Major starting issue

Reaper450128 · #1 12-31-2003, 07:13 PM

Three weeks ago, my SVX would start, but if I didn't let it warm up for a minute or two at least, it would die as soon as I put it in reverse. I could live with that, just meant I had to start the car a little before I needed to leave for work, and had the side effect of giving me a nice warm car for the entire ride to work. Then I went on vacation for a week, and the car sat undriven for 8 days. When I got home, it would start, but as soon as I turned the key back to run, it died. Gave it a little tiny bit of throttle, and then it would start and jump up to 2000rpm (or 5000 if I gave it more than I intended to). That was less than acceptable. So today I pulled the throttle bodys off, cleaned them out, and attempted to remove what I believe is the ISC from them, only to be thwarted by one impossible to remove screw. Put it all back together, same problem, only with the added bonus of no longer letting me release the throttle entirely or it would die. I had to drive two-footed to park it back in its parking spot so my dad could park in the garage, keeping the pedal down just enough to keep the revs at 600-800. Any idea what is wrong now? I assume I must have done something to the ISC or whatever it is that is on the bottom of the TBs, but I'm not sure what.

Subafreak · #2 12-31-2003, 07:30 PM

Any check engine lite?

Reaper450128 · #3 12-31-2003, 07:50 PM

Not since the first day after I got back. When I would let it idle that day, it would suddenly drop down about 100rpm lower and run real rough like it was on only 4 or 5 cylinders. When this happened the CEL came on. I turned the car off and back on (when it warmed up fully it would start without prodding the throttle) and it went away, and as long as it didn't sit idling, the light stayed off. The next day, that all stopped happening. I haven't checked the codes yet, I will tomorrow.

Reaper450128 · #4 01-01-2004, 01:37 PM

The BACV (By-Pass Air Control Valve, what I thought was the ISC) was not properly aligned. I attempted to put it back the way it was (it was slightly off-set from level when I removed it yesterday) yesterday, but apparently I made it worse. So today I pulled it all back apart, turned it so the harness was perpendicular to the engine block, and it started right up, working perfectly again.

Reaper450128 · #5 01-20-2004, 02:34 PM

Bah... didn't last, back to poor idle and difficulty starting as soon as it fully cooled off overnight. Until today it had settled into a behavior of requiring a little throttle to start and for about 5-10secs afterwards until it smoothed the idle, then a 5-10min wait until I could put it in gear without it dying. After it fully warmed up, if allowed to idle in park, that same check engine light I had before came back (code 24, BACV, as expected). Idle revs while in gear were around 1000RPM, in park about 1500RPM, until the check engine light came on when it would go to really rough and smelly idle at 1000RPM. Despite all that though, with some consideration for allowing it to warm up and use of the parking break to keep it parked while in gear if the need arose, it was driveable. Today, after some playing with the alignment of the the BACV solenoid as well as a thorough degreasing of the valve itself, I'm back to two-footed driving. I'm going to try to adjust the solenoid a little back to the parallel position I tried before, but I'm not optimistic. Any ideas for if and when this attempt fails? Time for a new BACV?

Subafreak · #6 01-21-2004, 06:43 PM

Do you meen your adjusting the BACV motor my lossening the two screws with the slots? I don't think thats supposed to be adjustable by anyone but the factory. It might be time for a new one$$$

Reaper450128 · #7 01-22-2004, 09:19 AM

I was kind of wondering that myself, since I can't find any info on how to adjust it, besides the fact that adjusting it would take forever given the need to remove the almost entire intake assembly up to the manifold between each adjustment. Besides, there is no reason why it should need adjustment after its been set right.

Anyway though, I pulled off the unit again yesterday, and while testing the driveshaft on the valve with my fingers, I decided it was awfully hard to turn. I gave it a good dose of PB Blaster around the moving parts, and after a few minutes of soaking, it suddenly broke free of the buildup and moved with ease. I put it all back together, lining up the solenoid with the paint marks on the side, hooked all the hoses back up (after replacing one that broke as I was taking it all apart for the sixth time or so), and started it up for the first time in over a month without any throttle input. Gave it a good run (still having issues with shifts until it gets almost to full temp, but that's another problem altogether), and the idle settled down to about 550rpm, well within the specs.

listed · #8 10-05-2004, 06:59 PM

I'm having almost the exact same problem as you code 24 started only with WOT, only now it won't start at all. Where/ What is the BACV.
Thank,
Chris

Earthworm · #9 10-06-2004, 11:26 AM

BACV = By-pass air control solenoid valve

oab_au · #10 10-06-2004, 05:01 PM

The By-pass Air Control valve controls the normal idle speed. When you start from cold the Auxiliary Air Control valve supplies the increase amount of air to allow the engine to run.

The Auxiliary Air Control valve will raise the speed to around 2000 rpm when it first starts cold, operates for about 30 to 40 seconds, slowly comming back to about 1000 rpm, when the By-pass idle control takes over to maintain the idle.

Depending which unit is the problem, it will either start and run for 30 to 40 sec, ok then start cutting out. Or it takes 30 to 40 seconds to warm up before it will idle.

Most problems of this type are caused by the By-pass idle unit, becoming stickey with goo. Most of the time it can be freed up with a Carb cleaner. The Auxiliary air valve (under the left side of the inlet manifold) could stick closed from the same cause.

Don't know which one it is on yours, but this may help you to find out which.

Harvey.