jim-mf2hd

I have a 90 C2 with 85K miles and a recent LWF and an even more recently added Autothority chip to help solve my engine cutting out at the most awkward times. The chip seems to solve the cold start problem of dying at low RPM until its warmed up. However, I have an idle surge/hunt problem. After a couple of minutes of driving in stop-n-go after a cold start, at a stop the idle will surge from 1000-1400 and repeat that cycle until gas is applied. After reading most of the posts related to LWF, I think I may have a somewhat sticky idle stabilizer. I took it off today to spray it with carb cleaner. My question is, should I soak it in carb cleaner or what? Also, the hose clamps are quite unusual, at least to me. How are they supposed to be removed ? On one side of the clamp they are crimped into what looks like a small triangle, and the other side looks like a small detent that goes through the clamp with the end mashed flat. Is there some quick way to get these off ? Should they be replaced by with different type of clamp to ease their "on and off" while I am working with the stabilizer for the next week(s)


Thanks
Jim

Adrian

Dear Jim,
I highly advise you do not soak the idle speed control in anything, especially carb cleaner. There is a torque motor inside that puppy. This is a motor driven valve. They do not take kindly to being soaked. You will find an electrical connector. This is from the DME.
Your idle surge whilst having a huge amount to your setup may well be the idle microswitch on the throttle body, please clean out with contact cleaner or your O2 sensor is playing up. My guess is the O2 sensor. There are lots of other possibilities actually. Once you have installed LWFs and aftermarket chips, the old DME gets a tad upset.
Ciao,
Adrian
911C4

slant911

Jim,

I am (was) in the same boat as you. I have a 90' C4 with a recently added LWF and had many problems all pointing to LWF issues. I've since come to discover that virtually all my issues were because of my ORIGINAL O2 sensor (93000 miles). After disconnecting it and running the car with it off all the problems went away. I am now waiting on the mail to show up with my new and improved O2 sensor. It is an easy test to perform. On the left side of your engine bay you will see a round plug about 1/8" round. One end goes to a wire loom while the other end goes to the O2 sensor kind of behind the left rear wheel. Unplug that 1/8" plug from each other and run the car. See how it performs. It my case the car ran flawlessly. If that's not it connect it back up. Takes 5 minutes for entire test.

jim-mf2hd

thanks for the tips. I'm sorry to report that they had no effect. I removed the O2 sensor and did the normal driving routine. If I depress the clutch while its above 1300 or so coming to a stop, the idle bobs from about that range to 1K. If I don't clutch until close to 1K, all is well. Unless anyone has any new tips, I'm resigned to approaching stops in a much more conservative fashion in order to keep people from thinking I'm revving my engine as I wait at the stop lights.

Jim

DaveK

Hi,
I had a problem with bouncing idle which was solved by replacing my distributor caps / rotor arms. They were well worn after 12 years / 125K miles. Probably not your problem, since the LWF is a common cause of idle hunting but it may be worth taking a look at the condition of them.

Dave
90 C4

slant911

Well I had another issue with my car that was a severely leaking throttle body. The shop used a special little gizmo (tech talk) that would pump air into the throttle body. It was supposed to test out at 3 pounds hold for 5 minutes or something like that. Anyway, mine leaked like a sieve. It wouldn't hold ANY pressure for even 5 seconds. The air leaked out all over the place from the shafts that go through. I had the same sort of symptoms as you describe and was convinced it had something to do with the LWF. Turned out it didn't. They put a new throttle body and air sensor and that issue totally went away. THe bad news is that the fix was $1800. Now obviously this is not something you can check at home, but, may be something to bring up to your wrench if all else fails.

danielheren

Does anyone know how difficult it would be to change out your own throttle body? I have the same problem with mine.

slant911

Daniel,

Keep in mind that I did not do the work myself on mine, but, did watch a portion of it. None of it looked really complicated. Just terribly time consuming. You pretty much have to disassemble the entire top of the engine. My wrench charged somewhere around 12 hours for labor (complete). That's someone who knows what they are doing. You have to imagine it will take you longer to do it yourself.

Rob/RSA

Hi Jim
I have a 93 RSA, with a LWF, and had the same problems, till yesterday. I installed the AutoThority chip, and their new Idle stabilizer valve. You need both. The clips open with a long thin blade screwdriver. Gently pry it back and fourth. Unplug the valve, and pull off the two hoses. install the new unit, and crimp the clamps with side cutting wire cutters (gently). I was so happy with the results, I called them and thanked them for selling a product, that worked as advertised. I can even run the A/C at idle.