bencb44

iTrader: (2)

I'm sure this has happened to other people before, but I couldn't find it by searching.
When I start my car, the idle is fine, but when I'm driving and come up to a stop light, it bounces between 1500 and about 1000 rpm. This is a brand new engine with about 50 miles on it, and a new Power fc. I haven't had it tuned yet, because I'm still breaking the engine in. Is it something that will go away then?

dinosaur

Mine does this too. Mine also stalls sometimes when approaching a stop with the car in gear, and closed throtle (coasting in gear), when I engage the clutch , it stalls (most ofter with the AC running). After a lot of searching, it seems to point to the throttle position sensor or "clutch switch".
My TPS readings are within spec:

CT
TPS1 .46 (0.1 - 0.7 )
TPS2 1.11 (0.75 - 1.25)

WOT
TPS1 4.35 (4.2 - 4.6)
TPS2 4.97 (4.8 - 5.0)

And the clutch switch (not the ignition interlock) shows okay too. (reading taken from Commander) The idle does settle down to 1,000 RPM after about 30 to 45 seconds of bouncing around.

Maybe someone can help us both.
I have about 3,000 miles on this engine, and we ( me and the engine builder/tunner) have tried the idle adjustment.

bencb44

iTrader: (2)

My clutch switch is good. I just had to check that a week ago to figure out a starting issue. How do you check the TPS?

dinosaur

With the engine fully warmed up to operating temp, shut off the engine, turn the key to the ON position (the dash lites are all lit up), you need to check the readings at wide open throttle and closed throttle.

commander use:
go to etc menu, than to sensor check.
Check the voltage for TPS1 and TPS2. (VTA1 is TPS1, VTA2 is TPS2)
See the ranges for both in my previous post.
It will also show the status of the clutch switch (CLT) in the middle colum, as you press the clutch the status will change.

The FD has two switches on the clutch, one for the interlock (don't want it to crank in gear with the clutch engaged), and one to tell the ECU/PFC that the clutch is engaged, (don't ask me why they couldn't use the same switch).

dinosaur

here is some more things to check.
http://howto.globalvicinity.com/gv_w...i=55&co=1&vi=1

ahad

can the tps adjustment be done without a power fc? cuz im facing similiar problems plus in lower rpms right after shifting the car does not respond when i hit the accelerator then after a second delay it responds...i thought it might be a fuel pump issue but it seems more likely that its a tps issue...

dinosaur

Yes, you'll need a digital volt/ohm meter.
Here's a writeup.
http://www.rx7.org/Robinette/tps_adj.htm
(bookmark this site, lots of stuff here)

ahad

thanks!

bencb44

iTrader: (2)

I don't have a commander. I do have a datalogit though. Can I check that stuff on there? So did you fix your throttle fluctuations?

bencb44

iTrader: (2)

I just noticed that the link you posted is for 2nd gens. Is the idle system the same as those?

dinosaur

I'm sure you can, although, I don't have Datalogic and can't tell you how. I have Chadwick do my tunning (I'd break something if I did it). Maybe some one who knows more than I do can add something to this thread (please ) or maybe you could ask this in the PowerFC subforum.

I still haven't solved my problem yet, the TPS looks to be okay. Dale Clark has a website that has a PFC FAQ on it and I found this:

2c. I've done the idle learn process, but the car revs up and down at idle?

You need to adjust the idle bleed screw. Under the throttle body elbow between the 2
10mm nuts that hold the elbow to the throttle body is a flathead screw in an indentation.
This is your idle adjust screw. Recommended setting is about 1/2 to 3/8ths of a turn out
from fully in.

It's been cold and wet here and my car is outside, so I haven't checked this yet( http://www.clubrx.org/ )
I have several threads about TPS/weird idle problems bookmarked and have tried everything mentioned without any luck, but none of them mentioned the idle blead screw. In one someone mentioned checking the TAS, AAS, & O2 FB switch, I'm still trying to figure out what they are. (beginning to see why I don't tune my own car now )
I'm watching the injector duty cycle now and reading about when it should be going to 0% and when it should not. I know it should drop to 0% when you decelerate and should come back up about 1500 RPM, I think. need to watch mine and see just when it's doing what. I feel like my injectors are not opening soon enough when I'm decelerating and press the clutch, like the RPM's are dropping to fast for them to react. (lite weight flywheel)

Mine is still a work in progress.

dinosaur

probably not exactly, look around that site too, there's good thing there.

bencb44

iTrader: (2)

Thanks. Yeah the weather's been crappy here too. It's actually sunny today though, so when I get out class, I'll go home and try to find that idle bleed screw. I'll let you know what I find.

dinosaur

there is a pix of the screw on Dale's site, in the FAQ comments I think.
I can't seem to find it right now, but it's on the bottom of the throttle body, between the two mounting bolts (recessed).

Osius

I had that problem once it turned out to be a loose valve

dinosaur

which valve?
Mine is behaving better in the cold temps but I still want to solve this idle problem.

bencb44

iTrader: (2)

I just got done trying the air bleed screw. It seems to have worked. I'm gonna drive it more and see what happens though, because it wasn't doing it consistently today, but it looks like that was the culprit.

I used a flat blade screwdriver to turn the screw clockwise (closing the screw) and that would stop the idle searching. Take it slow because turning that screw does affect the idle a lot. Just turn it a little bit until it stops searching, then blip your throttle and repeat until it goes away. My idle does surge up to 1300 or so, and then slowly come down to where I set it (a tiny bit under 1000)

Let me know if it works for you. I'll tell you if it stays fixed or not tomorrow. Gotta drive it more to see if it's fixed for good.

bencb44

iTrader: (2)

Ok, so I drove it around a bunch and it still needs some fiddling with, but that seems to have fixed it. Thanks for telling me about it and good luck with yours