Meltz

Hey guys, I'm not sure if this is the right place to ask, but I've been having some issues with my 3.4L '98 4runner (manual trans.) Every now and then when I try to start, it just cranks and cranks and never fully "catches". Also, this usually only happens when the motor's already warm, i.e. if I park somewhere, go get a cup of coffee, then come back out, I'll have trouble starting, but it never happens when I'm leaving to go to work in the morning.

Another thing worth mentioning is that it's been idling really high lately, as in 1k-1.5krpm. I pulled a check engine code the other day, and it said "Idle airflow control" (or something really similar), but that seems really generic. I cleaned out the mass-airflow sensor a couple weeks ago, but maybe it's actually bad? Does anyone have any ideas?

Thanks!

mschein1

Clean your Idle Airflow Control valve, there is a few writeups on it.

Meltz

Awesome - I will give that a shot perhaps this weekend. Thanks!

Meltz

So i did what you said - took off the whole throttle body and IAC, cleaned it spotless, and put a little wd-40 in the IAC (as one write-up said to do). I also hooked up the IAC to the battery to test it, make sure it opens and closes, and it seemed to be working. This was all a week and a half ago, however I'm still idling around 1.5-2k, and the starting issue doesn't seem to be fixed. Again, it usually starts up great when it's cool, but if i park it for 10 minutes and then try to start up again, it just cranks and cranks and dies. Sometimes it will sort of stutter on its own at a low RPM. I'm usually parked on a hill, so if this happens, I can roll it forward a bit and drop the clutch and it'll catch. Are there any more suggestions out there at what might be causing this? Thanks guys!

BigBallsMcFalls

maybe get a new TPS while you are messing with the throttle body...aftermarket ones
work great. I had a bad TPS and after messing with it, it idled high until I reset ecu, then
it actually stalled once, but it 'figured it out' and now runs minty fresh

after any changes, you must reset the ECU (disconnect battery for some minutes) so it
reprograms itself and recalibrates.

Meltz

Hmm - i'll try resetting. I actually replaced the TPS around a month ago - so I had already sort of ruled that out. However, i don't think i ever reset it.

BigBallsMcFalls

might be it. happened to me. new tps, high idle.

reset ecu, went to normal, then actually stalled...
but it was 'finding itself'... and after that 1 stall, it works great now...

DRCOFFEE

Okay so when you cleaned the IAC you probably sprayed the TB with carb cleaner. The liquid dissolves the carbon that had built up and drained down the holes in front of the butterfly valve. The cleaner evaporates quickly leaving the dry carbon on the pintle valve of the IAC lodging it open so that it stays in the cold engine mode ( ie high idle). So what to do? I had the same issue. Here's what worked for me. The engine has a fair amount of suction through the IAC and what you want to do is help it suck the carbon past the valve. Once it cleans itself, it will return to normal function. Go buy a can of MAF cleaner. It's more expensive but its less aggressive than carb cleaner and won't leave any residue. While the engine is stone cold, remove the plastic intake tube to the throttle body and push it aside. That will expose the throttle plate. Squirt 3 shots of MAF cleaner in the hole in front of the throttle plate. Then quickly start the engine. It will fire up and then stall out because the MAF is not reading any air movement. That's exactly what you want it to do. There's no harm so don't worry. Repeat this 3-4 more times. This will dissolve the carbon and then suck it past the valve. There's no reason to replace the IAC or remove it. It wants to work but can't. This will free it up to start moving again.

Then reinstall the intake tube and make sure everything is connected and try starting the engine. It should fire up and idle down as it warms.

The starting problem sounds like a fuel pump crapping out on you. here's a link that might help.

Engine cranks 3 times too long

Replacement fuel pump

JVICK

Intake leak? Is there a cold start injector helping you when it's cold? I'm going to reseal my entire engine soon head gaskets -> intake. I'll get some pics. I think cleaning is an easy/quick starting point but I'm sure more is needed then just cleaning. I know my head gasket is leaking as well as half the 4runners out there. White smoke after start up. I would like to know who makes an affordable gasket kit. OEM is best I know. FIPIG is my best friend.

Meltz

Okay, so I took it to the local mechanic and it turns out the relay for the fuel pump wasn't pushed in all the way However, it's still idling high - in fact even higher now. It'll rest at like 2-2.5k - i can start moving in first without giving it any gas at all. The mechanic said it looked like the IAC was probably bad (even though i tested it a couple weeks ago), the TPS was giving a reading "out of range" (which I replaced a few months ago), and the temperature sensor in the MAF was bad. He suggested getting a whole throttle body from a scrap yard (Im gonna head down to Jim's this weekend) and replacing that. Hopefully that'll work.

Edit: Actually, i'm gonna try what DRCOFFEE said first, and if that doesn't work, i'll head down to Jims