otis80

Well here is a little back ground details on my problem. My brakes have always been a little screwy, with the first push of the pedal it would go to the floor, if you pumped it again the brakes worked perfect. Well last week I parked it, went out the next morning and had no brakes at all. The pedal wouldn't tighten up at all. So I put a new master cylinder on it and the brakes started working perfect. Also for the past few months or so, every once and a while when I would apply the brake at a red light the idle would surge from about 500-1500. I could rev it up a little and it would go away. Well now, 3 days after I changed the master cylinder this happens... It first started like before sitting at a red light with the brake applied it surged, but now it goes from almost 2k or more to +-500. Then it started doing it when I would put in the clutch but it didn't surge as bad. And now it does it ALL THE TIME. The idle is all sorts of screwed up. When I go to change gears and I push in the clutch it revs up to about 3k rpm and then goes back down. When I let off the throttle going down the road it takes it like 2 seconds or so for it to act like I have let of the throttle. WTH is going on with this thing?! I did some reading around and people talked about the brake booster which would make sense since I just had that master cylinder put on it, maybe something got messed up? Please someone help me... Thanks for your time

otis80

Also I got some staring fluid and checked my vacuum lines and never found a leak.

HighLux

Carb or efi? 4 cyl I assume.

Gotta let us know what we are working with.

otis80

Its in my sig...22re

HighLux

Have you checked....

timing?
tps?
tune up?
cleaned throttle body?
checked vafm?

otis80

None of the above, one any of those cause this issue to happen pretty much over night?

otis80

Bump...

rokblok

iTrader: (1)

If rear seal went out on the master, it may have leaked fluid into the booster. In which case the rubber diaghram in the booster could gave gotten damaged and causing a vacuum leak. Maybe try pinching off the booster vacuum hose, or removing it and sticking an appropriate size bolt in it to seal it off. You should have a very hard brake pedal, since you will have no vacuum assist, so be very careful... (Just maybe run around the block?)

See if this helps your idle surge

toyota4x4907

Check coolant level, anti-freeze to water ratio, and burp the cooling system. Adjust ignition timing to spec and set idle speed correctly.

otis80

Hey rokblok, so are you saying if I plug the hose it may fix the idle problem? If so I just need a new booster? I feel like the booster is the problem. Because this all happened right after my issue of no brakes and putting a new master cylinder on it, and when I say after it, I mean like 2 days after it.

rokblok

iTrader: (1)

I'm saying its worth examining. Since you mentioned that it seems to be brake related, and that's really the only way the brakes could affect the engine idle, that I could think of. And I've seen it before on various makes/models. It was just a thought.

Inspect the vacuum hose going to the booster. Make sure it's not cracked/split anywhere. And it's tight on the intake port.

Then pinch/block the large vacuum hose going to the booster. Carefully drive around your yard or around the block to see if it helps your idle issue. Please know that it will be very hard to stop. The pedal will be rock solid..... (Perform at your own risk...). Or just replace the booster and see if that helps.

You can sometimes look on the inside of the firewall, where the brake pedal linkage comes through and where the booster mounts, pull the carpet back and see if the brake fluid leaked through and has eaten the paint off.

dropzone

iTrader: (6)

Fixed your thread title to be relevant

Mandy Tuning

very common for the ages of our truck when you bleed the brakes using brake pedal push method all the way to the floor that crack the boost diafragm. on my 2 trucks,3 brake booster and counting,now i bleed them using
suction method.

otis80

thanks for the help guys. I will try to plug up that hose this coming weekend. Off to school for the week and wont be back home till the weekend. I have a feeling thats it. And after the comment was made about bleeding them, it really makes me think thats what it is. The guy I had put the master cylinder on for me said he had to bleed each wheel about 5 times. So Im sure with all the bleeding it may have cracked that diaphragm like you said. Thanks for the help guys.

Discombobulated

Weird, sounds like my problem but my idle only surges upon warming up typical cold start is normal idles really high and gradually lowers like normal but once it gets to 1000 rpms it surges when the brake is applied, then after it warms up it's fine. Post up when you get it figured out

otis80

Will do, discombobulated. Anyone else with more input?

otis80

Well I plugged the hose with a bolt. It was idling pretty bad, I'm guessing because that vacuum hose was off? But when I pushed in the brake it still surged... so that means its not the booster correct? I of have an ohm letter, nor know how to use one, so is there any other was to test the tps? What's my next step here guys?

otis80

Well I have some more information for everyone. I just checked the trouble codes. I thought it was a 57 code. But after looking around it only has one digit codes, is that correct? If so then I have a code 5 and a code 7. If I am looking at the right thing then code 5 is an O2 sensor and code 7 is TPS. I unplugged the TPS and started it. It raised the rpm just a hair, but not by much. I had seen videos of people unplugging them while it was running and it reved up to like 6k rpm. Should it have done that? I'm lost on what to do. I could really use some insight. I do find it weird that everyone mentioned the tps with the issue I'm having and then I got a code for it. So it makes me think the tps is my problem, am I right???

4Crawler

iTrader: (3)

Likely the idle speed it too high and/or the TPS is bad or improperly adjusted:
- http://www.4crawler.com/4x4/TLCA_Tru...ech.04.09.html
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

otis80

Well I turned down the idle screw as far as I could and it never changed anything... So think the tps is my answer?