bondospecial

I am reading about how to adjust the TPS using the resistance method, and the idle speed on my 87 FC but I am not sure where the "initial set test connector" is that I am supposed to be jumpering (and jumpering to where?) Also I have the single plunger TPS and I see a lot of the articles reference how to set the TPS for a dual plunger setup. Which wires on my TPS are getting probed and am I still shooting for 1k ohm resistance? I am checking this with ignition power on and car off? Do I have to back probe the connector by inserting small strands of copper wire and re connecting the TPS plug?

Thanks

Steve

ifryrice

You shouldn't really have to do much with the initial set, but if i recall it's either a 2 wire or a single wire connector near the battery area. I think S4's are 2 wire and you just loop them together, but they might be a single that you just ground out. It's been a while since I've had a S4 to do that on.

Ted's site has most everything you need to know on setting the TPS, done with car off, connector disconnected usually (unless you use the volts method).
http://fc3spro.com/TECH/HOWTO/TPS/tps.html

Off-topic: I notice you have a '88 K1500 with a 327, i've got a '86 with a 396, i love those engine bays, can crawl in there and take a nap.

satch

iTrader: (1)

The initial set coupler is 2 wires and the connector is green and located by the leading coil and engine fuse box(rectangle). You should disconnect the tps plug when setting it. To backprobe just firmly insert the multimeter leads into the back of the tps plug. Befrore adjusting to ohms you need to zero out the multimeter. To do that just place the multimeter terminals together and if using an analog meter you might have to use the adjusting **** to help zero out the meter. Most people here rely on the voltage method for setting the tps though.

bondospecial

Thanks for the tip. The K1500 is a pain to work on because I need to stand on buckets to work on it because its up so high. I did the engine build and swap myself with no help and I had to climb in the engine bay at times because it was too tiring to lean over it.

ifryrice

Haha, i'm 6'5" so I usually dont have issues, and i don't have a lift or anything on it.

On-topic, often there's drop/resistance in the wires leading to the ECU, so even getting the TPS spot on can still not always resolve some issues. Using the TPS light method, or checking the ECU itself in conjunction with adjustments goes a long way into making sure the ECU sees exactly what it needs.

bondospecial

That site was a great help thanks. It says that if I have to adjust the idle screw to get the resistance to read 1k rpms that I might need to adjust the BAC. I have the cold start and BAC all functional, this car is all stock. How is the BAC adjusted?

ifryrice

The BAC is electronically controlled via the ECU, i wonder if he meant the air bypass screw (ontop of the TB) that you can use to adjust idle.

bondospecial

^gotcha, excellent, thanks!!

satch

iTrader: (1)

That site is for turbos. You can't adjust your bac.

bondospecial

So will the idle speed regulate itself once I set the TPS or do I need to adjust the air bypass screw potentially if the idle speed screw to set the TPS has to be changed?

ifryrice

Typically it'll try to sit at the lowest RPM with the bac fully closed. I usually try to avoid messing with the idle stop screw if i can avoid it. If the cars idling around the 700-800 mark (without BAC assistance), and the TPS seems way off at either end of the TPS screw, i'll usually adjust the TPS's arm (the bent arm that travels accross the TPS as the throttle opens) to get it within spec. If your idle with the BAC disabled is extremely low (ie 400, 500, and you can't get it near 700 with the screw ontop the TB), then go ahead and adjust the stop screw.

bondospecial

Ah maybe I'll just leave it alone. I am delivering the car for the prospective new owner's final inspection tomorrow, I have a deposit on it and the guy was happy with the way it ran when he test drove it but I am super picky and wanted to have fresh fluids and a fresh adjustment on it for the new owner just for kicks.

This car idled no problem at 750 rpms warm when it was above 40 degrees F outside but now that it is very cold (30 deg F and below) even if I drive the car for 20-30 minutes it will slowly come down from 1500 high idle to 1000 rpms but it never ever reaches down to 750

I am replacing the 'stat tonight just in case its actually running too cold for the idle compensation to ever kick out but if not, its not the end of the world.

Thanks so much again for the help, if I have the time I will at least check the TPS for my own knowledge and if its close I'll just leave everything alone (other than change the 'stat)