in open or closed loop, and you'll be better able to interpret the resistance readings.

A bad dme will drive you nutty. Did you ever change out the chip?

Joe6pack

Hi Russ - No, I was never able to find a chip to substitute. I got busy and am just now getting back to the car. I changed all the aforementioned parts in the last week and while the idle is significantly better, it still exhibits the drop. My theory is that the O2 sensory is intermittently dropping out and coming back. With the sensor unplugged, the idle is much smoother and doesn't drop. The trade off seems to be that the idle is too low on warm up. I have already ordered a new sensor. and hopefully I will get it next week. All in all, the car has never run better.

rusnak

It could be a vacuum leak (lean condition). Hate to see people buy parts and not see results. You might want to borrow an LM-1. What is your location?

Joe6pack

I have checked for vacuum leaks and so has a professional wrench - none found. I have looked for an LM-1 or LM-2 or equivalent to rent locally, but haven't managed to find one. I have even thought about buying one, using it and then reselling it on Ebay. Don't worry about the parts. They all needed changing except for maybe the coil, but now I have a spare.