HighDesertToy

Hey guys I need some help with my '90 3.0. I purchased it a year ago and it has always had a high idle and runs rough when cold. I did the usual tune up stuff (Toyota OEM cap, rotor, wires, fuel filter, Denso plugs) with no luck. I let the local Toyota indy shop look at her and they put a new intake hose, TB and intake gasket, PCV valve and did some checks like timing and EGR valve but could not fix the idle.

I have been searching lots of posts here to help me figure out the whats wrong and doing other little fixes like replacing all the vacum hoses with new, checking for proper routing, TPS setting, TB cleaning and a new t-stat. I've searched to find base setting of how many turns out the idle adujstment screw should be set at but could not find, does anyone know? Mine is now set at 1/2 turn out, does that sound correct? Also does anyone have a simular problem with on a cold morning it will start up just fine but if you hit the gas it will studder at low rpm then rev up normally. When you upshift and give it some gas it will almost want to die. If the engine dies when cold it is often hard to start again. Once it reaches operating temp it runs just fine.

When the engine is cold I can hear the cold start injector clicking. The only other weird thing I can think of is the temp gauge seems to take 10-15 min or so to show normal temp, but the heater seems to get warm in about 5 mins. Other than that most everything seems normal.

Any help will be appreciated! TIA

kimchee

high idle might mean a vacuum leak somewhere
might want to start checking around for bad gaskets and stuff

Memphis4X4

From what you are telling us, I think that your problem is that the tube that carries warm coolant to the temp sensor block that is on the back of the engine (right up against the firewall, underneath the intake plenum) is stopped up. This is why your truck is appearing to take longer to "warm" up. The sensor is not seeing warm coolant and is telling the ECU to run rich.....thus a high idle. You need to blow that tube clear. Those of us that have the 3.0l with an automatic transmission see this problem manifest itself in that we cannot get into Over Drive easily. Since you have a 5 speed, you don't have that problem but you are seeing it in engine performance. Just clear that tube (it runs from the thermostat through the guts of the motor and ends up on the backside of the motor. A U-shaped rubber tube connects the tube to the sensor block. When the thermostat opens, coolant is supposed to flow through the tube to the temp sensor. Pull off the u-shaped hose and make sure coolant flows out of the tube.....be careful because it the coolant is hot and it will spray!!!!

Hope this helps,
David

HighDesertToy

Hey David,

Thanks for the help with my truck. Thought I try to see if there was coolant with the engine cool this mornig so I would not have take a coolant shower in the driveway. I removed the hose next to the coolant temp sensor and coolant ran out. How do I make sure enough coolant is going through all the hoses? Does the engine need to be warm with the themastat open? As a side note my old mechanic mentioned some Toyotas have a problem with a switch in the bottom of the TB where coolant runs through, I checked this too and it seemed to have coolant. Every heard about that switch being a problem?

Thanks again!

Memphis4X4

I've never had that switch on the TB be a problem on mine....but there's a lot that I don't know when compared to a tech that see's these things everyday.

But back on the temp sensor tube/hose subject, just because coolant ran out of the hose doesn't mean that coolant is flowing freely through it. Coolant needs to flow freely so that the sensor is 'seeing' freshly heated fluid. Make sure that coolant is flowing....a coolant bath may be necessary. With everything assembled, let the truck warm up. Then turn it off, disconnect the rubber u-shaped hose. I know that it will be hot back there but you gotta do what you gotta do! Get in the truck and start it up. The thermostat should still be open and if the tube coming from the thermostat is not clogged, you will see coolant spray out. If it is clogged, you'll need to blow it out with comparessed air. The junk clogging it may be in the inlet, which is down in the thermostat housing.

Good luck,
David