drftem

ok i just bought my 91 rx7. she starts but the idle is really bad. it will goo from about 1000 to about 200 up and down continuously some times it will drop and die. if i turn on the ac and turn on the fan the idle will go to 1k and hold sometimes it will jump up and down but only up and down about 300 rpm.there is no belt hooked up to the ac pump. what should i check. im new to rotary motors so i have no clue were to check.

bigzman

iTrader: (1)

do a search and look up how to get the codes. It may be your narrow band on the TPS had the same problem. But donnot quote me as there a lot more guys out there whos know best. http://howto.globalvicinity.com/gv_w...i=50&co=1&vi=1 http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1

drftem

ummm my car isnt throwing codes. so are you sure?????

NoDOHC

Usually a surging idle is due to an improperly adjusted TPS or a vacuum leak (there are other causes too, just not as common.)

Hereis a link to the factory service manual (FSM) This will probably become one of your best friends.

You should be able to find all sorts of information in section 4 (a or b depends on whether or not it is turbo.)

The vacuum leak is my guess, sensors don't usually adjust themselves, and wise owners don't usually adjust them either without going through the troubleshooting procedure in the manual. Hoses get old and brittle and they leak vacuum.

Starting fluid or carb. cleaner works well for finding vacuum leaks, just spray it on all suspect locations until the engine reacts noticably and that is your problem.

I hope this helps a little bit.

Omixeo

iTrader: (1)

My idle was really bouncy, I replaced the TPS twice and it was still bad. Turns out my BAC was clogged up. Cleaned it out and it was fine.

drftem

ok ive tried unplugging the bac and nothing changed. so im guessing that has nothing to do with it. well i noticed if i rev it up to about 2500 it still surges. but anything pass that it starts to back fire . im guessing bad timming now. im gunna go check that if thats fine then what should i check next????

pfsantos

iTrader: (1)

It'll be hard to adjust timing with a funny idle. I'd try the starting fluid method (see above) just for ****'s and giggles because it's easy.

Roen

iTrader: (2)

It may just be that the TPS is bad. For S5's, once one of the TPS sensors are bad, you'll either trip the CEL or you'll be rewarded with a bouncy idle. The only way to completely get rid of that problem is to buy a new TPS. Note that this is when you're warming up the car.

Now, if the car is already warm and it's still bouncing, then that tells me it's most likely a vacuum leak somewhere, especially if none of your accessories are turned on.

drftem

so how much is a new tps? wouldnt the car run like crap if the tps was fried? because it runs fine but it just has a bad idle and it surges up untill 2500 rpm oh yeah i forgot to mention when i have the ac turned on and fan turned on ( the ac pump has no belt) and i push in the clutch pedal the idle smooths. as soon as i let the clutch back in it goes back to bouncing. could that shed some more light on what it could be or do i just have to buy and then hope i didnt just buy something for no reason?

Roen

iTrader: (2)

The TPS wouldn't run like crap when your foot is on the gas, but once you let off or are about to let off, you'll be rewarded with bucking, rough engagement of the throttle and possibly backfire.

S5 TPS is 360 from Mazdatrix, dunno about the S4, though you could possibly get it cheaper elsewhere. That being said, I wouldn't trust non-Mazda stuff.

How exactly does it surge? While you're warming up the car or after the car is already warm and settled?

If you turn the accessories on and it starts surging, that to me points to the BAC valve either being clogged or no good. Try cleaning the BAC valve.

drftem

ok well if the ac is turned off it idles even worse to the point were it might die. when i turn on the ac button then turn on the fan it ups the idle and smooths it out a bit. but the rough idle is there as soon a s i start it . even once it gets warm. so is there any way to make sure it is the tps before i try to get one???? does a n s4 tps work on an s5??? i have a 91s5. i might try one from a junk yard....

pfsantos

iTrader: (1)

What happens when you unplug the TPS? The FSM has a test for the TPS (see my sig.). S4 and S5 TPS are not interchangeable.

Unplugging the TPS should throw the computer into (let me check the FSM...) a default assumption i.e. assuming throttle is at full open if its the narrow range of the TPS, 20% open if TPS Full range that is bad. Not sure what'll do with the whole thing unplugged though.

drftem

so what can happen to my motor if i keep driving it like this? are there even any negative things other then just the poor idle? i need to know is this a stop driving the car and save up till i can fix it or is it fine to keep driving just keep an eye on it kinda thing?

Roen

iTrader: (2)

That's weird, I've never heard of problems with the idle being rough when the acc are off but smoothing out when the acc is turned on. I would doubt that it's the TPS. I think I did a write-up on the S5 TPS, it's in the forum's some where. Try adjusting it to see if that'll help any, though I think your TPS is shot. Just search for TPS and my name in the advanced search tool above.

drftem

will do.

drftem

ok today at work before i left to come home i decided id try and see what would happen if i disconnected the tps. well when i discoonect it the car adles just perfect revs fine just a little high so i plugged it back up and now it idles a little sputter here and there but it idles. now the problem is if i turn the steering wheel the idle drops almost to it dieing. now what to check?