rumblz

iTrader: (1)

1988 Turbo II
No engine mods except for exhaust

I attempted to adjust the TPS and BACV screws to fix an idling. I was having bad oscillation and the car would die when I'd reach stops sometimes. I replaced all my vacuum lines and the car would still die after reving and reaching a stop. I adjusted the TPS and BACV which fixed my oscillation/bad idle and also my car no longer stopped dying when reaching a stop. However, now my car doesnt do the high rev (3k RPM) at cold start. Instead it dies almost instantly as the car cranks and starts. If I hold the gas to keep it alive and warm it up for a couple minutes it'll idle and run fine. I checked the plug and wiring to the air bypass solenoid valve and I didnt see a problem. I tried reverting back the TPS and BACV to their former positions, but it didnt help. Any ideas why the cold rev doesnt start anymore?

Thanks, if you need anymore information let me know.

evot23

iTrader: (17)

Did you change anything else? Disconnect the battery? ECU need to relearn your tune? How much did you have to adjust those settings...were they way off to fix your idling issue? I've found that big adjustments to TPS and BACV will fix things temporarily but not underlying issues...more like a band aid than a true fix.

satch

iTrader: (1)

The cold rev should only occur on cold starts when the air temp is above 62 degrees or so. At coolant temps below that the system is overridden in addition to hot starts as well.

rumblz

iTrader: (1)

Yeah I tried disconnecting the battery to reset the ECU, but it didnt make a difference. The position of the TPS was waaaaay out, it was a pretty big adjustment. There probably is something else wrong D:

Yes I know, and it doesnt cold rev even when I start it in the cold morning

FB331

What happened here

rumblz

iTrader: (1)

Sorry, they changed the post requirement for this forum and I wasnt able to reply lol.

Well since this problem I have swapped in a jdm motor. Though I was still having similiar, if not the same exact start up and idle issues. Heres what I found out..

One thing was that the previous owner had installed an ebay universal aluminum radiator which doesnt have a spot for the radiator switch (only on the s4 and assist the AWS which I had unplugged). I had a friend drill and weld a bung for the switch, but do to poor planning and the weird fitment/installation of the radiator the oil lines were rubbing against the switch and eventually broke off the 2 prongs. I'm sure that had contributed to my cold start/idling issue somehow. However I didnt notice this till after I did the engine swap. I just ran a wire with bullet connectors in place of the radiator switch and start up got a little better.

Soon after I began to have another problem with cold start/idles. I would start the car and it wouldnt even hold an idle even if I tried to give it some gas. Turns out I bumped off the connector for the Water Thermo Sensor when I was installing an alternator. After replugging it in again it would hold an idle if I held the gas pedal for a while. Once warmed up it idled by itself.

After fixing a lot of vacuum hoses, bacv/o2 sensor wiring, and replaced the TPS with a spare I had it eventually held an idle on its own on cold start. The idle was still kind of rough, but then I did the timing and it ran 1000 times better.

Also at one point during all this ripped the wires on the Air Supply Valve on the back of the UIM, but I replaced it with a spare, not sure if that helped anything though.