Ok you diagnose this one

[drtbiker]

I would like to start off by saying i have a surging idle problem. This is what i came up with the car continues to surge 800 to 1100. But get this i pump the brakes alot until the brakes get really hard and the car idles perfect at 600-700rpms in the range. But i give it a while and let the brakes get soft again and there goes the surging again.

Can the brake booster affect this?
Is it a vaccum leak?
When the car's idle doesnt surge it runs good.
When the car has a surging idle problem it doesnt run as hard.
The weirdest part of it all is when i pump the brakes until they get really hard the a/f gauge gets readings when it is soft and surging the o2's read rich.....


Is it a bad brake booster?

Sometimes the brakes get really really soft when driving i can almost push it to the floor.


thanks
sorry about the length of the post

[95mustanggt]

My guess is something in the vacuum system. Although, not sure what

[chris91LX]

I've heard of cams causing vacuum problems, but I woudn't expect a B cam to cause that. You might want to do a search on the corral.

[jimberg]

Disconnect the vacuum line going to the brake booster and plug it. If the problem goes away, it's likely in your brake booster. Let us know what happens when you do that.

[drtbiker]

well i havent had a chance to mess with the car went to the track and was disapointed because of traction because of the blown shocks. The car is running more consistant time since the tfi module was changed... But now i have a bad header gasket.. What causes header gaskets to go bad all of a sudden thanks
raini

[LX5liter]

Originally posted by drtbiker
... But now i have a bad header gasket.. What causes header gaskets to go bad all of a sudden thanks
raini

Age and loose header bolts.

[drtbiker]

there only 5 months old and have been cranked down with lock tight

[84LX89GT]

Part of the reason header gaskets blow out is because they are thin paper and even a small amount of clearance will blow through the side of them....what causes this is that headers warp up over time. The ones on my car have warped and luckily haven't leaked yet. All headers warp, some just warp less than others. When you take the header off, take a straight edge and take a look across the ports of the header, sometimes using a feeler gauge will help find trouble spots. Also, using a copper header gasket helps alot because it is thick and tolerates more variance in the surface if you decide you don't want to mill the headers down flat again.
One of the reason headers warp is that they heat up really fast and cool down really fast, this tends to warp metal. Also, if you don't torque down the header bolts evenly this will aid in warping the flange.

[drtbiker]

I forgot to add i have aluminum header gaskets i think made by earl or somthing like that... I tried pulling off the hose for the brake booster and it seamed there was still a small idle issue but not quite as bad though.... I also noticed that i have brake fluid dripping does and brake fluid go in to the booster? I think i defiently need a new one. What brand should i get or should i just autozone it? Also the header gaskets almost sounds like a valve noise now... But it still sounds like bad header gasket. If it is a valve issue that could be part of my idle surge problem aswell. Under deaccleration the car pops like small detenation. And it seams like it is coming from the same side that is haveing the header gasket issue.


sorry about the length guys

im just starting to ramble

later
Raini

[84LX89GT]

A header leak can and will cause your car to run bad because the exhaust pulses will pull air in from the header leak and make the 02 sensor think it's running lean on that bank. Fix the header leak and see what happens, hopefully that's all that is wrong.

[FritzDaKat]

And no, you shouldnt see fluid coming from the booster, if there is, then your master cylinder is leaking, and this could have possibly caused damage to the booster, grab a booster form the scrapyard, pop it in (Along with a new master cylinder if youre positive the fluid isnt just from a spill or there are no leaks in your lines) and that portion of the problem should be solved.

Also be very sure to properly torque down the heads in the exact sequence that whatever book you have suggests for that motor, otherwise you'll have an area slighly less compressed than another and this could have caused that exact problem. I learned the hard way myself on an old Buick with a 350 block, changed head gaskets twice before I went and got the torque wrench.

[drtbiker]

150 dollars later brakes work great. master cylinder was shot then messed up the darn brake booster. But they work good now all i have to do is get rid of the tractor noise blown header gasket

later and thanks everyone
raini

[PKRWUD]

FYI, if there had been a vacuum leak of any size in the booster, your brake pedal would have become hard, not soft. Anytime the brake pedal becomes soft, it's because fluid is being allowed to slip past a seal, either in the master or a caliper, or, a brake hose from the frame to the caliper could be expanding.

If your idle improved after pumping the brakes, then you need an external vacuum tank. By pumping the brake pedal, that's what you turned the booster into.

Now that your brakes are better, and the pedal isn't going soft, the booster isn't bleeding off the vacuum as often, so the idle should maintain.

In other words, your total problem was the master cylinder, however, and additional vacuum tank would have taken care of the idle problem until you replaced the master.



Take care,
~Chris

[drtbiker]

Yes finally we got things straightend out now to the header gasket and i really need to buy a code scanner so i went to buy a cheap one at auto zone and they had a recall on them.. isnt that somthing... its nice to see ya back pkrwud, i got one question for you bad header gasket. Will that cause fuel efficiency aswell as running like crap or do i have some other issues..

later
and thanks
raini

[PKRWUD]

A bad header gasket will have a minimal effect on performance, at first, but will soon lead to a burned exhaust valve in the cylinder where the gasket is blown out.

The only reasons a header gasket will blow out are loose bolts or an uneven surface. If the bolts were always tight, then either your head or the header is warped slightly. Odds are it's the header.

Are you positive it's the header, and not some other part of your system, like the plugs at the back of the heads?

[PKRWUD]

Originally posted by drtbiker
its nice to see ya back pkrwud

Thank you. I've just been real busy with the Rice Haters Club website, sprint car racing, and running Peckerwoods Pit Stop. I don't make it by here very much anymore.

[drtbiker]

yeah unfortunitly it is the driverside header if i am correct it is cylinder # 5

later