GreasyFingerz

Hello, this is my first thread. I have an '89 Toyota Pickup 4x4 5spd that has a rough idle. It hasn't been driven since 2006 and I now need to get it running so I can use it as a daily driver (First car! )

I starts up ok and probably idles at about 1,500 RPM when cold (no tach). About 20-30 seconds later, the idle drops and gets rough to the point where it starts Stalling. We took it around the block a few times and got it to operating temp, stalls at every stop sign. Seems to accelerate ok but sometimes the gear change is a bit rough. Also the idle gets even worse with the brakes applied.

Here's what I've changed so far:
-Fuel tank, filter, pump and injectors
-Air filter
-Spark plugs (gapped to 0.32) wires, distributor cap/rotor
-Engine temp sensor (for ECU)
-Coolant flush with new thermostat
-Throttle body and intake cleaned
-EGR cleaned ( soak in carb cleaner overnight)
-TPS ok
-No vacuum leaks that I can find
-AFM works fine
-Cleaned IACV
-Idle adjustment screw seems inaffecive
-Fuel pressure regulator
-PCV valve

Sorry for the long post but I need this truck running by summer. No check engine light btw. Thanks in advance.

bearcat2

Could be sucking air around your EGR valve, my 89 was after I pulled the head and it ran like a top driving but idled very rough, in fact wouldn't hardly idle at all warm. Get yourself some carb cleaner and spray it back around the EGR valve both where it enters the intake and where the pipe enters the valve itself, while running. If it is as bad as mine you might have to give it a bit of throttle with your right hand while spraying with your left hand. If it revs up on its own at any point, wherever you are spraying the carb cleaner is where it is sucking air. If you don't find it around the EGR I would check the rest of the intake in the same way, judiciously spraying from several angles.

Not sure what you mean by the gear change being rough, if it is just stiff to get into gear I suspect it is the fluid. Sitting that long it wouldn't hurt to change it anyways. I can't give you a recommendation on any of the newer synthetics because I've never tried them, but when I change fluid in the transmission and transfer case I do what the dealership used to do to these trucks back when they got them new (dealership by me at the time these trucks were new) and add a half pint of ATF to both tranny and transfer case and then fill them with 90w. The ATF thins the gear lube and makes them shift a lot smoother, especially cold.

GreasyFingerz

Thanks a lot bearcat2, I'll definitely have to try that. As for the shifting, I replaced the trans fluid with some Walmart 75w90 synthetic oil. It goes into gear OK just sometimes when I let off the clutch, there is a slight jerkiness as I start to accelerate again (Could be my amateur shifting skills).

Co_94_PU

iTrader: (-1)

Idle adjustment screw.

If it has no effect and the engine doesn't stall out when it's ran in all the way you've got a big leak. Try grabbing a cap for the brake booster line at the auto store, then you can eliminate or confirm it as a leaking part.

scope103

Rough idle when braking sure points to a leak in the vacuum line or the brake booster. Capping the brake booster line at the engine should tell you. (Don't try driving around like that; you'll have a lot less braking than you expect!)

GreasyFingerz

Thank you guys for taking the time to help me out. I looked again at the vacuum lines and noticed there is a small hole in the tube leading to the resonator and a small crack at the start of the hose that's located towards the front of the valve cover. Also, when I took off the vacuum line leading to the brake booster to inspect it, I heard a small hiss sound from the booster itself. Is that normal?

Co_94_PU

iTrader: (-1)

There is a one way valve in that line, it's probably/maybe leaking, it is supposed to give you power braking if the motor stalls.

GreasyFingerz

I blocked off the vacuum line running off the brake booster and it made the engine idle worse. So now I'm considering getting a set of silicone vacuum lines from LC Engineering for $30. Maybe there's a small leak that I can't find? Like I said, I starts up fine, but as the truck slowly warms up the idle will continue to get lower and rougher. Almost sounds like it has a cam or something.

Co_94_PU

iTrader: (-1)

Did you try the idle air adjustment screw while the brake assist was capped off?

GreasyFingerz

I did not. Should I try that?

RAD4Runner

If you do, please let us know if that kit replaces all the vacuum lines and has the right sizes and lengths

You should. Just mark original setting so you can revert to it.

Co_94_PU

iTrader: (-1)

Might need a new oring on the idle also.

GreasyFingerz

Thanks guys for the replies. If I get the vacuum lines, I'll let you know!

yota tay

That's a thorough check list. I had the same symptoms on my 94. Turns out the valves needed adjustment. Check the valves.

Co_94_PU

iTrader: (-1)

Not a bad idea particularly if you don't know when they were done. However your air intake system is the first step. Get the idle adjustment working first, then you can diagnose the brake booster.

It's also worth mentioning the throttle body maybe sticking due to crud in the springs, weak springs, or even just wore out (the shaft seals wear out, then the throttle plate bar eats into the throttle body housing)... But since you can bottom out the idle screw with no effect, it's leaking like a sieve which can keep the vafm from closing the circuit that runs the fuel pump.

GreasyFingerz

So I adjusted the idle screw again with the brake booster plugged but nothing changed. Throttle body is as clean as could be but still no change. Intake duct has no cracks/holes and there's no vacuum leaks that I can find. Haven't checked the valves yet though.

Could I have adjusted the TPS wrong? After I rev it, the truck will stumble and eventually stall. It's also hard to keep it running after I start it with it warmed up too.

Co_94_PU

iTrader: (-1)

Clean is a relative term..

First make sure the throttle valve plate is closing. Remove the idle adjustment screw and force air I to the hole it came out of (there should be air coming out in front of and behind the throttle plate).
If you have air flow thru both sides of the idle air passage (front and rear of the throttle plate), you still have a leak (a substantial one).

I don't recall how big that orriface is off hand but it is going to be probably bigger than two of the vacuum lines.

If you cap all of the vacuum lines behind the throttle plate and the idle adjustment isn't functioning to control idle you have a bad gasket on either the EGR, the cold start injector, the throttle body, the lower intake to upper intake, or the lower intake to head junction. (I might of actually left some out here, but it is kind of late..)

Yeah I reckon if your tps is holding the throttle plate open that would be an issue, but I don't see how you would have done that following the FSM.

GreasyFingerz

After some research I looked at my engine coolant temp sensor and as I was taking it off to swap out the original one, the "new" one broke in half. So I put in the original but didn't fix the issue. Got a new OEM Denso TPS and adjusted it to spec but it didn't help either. I looked at the adjustment sheet and it said to put it between 0.47 and 6.1k for idle, that's a wide range. I set it at 0.57, is that too low?

Truck starts up great when cold but sometimes seems to hunt for an idle speed after a few seconds between maybe 1,200 to 1,600 RPM. After about 2 minutes of idling, the idle will get rougher and lower. When I rev it the rpms seem to jump higher than they should too. Revving it also makes it idle worse as well as pushing the brakes.

Itsjaibreh

Hello I have the 88 22re with a misfire. Driving home one day came to a stop. Went into first just fine, shifted to 2nd ran fine went to 3rd it’s started to misfire bad. I babied it home which was a mile or two. Swapped out fuel filter, plugs, wires, cap and rotor button, and new injectors. Still no luck. Any help? Engine has 195k on it . Thanks in advance