raidinmd

hey everyone, been looking at some of the threads on here and have not been able to find a fix for my problem, I have a 1990 Toyota p/u v6 3.0 5-speed. when she's cold idles fine but warmed upped she doesn't idle as well, drops to about 500rpm whenever the brake is applied, hot or cold the rpm drops, and she'll straight up die if when coming to a stop you hit the brakes too hard. a friend and I have done lot of work to this truck, we have put on a new timing belt checked timing twice to make sure it was on TDC and the cams up back around good, replaced all the other belts, new alternator, new fuel filter, cleaned throttle body, switched dash-pot from another 92 4runner (same engine), new spark plugs, wires, cap, and rotor, new fuel regulator, new air intake hose since when i bought it it had some jerry rigged pipe on it, and new brake booster, each part has helped it run just a bit better but i'm running out of ideas (and money) on what to do the previous owner seemed to have half assed a lot of the work he did, such as only installing one valve cover gasket and one side of new spark plugs, I don't know what else h half did also the cruise control is not connected and is capped off, any help would be highly appreciated, thanks for reading

Mountain Cop

It still sounds like a vacuum leak. Check all your hoses, replace if they look cracked or hard.

raidinmd

i'm at the point where i'm just about to just replace all the lines I can,this is driving me crazy.

Mountain Cop

Wouldn't be a bad idea.

92yoterDD

Definitely a vacuum issue. Start by plugging vacuum ports one at a time until the issue is gone. Then you know what vacuum systems are affected and start from there.

raidinmd

thank you, I will try that Saturday hopefully. i drove it today since i have nothing else and it seems to be worse, after a short stretch on the highway every time I came to a stop it was barely at 150 rpms and would die unless i gave it gas. hope to fix this soon since my motorcycle is down as well.

raidinmd

okay got an update, I replaced a bunch of the vaccum lines and that didn't do anything, the PVC was utter garbage and looks someone stuffed it full of turds, a new one was installed and so was a the second valve cover gasket P/O did not install. now my friend and I discovered something new, when the brake is applied you can hear it sound like the power steering reservoir takes a dump and then this part here (circled in red) in the picture also sounds like it takes a dive, but we don't know what it is. can someone help us out and tell us what that is? my friend thinks it is a module of some sort to do with the brakes but not really sure, any help is appreciated.

Ajbedard

I am having the exact same problem with my 95 4runner. I can't figure out either.

raidinmd

i just went and looked and was tracing some of the lines off it and it looked connected to the power steering and brake system, but i can't find a part number on it, I suspect this is the actual problem, just need to figure out what it is, gonna pour over the book a little more and see what I can find, any help is appreciated. I also noticed a tube off the bottom of the charcoal canister that is not connected to anything while tracing lines just a bit ago, is that supposed to be like that?

raidinmd

may have found the issue, the power steering air control valve here is broke and there were no lines connected to it which it should, my friend who has the exact same engine has two ports on it and lines going to the intake manifold, currently trying to get the part and see what happens after replacing, from what i've read it's supposed to idle up the engine when turning the wheel at slow speeds, which at this point idles down when i turn the wheel left or right, looks like someone tried to fixed it and it broke off.

Ajbedard

Good luck. Keep us posted. I've found only one vacuum line that was leaking. Fixing it didn't seem to help. I hope that broken valve is the problem. Might point me in the right direction.

raidinmd

alright put on a used power steering air control valve and it did nothing to fix the problem, i really don't know what else I can do, gonna take it to a mech tomorrow that does toyotas and maybe he can see what the heck is wrong., the only thing i can think of is the cruise control, it was never hooked up when i got it, the p/o capped it off , this is very frustrating

scope103

Have you checked the vacuum plumbing to the brake booster? http://personal.utulsa.edu/~nathan-b.../5brakeboo.pdf

If the idle drops when you press on the brakes, it's not likely to have anything to do with the power steering, the valve cover gasket, PCV valve ... But the brake booster is powered by engine vacuum. Try disconnecting the larger vacuum line to the booster and plugging the port into the plenum. Does it make a difference?

(Don't drive around like that; having brakes is a "good thing.")

raidinmd

I replaced the brake booster and that line all the way down. the idle will drop under three conditions, if the brake is applied, when you turn the steering wheel over, and when you flip on the headlights, the last one I just discovered yesterday

raidinmd

update: I took my truck down to a 4x4 shop and the owner took a look and told me my injectors 1 and 6 are not working properly, I have takin them off and cleaned them thoroughly and he was right, 1 and 6 were pretty dang dirty, my friend and I put everything back on and fired her up, and then fuel started leaking everywhere, so now i'm gonna go get a seal kit for the injectors and slap those on to stop the leaks, hopefully this will solve the problem at hand, if not i'm looking at a valve job and 200$. will keep updated

Ajbedard

Did he explain how two dirty injectors are causing the idle drop when braking? I don't understand how one effects the other

raidinmd

what he did was, while the engine was running, was pull the plugs at the distributor cap, and each one would cause the the engine to lag, except on 1 and 6. 6 caused no drop and 1 cause just a slight drop, if these injectors are not dropping the engine when you pull them then that means it isn't working or clogged thus not providing the correct amount of power and not creating the right vacuum level since it not getting anything out of those cylinders. at least that's how I saw it and form what I could hear. my friend and I cleaned all of them but 1 and 6 were dirty, when hooked to a power source the injector would click which ment it was open but when you spray b-12 in it at first nothing would come out, after cleaning it some more and using some compressed air it cleared up and was spraying a good firm spray in the shape of a cone so now it will be getting the right amount of fuel and fire correctly, i'm going to put on the injector seal kit today that has the o-rings and boots and will update afterwards

snobdds

If this question would have been asked 5 years ago on here, you would have had five people telling you that this question gets beat to death. To search...

It's well known, or use to be, that this is related to your idle. The little idle screw on the throttle body is not adjusted correctly. It's allowing to much air through and the engine is cutting the fuel to compensate for the extra air. Just turn down your idle a bit. If it still happens, you will need to get a new o-ring to make sure no extra air gets through...

Damm shame this forum has changed so much from it's golden years...

scope103

Did you use all new crush washers on the parts of the fuel rail you unhooked to pull the injectors? They are one-time-use, and if you attempt to re-use them you are likely to get leaks.

They are aluminum, a dealer-only item, but (surprise!) cheaper than dirt.

raidinmd

if If turn down the idle its not even gonna stay going, the idle sits at 800 as per spec, if the o ring is bad i'll replace that, thanks I had not seen anyone say something about an o ring being there.

no i did not use new washers, I think mine were copper, I'll pick some up at the dealer down the street, thanks man, i'll pick up an o ring for the idle screw as well in case I need it